From 2aa4a82499d4becd2284cdb482213d541b8804dd Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 28 Apr 2024 16:29:10 +0200
Subject: Adding upstream version 86.0.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../extensions/test/browser/.eslintrc.js           |   11 +
 .../test/browser/browser-serviceworker.ini         |    9 +
 .../components/extensions/test/browser/browser.ini |   50 +
 .../browser_ext_background_serviceworker.js        |  292 +++
 ...r_ext_background_serviceworker_pref_disabled.js |  122 ++
 .../test/browser/browser_ext_downloads_filters.js  |  138 ++
 .../test/browser/browser_ext_downloads_referrer.js |   82 +
 .../test/browser/browser_ext_management_themes.js  |  149 ++
 .../test/browser/browser_ext_test_mock.js          |   45 +
 ..._ext_themes_additional_backgrounds_alignment.js |  102 +
 .../browser_ext_themes_alpha_accentcolor.js        |   34 +
 .../test/browser/browser_ext_themes_arrowpanels.js |   99 +
 .../browser_ext_themes_autocomplete_popup.js       |  170 ++
 .../browser/browser_ext_themes_chromeparity.js     |  161 ++
 .../browser_ext_themes_dynamic_getCurrent.js       |  203 ++
 .../browser_ext_themes_dynamic_onUpdated.js        |  154 ++
 .../browser/browser_ext_themes_dynamic_updates.js  |  185 ++
 .../test/browser/browser_ext_themes_experiment.js  |  401 ++++
 .../test/browser/browser_ext_themes_findbar.js     |  217 ++
 .../browser_ext_themes_getCurrent_differentExt.js  |   66 +
 .../test/browser/browser_ext_themes_highlight.js   |   61 +
 .../test/browser/browser_ext_themes_incognito.js   |   81 +
 .../test/browser/browser_ext_themes_lwtsupport.js  |   57 +
 .../browser_ext_themes_multiple_backgrounds.js     |  216 ++
 .../test/browser/browser_ext_themes_ntp_colors.js  |  157 ++
 .../browser_ext_themes_ntp_colors_perwindow.js     |  249 +++
 .../test/browser/browser_ext_themes_persistence.js |   58 +
 .../test/browser/browser_ext_themes_reset.js       |  112 +
 .../browser/browser_ext_themes_sanitization.js     |  175 ++
 .../test/browser/browser_ext_themes_separators.js  |   69 +
 .../test/browser/browser_ext_themes_sidebars.js    |  274 +++
 .../browser/browser_ext_themes_static_onUpdated.js |   66 +
 .../test/browser/browser_ext_themes_tab_line.js    |   50 +
 .../test/browser/browser_ext_themes_tab_loading.js |   51 +
 .../browser/browser_ext_themes_tab_selected.js     |   54 +
 .../browser/browser_ext_themes_tab_separators.js   |   38 +
 .../test/browser/browser_ext_themes_tab_text.js    |   70 +
 .../browser/browser_ext_themes_theme_transition.js |   48 +
 .../browser/browser_ext_themes_toolbar_fields.js   |  145 ++
 .../browser_ext_themes_toolbar_fields_focus.js     |  102 +
 .../browser_ext_themes_toolbarbutton_colors.js     |   56 +
 .../browser_ext_themes_toolbarbutton_icons.js      |  107 +
 .../test/browser/browser_ext_themes_toolbars.js    |  105 +
 .../test/browser/browser_ext_themes_warnings.js    |  143 ++
 .../browser/browser_ext_thumbnails_bg_extension.js |   94 +
 ...browser_ext_webRequest_redirect_mozextension.js |   48 +
 .../browser/browser_ext_windows_popup_title.js     |   61 +
 .../extensions/test/browser/data/test-download.txt |    1 +
 .../test/browser/data/test_downloads_referrer.html |   10 +
 toolkit/components/extensions/test/browser/head.js |  103 +
 .../extensions/test/browser/head_serviceworker.js  |  123 ++
 .../data/extension-with-bg-sw/manifest.json        |   11 +
 .../marionette/data/extension-with-bg-sw/sw.js     |    3 +
 .../extensions/test/marionette/manifest.ini        |    1 +
 ...nsion_serviceworkers_purged_on_pref_disabled.py |   82 +
 .../extensions/test/mochitest/.eslintrc.js         |   12 +
 .../extensions/test/mochitest/chrome.ini           |   37 +
 .../test/mochitest/chrome_cleanup_script.js        |   66 +
 .../extensions/test/mochitest/chrome_head.js       |    1 +
 .../test/mochitest/file_WebNavigation_page1.html   |   12 +
 .../test/mochitest/file_WebNavigation_page2.html   |    7 +
 .../test/mochitest/file_WebNavigation_page3.html   |    9 +
 .../test/mochitest/file_WebRequest_page3.html      |   10 +
 .../test/mochitest/file_contains_iframe.html       |   12 +
 .../test/mochitest/file_contains_img.html          |   11 +
 .../mochitest/file_contentscript_activeTab.html    |   11 +
 .../mochitest/file_contentscript_activeTab2.html   |   10 +
 .../test/mochitest/file_contentscript_iframe.html  |   10 +
 .../extensions/test/mochitest/file_green.html      |    3 +
 .../extensions/test/mochitest/file_image_bad.png   |  Bin 0 -> 5401 bytes
 .../extensions/test/mochitest/file_image_good.png  |  Bin 0 -> 580 bytes
 .../extensions/test/mochitest/file_image_great.png |  Bin 0 -> 580 bytes
 .../test/mochitest/file_image_redirect.png         |  Bin 0 -> 5401 bytes
 .../extensions/test/mochitest/file_indexedDB.html  |   28 +
 .../extensions/test/mochitest/file_mixed.html      |   13 +
 .../test/mochitest/file_redirect_cors_bypass.html  |   30 +
 .../test/mochitest/file_redirect_data_uri.html     |    9 +
 .../test/mochitest/file_remote_frame.html          |   20 +
 .../extensions/test/mochitest/file_sample.html     |   12 +
 .../extensions/test/mochitest/file_sample.txt      |    1 +
 .../test/mochitest/file_sample.txt^headers^        |    1 +
 .../extensions/test/mochitest/file_script_bad.js   |    3 +
 .../extensions/test/mochitest/file_script_good.js  |   12 +
 .../test/mochitest/file_script_redirect.js         |    3 +
 .../extensions/test/mochitest/file_script_xhr.js   |    9 +
 .../test/mochitest/file_serviceWorker.html         |   16 +
 .../mochitest/file_simple_sandboxed_frame.html     |   23 +
 .../mochitest/file_simple_sandboxed_subframe.html  |   10 +
 .../extensions/test/mochitest/file_simple_xhr.html |   19 +
 .../test/mochitest/file_simple_xhr_frame.html      |   19 +
 .../test/mochitest/file_simple_xhr_frame2.html     |   23 +
 .../test/mochitest/file_streamfilter.txt           |    1 +
 .../extensions/test/mochitest/file_style_bad.css   |    3 +
 .../extensions/test/mochitest/file_style_good.css  |    3 +
 .../test/mochitest/file_style_redirect.css         |    3 +
 .../test/mochitest/file_tabs_permission_page1.html |   10 +
 .../test/mochitest/file_tabs_permission_page2.html |   11 +
 .../test/mochitest/file_third_party.html           |   21 +
 .../test/mochitest/file_to_drawWindow.html         |    9 +
 .../file_webNavigation_clientRedirect.html         |    9 +
 ...e_webNavigation_clientRedirect_httpHeaders.html |    8 +
 ...gation_clientRedirect_httpHeaders.html^headers^ |    1 +
 .../file_webNavigation_frameClientRedirect.html    |   12 +
 .../file_webNavigation_frameRedirect.html          |   12 +
 .../file_webNavigation_manualSubframe.html         |   12 +
 .../file_webNavigation_manualSubframe_page1.html   |    8 +
 .../file_webNavigation_manualSubframe_page2.html   |    7 +
 .../test/mochitest/file_with_about_blank.html      |   10 +
 .../test/mochitest/file_with_images.html           |   10 +
 .../test/mochitest/file_with_xorigin_frame.html    |    6 +
 .../components/extensions/test/mochitest/head.js   |  123 ++
 .../extensions/test/mochitest/head_cookies.js      |  287 +++
 .../test/mochitest/head_notifications.js           |  169 ++
 .../test/mochitest/head_unlimitedStorage.js        |   50 +
 .../extensions/test/mochitest/head_webrequest.js   |  482 ++++
 .../components/extensions/test/mochitest/hsts.sjs  |    8 +
 .../extensions/test/mochitest/mochitest-common.ini |  206 ++
 .../extensions/test/mochitest/mochitest-remote.ini |    8 +
 .../extensions/test/mochitest/mochitest.ini        |   12 +
 .../extensions/test/mochitest/mochitest_console.js |   53 +
 .../extensions/test/mochitest/oauth.html           |   26 +
 .../extensions/test/mochitest/redirect_auto.sjs    |   21 +
 .../extensions/test/mochitest/redirection.sjs      |    4 +
 .../extensions/test/mochitest/return_headers.sjs   |   20 +
 .../extensions/test/mochitest/serviceWorker.js     |    0
 .../extensions/test/mochitest/slow_response.sjs    |   55 +
 .../test_chrome_ext_contentscript_data_uri.html    |  104 +
 .../test_chrome_ext_contentscript_telemetry.html   |   64 +
 ...ext_contentscript_unrecognizedprop_warning.html |   80 +
 .../mochitest/test_chrome_ext_downloads_open.html  |  114 +
 .../test_chrome_ext_downloads_saveAs.html          |  257 +++
 .../test_chrome_ext_downloads_uniquify.html        |  116 +
 .../mochitest/test_chrome_ext_permissions.html     |  176 ++
 .../test_chrome_ext_trackingprotection.html        |   98 +
 ...est_chrome_ext_webnavigation_resolved_urls.html |   81 +
 ...st_chrome_ext_webrequest_background_events.html |   94 +
 ...est_chrome_ext_webrequest_host_permissions.html |   89 +
 .../test_chrome_ext_webrequest_mozextension.html   |  193 ++
 .../test_chrome_native_messaging_paths.html        |   56 +
 .../test/mochitest/test_ext_activityLog.html       |  390 ++++
 .../extensions/test/mochitest/test_ext_all_apis.js |  181 ++
 .../test/mochitest/test_ext_async_clipboard.html   |  376 ++++
 .../test/mochitest/test_ext_background_canvas.html |   50 +
 .../test/mochitest/test_ext_background_page.html   |   84 +
 .../mochitest/test_ext_browsingData_indexedDB.html |  161 ++
 .../test_ext_browsingData_localStorage.html        |  322 +++
 .../test_ext_browsingData_pluginData.html          |   71 +
 .../test_ext_browsingData_serviceWorkers.html      |  141 ++
 .../mochitest/test_ext_browsingData_settings.html  |   67 +
 .../test_ext_canvas_resistFingerprinting.html      |   64 +
 .../test/mochitest/test_ext_clipboard.html         |  210 ++
 .../test/mochitest/test_ext_clipboard_image.html   |  262 +++
 .../test_ext_contentscript_about_blank.html        |  116 +
 .../test_ext_contentscript_activeTab.html          |  371 ++++
 .../mochitest/test_ext_contentscript_cache.html    |  113 +
 .../mochitest/test_ext_contentscript_canvas.html   |  138 ++
 .../test_ext_contentscript_devtools_metadata.html  |   77 +
 .../test_ext_contentscript_fission_frame.html      |  100 +
 .../test_ext_contentscript_incognito.html          |  105 +
 .../test_ext_contentscript_permission.html         |   61 +
 .../test/mochitest/test_ext_cookies.html           |  366 ++++
 .../mochitest/test_ext_cookies_containers.html     |   97 +
 .../test/mochitest/test_ext_cookies_expiry.html    |   72 +
 .../mochitest/test_ext_cookies_first_party.html    |  316 +++
 .../test/mochitest/test_ext_cookies_incognito.html |  112 +
 .../test_ext_cookies_permissions_bad.html          |  115 +
 .../test_ext_cookies_permissions_good.html         |   89 +
 .../mochitest/test_ext_downloads_download.html     |   90 +
 ...test_ext_embeddedimg_iframe_frameAncestors.html |   94 +
 .../mochitest/test_ext_exclude_include_globs.html  |   91 +
 .../mochitest/test_ext_external_messaging.html     |  110 +
 .../test/mochitest/test_ext_generate.html          |   48 +
 .../test/mochitest/test_ext_geolocation.html       |   86 +
 .../test/mochitest/test_ext_identity.html          |  390 ++++
 .../extensions/test/mochitest/test_ext_idle.html   |   68 +
 .../test_ext_inIncognitoContext_window.html        |   49 +
 .../test/mochitest/test_ext_listener_proxies.html  |   62 +
 .../mochitest/test_ext_new_tab_processType.html    |  152 ++
 .../test/mochitest/test_ext_notifications.html     |  340 +++
 .../test/mochitest/test_ext_protocolHandlers.html  |  394 ++++
 .../test/mochitest/test_ext_redirect_jar.html      |   92 +
 .../test_ext_request_urlClassification.html        |  129 ++
 .../test/mochitest/test_ext_runtime_connect.html   |   82 +
 .../test/mochitest/test_ext_runtime_connect2.html  |  102 +
 .../mochitest/test_ext_runtime_connect_twoway.html |  126 ++
 .../mochitest/test_ext_runtime_disconnect.html     |   77 +
 .../test_ext_sendmessage_doublereply.html          |  100 +
 .../mochitest/test_ext_sendmessage_frameId.html    |   49 +
 .../test_ext_sendmessage_no_receiver.html          |   82 +
 .../test/mochitest/test_ext_sendmessage_reply.html |   78 +
 .../mochitest/test_ext_sendmessage_reply2.html     |  204 ++
 .../test/mochitest/test_ext_storage_cleanup.html   |  235 ++
 .../test_ext_storage_manager_capabilities.html     |  126 ++
 .../mochitest/test_ext_storage_smoke_test.html     |  110 +
 .../mochitest/test_ext_streamfilter_multiple.html  |   91 +
 .../test_ext_streamfilter_processswitch.html       |   73 +
 .../mochitest/test_ext_subframes_privileges.html   |  340 +++
 .../test/mochitest/test_ext_tabs_captureTab.html   |  301 +++
 .../test/mochitest/test_ext_tabs_permissions.html  |  780 +++++++
 .../test/mochitest/test_ext_tabs_query_popup.html  |   95 +
 .../test/mochitest/test_ext_tabs_sendMessage.html  |   95 +
 .../extensions/test/mochitest/test_ext_test.html   |  196 ++
 .../test/mochitest/test_ext_unlimitedStorage.html  |  139 ++
 ...limitedStorage_legacy_persistent_indexedDB.html |   81 +
 .../test_ext_web_accessible_incognito.html         |  174 ++
 .../test_ext_web_accessible_resources.html         |  265 +++
 .../test/mochitest/test_ext_webnavigation.html     |  611 ++++++
 .../mochitest/test_ext_webnavigation_filters.html  |  299 +++
 .../test_ext_webnavigation_incognito.html          |  109 +
 .../test_ext_webrequest_and_proxy_filter.html      |  134 ++
 .../test/mochitest/test_ext_webrequest_auth.html   |  182 ++
 .../test_ext_webrequest_background_events.html     |  120 +
 .../test/mochitest/test_ext_webrequest_basic.html  |  446 ++++
 .../test/mochitest/test_ext_webrequest_errors.html |   61 +
 .../test/mochitest/test_ext_webrequest_filter.html |  227 ++
 .../mochitest/test_ext_webrequest_frameId.html     |  214 ++
 .../test/mochitest/test_ext_webrequest_hsts.html   |  223 ++
 .../test_ext_webrequest_redirect_bypass_cors.html  |   70 +
 .../test_ext_webrequest_redirect_data_uri.html     |   83 +
 .../mochitest/test_ext_webrequest_upgrade.html     |   89 +
 .../test/mochitest/test_ext_webrequest_upload.html |  212 ++
 .../mochitest/test_ext_window_postMessage.html     |  104 +
 .../mochitest/test_verify_non_remote_mode.html     |   31 +
 .../test/mochitest/test_verify_remote_mode.html    |   22 +
 .../test/mochitest/webrequest_chromeworker.js      |    9 +
 .../extensions/test/mochitest/webrequest_test.jsm  |   22 +
 .../extensions/test/mochitest/webrequest_worker.js |    3 +
 .../extensions/test/xpcshell/.eslintrc.js          |    9 +
 .../extensions/test/xpcshell/data/dummy_page.html  |    7 +
 .../test/xpcshell/data/empty_file_download.txt     |    0
 .../test/xpcshell/data/file   download.txt         |    1 +
 .../test/xpcshell/data/file_WebRequest_page2.html  |   25 +
 .../data/file_WebRequest_permission_original.html  |   19 +
 .../data/file_WebRequest_permission_original.js    |    2 +
 .../file_WebRequest_permission_redirected.html     |   19 +
 .../data/file_WebRequest_permission_redirected.js  |    2 +
 .../extensions/test/xpcshell/data/file_csp.html    |   14 +
 .../test/xpcshell/data/file_csp.html^headers^      |    1 +
 .../data/file_do_load_script_subresource.html      |    9 +
 .../test/xpcshell/data/file_document_open.html     |   21 +
 .../test/xpcshell/data/file_document_write.html    |   35 +
 .../test/xpcshell/data/file_download.html          |   12 +
 .../test/xpcshell/data/file_download.txt           |    1 +
 .../extensions/test/xpcshell/data/file_iframe.html |    9 +
 .../test/xpcshell/data/file_image_bad.png          |  Bin 0 -> 5401 bytes
 .../test/xpcshell/data/file_image_good.png         |  Bin 0 -> 580 bytes
 .../test/xpcshell/data/file_image_redirect.png     |  Bin 0 -> 5401 bytes
 .../test/xpcshell/data/file_page_xhr.html          |   34 +
 .../test/xpcshell/data/file_permission_xhr.html    |   61 +
 .../xpcshell/data/file_privilege_escalation.html   |   13 +
 .../extensions/test/xpcshell/data/file_sample.html |   12 +
 .../data/file_sample_registered_styles.html        |   13 +
 .../extensions/test/xpcshell/data/file_script.html |   14 +
 .../test/xpcshell/data/file_script_bad.js          |   12 +
 .../test/xpcshell/data/file_script_good.js         |   12 +
 .../test/xpcshell/data/file_script_redirect.js     |    3 +
 .../test/xpcshell/data/file_script_xhr.js          |    9 +
 .../test/xpcshell/data/file_shadowdom.html         |   13 +
 .../test/xpcshell/data/file_style_bad.css          |    3 +
 .../test/xpcshell/data/file_style_good.css         |    3 +
 .../test/xpcshell/data/file_style_redirect.css     |    3 +
 .../test/xpcshell/data/file_stylesheet_cache.css   |    1 +
 .../test/xpcshell/data/file_stylesheet_cache.html  |    3 +
 .../xpcshell/data/file_stylesheet_cache_2.html     |   19 +
 .../test/xpcshell/data/file_toplevel.html          |   12 +
 .../xpcshell/data/file_with_xorigin_frame.html     |   10 +
 .../extensions/test/xpcshell/data/lorem.html.gz    |  Bin 0 -> 392 bytes
 .../extensions/test/xpcshell/data/pixel_green.gif  |  Bin 0 -> 35 bytes
 .../extensions/test/xpcshell/data/pixel_red.gif    |  Bin 0 -> 35 bytes
 .../components/extensions/test/xpcshell/head.js    |  277 +++
 .../extensions/test/xpcshell/head_e10s.js          |    8 +
 .../extensions/test/xpcshell/head_legacy_ep.js     |   13 +
 .../test/xpcshell/head_native_messaging.js         |  153 ++
 .../extensions/test/xpcshell/head_remote.js        |    7 +
 .../extensions/test/xpcshell/head_storage.js       | 1227 +++++++++++
 .../extensions/test/xpcshell/head_sync.js          |   65 +
 .../extensions/test/xpcshell/head_telemetry.js     |  110 +
 .../extensions/test/xpcshell/native_messaging.ini  |   15 +
 .../test_ExtensionStorageSync_migration_kinto.js   |   86 +
 .../extensions/test/xpcshell/test_MatchPattern.js  |  552 +++++
 .../test/xpcshell/test_StorageSyncService.js       |  286 +++
 .../xpcshell/test_WebExtensionContentScript.js     |  209 ++
 .../test/xpcshell/test_WebExtensionPolicy.js       |  376 ++++
 .../test/xpcshell/test_change_remote_mode.js       |   20 +
 .../test/xpcshell/test_csp_custom_policies.js      |  278 +++
 .../extensions/test/xpcshell/test_csp_validator.js |  298 +++
 .../test/xpcshell/test_ext_MessageManagerProxy.js  |   80 +
 .../test/xpcshell/test_ext_activityLog.js          |   21 +
 .../test_ext_adoption_with_private_field_xrays.js  |  160 ++
 .../test/xpcshell/test_ext_adoption_with_xrays.js  |  129 ++
 .../extensions/test/xpcshell/test_ext_alarms.js    |  219 ++
 .../test/xpcshell/test_ext_alarms_does_not_fire.js |   34 +
 .../test/xpcshell/test_ext_alarms_periodic.js      |   50 +
 .../test/xpcshell/test_ext_alarms_replaces.js      |   56 +
 .../test/xpcshell/test_ext_api_permissions.js      |   76 +
 .../xpcshell/test_ext_background_api_injection.js  |   35 +
 .../xpcshell/test_ext_background_early_shutdown.js |  195 ++
 .../test_ext_background_generated_load_events.js   |   23 +
 .../test_ext_background_generated_reload.js        |   24 +
 .../xpcshell/test_ext_background_global_history.js |   24 +
 .../test_ext_background_private_browsing.js        |   46 +
 .../test_ext_background_runtime_connect_params.js  |   88 +
 .../xpcshell/test_ext_background_sub_windows.js    |   46 +
 .../test/xpcshell/test_ext_background_teardown.js  |   99 +
 .../test/xpcshell/test_ext_background_telemetry.js |  104 +
 .../test_ext_background_window_properties.js       |   41 +
 .../test/xpcshell/test_ext_brokenlinks.js          |   54 +
 .../test/xpcshell/test_ext_browserSettings.js      |  454 ++++
 .../xpcshell/test_ext_browserSettings_homepage.js  |   36 +
 .../test/xpcshell/test_ext_browsingData.js         |   48 +
 .../test_ext_browsingData_cookies_cache.js         |  456 ++++
 .../test_ext_browsingData_cookies_cookieStoreId.js |  192 ++
 .../test/xpcshell/test_ext_captivePortal.js        |  109 +
 .../test/xpcshell/test_ext_captivePortal_url.js    |   53 +
 .../xpcshell/test_ext_contentScripts_register.js   |  591 +++++
 .../xpcshell/test_ext_content_security_policy.js   |  251 +++
 .../test/xpcshell/test_ext_contentscript.js        |  266 +++
 .../test_ext_contentscript_about_blank_start.js    |   78 +
 .../test_ext_contentscript_api_injection.js        |   65 +
 .../test_ext_contentscript_async_loading.js        |   79 +
 .../test_ext_contentscript_canvas_tainting.js      |  128 ++
 .../xpcshell/test_ext_contentscript_context.js     |  348 +++
 .../test_ext_contentscript_context_isolation.js    |  160 ++
 .../test_ext_contentscript_create_iframe.js        |  177 ++
 .../test/xpcshell/test_ext_contentscript_csp.js    |  355 +++
 .../test/xpcshell/test_ext_contentscript_css.js    |   48 +
 .../test_ext_contentscript_exporthelpers.js        |   98 +
 .../test_ext_contentscript_in_background.js        |   61 +
 .../test_ext_contentscript_perf_observers.js       |   71 +
 .../test_ext_contentscript_restrictSchemes.js      |   70 +
 .../test_ext_contentscript_scriptCreated.js        |   61 +
 .../xpcshell/test_ext_contentscript_teardown.js    |  102 +
 .../test_ext_contentscript_triggeringPrincipal.js  | 1373 ++++++++++++
 ...ntscript_unregister_during_loadContentScript.js |   91 +
 .../test_ext_contentscript_xml_prettyprint.js      |   75 +
 .../test_ext_contentscript_xorigin_frame.js        |   85 +
 .../test/xpcshell/test_ext_contentscript_xrays.js  |   59 +
 .../extensions/test/xpcshell/test_ext_contexts.js  |  198 ++
 .../test/xpcshell/test_ext_contexts_gc.js          |  273 +++
 .../xpcshell/test_ext_contextual_identities.js     |  513 +++++
 .../test/xpcshell/test_ext_cookieBehaviors.js      |  675 ++++++
 .../test/xpcshell/test_ext_cookies_firstParty.js   |  334 +++
 .../test/xpcshell/test_ext_cookies_samesite.js     |  109 +
 .../test/xpcshell/test_ext_debugging_utils.js      |  316 +++
 .../extensions/test/xpcshell/test_ext_dns.js       |  176 ++
 .../extensions/test/xpcshell/test_ext_downloads.js |   38 +
 .../test/xpcshell/test_ext_downloads_cookies.js    |  216 ++
 .../test/xpcshell/test_ext_downloads_download.js   |  680 ++++++
 .../test/xpcshell/test_ext_downloads_misc.js       | 1069 +++++++++
 .../test/xpcshell/test_ext_downloads_private.js    |  308 +++
 .../test/xpcshell/test_ext_downloads_search.js     |  682 ++++++
 .../test/xpcshell/test_ext_downloads_urlencoded.js |  235 ++
 .../test/xpcshell/test_ext_error_location.js       |   48 +
 .../test/xpcshell/test_ext_eventpage_warning.js    |   90 +
 .../test/xpcshell/test_ext_experiments.js          |  358 +++
 .../extensions/test/xpcshell/test_ext_extension.js |   80 +
 .../test_ext_extensionPreferencesManager.js        |  887 ++++++++
 .../xpcshell/test_ext_extensionSettingsStore.js    | 1089 ++++++++++
 .../test_ext_extension_content_telemetry.js        |  151 ++
 .../xpcshell/test_ext_extension_startup_failure.js |   46 +
 .../test_ext_extension_startup_telemetry.js        |   93 +
 .../test/xpcshell/test_ext_file_access.js          |  193 ++
 .../xpcshell/test_ext_geckoProfiler_control.js     |  208 ++
 .../test/xpcshell/test_ext_geckoProfiler_schema.js |   56 +
 .../extensions/test/xpcshell/test_ext_geturl.js    |   61 +
 .../extensions/test/xpcshell/test_ext_i18n.js      |  574 +++++
 .../extensions/test/xpcshell/test_ext_i18n_css.js  |  197 ++
 .../extensions/test/xpcshell/test_ext_idle.js      |  270 +++
 .../extensions/test/xpcshell/test_ext_incognito.js |  302 +++
 .../test/xpcshell/test_ext_indexedDB_principal.js  |  101 +
 .../extensions/test/xpcshell/test_ext_ipcBlob.js   |  150 ++
 .../test/xpcshell/test_ext_json_parser.js          |   39 +
 .../extensions/test/xpcshell/test_ext_l10n.js      |  150 ++
 .../test/xpcshell/test_ext_localStorage.js         |   50 +
 .../test/xpcshell/test_ext_management.js           |  205 ++
 .../xpcshell/test_ext_management_uninstall_self.js |  146 ++
 .../extensions/test/xpcshell/test_ext_manifest.js  |   95 +
 .../test_ext_manifest_content_security_policy.js   |   82 +
 .../test/xpcshell/test_ext_manifest_incognito.js   |   48 +
 .../test_ext_manifest_minimum_chrome_version.js    |   12 +
 .../test_ext_manifest_minimum_opera_version.js     |   12 +
 .../test/xpcshell/test_ext_manifest_themes.js      |   35 +
 .../test/xpcshell/test_ext_messaging_startup.js    |  270 +++
 .../test/xpcshell/test_ext_native_messaging.js     |  685 ++++++
 .../xpcshell/test_ext_native_messaging_perf.js     |  130 ++
 .../test_ext_native_messaging_unresponsive.js      |   85 +
 .../test/xpcshell/test_ext_networkStatus.js        |  190 ++
 .../xpcshell/test_ext_notifications_incognito.js   |  108 +
 .../xpcshell/test_ext_notifications_unsupported.js |   41 +
 .../xpcshell/test_ext_onmessage_removelistener.js  |   30 +
 .../test/xpcshell/test_ext_performance_counters.js |   86 +
 .../test/xpcshell/test_ext_permission_warnings.js  |  654 ++++++
 .../test/xpcshell/test_ext_permission_xhr.js       |  235 ++
 .../test/xpcshell/test_ext_permissions.js          |  845 ++++++++
 .../test/xpcshell/test_ext_permissions_api.js      |  397 ++++
 .../test/xpcshell/test_ext_permissions_migrate.js  |  252 +++
 .../xpcshell/test_ext_permissions_uninstall.js     |  160 ++
 .../test/xpcshell/test_ext_persistent_events.js    |  521 +++++
 .../extensions/test/xpcshell/test_ext_privacy.js   |  964 ++++++++
 .../test/xpcshell/test_ext_privacy_disable.js      |  201 ++
 .../test/xpcshell/test_ext_privacy_update.js       |  167 ++
 .../test_ext_proxy_authorization_via_proxyinfo.js  |  116 +
 .../test/xpcshell/test_ext_proxy_config.js         |  633 ++++++
 .../test/xpcshell/test_ext_proxy_onauthrequired.js |  302 +++
 .../test/xpcshell/test_ext_proxy_settings.js       |  107 +
 .../test/xpcshell/test_ext_proxy_socks.js          |  557 +++++
 .../test/xpcshell/test_ext_proxy_speculative.js    |   52 +
 .../test/xpcshell/test_ext_proxy_startup.js        |  158 ++
 .../extensions/test/xpcshell/test_ext_redirects.js |  567 +++++
 .../test_ext_runtime_connect_no_receiver.js        |   26 +
 .../xpcshell/test_ext_runtime_getBrowserInfo.js    |   26 +
 .../xpcshell/test_ext_runtime_getPlatformInfo.js   |   36 +
 .../test/xpcshell/test_ext_runtime_id.js           |   46 +
 .../xpcshell/test_ext_runtime_messaging_self.js    |   84 +
 .../test_ext_runtime_onInstalled_and_onStartup.js  |  401 ++++
 .../test/xpcshell/test_ext_runtime_ports.js        |   69 +
 .../test/xpcshell/test_ext_runtime_ports_gc.js     |  168 ++
 .../test/xpcshell/test_ext_runtime_sendMessage.js  |  452 ++++
 .../xpcshell/test_ext_runtime_sendMessage_args.js  |  101 +
 .../test_ext_runtime_sendMessage_errors.js         |   66 +
 .../test_ext_runtime_sendMessage_multiple.js       |   67 +
 .../test_ext_runtime_sendMessage_no_receiver.js    |   93 +
 .../test/xpcshell/test_ext_same_site_cookies.js    |  131 ++
 .../test/xpcshell/test_ext_same_site_redirects.js  |  233 ++
 .../test/xpcshell/test_ext_sandbox_var.js          |   42 +
 .../extensions/test/xpcshell/test_ext_schema.js    |   79 +
 .../extensions/test/xpcshell/test_ext_schemas.js   | 2097 ++++++++++++++++++
 .../xpcshell/test_ext_schemas_allowed_contexts.js  |  157 ++
 .../test/xpcshell/test_ext_schemas_async.js        |  352 +++
 .../test/xpcshell/test_ext_schemas_interactive.js  |  174 ++
 .../test_ext_schemas_manifest_permissions.js       |  174 ++
 .../test/xpcshell/test_ext_schemas_privileged.js   |  103 +
 .../test/xpcshell/test_ext_schemas_revoke.js       |  507 +++++
 .../test/xpcshell/test_ext_schemas_roots.js        |  242 +++
 .../extensions/test/xpcshell/test_ext_shadowdom.js |   59 +
 .../test/xpcshell/test_ext_shared_workers.js       |   40 +
 .../test/xpcshell/test_ext_shutdown_cleanup.js     |   42 +
 .../extensions/test/xpcshell/test_ext_simple.js    |  111 +
 .../test/xpcshell/test_ext_startupData.js          |   55 +
 .../test/xpcshell/test_ext_startup_cache.js        |  172 ++
 .../test/xpcshell/test_ext_startup_perf.js         |   73 +
 .../xpcshell/test_ext_startup_request_handler.js   |   64 +
 .../xpcshell/test_ext_storage_content_local.js     |   39 +
 .../test/xpcshell/test_ext_storage_content_sync.js |   31 +
 .../test_ext_storage_content_sync_kinto.js         |   31 +
 .../test_ext_storage_idb_data_migration.js         |  787 +++++++
 .../test/xpcshell/test_ext_storage_local.js        |   73 +
 .../test/xpcshell/test_ext_storage_managed.js      |  170 ++
 .../xpcshell/test_ext_storage_managed_policy.js    |   55 +
 .../test_ext_storage_quota_exceeded_errors.js      |   82 +
 .../test/xpcshell/test_ext_storage_sanitizer.js    |  106 +
 .../test/xpcshell/test_ext_storage_sync.js         |   29 +
 .../test/xpcshell/test_ext_storage_sync_kinto.js   | 2290 ++++++++++++++++++++
 .../xpcshell/test_ext_storage_sync_kinto_crypto.js |  122 ++
 .../test/xpcshell/test_ext_storage_tab.js          |  245 +++
 .../test/xpcshell/test_ext_storage_telemetry.js    |  369 ++++
 .../test/xpcshell/test_ext_tab_teardown.js         |   98 +
 .../extensions/test/xpcshell/test_ext_telemetry.js |  870 ++++++++
 .../extensions/test/xpcshell/test_ext_test_mock.js |   55 +
 .../test/xpcshell/test_ext_test_wrapper.js         |   64 +
 .../test/xpcshell/test_ext_trustworthy_origin.js   |   20 +
 .../test/xpcshell/test_ext_unknown_permissions.js  |   63 +
 .../test/xpcshell/test_ext_unlimitedStorage.js     |  213 ++
 .../test/xpcshell/test_ext_unload_frame.js         |  230 ++
 .../test/xpcshell/test_ext_userScripts.js          |  671 ++++++
 .../test/xpcshell/test_ext_userScripts_exports.js  | 1108 ++++++++++
 .../xpcshell/test_ext_userScripts_telemetry.js     |  175 ++
 .../test/xpcshell/test_ext_webRequest_auth.js      |  425 ++++
 .../test/xpcshell/test_ext_webRequest_cached.js    |  311 +++
 .../test_ext_webRequest_cancelWithReason.js        |   69 +
 .../test/xpcshell/test_ext_webRequest_download.js  |   43 +
 .../test_ext_webRequest_filterResponseData.js      |  523 +++++
 .../xpcshell/test_ext_webRequest_filterTypes.js    |   85 +
 .../xpcshell/test_ext_webRequest_filter_urls.js    |   35 +
 .../test_ext_webRequest_from_extension_page.js     |   57 +
 .../test/xpcshell/test_ext_webRequest_host.js      |   99 +
 .../test/xpcshell/test_ext_webRequest_incognito.js |   81 +
 .../test/xpcshell/test_ext_webRequest_mergecsp.js  |  214 ++
 .../xpcshell/test_ext_webRequest_permission.js     |  154 ++
 .../test_ext_webRequest_redirect_StreamFilter.js   |  129 ++
 .../test_ext_webRequest_redirect_mozextension.js   |   47 +
 .../xpcshell/test_ext_webRequest_requestSize.js    |   57 +
 .../xpcshell/test_ext_webRequest_responseBody.js   |  765 +++++++
 .../xpcshell/test_ext_webRequest_set_cookie.js     |  308 +++
 .../test/xpcshell/test_ext_webRequest_startup.js   |  603 ++++++
 .../test_ext_webRequest_startup_StreamFilter.js    |   84 +
 .../xpcshell/test_ext_webRequest_style_cache.js    |   49 +
 .../test/xpcshell/test_ext_webRequest_suspend.js   |  294 +++
 .../test_ext_webRequest_urlclassification.js       |   33 +
 .../xpcshell/test_ext_webRequest_userContextId.js  |   41 +
 .../xpcshell/test_ext_webRequest_viewsource.js     |   95 +
 .../test_ext_webRequest_viewsource_StreamFilter.js |  144 ++
 .../test/xpcshell/test_ext_webRequest_webSocket.js |   55 +
 .../xpcshell/test_ext_web_accessible_resources.js  |  150 ++
 .../test/xpcshell/test_ext_xhr_capabilities.js     |   72 +
 .../test_extension_permissions_migration.js        |   99 +
 .../test/xpcshell/test_load_all_api_modules.js     |  172 ++
 .../test/xpcshell/test_locale_converter.js         |  146 ++
 .../extensions/test/xpcshell/test_locale_data.js   |  221 ++
 .../test/xpcshell/test_native_manifests.js         |  443 ++++
 .../test/xpcshell/test_proxy_incognito.js          |  103 +
 .../test/xpcshell/test_proxy_info_results.js       |  469 ++++
 .../test/xpcshell/test_proxy_listener.js           |  318 +++
 .../test/xpcshell/test_proxy_userContextId.js      |   43 +
 .../test/xpcshell/test_webRequest_ancestors.js     |   79 +
 .../test/xpcshell/test_webRequest_cookies.js       |  102 +
 .../test/xpcshell/test_webRequest_filtering.js     |  182 ++
 .../test/xpcshell/xpcshell-common-e10s.ini         |   13 +
 .../extensions/test/xpcshell/xpcshell-common.ini   |  260 +++
 .../extensions/test/xpcshell/xpcshell-content.ini  |   22 +
 .../extensions/test/xpcshell/xpcshell-e10s.ini     |   28 +
 .../test/xpcshell/xpcshell-legacy-ep.ini           |   23 +
 .../extensions/test/xpcshell/xpcshell-remote.ini   |   30 +
 .../extensions/test/xpcshell/xpcshell.ini          |   89 +
 514 files changed, 78154 insertions(+)
 create mode 100644 toolkit/components/extensions/test/browser/.eslintrc.js
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 create mode 100644 toolkit/components/extensions/test/browser/browser_ext_themes_getCurrent_differentExt.js
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 create mode 100644 toolkit/components/extensions/test/browser/browser_ext_themes_reset.js
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 create mode 100644 toolkit/components/extensions/test/browser/browser_ext_themes_toolbar_fields.js
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 create mode 100644 toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_colors.js
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 create mode 100644 toolkit/components/extensions/test/browser/browser_ext_thumbnails_bg_extension.js
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 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_connect_no_receiver.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_getBrowserInfo.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_getPlatformInfo.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_id.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_messaging_self.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_onInstalled_and_onStartup.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports_gc.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_args.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_errors.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_multiple.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_no_receiver.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_same_site_cookies.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_same_site_redirects.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_sandbox_var.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schema.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas_allowed_contexts.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas_async.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas_interactive.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas_manifest_permissions.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas_privileged.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas_revoke.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_schemas_roots.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_shadowdom.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_shared_workers.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_shutdown_cleanup.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_simple.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_startupData.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_startup_cache.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_startup_request_handler.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_content_local.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync_kinto.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_idb_data_migration.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_local.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_managed.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_managed_policy.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_quota_exceeded_errors.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_sanitizer.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_sync.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto_crypto.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_tab.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_tab_teardown.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_telemetry.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_test_mock.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_test_wrapper.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_trustworthy_origin.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_unknown_permissions.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_unlimitedStorage.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_unload_frame.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_userScripts.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_userScripts_exports.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_userScripts_telemetry.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_auth.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cached.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cancelWithReason.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_download.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterResponseData.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterTypes.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filter_urls.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_from_extension_page.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_host.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_incognito.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_mergecsp.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_permission.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_StreamFilter.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_mozextension.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_requestSize.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_responseBody.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_set_cookie.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup_StreamFilter.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_style_cache.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_suspend.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_urlclassification.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_userContextId.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource_StreamFilter.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_webRequest_webSocket.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_web_accessible_resources.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_ext_xhr_capabilities.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_extension_permissions_migration.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_load_all_api_modules.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_locale_converter.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_locale_data.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_native_manifests.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_proxy_incognito.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_proxy_info_results.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_proxy_listener.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_proxy_userContextId.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_webRequest_ancestors.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_webRequest_cookies.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/test_webRequest_filtering.js
 create mode 100644 toolkit/components/extensions/test/xpcshell/xpcshell-common-e10s.ini
 create mode 100644 toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
 create mode 100644 toolkit/components/extensions/test/xpcshell/xpcshell-content.ini
 create mode 100644 toolkit/components/extensions/test/xpcshell/xpcshell-e10s.ini
 create mode 100644 toolkit/components/extensions/test/xpcshell/xpcshell-legacy-ep.ini
 create mode 100644 toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini
 create mode 100644 toolkit/components/extensions/test/xpcshell/xpcshell.ini

(limited to 'toolkit/components/extensions/test')

diff --git a/toolkit/components/extensions/test/browser/.eslintrc.js b/toolkit/components/extensions/test/browser/.eslintrc.js
new file mode 100644
index 0000000000..ef228570e3
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/.eslintrc.js
@@ -0,0 +1,11 @@
+"use strict";
+
+module.exports = {
+  env: {
+    webextensions: true,
+  },
+
+  rules: {
+    "no-shadow": "off",
+  },
+};
diff --git a/toolkit/components/extensions/test/browser/browser-serviceworker.ini b/toolkit/components/extensions/test/browser/browser-serviceworker.ini
new file mode 100644
index 0000000000..58e9082f7b
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser-serviceworker.ini
@@ -0,0 +1,9 @@
+[DEFAULT]
+support-files =
+  head_serviceworker.js
+  data/**
+
+prefs =
+  extensions.backgroundServiceWorker.enabled=true
+
+[browser_ext_background_serviceworker.js]
diff --git a/toolkit/components/extensions/test/browser/browser.ini b/toolkit/components/extensions/test/browser/browser.ini
new file mode 100644
index 0000000000..0cfb5fcd89
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser.ini
@@ -0,0 +1,50 @@
+[DEFAULT]
+support-files =
+  head.js
+  data/**
+
+[browser_ext_background_serviceworker_pref_disabled.js]
+[browser_ext_downloads_filters.js]
+[browser_ext_downloads_referrer.js]
+[browser_ext_management_themes.js]
+skip-if = verify
+[browser_ext_test_mock.js]
+[browser_ext_themes_additional_backgrounds_alignment.js]
+[browser_ext_themes_alpha_accentcolor.js]
+[browser_ext_themes_arrowpanels.js]
+[browser_ext_themes_autocomplete_popup.js]
+[browser_ext_themes_chromeparity.js]
+[browser_ext_themes_dynamic_getCurrent.js]
+[browser_ext_themes_dynamic_onUpdated.js]
+[browser_ext_themes_dynamic_updates.js]
+[browser_ext_themes_experiment.js]
+[browser_ext_themes_findbar.js]
+[browser_ext_themes_getCurrent_differentExt.js]
+[browser_ext_themes_highlight.js]
+[browser_ext_themes_incognito.js]
+[browser_ext_themes_lwtsupport.js]
+[browser_ext_themes_multiple_backgrounds.js]
+[browser_ext_themes_ntp_colors.js]
+[browser_ext_themes_ntp_colors_perwindow.js]
+[browser_ext_themes_persistence.js]
+[browser_ext_themes_reset.js]
+[browser_ext_themes_sanitization.js]
+[browser_ext_themes_separators.js]
+[browser_ext_themes_sidebars.js]
+[browser_ext_themes_static_onUpdated.js]
+[browser_ext_themes_tab_line.js]
+[browser_ext_themes_tab_loading.js]
+[browser_ext_themes_tab_selected.js]
+[browser_ext_themes_tab_separators.js]
+[browser_ext_themes_tab_text.js]
+[browser_ext_themes_toolbar_fields_focus.js]
+[browser_ext_themes_toolbar_fields.js]
+[browser_ext_themes_toolbarbutton_colors.js]
+[browser_ext_themes_toolbarbutton_icons.js]
+[browser_ext_themes_toolbars.js]
+[browser_ext_themes_theme_transition.js]
+[browser_ext_themes_warnings.js]
+[browser_ext_thumbnails_bg_extension.js]
+support-files = !/toolkit/components/thumbnails/test/head.js
+[browser_ext_webRequest_redirect_mozextension.js]
+[browser_ext_windows_popup_title.js]
diff --git a/toolkit/components/extensions/test/browser/browser_ext_background_serviceworker.js b/toolkit/components/extensions/test/browser/browser_ext_background_serviceworker.js
new file mode 100644
index 0000000000..a43a49cc0a
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_background_serviceworker.js
@@ -0,0 +1,292 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* globals getBackgroundServiceWorkerRegistration, waitForServiceWorkerTerminated */
+
+Services.scriptloader.loadSubScript(
+  new URL("head_serviceworker.js", gTestPath).href,
+  this
+);
+
+add_task(assert_background_serviceworker_pref_enabled);
+
+add_task(async function test_serviceWorker_register_guarded_by_pref() {
+  // Test with backgroundServiceWorkeEnable set to true and the
+  // extensions.serviceWorkerRegist.allowed pref set to false.
+  // NOTE: the scenario with backgroundServiceWorkeEnable set to false
+  // is part of "browser_ext_background_serviceworker_pref_disabled.js".
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.serviceWorkerRegister.allowed", false]],
+  });
+
+  let extensionData = {
+    files: {
+      "page.html": "<!DOCTYPE html><script src='page.js'></script>",
+      "page.js": async function() {
+        try {
+          await navigator.serviceWorker.register("sw.js");
+          browser.test.fail(
+            `An extension page should not be able to register a serviceworker successfully`
+          );
+        } catch (err) {
+          browser.test.assertEq(
+            String(err),
+            "SecurityError: The operation is insecure.",
+            "Got the expected error on registering a service worker from a script"
+          );
+        }
+        browser.test.sendMessage("test-serviceWorker-register-disallowed");
+      },
+      "sw.js": "",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  // Verify that an extension page can't register a moz-extension url
+  // as a service worker.
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: `moz-extension://${extension.uuid}/page.html`,
+    },
+    async () => {
+      await extension.awaitMessage("test-serviceWorker-register-disallowed");
+    }
+  );
+
+  await extension.unload();
+
+  await SpecialPowers.popPrefEnv();
+
+  // Test again with the pref set to true.
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.serviceWorkerRegister.allowed", true]],
+  });
+
+  extension = ExtensionTestUtils.loadExtension({
+    files: {
+      ...extensionData.files,
+      "page.js": async function() {
+        try {
+          await navigator.serviceWorker.register("sw.js");
+        } catch (err) {
+          browser.test.fail(
+            `Unexpected error on registering a service worker: ${err}`
+          );
+          throw err;
+        } finally {
+          browser.test.sendMessage("test-serviceworker-register-allowed");
+        }
+      },
+    },
+  });
+  await extension.startup();
+
+  // Verify that an extension page can register a moz-extension url
+  // as a service worker if enabled by the related pref.
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: `moz-extension://${extension.uuid}/page.html`,
+    },
+    async () => {
+      await extension.awaitMessage("test-serviceworker-register-allowed");
+    }
+  );
+
+  await extension.unload();
+
+  await SpecialPowers.popPrefEnv();
+});
+
+add_task(async function test_cache_api_allowed() {
+  // Verify that Cache API support for moz-extension url availability is also
+  // conditioned by the extensions.backgroundServiceWorker.enabled pref.
+  // NOTE: the scenario with backgroundServiceWorkeEnable set to false
+  // is part of "browser_ext_background_serviceworker_pref_disabled.js".
+  const extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      try {
+        let cache = await window.caches.open("test-cache-api");
+        browser.test.assertTrue(
+          await window.caches.has("test-cache-api"),
+          "CacheStorage.has should resolve to true"
+        );
+
+        // Test that adding and requesting cached moz-extension urls
+        // works as well.
+        let url = browser.runtime.getURL("file.txt");
+        await cache.add(url);
+        const content = await cache.match(url).then(res => res.text());
+        browser.test.assertEq(
+          "file content",
+          content,
+          "Got the expected content from the cached moz-extension url"
+        );
+
+        // Test that deleting the cache storage works as expected.
+        browser.test.assertTrue(
+          await window.caches.delete("test-cache-api"),
+          "Cache deleted successfully"
+        );
+        browser.test.assertTrue(
+          !(await window.caches.has("test-cache-api")),
+          "CacheStorage.has should resolve to false"
+        );
+      } catch (err) {
+        browser.test.fail(`Unexpected error on using Cache API: ${err}`);
+        throw err;
+      } finally {
+        browser.test.sendMessage("test-cache-api-allowed");
+      }
+    },
+    files: {
+      "file.txt": "file content",
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("test-cache-api-allowed");
+  await extension.unload();
+});
+
+function createTestSWScript({ postMessageReply }) {
+  return `
+    self.onmessage = msg => {
+      dump("Background ServiceWorker - onmessage handler\\n");
+      msg.ports[0].postMessage("${postMessageReply}");
+      dump("Background ServiceWorker - postMessage\\n");
+    };
+    dump("Background ServiceWorker - executed\\n");
+  `;
+}
+
+async function testServiceWorker({ extension, expectMessageReply }) {
+  // Verify that the WebExtensions framework has successfully registered the
+  // background service worker declared in the extension manifest.
+  const swRegInfo = getBackgroundServiceWorkerRegistration(extension);
+
+  // Activate the background service worker by exchanging a message
+  // with it.
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: `moz-extension://${extension.uuid}/page.html`,
+    },
+    async browser => {
+      let msgFromV1 = await SpecialPowers.spawn(
+        browser,
+        [swRegInfo.scriptURL],
+        async url => {
+          const { active } = await content.navigator.serviceWorker.ready;
+          const { port1, port2 } = new content.MessageChannel();
+
+          return new Promise(resolve => {
+            port1.onmessage = msg => resolve(msg.data);
+            active.postMessage("test", [port2]);
+          });
+        }
+      );
+
+      Assert.deepEqual(
+        msgFromV1,
+        expectMessageReply,
+        "Got the expected reply from the extension service worker"
+      );
+    }
+  );
+}
+
+function loadTestExtension({ version }) {
+  const postMessageReply = `reply:sw-v${version}`;
+
+  return ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      version,
+      background: {
+        service_worker: "sw.js",
+      },
+      applications: { gecko: { id: "test-bg-sw@mochi.test" } },
+    },
+    files: {
+      "page.html": "<!DOCTYPE html><body></body>",
+      "sw.js": createTestSWScript({ postMessageReply }),
+    },
+  });
+}
+
+async function assertWorkerIsRunningInExtensionProcess(extension) {
+  // Activate the background service worker by exchanging a message
+  // with it.
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: `moz-extension://${extension.uuid}/page.html`,
+    },
+    async browser => {
+      const workerScriptURL = `moz-extension://${extension.uuid}/sw.js`;
+      const workerDebuggerURLs = await SpecialPowers.spawn(
+        browser,
+        [workerScriptURL],
+        async url => {
+          await content.navigator.serviceWorker.ready;
+          const wdm = Cc[
+            "@mozilla.org/dom/workers/workerdebuggermanager;1"
+          ].getService(Ci.nsIWorkerDebuggerManager);
+
+          return Array.from(wdm.getWorkerDebuggerEnumerator())
+            .map(wd => {
+              return wd.url;
+            })
+            .filter(swURL => swURL == url);
+        }
+      );
+
+      Assert.deepEqual(
+        workerDebuggerURLs,
+        [workerScriptURL],
+        "The worker should be running in the extension child process"
+      );
+    }
+  );
+}
+
+add_task(async function test_background_serviceworker_with_no_ext_apis() {
+  const extensionV1 = loadTestExtension({ version: "1" });
+  await extensionV1.startup();
+
+  const swRegInfo = getBackgroundServiceWorkerRegistration(extensionV1);
+  const { uuid } = extensionV1;
+
+  await assertWorkerIsRunningInExtensionProcess(extensionV1);
+  await testServiceWorker({
+    extension: extensionV1,
+    expectMessageReply: "reply:sw-v1",
+  });
+
+  // Load a new version of the same addon and verify that the
+  // expected worker script is being executed.
+  const extensionV2 = loadTestExtension({ version: "2" });
+  await extensionV2.startup();
+  is(extensionV2.uuid, uuid, "The extension uuid did not change as expected");
+
+  await testServiceWorker({
+    extension: extensionV2,
+    expectMessageReply: "reply:sw-v2",
+  });
+
+  await Promise.all([
+    extensionV2.unload(),
+    // test extension v1 wrapper has to be unloaded explicitly, otherwise
+    // will be detected as a failure by the test harness.
+    extensionV1.unload(),
+  ]);
+  await waitForServiceWorkerTerminated(swRegInfo);
+  await waitForServiceWorkerRegistrationsRemoved(extensionV2);
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_background_serviceworker_pref_disabled.js b/toolkit/components/extensions/test/browser/browser_ext_background_serviceworker_pref_disabled.js
new file mode 100644
index 0000000000..a2d9004801
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_background_serviceworker_pref_disabled.js
@@ -0,0 +1,122 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function assert_background_serviceworker_pref_disabled() {
+  is(
+    WebExtensionPolicy.backgroundServiceWorkerEnabled,
+    false,
+    "Expect extensions.backgroundServiceWorker.enabled to be false"
+  );
+});
+
+add_task(async function test_background_serviceworker_disallowed() {
+  const id = "test-disallowed-worker@test";
+
+  const extensionData = {
+    manifest: {
+      background: {
+        service_worker: "sw.js",
+      },
+      applicantions: { gecko: { id } },
+      useAddonManager: "temporary",
+    },
+  };
+
+  SimpleTest.waitForExplicitFinish();
+  let waitForConsole = new Promise(resolve => {
+    SimpleTest.monitorConsole(resolve, [
+      {
+        message: /Reading manifest: Error processing background: background.service_worker is currently disabled/,
+      },
+    ]);
+  });
+
+  const extension = ExtensionTestUtils.loadExtension(extensionData);
+  await Assert.rejects(
+    extension.startup(),
+    /startup failed/,
+    "Startup failed with background.service_worker while disabled by pref"
+  );
+
+  SimpleTest.endMonitorConsole();
+  await waitForConsole;
+});
+
+add_task(async function test_serviceWorker_register_disallowed() {
+  // Verify that setting extensions.serviceWorkerRegist.allowed pref to false
+  // doesn't allow serviceWorker.register if backgroundServiceWorkeEnable is
+  // set to false
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.serviceWorkerRegister.allowed", true]],
+  });
+
+  let extensionData = {
+    files: {
+      "page.html": "<!DOCTYPE html><script src='page.js'></script>",
+      "page.js": async function() {
+        try {
+          await navigator.serviceWorker.register("sw.js");
+          browser.test.fail(
+            `An extension page should not be able to register a serviceworker successfully`
+          );
+        } catch (err) {
+          browser.test.assertEq(
+            String(err),
+            "SecurityError: The operation is insecure.",
+            "Got the expected error on registering a service worker from a script"
+          );
+        }
+        browser.test.sendMessage("test-serviceWorker-register-disallowed");
+      },
+      "sw.js": "",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  // Verify that an extension page can't register a moz-extension url
+  // as a service worker.
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url: `moz-extension://${extension.uuid}/page.html`,
+    },
+    async () => {
+      await extension.awaitMessage("test-serviceWorker-register-disallowed");
+    }
+  );
+
+  await extension.unload();
+
+  await SpecialPowers.popPrefEnv();
+});
+
+add_task(async function test_cache_api_disallowed() {
+  // Verify that Cache API support for moz-extension url availability is also
+  // conditioned by the extensions.backgroundServiceWorker.enabled pref.
+  const extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      try {
+        await window.caches.open("test-cache-api");
+        browser.test.fail(
+          `An extension page should not be allowed to use the Cache API successfully`
+        );
+      } catch (err) {
+        browser.test.assertEq(
+          String(err),
+          "SecurityError: The operation is insecure.",
+          "Got the expected error on registering a service worker from a script"
+        );
+      } finally {
+        browser.test.sendMessage("test-cache-api-disallowed");
+      }
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("test-cache-api-disallowed");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_downloads_filters.js b/toolkit/components/extensions/test/browser/browser_ext_downloads_filters.js
new file mode 100644
index 0000000000..f8672597cd
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_downloads_filters.js
@@ -0,0 +1,138 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+
+"use strict";
+
+async function testAppliedFilters(ext, expectedFilter, expectedFilterCount) {
+  let tempDir = FileUtils.getDir(
+    "TmpD",
+    [`testDownloadDir-${Math.random()}`],
+    true
+  );
+
+  let filterCount = 0;
+
+  let MockFilePicker = SpecialPowers.MockFilePicker;
+  MockFilePicker.init(window);
+  MockFilePicker.displayDirectory = tempDir;
+  MockFilePicker.returnValue = MockFilePicker.returnCancel;
+  MockFilePicker.appendFiltersCallback = function(fp, val) {
+    const hexstr = "0x" + ("000" + val.toString(16)).substr(-3);
+    filterCount++;
+    if (filterCount < expectedFilterCount) {
+      is(val, expectedFilter, "Got expected filter: " + hexstr);
+    } else if (filterCount == expectedFilterCount) {
+      is(val, MockFilePicker.filterAll, "Got all files filter: " + hexstr);
+    } else {
+      is(val, null, "Got unexpected filter: " + hexstr);
+    }
+  };
+  MockFilePicker.showCallback = function(fp) {
+    const filename = fp.defaultString;
+    info("MockFilePicker - save as: " + filename);
+  };
+
+  let manifest = {
+    description: ext,
+    permissions: ["downloads"],
+  };
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: manifest,
+
+    background: async function() {
+      let ext = chrome.runtime.getManifest().description;
+      await browser.test.assertRejects(
+        browser.downloads.download({
+          url: "http://any-origin/any-path/any-resource",
+          filename: "any-file" + ext,
+          saveAs: true,
+        }),
+        "Download canceled by the user",
+        "expected request to be canceled"
+      );
+      browser.test.sendMessage("canceled");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("canceled");
+  await extension.unload();
+
+  is(
+    filterCount,
+    expectedFilterCount,
+    "Got correct number of filters: " + filterCount
+  );
+
+  MockFilePicker.cleanup();
+
+  tempDir.remove(true);
+}
+
+// Missing extension
+add_task(async function testDownload_missing_All() {
+  await testAppliedFilters("", null, 1);
+});
+
+// Unrecognized extension
+add_task(async function testDownload_unrecognized_All() {
+  await testAppliedFilters(".xxx", null, 1);
+});
+
+// Recognized extensions
+add_task(async function testDownload_html_HTML() {
+  await testAppliedFilters(".html", Ci.nsIFilePicker.filterHTML, 2);
+});
+
+add_task(async function testDownload_xhtml_HTML() {
+  await testAppliedFilters(".xhtml", Ci.nsIFilePicker.filterHTML, 2);
+});
+
+add_task(async function testDownload_txt_Text() {
+  await testAppliedFilters(".txt", Ci.nsIFilePicker.filterText, 2);
+});
+
+add_task(async function testDownload_text_Text() {
+  await testAppliedFilters(".text", Ci.nsIFilePicker.filterText, 2);
+});
+
+add_task(async function testDownload_jpe_Images() {
+  await testAppliedFilters(".jpe", Ci.nsIFilePicker.filterImages, 2);
+});
+
+add_task(async function testDownload_tif_Images() {
+  await testAppliedFilters(".tif", Ci.nsIFilePicker.filterImages, 2);
+});
+
+add_task(async function testDownload_webp_Images() {
+  await testAppliedFilters(".webp", Ci.nsIFilePicker.filterImages, 2);
+});
+
+add_task(async function testDownload_xml_XML() {
+  await testAppliedFilters(".xml", Ci.nsIFilePicker.filterXML, 2);
+});
+
+add_task(async function testDownload_aac_Audio() {
+  await testAppliedFilters(".aac", Ci.nsIFilePicker.filterAudio, 2);
+});
+
+add_task(async function testDownload_mp3_Audio() {
+  await testAppliedFilters(".mp3", Ci.nsIFilePicker.filterAudio, 2);
+});
+
+add_task(async function testDownload_wma_Audio() {
+  await testAppliedFilters(".wma", Ci.nsIFilePicker.filterAudio, 2);
+});
+
+add_task(async function testDownload_avi_Video() {
+  await testAppliedFilters(".avi", Ci.nsIFilePicker.filterVideo, 2);
+});
+
+add_task(async function testDownload_mp4_Video() {
+  await testAppliedFilters(".mp4", Ci.nsIFilePicker.filterVideo, 2);
+});
+
+add_task(async function testDownload_xvid_Video() {
+  await testAppliedFilters(".xvid", Ci.nsIFilePicker.filterVideo, 2);
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_downloads_referrer.js b/toolkit/components/extensions/test/browser/browser_ext_downloads_referrer.js
new file mode 100644
index 0000000000..b2931e0b6f
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_downloads_referrer.js
@@ -0,0 +1,82 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+
+"use strict";
+
+const { BrowserTestUtils } = ChromeUtils.import(
+  "resource://testing-common/BrowserTestUtils.jsm"
+);
+
+const URL_PATH = "browser/toolkit/components/extensions/test/browser/data";
+const TEST_URL = `http://example.com/${URL_PATH}/test_downloads_referrer.html`;
+const DOWNLOAD_URL = `http://example.com/${URL_PATH}/test-download.txt`;
+
+async function triggerSaveAs({ selector }) {
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    selector,
+    { type: "contextmenu", button: 2 },
+    gBrowser.selectedBrowser
+  );
+  let saveLinkCommand = window.document.getElementById("context-savelink");
+  saveLinkCommand.doCommand();
+}
+
+add_task(function test_setup() {
+  const tempDir = Services.dirsvc.get("TmpD", Ci.nsIFile);
+  tempDir.append("test-download-dir");
+  if (!tempDir.exists()) {
+    tempDir.create(Ci.nsIFile.DIRECTORY_TYPE, 0o755);
+  }
+
+  let MockFilePicker = SpecialPowers.MockFilePicker;
+  MockFilePicker.init(window);
+  registerCleanupFunction(function() {
+    MockFilePicker.cleanup();
+
+    if (tempDir.exists()) {
+      tempDir.remove(true);
+    }
+  });
+
+  MockFilePicker.displayDirectory = tempDir;
+  MockFilePicker.showCallback = function(fp) {
+    info("MockFilePicker: shown");
+    const filename = fp.defaultString;
+    info("MockFilePicker: save as " + filename);
+    const destFile = tempDir.clone();
+    destFile.append(filename);
+    MockFilePicker.setFiles([destFile]);
+    info("MockFilePicker: showCallback done");
+  };
+});
+
+add_task(async function test_download_item_referrer_info() {
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["downloads"],
+    },
+    async background() {
+      browser.downloads.onCreated.addListener(async downloadInfo => {
+        browser.test.sendMessage("download-on-created", downloadInfo);
+      });
+
+      // Call an API method implemented in the parent process to make sure
+      // registering the downloas.onCreated event listener has been completed.
+      await browser.runtime.getBrowserInfo();
+
+      browser.test.sendMessage("bg-page:ready");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("bg-page:ready");
+
+  await BrowserTestUtils.withNewTab({ gBrowser, url: TEST_URL }, async () => {
+    await triggerSaveAs({ selector: "a.test-link" });
+    const downloadInfo = await extension.awaitMessage("download-on-created");
+    is(downloadInfo.url, DOWNLOAD_URL, "Got the expected download url");
+    is(downloadInfo.referrer, TEST_URL, "Got the expected referrer");
+  });
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_management_themes.js b/toolkit/components/extensions/test/browser/browser_ext_management_themes.js
new file mode 100644
index 0000000000..f74f418ace
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_management_themes.js
@@ -0,0 +1,149 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { PromiseTestUtils } = ChromeUtils.import(
+  "resource://testing-common/PromiseTestUtils.jsm"
+);
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /Message manager disconnected/
+);
+
+add_task(async function test_management_themes() {
+  const TEST_ID = "test_management_themes@tests.mozilla.com";
+
+  let theme = ExtensionTestUtils.loadExtension({
+    manifest: {
+      name: "Simple theme test",
+      version: "1.0",
+      description: "test theme",
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+    useAddonManager: "temporary",
+  });
+
+  async function background(TEST_ID) {
+    browser.management.onInstalled.addListener(info => {
+      if (info.name == TEST_ID) {
+        return;
+      }
+      browser.test.log(`${info.name} was installed`);
+      browser.test.assertEq(info.type, "theme", "addon is theme");
+      browser.test.sendMessage("onInstalled", info.name);
+    });
+    browser.management.onDisabled.addListener(info => {
+      browser.test.log(`${info.name} was disabled`);
+      browser.test.assertEq(info.type, "theme", "addon is theme");
+      browser.test.sendMessage("onDisabled", info.name);
+    });
+    browser.management.onEnabled.addListener(info => {
+      browser.test.log(`${info.name} was enabled`);
+      browser.test.assertEq(info.type, "theme", "addon is theme");
+      browser.test.sendMessage("onEnabled", info.name);
+    });
+    browser.management.onUninstalled.addListener(info => {
+      browser.test.log(`${info.name} was uninstalled`);
+      browser.test.assertEq(info.type, "theme", "addon is theme");
+      browser.test.sendMessage("onUninstalled", info.name);
+    });
+
+    async function getAddon(type) {
+      let addons = await browser.management.getAll();
+      let themes = addons.filter(addon => addon.type === "theme");
+      // We get the 4 built-in themes plus the lwt and our addon.
+      browser.test.assertEq(5, themes.length, "got expected addons");
+      // We should also get our test extension.
+      let testExtension = addons.find(addon => {
+        return addon.id === TEST_ID;
+      });
+      browser.test.assertTrue(
+        !!testExtension,
+        `The extension with id ${TEST_ID} was returned by getAll.`
+      );
+      let found;
+      for (let addon of themes) {
+        browser.test.assertEq(addon.type, "theme", "addon is theme");
+        if (type == "theme" && addon.id.includes("temporary-addon")) {
+          found = addon;
+        } else if (type == "enabled" && addon.enabled) {
+          found = addon;
+        }
+      }
+      return found;
+    }
+
+    browser.test.onMessage.addListener(async msg => {
+      let theme = await getAddon("theme");
+      browser.test.assertEq(
+        theme.description,
+        "test theme",
+        "description is correct"
+      );
+      browser.test.assertTrue(theme.enabled, "theme is enabled");
+      await browser.management.setEnabled(theme.id, false);
+
+      theme = await getAddon("theme");
+
+      browser.test.assertTrue(!theme.enabled, "theme is disabled");
+      let addon = getAddon("enabled");
+      browser.test.assertTrue(addon, "another theme was enabled");
+
+      await browser.management.setEnabled(theme.id, true);
+      theme = await getAddon("theme");
+      addon = await getAddon("enabled");
+      browser.test.assertEq(theme.id, addon.id, "theme is enabled");
+
+      browser.test.sendMessage("done");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: TEST_ID,
+        },
+      },
+      name: TEST_ID,
+      permissions: ["management"],
+    },
+    background: `(${background})("${TEST_ID}")`,
+    useAddonManager: "temporary",
+  });
+  await extension.startup();
+
+  await theme.startup();
+  is(
+    await extension.awaitMessage("onInstalled"),
+    "Simple theme test",
+    "webextension theme installed"
+  );
+  is(await extension.awaitMessage("onDisabled"), "Default", "default disabled");
+
+  extension.sendMessage("test");
+  is(await extension.awaitMessage("onEnabled"), "Default", "default enabled");
+  is(
+    await extension.awaitMessage("onDisabled"),
+    "Simple theme test",
+    "addon disabled"
+  );
+  is(
+    await extension.awaitMessage("onEnabled"),
+    "Simple theme test",
+    "addon enabled"
+  );
+  is(await extension.awaitMessage("onDisabled"), "Default", "default disabled");
+  await extension.awaitMessage("done");
+
+  await Promise.all([theme.unload(), extension.awaitMessage("onUninstalled")]);
+
+  is(await extension.awaitMessage("onEnabled"), "Default", "default enabled");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_test_mock.js b/toolkit/components/extensions/test/browser/browser_ext_test_mock.js
new file mode 100644
index 0000000000..fc71cacc66
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_test_mock.js
@@ -0,0 +1,45 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+// This test verifies that the extension mocks behave consistently, regardless
+// of test type (xpcshell vs browser test).
+// See also toolkit/components/extensions/test/xpcshell/test_ext_test_mock.js
+
+// Check the state of the extension object. This should be consistent between
+// browser tests and xpcshell tests.
+async function checkExtensionStartupAndUnload(ext) {
+  await ext.startup();
+  Assert.ok(ext.id, "Extension ID should be available");
+  Assert.ok(ext.uuid, "Extension UUID should be available");
+  await ext.unload();
+  // Once set nothing clears the UUID.
+  Assert.ok(ext.uuid, "Extension UUID exists after unload");
+}
+
+add_task(async function test_MockExtension() {
+  // When "useAddonManager" is set, a MockExtension is created in the main
+  // process, which does not necessarily behave identically to an Extension.
+  let ext = ExtensionTestUtils.loadExtension({
+    // xpcshell/test_ext_test_mock.js tests "temporary", so here we use
+    // "permanent" to have even more test coverage.
+    useAddonManager: "permanent",
+    manifest: { applications: { gecko: { id: "@permanent-mock-extension" } } },
+  });
+
+  Assert.ok(!ext.id, "Extension ID is initially unavailable");
+  Assert.ok(!ext.uuid, "Extension UUID is initially unavailable");
+  await checkExtensionStartupAndUnload(ext);
+  Assert.ok(ext.id, "Extension ID exists after unload");
+});
+
+add_task(async function test_generated_Extension() {
+  let ext = ExtensionTestUtils.loadExtension({
+    manifest: {},
+  });
+
+  Assert.ok(!ext.id, "Extension ID is initially unavailable");
+  Assert.ok(!ext.uuid, "Extension UUID is initially unavailable");
+  await checkExtensionStartupAndUnload(ext);
+  Assert.ok(ext.id, "Extension ID exists after unload");
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_additional_backgrounds_alignment.js b/toolkit/components/extensions/test/browser/browser_ext_themes_additional_backgrounds_alignment.js
new file mode 100644
index 0000000000..f265a724e5
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_additional_backgrounds_alignment.js
@@ -0,0 +1,102 @@
+"use strict";
+
+// Case 1 - When there is a theme_frame image and additional_backgrounds_alignment is not specified.
+// So background-position should default to "right top"
+add_task(async function test_default_additional_backgrounds_alignment() {
+  const RIGHT_TOP = "100% 0%";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+          additional_backgrounds: ["image1.png", "image1.png"],
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = document.documentElement;
+  let rootCS = window.getComputedStyle(docEl);
+
+  Assert.equal(
+    rootCS.getPropertyValue("background-position"),
+    RIGHT_TOP,
+    "root only contains theme_frame alignment property"
+  );
+
+  let toolbox = document.querySelector("#navigator-toolbox");
+  let toolboxCS = window.getComputedStyle(toolbox);
+
+  Assert.equal(
+    toolboxCS.getPropertyValue("background-position"),
+    RIGHT_TOP,
+    toolbox.id +
+      " only contains default additional backgrounds alignment property"
+  );
+
+  await extension.unload();
+});
+
+// Case 2 - When there is a theme_frame image and additional_backgrounds_alignment is specified.
+add_task(async function test_additional_backgrounds_alignment() {
+  const LEFT_BOTTOM = "0% 100%";
+  const CENTER_CENTER = "50% 50%";
+  const RIGHT_TOP = "100% 0%";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+          additional_backgrounds: ["image1.png", "image1.png", "image1.png"],
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+        },
+        properties: {
+          additional_backgrounds_alignment: [
+            "left bottom",
+            "center center",
+            "right top",
+          ],
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = document.documentElement;
+  let rootCS = window.getComputedStyle(docEl);
+
+  Assert.equal(
+    rootCS.getPropertyValue("background-position"),
+    RIGHT_TOP,
+    "root only contains theme_frame alignment property"
+  );
+
+  let toolbox = document.querySelector("#navigator-toolbox");
+  let toolboxCS = window.getComputedStyle(toolbox);
+
+  Assert.equal(
+    toolboxCS.getPropertyValue("background-position"),
+    LEFT_BOTTOM + ", " + CENTER_CENTER + ", " + RIGHT_TOP,
+    toolbox.id + " contains additional backgrounds alignment properties"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_alpha_accentcolor.js b/toolkit/components/extensions/test/browser/browser_ext_themes_alpha_accentcolor.js
new file mode 100644
index 0000000000..65e3a6c9bf
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_alpha_accentcolor.js
@@ -0,0 +1,34 @@
+"use strict";
+
+add_task(async function test_alpha_frame_color() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: "rgba(230, 128, 0, 0.1)",
+          tab_background_text: TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  // Add the event listener before loading the extension
+  let docEl = window.document.documentElement;
+  let style = window.getComputedStyle(docEl);
+
+  Assert.equal(
+    style.backgroundColor,
+    "rgb(230, 128, 0)",
+    "Window background color should be opaque"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_arrowpanels.js b/toolkit/components/extensions/test/browser/browser_ext_themes_arrowpanels.js
new file mode 100644
index 0000000000..e7024b0479
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_arrowpanels.js
@@ -0,0 +1,99 @@
+"use strict";
+
+function openIdentityPopup() {
+  let promise = BrowserTestUtils.waitForEvent(
+    window,
+    "popupshown",
+    true,
+    event => event.target == gIdentityHandler._identityPopup
+  );
+  gIdentityHandler._identityBox.click();
+  return promise;
+}
+
+function closeIdentityPopup() {
+  let promise = BrowserTestUtils.waitForEvent(
+    gIdentityHandler._identityPopup,
+    "popuphidden"
+  );
+  gIdentityHandler._identityPopup.hidePopup();
+  return promise;
+}
+
+// This test checks applied WebExtension themes that attempt to change
+// popup properties
+
+add_task(async function test_popup_styling(browser, accDoc) {
+  const POPUP_BACKGROUND_COLOR = "#FF0000";
+  const POPUP_TEXT_COLOR = "#008000";
+  const POPUP_BORDER_COLOR = "#0000FF";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          popup: POPUP_BACKGROUND_COLOR,
+          popup_text: POPUP_TEXT_COLOR,
+          popup_border: POPUP_BORDER_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await BrowserTestUtils.withNewTab(
+    { gBrowser, url: "https://example.com" },
+    async function(browser) {
+      await extension.startup();
+
+      // Open the information arrow panel
+      await openIdentityPopup();
+
+      let arrowContent = gIdentityHandler._identityPopup.shadowRoot.querySelector(
+        ".panel-arrowcontent"
+      );
+      let arrowContentComputedStyle = window.getComputedStyle(arrowContent);
+      // Ensure popup background color was set properly
+      Assert.equal(
+        arrowContentComputedStyle.getPropertyValue("background-color"),
+        `rgb(${hexToRGB(POPUP_BACKGROUND_COLOR).join(", ")})`,
+        "Popup background color should have been themed"
+      );
+
+      // Ensure popup text color was set properly
+      Assert.equal(
+        arrowContentComputedStyle.getPropertyValue("color"),
+        `rgb(${hexToRGB(POPUP_TEXT_COLOR).join(", ")})`,
+        "Popup text color should have been themed"
+      );
+
+      Assert.equal(
+        arrowContentComputedStyle.getPropertyValue("--panel-description-color"),
+        `rgba(${hexToRGB(POPUP_TEXT_COLOR).join(", ")}, 0.65)`,
+        "Popup text description color should have been themed"
+      );
+
+      // Ensure popup border color was set properly
+      if (AppConstants.platform == "macosx") {
+        Assert.ok(
+          arrowContentComputedStyle
+            .getPropertyValue("box-shadow")
+            .includes(`rgb(${hexToRGB(POPUP_BORDER_COLOR).join(", ")})`),
+          "Popup border color should be set"
+        );
+      } else {
+        testBorderColor(arrowContent, POPUP_BORDER_COLOR);
+      }
+
+      await closeIdentityPopup();
+      await extension.unload();
+    }
+  );
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_autocomplete_popup.js b/toolkit/components/extensions/test/browser/browser_ext_themes_autocomplete_popup.js
new file mode 100644
index 0000000000..2c5a0123f4
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_autocomplete_popup.js
@@ -0,0 +1,170 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// popup properties are applied correctly to the autocomplete bar.
+const POPUP_COLOR = "#85A400";
+const POPUP_TEXT_COLOR_DARK = "#000000";
+const POPUP_TEXT_COLOR_BRIGHT = "#ffffff";
+const POPUP_SELECTED_COLOR = "#9400ff";
+const POPUP_SELECTED_TEXT_COLOR = "#09b9a6";
+
+const POPUP_URL_COLOR_DARK = "#1c78d4";
+const POPUP_ACTION_COLOR_DARK = "#008f8a";
+const POPUP_URL_COLOR_BRIGHT = "#74c0ff";
+const POPUP_ACTION_COLOR_BRIGHT = "#30e60b";
+
+const SEARCH_TERM = "urlbar-reflows-" + Date.now();
+
+XPCOMUtils.defineLazyModuleGetters(this, {
+  PlacesTestUtils: "resource://testing-common/PlacesTestUtils.jsm",
+  UrlbarTestUtils: "resource://testing-common/UrlbarTestUtils.jsm",
+});
+
+add_task(async function setup() {
+  await PlacesUtils.history.clear();
+  const NUM_VISITS = 10;
+  let visits = [];
+
+  for (let i = 0; i < NUM_VISITS; ++i) {
+    visits.push({
+      uri: `http://example.com/urlbar-reflows-${i}`,
+      title: `Reflow test for URL bar entry #${i} - ${SEARCH_TERM}`,
+    });
+  }
+
+  await PlacesTestUtils.addVisits(visits);
+
+  registerCleanupFunction(async function() {
+    await PlacesUtils.history.clear();
+  });
+});
+
+add_task(async function test_popup_url() {
+  // Load extension with brighttext not set
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_field_focus: POPUP_COLOR,
+          toolbar_field_text_focus: POPUP_TEXT_COLOR_DARK,
+          popup_highlight: POPUP_SELECTED_COLOR,
+          popup_highlight_text: POPUP_SELECTED_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let maxResults = Services.prefs.getIntPref("browser.urlbar.maxRichResults");
+  let tab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "about:mozilla"
+  );
+  registerCleanupFunction(async function() {
+    await PlacesUtils.history.clear();
+    await BrowserTestUtils.removeTab(tab);
+  });
+
+  let visits = [];
+
+  for (let i = 0; i < maxResults; i++) {
+    visits.push({ uri: makeURI("http://example.com/autocomplete/?" + i) });
+  }
+
+  await PlacesTestUtils.addVisits(visits);
+  await UrlbarTestUtils.promiseAutocompleteResultPopup({
+    window,
+    waitForFocus,
+    value: "example.com/autocomplete",
+  });
+  await UrlbarTestUtils.waitForAutocompleteResultAt(window, maxResults - 1);
+
+  Assert.equal(
+    UrlbarTestUtils.getResultCount(window),
+    maxResults,
+    "Should get maxResults=" + maxResults + " results"
+  );
+
+  // Set the selected attribute to true to test the highlight popup properties
+  UrlbarTestUtils.setSelectedRowIndex(window, 1);
+  let actionResult = await UrlbarTestUtils.getDetailsOfResultAt(window, 0);
+  let urlResult = await UrlbarTestUtils.getDetailsOfResultAt(window, 1);
+  let resultCS = window.getComputedStyle(urlResult.element.row._content);
+
+  Assert.equal(
+    resultCS.backgroundColor,
+    `rgb(${hexToRGB(POPUP_SELECTED_COLOR).join(", ")})`,
+    `Popup highlight background color should be set to ${POPUP_SELECTED_COLOR}`
+  );
+
+  Assert.equal(
+    resultCS.color,
+    `rgb(${hexToRGB(POPUP_SELECTED_TEXT_COLOR).join(", ")})`,
+    `Popup highlight color should be set to ${POPUP_SELECTED_TEXT_COLOR}`
+  );
+
+  // Now set the index to somewhere not on the first two, so that we can test both
+  // url and action text colors.
+  UrlbarTestUtils.setSelectedRowIndex(window, 2);
+
+  Assert.equal(
+    window.getComputedStyle(urlResult.element.url).color,
+    `rgb(${hexToRGB(POPUP_URL_COLOR_DARK).join(", ")})`,
+    `Urlbar popup url color should be set to ${POPUP_URL_COLOR_DARK}`
+  );
+
+  Assert.equal(
+    window.getComputedStyle(actionResult.element.action).color,
+    `rgb(${hexToRGB(POPUP_ACTION_COLOR_DARK).join(", ")})`,
+    `Urlbar popup action color should be set to ${POPUP_ACTION_COLOR_DARK}`
+  );
+
+  await extension.unload();
+
+  // Load a manifest with popup_text being bright. Test for bright text properties.
+  extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_field_focus: POPUP_COLOR,
+          toolbar_field_text_focus: POPUP_TEXT_COLOR_BRIGHT,
+          popup_highlight: POPUP_SELECTED_COLOR,
+          popup_highlight_text: POPUP_SELECTED_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  Assert.equal(
+    window.getComputedStyle(urlResult.element.url).color,
+    `rgb(${hexToRGB(POPUP_URL_COLOR_BRIGHT).join(", ")})`,
+    `Urlbar popup url color should be set to ${POPUP_URL_COLOR_BRIGHT}`
+  );
+
+  Assert.equal(
+    window.getComputedStyle(actionResult.element.action).color,
+    `rgb(${hexToRGB(POPUP_ACTION_COLOR_BRIGHT).join(", ")})`,
+    `Urlbar popup action color should be set to ${POPUP_ACTION_COLOR_BRIGHT}`
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_chromeparity.js b/toolkit/components/extensions/test/browser/browser_ext_themes_chromeparity.js
new file mode 100644
index 0000000000..4366764a20
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_chromeparity.js
@@ -0,0 +1,161 @@
+"use strict";
+
+add_task(async function test_support_theme_frame() {
+  const FRAME_COLOR = [71, 105, 91];
+  const TAB_TEXT_COLOR = [0, 0, 0];
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "face.png",
+        },
+        colors: {
+          frame: FRAME_COLOR,
+          tab_background_text: TAB_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "face.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+
+  Assert.ok(
+    docEl.hasAttribute("lwtheme-image"),
+    "LWT image attribute should be set"
+  );
+
+  Assert.equal(
+    docEl.getAttribute("lwthemetextcolor"),
+    "dark",
+    "LWT text color attribute should be set"
+  );
+
+  let style = window.getComputedStyle(docEl);
+  Assert.ok(
+    style.backgroundImage.includes("face.png"),
+    `The backgroundImage should use face.png. Actual value is: ${style.backgroundImage}`
+  );
+  Assert.equal(
+    style.backgroundColor,
+    "rgb(" + FRAME_COLOR.join(", ") + ")",
+    "Expected correct background color"
+  );
+  Assert.equal(
+    style.color,
+    "rgb(" + TAB_TEXT_COLOR.join(", ") + ")",
+    "Expected correct text color"
+  );
+
+  await extension.unload();
+
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+
+  Assert.ok(
+    !docEl.hasAttribute("lwtheme-image"),
+    "LWT image attribute should not be set"
+  );
+
+  Assert.ok(
+    !docEl.hasAttribute("lwthemetextcolor"),
+    "LWT text color attribute should not be set"
+  );
+});
+
+add_task(async function test_support_theme_frame_inactive() {
+  const FRAME_COLOR = [71, 105, 91];
+  const FRAME_COLOR_INACTIVE = [255, 0, 0];
+  const TAB_TEXT_COLOR = [207, 221, 192];
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: FRAME_COLOR,
+          frame_inactive: FRAME_COLOR_INACTIVE,
+          tab_background_text: TAB_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  let style = window.getComputedStyle(docEl);
+
+  Assert.equal(
+    style.backgroundColor,
+    "rgb(" + FRAME_COLOR.join(", ") + ")",
+    "Window background is set to the colors.frame property"
+  );
+
+  // Now we'll open a new window to see if the inactive browser accent color changed
+  let window2 = await BrowserTestUtils.openNewBrowserWindow();
+  Assert.equal(
+    style.backgroundColor,
+    "rgb(" + FRAME_COLOR_INACTIVE.join(", ") + ")",
+    `Inactive window background color should be ${FRAME_COLOR_INACTIVE}`
+  );
+
+  await BrowserTestUtils.closeWindow(window2);
+  await extension.unload();
+
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+});
+
+add_task(async function test_lack_of_theme_frame_inactive() {
+  const FRAME_COLOR = [71, 105, 91];
+  const TAB_TEXT_COLOR = [207, 221, 192];
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: FRAME_COLOR,
+          tab_background_text: TAB_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  let style = window.getComputedStyle(docEl);
+
+  Assert.equal(
+    style.backgroundColor,
+    "rgb(" + FRAME_COLOR.join(", ") + ")",
+    "Window background is set to the colors.frame property"
+  );
+
+  // Now we'll open a new window to make sure the inactive browser accent color stayed the same
+  let window2 = await BrowserTestUtils.openNewBrowserWindow();
+
+  Assert.equal(
+    style.backgroundColor,
+    "rgb(" + FRAME_COLOR.join(", ") + ")",
+    "Inactive window background should not change if colors.frame_inactive isn't set"
+  );
+
+  await BrowserTestUtils.closeWindow(window2);
+  await extension.unload();
+
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_getCurrent.js b/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_getCurrent.js
new file mode 100644
index 0000000000..4a379edfbf
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_getCurrent.js
@@ -0,0 +1,203 @@
+"use strict";
+
+// This test checks whether browser.theme.getCurrent() works correctly in different
+// configurations and with different parameter.
+
+// PNG image data for a simple red dot.
+const BACKGROUND_1 =
+  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";
+// PNG image data for the Mozilla dino head.
+const BACKGROUND_2 =
+  "data:image/png;base64,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";
+
+add_task(async function test_get_current() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      const ACCENT_COLOR_1 = "#a14040";
+      const TEXT_COLOR_1 = "#fac96e";
+
+      const ACCENT_COLOR_2 = "#03fe03";
+      const TEXT_COLOR_2 = "#0ef325";
+
+      const theme1 = {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR_1,
+          tab_background_text: TEXT_COLOR_1,
+        },
+      };
+
+      const theme2 = {
+        images: {
+          theme_frame: "image2.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR_2,
+          tab_background_text: TEXT_COLOR_2,
+        },
+      };
+
+      function ensureWindowFocused(winId) {
+        browser.test.log("Waiting for focused window to be " + winId);
+        // eslint-disable-next-line no-async-promise-executor
+        return new Promise(async resolve => {
+          let listener = windowId => {
+            if (windowId === winId) {
+              browser.windows.onFocusChanged.removeListener(listener);
+              resolve();
+            }
+          };
+          // We first add a listener and then check whether the window is
+          // focused using .get(), because the .get() Promise resolving
+          // could race with the listener running, in which case we'd
+          // never be notified.
+          browser.windows.onFocusChanged.addListener(listener);
+          let { focused } = await browser.windows.get(winId);
+          if (focused) {
+            browser.windows.onFocusChanged.removeListener(listener);
+            resolve();
+          }
+        });
+      }
+
+      function testTheme1(returnedTheme) {
+        browser.test.assertTrue(
+          returnedTheme.images.theme_frame.includes("image1.png"),
+          "Theme 1 theme_frame image should be applied"
+        );
+        browser.test.assertEq(
+          ACCENT_COLOR_1,
+          returnedTheme.colors.frame,
+          "Theme 1 frame color should be applied"
+        );
+        browser.test.assertEq(
+          TEXT_COLOR_1,
+          returnedTheme.colors.tab_background_text,
+          "Theme 1 tab_background_text color should be applied"
+        );
+      }
+
+      function testTheme2(returnedTheme) {
+        browser.test.assertTrue(
+          returnedTheme.images.theme_frame.includes("image2.png"),
+          "Theme 2 theme_frame image should be applied"
+        );
+        browser.test.assertEq(
+          ACCENT_COLOR_2,
+          returnedTheme.colors.frame,
+          "Theme 2 frame color should be applied"
+        );
+        browser.test.assertEq(
+          TEXT_COLOR_2,
+          returnedTheme.colors.tab_background_text,
+          "Theme 2 tab_background_text color should be applied"
+        );
+      }
+
+      function testEmptyTheme(returnedTheme) {
+        browser.test.assertEq(
+          JSON.stringify({ colors: null, images: null, properties: null }),
+          JSON.stringify(returnedTheme),
+          JSON.stringify(returnedTheme, null, 2)
+        );
+      }
+
+      browser.test.log("Testing getCurrent() with initial unthemed window");
+      const firstWin = await browser.windows.getCurrent();
+      testEmptyTheme(await browser.theme.getCurrent());
+      testEmptyTheme(await browser.theme.getCurrent(firstWin.id));
+
+      browser.test.log("Testing getCurrent() with after theme.update()");
+      await browser.theme.update(theme1);
+      testTheme1(await browser.theme.getCurrent());
+      testTheme1(await browser.theme.getCurrent(firstWin.id));
+
+      browser.test.log(
+        "Testing getCurrent() with after theme.update(windowId)"
+      );
+      const secondWin = await browser.windows.create();
+      await ensureWindowFocused(secondWin.id);
+      await browser.theme.update(secondWin.id, theme2);
+      testTheme2(await browser.theme.getCurrent());
+      testTheme1(await browser.theme.getCurrent(firstWin.id));
+      testTheme2(await browser.theme.getCurrent(secondWin.id));
+
+      browser.test.log("Testing getCurrent() after window focus change");
+      let focusChanged = ensureWindowFocused(firstWin.id);
+      await browser.windows.update(firstWin.id, { focused: true });
+      await focusChanged;
+      testTheme1(await browser.theme.getCurrent());
+      testTheme1(await browser.theme.getCurrent(firstWin.id));
+      testTheme2(await browser.theme.getCurrent(secondWin.id));
+
+      browser.test.log(
+        "Testing getCurrent() after another window focus change"
+      );
+      focusChanged = ensureWindowFocused(secondWin.id);
+      await browser.windows.update(secondWin.id, { focused: true });
+      await focusChanged;
+      testTheme2(await browser.theme.getCurrent());
+      testTheme1(await browser.theme.getCurrent(firstWin.id));
+      testTheme2(await browser.theme.getCurrent(secondWin.id));
+
+      browser.test.log("Testing getCurrent() after theme.reset(windowId)");
+      await browser.theme.reset(firstWin.id);
+      testTheme2(await browser.theme.getCurrent());
+      testTheme1(await browser.theme.getCurrent(firstWin.id));
+      testTheme2(await browser.theme.getCurrent(secondWin.id));
+
+      browser.test.log(
+        "Testing getCurrent() after reset and window focus change"
+      );
+      focusChanged = ensureWindowFocused(firstWin.id);
+      await browser.windows.update(firstWin.id, { focused: true });
+      await focusChanged;
+      testTheme1(await browser.theme.getCurrent());
+      testTheme1(await browser.theme.getCurrent(firstWin.id));
+      testTheme2(await browser.theme.getCurrent(secondWin.id));
+
+      browser.test.log("Testing getCurrent() after theme.update(windowId)");
+      await browser.theme.update(firstWin.id, theme1);
+      testTheme1(await browser.theme.getCurrent());
+      testTheme1(await browser.theme.getCurrent(firstWin.id));
+      testTheme2(await browser.theme.getCurrent(secondWin.id));
+
+      browser.test.log("Testing getCurrent() after theme.reset()");
+      await browser.theme.reset();
+      testEmptyTheme(await browser.theme.getCurrent());
+      testEmptyTheme(await browser.theme.getCurrent(firstWin.id));
+      testEmptyTheme(await browser.theme.getCurrent(secondWin.id));
+
+      browser.test.log("Testing getCurrent() after closing a window");
+      await browser.windows.remove(secondWin.id);
+      testEmptyTheme(await browser.theme.getCurrent());
+      testEmptyTheme(await browser.theme.getCurrent(firstWin.id));
+
+      browser.test.log("Testing update calls with invalid window ID");
+      await browser.test.assertRejects(
+        browser.theme.reset(secondWin.id),
+        /Invalid window/,
+        "Invalid window should throw"
+      );
+      await browser.test.assertRejects(
+        browser.theme.update(secondWin.id, theme2),
+        /Invalid window/,
+        "Invalid window should throw"
+      );
+      browser.test.notifyPass("get_current");
+    },
+    manifest: {
+      permissions: ["theme"],
+    },
+    files: {
+      "image1.png": BACKGROUND_1,
+      "image2.png": BACKGROUND_2,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("get_current");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_onUpdated.js b/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_onUpdated.js
new file mode 100644
index 0000000000..34c7162810
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_onUpdated.js
@@ -0,0 +1,154 @@
+"use strict";
+
+// This test checks whether browser.theme.onUpdated works correctly with different
+// types of dynamic theme updates.
+
+// PNG image data for a simple red dot.
+const BACKGROUND_1 =
+  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";
+// PNG image data for the Mozilla dino head.
+const BACKGROUND_2 =
+  "data:image/png;base64,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";
+
+add_task(async function test_on_updated() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      const ACCENT_COLOR_1 = "#a14040";
+      const TEXT_COLOR_1 = "#fac96e";
+
+      const ACCENT_COLOR_2 = "#03fe03";
+      const TEXT_COLOR_2 = "#0ef325";
+
+      const theme1 = {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR_1,
+          tab_background_text: TEXT_COLOR_1,
+        },
+      };
+
+      const theme2 = {
+        images: {
+          theme_frame: "image2.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR_2,
+          tab_background_text: TEXT_COLOR_2,
+        },
+      };
+
+      function testTheme1(returnedTheme) {
+        browser.test.assertTrue(
+          returnedTheme.images.theme_frame.includes("image1.png"),
+          "Theme 1 theme_frame image should be applied"
+        );
+        browser.test.assertEq(
+          ACCENT_COLOR_1,
+          returnedTheme.colors.frame,
+          "Theme 1 frame color should be applied"
+        );
+        browser.test.assertEq(
+          TEXT_COLOR_1,
+          returnedTheme.colors.tab_background_text,
+          "Theme 1 tab_background_text color should be applied"
+        );
+      }
+
+      function testTheme2(returnedTheme) {
+        browser.test.assertTrue(
+          returnedTheme.images.theme_frame.includes("image2.png"),
+          "Theme 2 theme_frame image should be applied"
+        );
+        browser.test.assertEq(
+          ACCENT_COLOR_2,
+          returnedTheme.colors.frame,
+          "Theme 2 frame color should be applied"
+        );
+        browser.test.assertEq(
+          TEXT_COLOR_2,
+          returnedTheme.colors.tab_background_text,
+          "Theme 2 tab_background_text color should be applied"
+        );
+      }
+
+      const firstWin = await browser.windows.getCurrent();
+      const secondWin = await browser.windows.create();
+
+      const onceThemeUpdated = () =>
+        new Promise(resolve => {
+          const listener = updateInfo => {
+            browser.theme.onUpdated.removeListener(listener);
+            resolve(updateInfo);
+          };
+          browser.theme.onUpdated.addListener(listener);
+        });
+
+      browser.test.log("Testing update with no windowId parameter");
+      let updateInfo1 = onceThemeUpdated();
+      await browser.theme.update(theme1);
+      updateInfo1 = await updateInfo1;
+      testTheme1(updateInfo1.theme);
+      browser.test.assertTrue(
+        !updateInfo1.windowId,
+        "No window id on first update"
+      );
+
+      browser.test.log("Testing update with windowId parameter");
+      let updateInfo2 = onceThemeUpdated();
+      await browser.theme.update(secondWin.id, theme2);
+      updateInfo2 = await updateInfo2;
+      testTheme2(updateInfo2.theme);
+      browser.test.assertEq(
+        secondWin.id,
+        updateInfo2.windowId,
+        "window id on second update"
+      );
+
+      browser.test.log("Testing reset with windowId parameter");
+      let updateInfo3 = onceThemeUpdated();
+      await browser.theme.reset(firstWin.id);
+      updateInfo3 = await updateInfo3;
+      browser.test.assertEq(
+        0,
+        Object.keys(updateInfo3.theme).length,
+        "Empty theme given on reset"
+      );
+      browser.test.assertEq(
+        firstWin.id,
+        updateInfo3.windowId,
+        "window id on third update"
+      );
+
+      browser.test.log("Testing reset with no windowId parameter");
+      let updateInfo4 = onceThemeUpdated();
+      await browser.theme.reset();
+      updateInfo4 = await updateInfo4;
+      browser.test.assertEq(
+        0,
+        Object.keys(updateInfo4.theme).length,
+        "Empty theme given on reset"
+      );
+      browser.test.assertTrue(
+        !updateInfo4.windowId,
+        "no window id on fourth update"
+      );
+
+      browser.test.log("Cleaning up test");
+      await browser.windows.remove(secondWin.id);
+      browser.test.notifyPass("onUpdated");
+    },
+    manifest: {
+      permissions: ["theme"],
+    },
+    files: {
+      "image1.png": BACKGROUND_1,
+      "image2.png": BACKGROUND_2,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("onUpdated");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_updates.js b/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_updates.js
new file mode 100644
index 0000000000..34e719262d
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_dynamic_updates.js
@@ -0,0 +1,185 @@
+"use strict";
+
+// PNG image data for a simple red dot.
+const BACKGROUND_1 =
+  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";
+const ACCENT_COLOR_1 = "#a14040";
+const TEXT_COLOR_1 = "#fac96e";
+
+// PNG image data for the Mozilla dino head.
+const BACKGROUND_2 =
+  "data:image/png;base64,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";
+const ACCENT_COLOR_2 = "#03fe03";
+const TEXT_COLOR_2 = "#0ef325";
+
+function hexToRGB(hex) {
+  hex = parseInt(hex.indexOf("#") > -1 ? hex.substring(1) : hex, 16);
+  return (
+    "rgb(" + [hex >> 16, (hex & 0x00ff00) >> 8, hex & 0x0000ff].join(", ") + ")"
+  );
+}
+
+function validateTheme(backgroundImage, accentColor, textColor, isLWT) {
+  let docEl = window.document.documentElement;
+  let style = window.getComputedStyle(docEl);
+
+  if (isLWT) {
+    Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+    Assert.equal(
+      docEl.getAttribute("lwthemetextcolor"),
+      "bright",
+      "LWT text color attribute should be set"
+    );
+  }
+
+  Assert.ok(
+    style.backgroundImage.includes(backgroundImage),
+    "Expected correct background image"
+  );
+  if (accentColor.startsWith("#")) {
+    accentColor = hexToRGB(accentColor);
+  }
+  if (textColor.startsWith("#")) {
+    textColor = hexToRGB(textColor);
+  }
+  Assert.equal(
+    style.backgroundColor,
+    accentColor,
+    "Expected correct accent color"
+  );
+  Assert.equal(style.color, textColor, "Expected correct text color");
+}
+
+add_task(async function test_dynamic_theme_updates() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+    },
+    files: {
+      "image1.png": BACKGROUND_1,
+      "image2.png": BACKGROUND_2,
+    },
+    background() {
+      browser.test.onMessage.addListener((msg, details) => {
+        if (msg === "update-theme") {
+          browser.theme.update(details).then(() => {
+            browser.test.sendMessage("theme-updated");
+          });
+        } else {
+          browser.theme.reset().then(() => {
+            browser.test.sendMessage("theme-reset");
+          });
+        }
+      });
+    },
+  });
+
+  let defaultStyle = window.getComputedStyle(window.document.documentElement);
+  await extension.startup();
+
+  extension.sendMessage("update-theme", {
+    images: {
+      theme_frame: "image1.png",
+    },
+    colors: {
+      frame: ACCENT_COLOR_1,
+      tab_background_text: TEXT_COLOR_1,
+    },
+  });
+
+  await extension.awaitMessage("theme-updated");
+
+  validateTheme("image1.png", ACCENT_COLOR_1, TEXT_COLOR_1, true);
+
+  // Check with the LWT aliases (to update on Firefox 69, because the
+  // LWT aliases are going to be removed).
+  extension.sendMessage("update-theme", {
+    images: {
+      theme_frame: "image2.png",
+    },
+    colors: {
+      frame: ACCENT_COLOR_2,
+      tab_background_text: TEXT_COLOR_2,
+    },
+  });
+
+  await extension.awaitMessage("theme-updated");
+
+  validateTheme("image2.png", ACCENT_COLOR_2, TEXT_COLOR_2, true);
+
+  extension.sendMessage("reset-theme");
+
+  await extension.awaitMessage("theme-reset");
+
+  let { backgroundImage, backgroundColor, color } = defaultStyle;
+  validateTheme(backgroundImage, backgroundColor, color, false);
+
+  await extension.unload();
+
+  let docEl = window.document.documentElement;
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+});
+
+add_task(async function test_dynamic_theme_updates_with_data_url() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+    },
+    background() {
+      browser.test.onMessage.addListener((msg, details) => {
+        if (msg === "update-theme") {
+          browser.theme.update(details).then(() => {
+            browser.test.sendMessage("theme-updated");
+          });
+        } else {
+          browser.theme.reset().then(() => {
+            browser.test.sendMessage("theme-reset");
+          });
+        }
+      });
+    },
+  });
+
+  let defaultStyle = window.getComputedStyle(window.document.documentElement);
+  await extension.startup();
+
+  extension.sendMessage("update-theme", {
+    images: {
+      theme_frame: BACKGROUND_1,
+    },
+    colors: {
+      frame: ACCENT_COLOR_1,
+      tab_background_text: TEXT_COLOR_1,
+    },
+  });
+
+  await extension.awaitMessage("theme-updated");
+
+  validateTheme(BACKGROUND_1, ACCENT_COLOR_1, TEXT_COLOR_1, true);
+
+  extension.sendMessage("update-theme", {
+    images: {
+      theme_frame: BACKGROUND_2,
+    },
+    colors: {
+      frame: ACCENT_COLOR_2,
+      tab_background_text: TEXT_COLOR_2,
+    },
+  });
+
+  await extension.awaitMessage("theme-updated");
+
+  validateTheme(BACKGROUND_2, ACCENT_COLOR_2, TEXT_COLOR_2, true);
+
+  extension.sendMessage("reset-theme");
+
+  await extension.awaitMessage("theme-reset");
+
+  let { backgroundImage, backgroundColor, color } = defaultStyle;
+  validateTheme(backgroundImage, backgroundColor, color, false);
+
+  await extension.unload();
+
+  let docEl = window.document.documentElement;
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_experiment.js b/toolkit/components/extensions/test/browser/browser_ext_themes_experiment.js
new file mode 100644
index 0000000000..7b362498e7
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_experiment.js
@@ -0,0 +1,401 @@
+"use strict";
+
+const { AddonSettings } = ChromeUtils.import(
+  "resource://gre/modules/addons/AddonSettings.jsm"
+);
+
+// This test checks whether the theme experiments work
+add_task(async function test_experiment_static_theme() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          some_color_property: "#ff00ff",
+        },
+        images: {
+          some_image_property: "background.jpg",
+        },
+        properties: {
+          some_random_property: "no-repeat",
+        },
+      },
+      theme_experiment: {
+        colors: {
+          some_color_property: "--some-color-property",
+        },
+        images: {
+          some_image_property: "--some-image-property",
+        },
+        properties: {
+          some_random_property: "--some-random-property",
+        },
+      },
+    },
+  });
+
+  const root = window.document.documentElement;
+
+  is(
+    root.style.getPropertyValue("--some-color-property"),
+    "",
+    "Color property should be unset"
+  );
+  is(
+    root.style.getPropertyValue("--some-image-property"),
+    "",
+    "Image property should be unset"
+  );
+  is(
+    root.style.getPropertyValue("--some-random-property"),
+    "",
+    "Generic Property should be unset."
+  );
+
+  await extension.startup();
+
+  const testExperimentApplied = rootEl => {
+    if (AddonSettings.EXPERIMENTS_ENABLED) {
+      is(
+        rootEl.style.getPropertyValue("--some-color-property"),
+        hexToCSS("#ff00ff"),
+        "Color property should be parsed and set."
+      );
+      ok(
+        rootEl.style
+          .getPropertyValue("--some-image-property")
+          .startsWith("url("),
+        "Image property should be parsed."
+      );
+      ok(
+        rootEl.style
+          .getPropertyValue("--some-image-property")
+          .endsWith("background.jpg)"),
+        "Image property should be set."
+      );
+      is(
+        rootEl.style.getPropertyValue("--some-random-property"),
+        "no-repeat",
+        "Generic Property should be set."
+      );
+    } else {
+      is(
+        rootEl.style.getPropertyValue("--some-color-property"),
+        "",
+        "Color property should be unset"
+      );
+      is(
+        rootEl.style.getPropertyValue("--some-image-property"),
+        "",
+        "Image property should be unset"
+      );
+      is(
+        rootEl.style.getPropertyValue("--some-random-property"),
+        "",
+        "Generic Property should be unset."
+      );
+    }
+  };
+
+  info("Testing that current window updated with the experiment applied");
+  testExperimentApplied(root);
+
+  info("Testing that new window initialized with the experiment applied");
+  const newWindow = await BrowserTestUtils.openNewBrowserWindow();
+  const newWindowRoot = newWindow.document.documentElement;
+  testExperimentApplied(newWindowRoot);
+
+  await extension.unload();
+
+  info("Testing that both windows unapplied the experiment");
+  for (const rootEl of [root, newWindowRoot]) {
+    is(
+      rootEl.style.getPropertyValue("--some-color-property"),
+      "",
+      "Color property should be unset"
+    );
+    is(
+      rootEl.style.getPropertyValue("--some-image-property"),
+      "",
+      "Image property should be unset"
+    );
+    is(
+      rootEl.style.getPropertyValue("--some-random-property"),
+      "",
+      "Generic Property should be unset."
+    );
+  }
+  await BrowserTestUtils.closeWindow(newWindow);
+});
+
+add_task(async function test_experiment_dynamic_theme() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+      theme_experiment: {
+        colors: {
+          some_color_property: "--some-color-property",
+        },
+        images: {
+          some_image_property: "--some-image-property",
+        },
+        properties: {
+          some_random_property: "--some-random-property",
+        },
+      },
+    },
+    background() {
+      const theme = {
+        colors: {
+          some_color_property: "#ff00ff",
+        },
+        images: {
+          some_image_property: "background.jpg",
+        },
+        properties: {
+          some_random_property: "no-repeat",
+        },
+      };
+      browser.test.onMessage.addListener(msg => {
+        if (msg === "update-theme") {
+          browser.theme.update(theme).then(() => {
+            browser.test.sendMessage("theme-updated");
+          });
+        } else {
+          browser.theme.reset().then(() => {
+            browser.test.sendMessage("theme-reset");
+          });
+        }
+      });
+    },
+  });
+
+  await extension.startup();
+
+  const root = window.document.documentElement;
+
+  is(
+    root.style.getPropertyValue("--some-color-property"),
+    "",
+    "Color property should be unset"
+  );
+  is(
+    root.style.getPropertyValue("--some-image-property"),
+    "",
+    "Image property should be unset"
+  );
+  is(
+    root.style.getPropertyValue("--some-random-property"),
+    "",
+    "Generic Property should be unset."
+  );
+
+  extension.sendMessage("update-theme");
+  await extension.awaitMessage("theme-updated");
+
+  const testExperimentApplied = rootEl => {
+    if (AddonSettings.EXPERIMENTS_ENABLED) {
+      is(
+        rootEl.style.getPropertyValue("--some-color-property"),
+        hexToCSS("#ff00ff"),
+        "Color property should be parsed and set."
+      );
+      ok(
+        rootEl.style
+          .getPropertyValue("--some-image-property")
+          .startsWith("url("),
+        "Image property should be parsed."
+      );
+      ok(
+        rootEl.style
+          .getPropertyValue("--some-image-property")
+          .endsWith("background.jpg)"),
+        "Image property should be set."
+      );
+      is(
+        rootEl.style.getPropertyValue("--some-random-property"),
+        "no-repeat",
+        "Generic Property should be set."
+      );
+    } else {
+      is(
+        rootEl.style.getPropertyValue("--some-color-property"),
+        "",
+        "Color property should be unset"
+      );
+      is(
+        rootEl.style.getPropertyValue("--some-image-property"),
+        "",
+        "Image property should be unset"
+      );
+      is(
+        rootEl.style.getPropertyValue("--some-random-property"),
+        "",
+        "Generic Property should be unset."
+      );
+    }
+  };
+  testExperimentApplied(root);
+
+  const newWindow = await BrowserTestUtils.openNewBrowserWindow();
+  const newWindowRoot = newWindow.document.documentElement;
+
+  testExperimentApplied(newWindowRoot);
+
+  extension.sendMessage("reset-theme");
+  await extension.awaitMessage("theme-reset");
+
+  for (const rootEl of [root, newWindowRoot]) {
+    is(
+      rootEl.style.getPropertyValue("--some-color-property"),
+      "",
+      "Color property should be unset"
+    );
+    is(
+      rootEl.style.getPropertyValue("--some-image-property"),
+      "",
+      "Image property should be unset"
+    );
+    is(
+      rootEl.style.getPropertyValue("--some-random-property"),
+      "",
+      "Generic Property should be unset."
+    );
+  }
+
+  extension.sendMessage("update-theme");
+  await extension.awaitMessage("theme-updated");
+
+  testExperimentApplied(root);
+  testExperimentApplied(newWindowRoot);
+
+  await extension.unload();
+
+  for (const rootEl of [root, newWindowRoot]) {
+    is(
+      rootEl.style.getPropertyValue("--some-color-property"),
+      "",
+      "Color property should be unset"
+    );
+    is(
+      rootEl.style.getPropertyValue("--some-image-property"),
+      "",
+      "Image property should be unset"
+    );
+    is(
+      rootEl.style.getPropertyValue("--some-random-property"),
+      "",
+      "Generic Property should be unset."
+    );
+  }
+
+  await BrowserTestUtils.closeWindow(newWindow);
+});
+
+add_task(async function test_experiment_stylesheet() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          menu_button_background: "#ff00ff",
+        },
+      },
+      theme_experiment: {
+        stylesheet: "experiment.css",
+        colors: {
+          menu_button_background: "--menu-button-background",
+        },
+      },
+    },
+    files: {
+      "experiment.css": `#PanelUI-menu-button {
+        background-color: var(--menu-button-background);
+        fill: white;
+      }`,
+    },
+  });
+
+  const root = window.document.documentElement;
+  const menuButton = document.getElementById("PanelUI-menu-button");
+  const computedStyle = window.getComputedStyle(menuButton);
+  const expectedColor = hexToCSS("#ff00ff");
+  const expectedFill = hexToCSS("#ffffff");
+
+  is(
+    root.style.getPropertyValue("--menu-button-background"),
+    "",
+    "Variable should be unset"
+  );
+  isnot(
+    computedStyle.backgroundColor,
+    expectedColor,
+    "Menu button should not have custom background"
+  );
+  isnot(
+    computedStyle.fill,
+    expectedFill,
+    "Menu button should not have stylesheet fill"
+  );
+
+  await extension.startup();
+
+  if (AddonSettings.EXPERIMENTS_ENABLED) {
+    // Wait for stylesheet load.
+    await BrowserTestUtils.waitForCondition(
+      () => computedStyle.fill === expectedFill
+    );
+
+    is(
+      root.style.getPropertyValue("--menu-button-background"),
+      expectedColor,
+      "Variable should be parsed and set."
+    );
+    is(
+      computedStyle.backgroundColor,
+      expectedColor,
+      "Menu button should be have correct background"
+    );
+    is(
+      computedStyle.fill,
+      expectedFill,
+      "Menu button should be have correct fill"
+    );
+  } else {
+    is(
+      root.style.getPropertyValue("--menu-button-background"),
+      "",
+      "Variable should be unset"
+    );
+    isnot(
+      computedStyle.backgroundColor,
+      expectedColor,
+      "Menu button should not have custom background"
+    );
+    isnot(
+      computedStyle.fill,
+      expectedFill,
+      "Menu button should not have stylesheet fill"
+    );
+  }
+
+  await extension.unload();
+
+  is(
+    root.style.getPropertyValue("--menu-button-background"),
+    "",
+    "Variable should be unset"
+  );
+  isnot(
+    computedStyle.backgroundColor,
+    expectedColor,
+    "Menu button should not have custom background"
+  );
+  isnot(
+    computedStyle.fill,
+    expectedFill,
+    "Menu button should not have stylesheet fill"
+  );
+});
+
+add_task(async function cleanup() {
+  await SpecialPowers.popPrefEnv();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_findbar.js b/toolkit/components/extensions/test/browser/browser_ext_themes_findbar.js
new file mode 100644
index 0000000000..fe9689bc74
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_findbar.js
@@ -0,0 +1,217 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the toolbar and toolbar_field properties also theme the findbar.
+
+add_task(async function test_support_toolbar_properties_on_findbar() {
+  const TOOLBAR_COLOR = "#ff00ff";
+  const TOOLBAR_TEXT_COLOR = "#9400ff";
+  const ACCENT_COLOR_INACTIVE = "#ffff00";
+  // The TabContextMenu initializes its strings only on a focus or mouseover event.
+  // Calls focus event on the TabContextMenu early in the test.
+  gBrowser.selectedTab.focus();
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          frame_inactive: ACCENT_COLOR_INACTIVE,
+          tab_background_text: TEXT_COLOR,
+          toolbar: TOOLBAR_COLOR,
+          bookmark_text: TOOLBAR_TEXT_COLOR,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+  await gBrowser.getFindBar();
+
+  let findbar_button = gFindBar.getElement("highlight");
+
+  info("Checking findbar background is set as toolbar color");
+  Assert.equal(
+    window.getComputedStyle(gFindBar).backgroundColor,
+    hexToCSS(ACCENT_COLOR),
+    "Findbar background color should be the same as toolbar background color."
+  );
+
+  info("Checking findbar and button text color is set as toolbar text color");
+  Assert.equal(
+    window.getComputedStyle(gFindBar).color,
+    hexToCSS(TOOLBAR_TEXT_COLOR),
+    "Findbar text color should be the same as toolbar text color."
+  );
+  Assert.equal(
+    window.getComputedStyle(findbar_button).color,
+    hexToCSS(TOOLBAR_TEXT_COLOR),
+    "Findbar button text color should be the same as toolbar text color."
+  );
+
+  // Open a new window to check frame_inactive
+  let window2 = await BrowserTestUtils.openNewBrowserWindow();
+  Assert.equal(
+    window.getComputedStyle(gFindBar).backgroundColor,
+    hexToCSS(ACCENT_COLOR_INACTIVE),
+    "Findbar background changed in inactive window."
+  );
+  await BrowserTestUtils.closeWindow(window2);
+
+  await extension.unload();
+});
+
+add_task(async function test_support_toolbar_field_properties_on_findbar() {
+  const TOOLBAR_FIELD_COLOR = "#ff00ff";
+  const TOOLBAR_FIELD_TEXT_COLOR = "#9400ff";
+  const TOOLBAR_FIELD_BORDER_COLOR = "#ffffff";
+  // The TabContextMenu initializes its strings only on a focus or mouseover event.
+  // Calls focus event on the TabContextMenu early in the test.
+  gBrowser.selectedTab.focus();
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_field: TOOLBAR_FIELD_COLOR,
+          toolbar_field_text: TOOLBAR_FIELD_TEXT_COLOR,
+          toolbar_field_border: TOOLBAR_FIELD_BORDER_COLOR,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+  await gBrowser.getFindBar();
+
+  let findbar_textbox = gFindBar.getElement("findbar-textbox");
+
+  let findbar_prev_button = gFindBar.getElement("find-previous");
+
+  let findbar_next_button = gFindBar.getElement("find-next");
+
+  info(
+    "Checking findbar textbox background is set as toolbar field background color"
+  );
+  Assert.equal(
+    window.getComputedStyle(findbar_textbox).backgroundColor,
+    hexToCSS(TOOLBAR_FIELD_COLOR),
+    "Findbar textbox background color should be the same as toolbar field color."
+  );
+
+  info("Checking findbar textbox color is set as toolbar field text color");
+  Assert.equal(
+    window.getComputedStyle(findbar_textbox).color,
+    hexToCSS(TOOLBAR_FIELD_TEXT_COLOR),
+    "Findbar textbox text color should be the same as toolbar field text color."
+  );
+  testBorderColor(findbar_textbox, TOOLBAR_FIELD_BORDER_COLOR);
+  testBorderColor(findbar_prev_button, TOOLBAR_FIELD_BORDER_COLOR);
+  testBorderColor(findbar_next_button, TOOLBAR_FIELD_BORDER_COLOR);
+
+  await extension.unload();
+});
+
+// Test that theme properties are *not* applied with a theme_frame (see bug 1506913)
+add_task(async function test_toolbar_properties_on_findbar_with_theme_frame() {
+  const TOOLBAR_COLOR = "#ff00ff";
+  const TOOLBAR_TEXT_COLOR = "#9400ff";
+  // The TabContextMenu initializes its strings only on a focus or mouseover event.
+  // Calls focus event on the TabContextMenu early in the test.
+  gBrowser.selectedTab.focus();
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar: TOOLBAR_COLOR,
+          bookmark_text: TOOLBAR_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+  await gBrowser.getFindBar();
+
+  let findbar_button = gFindBar.getElement("highlight");
+
+  info("Checking findbar background is *not* set as toolbar color");
+  Assert.notEqual(
+    window.getComputedStyle(gFindBar).backgroundColor,
+    hexToCSS(ACCENT_COLOR),
+    "Findbar background color should not be set by theme."
+  );
+
+  info(
+    "Checking findbar and button text color is *not* set as toolbar text color"
+  );
+  Assert.notEqual(
+    window.getComputedStyle(gFindBar).color,
+    hexToCSS(TOOLBAR_TEXT_COLOR),
+    "Findbar text color should not be set by theme."
+  );
+  Assert.notEqual(
+    window.getComputedStyle(findbar_button).color,
+    hexToCSS(TOOLBAR_TEXT_COLOR),
+    "Findbar button text color should not be set by theme."
+  );
+
+  await extension.unload();
+});
+
+add_task(
+  async function test_toolbar_field_properties_on_findbar_with_theme_frame() {
+    const TOOLBAR_FIELD_COLOR = "#ff00ff";
+    const TOOLBAR_FIELD_TEXT_COLOR = "#9400ff";
+    const TOOLBAR_FIELD_BORDER_COLOR = "#ffffff";
+    // The TabContextMenu initializes its strings only on a focus or mouseover event.
+    // Calls focus event on the TabContextMenu early in the test.
+    gBrowser.selectedTab.focus();
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        theme: {
+          images: {
+            theme_frame: "image1.png",
+          },
+          colors: {
+            frame: ACCENT_COLOR,
+            tab_background_text: TEXT_COLOR,
+            toolbar_field: TOOLBAR_FIELD_COLOR,
+            toolbar_field_text: TOOLBAR_FIELD_TEXT_COLOR,
+            toolbar_field_border: TOOLBAR_FIELD_BORDER_COLOR,
+          },
+        },
+      },
+      files: {
+        "image1.png": BACKGROUND,
+      },
+    });
+
+    await extension.startup();
+    await gBrowser.getFindBar();
+
+    let findbar_textbox = gFindBar.getElement("findbar-textbox");
+
+    Assert.notEqual(
+      window.getComputedStyle(findbar_textbox).backgroundColor,
+      hexToCSS(TOOLBAR_FIELD_COLOR),
+      "Findbar textbox background color should not be set by theme."
+    );
+
+    Assert.notEqual(
+      window.getComputedStyle(findbar_textbox).color,
+      hexToCSS(TOOLBAR_FIELD_TEXT_COLOR),
+      "Findbar textbox text color should not be set by theme."
+    );
+
+    await extension.unload();
+  }
+);
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_getCurrent_differentExt.js b/toolkit/components/extensions/test/browser/browser_ext_themes_getCurrent_differentExt.js
new file mode 100644
index 0000000000..981f32d7fb
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_getCurrent_differentExt.js
@@ -0,0 +1,66 @@
+"use strict";
+
+// This test checks whether browser.theme.getCurrent() works correctly when theme
+// does not originate from extension querying the theme.
+
+add_task(async function test_getcurrent() {
+  const theme = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  const extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.theme.onUpdated.addListener(() => {
+        browser.theme.getCurrent().then(theme => {
+          browser.test.sendMessage("theme-updated", theme);
+        });
+      });
+    },
+  });
+
+  await extension.startup();
+
+  info("Testing getCurrent after static theme startup");
+  let updatedPromise = extension.awaitMessage("theme-updated");
+  await theme.startup();
+  let receivedTheme = await updatedPromise;
+  Assert.ok(
+    receivedTheme.images.theme_frame.includes("image1.png"),
+    "getCurrent returns correct theme_frame image"
+  );
+  Assert.equal(
+    receivedTheme.colors.frame,
+    ACCENT_COLOR,
+    "getCurrent returns correct frame color"
+  );
+  Assert.equal(
+    receivedTheme.colors.tab_background_text,
+    TEXT_COLOR,
+    "getCurrent returns correct tab_background_text color"
+  );
+
+  info("Testing getCurrent after static theme unload");
+  updatedPromise = extension.awaitMessage("theme-updated");
+  await theme.unload();
+  receivedTheme = await updatedPromise;
+  Assert.equal(
+    JSON.stringify({ colors: null, images: null, properties: null }),
+    JSON.stringify(receivedTheme),
+    "getCurrent returns empty theme"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_highlight.js b/toolkit/components/extensions/test/browser/browser_ext_themes_highlight.js
new file mode 100644
index 0000000000..083eb85486
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_highlight.js
@@ -0,0 +1,61 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the color of the font and background in a selection are applied properly.
+ChromeUtils.import(
+  "resource://testing-common/CustomizableUITestUtils.jsm",
+  this
+);
+let gCUITestUtils = new CustomizableUITestUtils(window);
+add_task(async function setup() {
+  await gCUITestUtils.addSearchBar();
+  registerCleanupFunction(() => {
+    gCUITestUtils.removeSearchBar();
+  });
+});
+
+add_task(async function test_support_selection() {
+  const HIGHLIGHT_TEXT_COLOR = "#9400FF";
+  const HIGHLIGHT_COLOR = "#F89919";
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          toolbar_field_highlight: HIGHLIGHT_COLOR,
+          toolbar_field_highlight_text: HIGHLIGHT_TEXT_COLOR,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let fields = [
+    gURLBar.inputField,
+    document.querySelector("#searchbar .searchbar-textbox"),
+  ].filter(field => {
+    let bounds = field.getBoundingClientRect();
+    return bounds.width > 0 && bounds.height > 0;
+  });
+
+  Assert.equal(fields.length, 2, "Should be testing two elements");
+
+  info(
+    `Checking background colors and colors for ${fields.length} toolbar input fields.`
+  );
+  for (let field of fields) {
+    info(`Testing ${field.id || field.className}`);
+    Assert.equal(
+      window.getComputedStyle(field, "::selection").backgroundColor,
+      hexToCSS(HIGHLIGHT_COLOR),
+      "Input selection background should be set."
+    );
+    Assert.equal(
+      window.getComputedStyle(field, "::selection").color,
+      hexToCSS(HIGHLIGHT_TEXT_COLOR),
+      "Input selection color should be set."
+    );
+  }
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_incognito.js b/toolkit/components/extensions/test/browser/browser_ext_themes_incognito.js
new file mode 100644
index 0000000000..4917f6f830
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_incognito.js
@@ -0,0 +1,81 @@
+"use strict";
+
+add_task(async function test_theme_incognito_not_allowed() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.allowPrivateBrowsingByDefault", false]],
+  });
+
+  let windowExtension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    async background() {
+      const theme = {
+        colors: {
+          frame: "black",
+          tab_background_text: "black",
+        },
+      };
+      let window = await browser.windows.create({ incognito: true });
+      browser.test.onMessage.addListener(async message => {
+        if (message == "update") {
+          browser.theme.update(window.id, theme);
+          return;
+        }
+        await browser.windows.remove(window.id);
+        browser.test.sendMessage("done");
+      });
+      browser.test.sendMessage("ready", window.id);
+    },
+    manifest: {
+      permissions: ["theme"],
+    },
+  });
+  await windowExtension.startup();
+  let wId = await windowExtension.awaitMessage("ready");
+
+  async function background(windowId) {
+    const theme = {
+      colors: {
+        frame: "black",
+        tab_background_text: "black",
+      },
+    };
+
+    browser.theme.onUpdated.addListener(info => {
+      browser.test.log("got theme onChanged");
+      browser.test.fail("theme");
+    });
+    await browser.test.assertRejects(
+      browser.theme.getCurrent(windowId),
+      /Invalid window ID/,
+      "API should reject getting window theme"
+    );
+    await browser.test.assertRejects(
+      browser.theme.update(windowId, theme),
+      /Invalid window ID/,
+      "API should reject updating theme"
+    );
+    await browser.test.assertRejects(
+      browser.theme.reset(windowId),
+      /Invalid window ID/,
+      "API should reject reseting theme on window"
+    );
+
+    browser.test.sendMessage("start");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${background})(${wId})`,
+    manifest: {
+      permissions: ["theme"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("start");
+  windowExtension.sendMessage("update");
+
+  windowExtension.sendMessage("close");
+  await windowExtension.awaitMessage("done");
+  await windowExtension.unload();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_lwtsupport.js b/toolkit/components/extensions/test/browser/browser_ext_themes_lwtsupport.js
new file mode 100644
index 0000000000..af2eef6ffb
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_lwtsupport.js
@@ -0,0 +1,57 @@
+"use strict";
+
+const DEFAULT_THEME_BG_COLOR = "rgb(255, 255, 255)";
+const DEFAULT_THEME_TEXT_COLOR = "rgb(0, 0, 0)";
+
+add_task(async function test_deprecated_LWT_properties_ignored() {
+  // This test uses deprecated theme properties, so warnings are expected.
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          headerURL: "image1.png",
+        },
+        colors: {
+          accentcolor: ACCENT_COLOR,
+          textcolor: TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  let style = window.getComputedStyle(docEl);
+
+  Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+  Assert.ok(
+    !docEl.hasAttribute("lwtheme-image"),
+    "LWT image attribute should not be set on deprecated headerURL alias"
+  );
+  Assert.equal(
+    docEl.getAttribute("lwthemetextcolor"),
+    "dark",
+    "LWT text color attribute should not be set on deprecated textcolor alias"
+  );
+
+  Assert.equal(
+    style.backgroundColor,
+    DEFAULT_THEME_BG_COLOR,
+    "Expected default theme background color"
+  );
+  Assert.equal(
+    style.color,
+    DEFAULT_THEME_TEXT_COLOR,
+    "Expected default theme text color"
+  );
+
+  await extension.unload();
+
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_multiple_backgrounds.js b/toolkit/components/extensions/test/browser/browser_ext_themes_multiple_backgrounds.js
new file mode 100644
index 0000000000..1395647683
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_multiple_backgrounds.js
@@ -0,0 +1,216 @@
+"use strict";
+
+add_task(async function test_support_backgrounds_position() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "face1.png",
+          additional_backgrounds: ["face2.png", "face2.png", "face2.png"],
+        },
+        colors: {
+          frame: `rgb(${FRAME_COLOR.join(",")})`,
+          tab_background_text: `rgb(${TAB_BACKGROUND_TEXT_COLOR.join(",")})`,
+        },
+        properties: {
+          additional_backgrounds_alignment: [
+            "left top",
+            "center top",
+            "right bottom",
+          ],
+        },
+      },
+    },
+    files: {
+      "face1.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+      "face2.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  let toolbox = document.querySelector("#navigator-toolbox");
+
+  Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+  Assert.equal(
+    docEl.getAttribute("lwthemetextcolor"),
+    "bright",
+    "LWT text color attribute should be set"
+  );
+
+  let toolboxCS = window.getComputedStyle(toolbox);
+  let rootCS = window.getComputedStyle(docEl);
+  let rootBgImage = rootCS.backgroundImage.split(",")[0].trim();
+  let bgImage = toolboxCS.backgroundImage.split(",")[0].trim();
+  Assert.ok(
+    rootBgImage.includes("face1.png"),
+    `The backgroundImage should use face1.png. Actual value is: ${rootBgImage}`
+  );
+  Assert.equal(
+    toolboxCS.backgroundImage,
+    Array(3)
+      .fill(bgImage)
+      .join(", "),
+    "The backgroundImage should use face2.png three times."
+  );
+  Assert.equal(
+    toolboxCS.backgroundPosition,
+    "0% 0%, 50% 0%, 100% 100%",
+    "The backgroundPosition should use the three values provided."
+  );
+  Assert.equal(
+    toolboxCS.backgroundRepeat,
+    "no-repeat",
+    "The backgroundPosition should use the default value."
+  );
+
+  await extension.unload();
+
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+  toolboxCS = window.getComputedStyle(toolbox);
+
+  // Styles should've reverted to their initial values.
+  Assert.equal(rootCS.backgroundImage, "none");
+  Assert.equal(rootCS.backgroundPosition, "0% 0%");
+  Assert.equal(rootCS.backgroundRepeat, "repeat");
+  Assert.equal(toolboxCS.backgroundImage, "none");
+  Assert.equal(toolboxCS.backgroundPosition, "0% 0%");
+  Assert.equal(toolboxCS.backgroundRepeat, "repeat");
+});
+
+add_task(async function test_support_backgrounds_repeat() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "face0.png",
+          additional_backgrounds: ["face1.png", "face2.png", "face3.png"],
+        },
+        colors: {
+          frame: FRAME_COLOR,
+          tab_background_text: TAB_BACKGROUND_TEXT_COLOR,
+        },
+        properties: {
+          additional_backgrounds_tiling: ["repeat-x", "repeat-y", "repeat"],
+        },
+      },
+    },
+    files: {
+      "face0.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+      "face1.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+      "face2.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+      "face3.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  let toolbox = document.querySelector("#navigator-toolbox");
+
+  Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+  Assert.equal(
+    docEl.getAttribute("lwthemetextcolor"),
+    "bright",
+    "LWT text color attribute should be set"
+  );
+
+  let rootCS = window.getComputedStyle(docEl);
+  let toolboxCS = window.getComputedStyle(toolbox);
+  let bgImage = rootCS.backgroundImage.split(",")[0].trim();
+  Assert.ok(
+    bgImage.includes("face0.png"),
+    `The backgroundImage should use face.png. Actual value is: ${bgImage}`
+  );
+  Assert.equal(
+    [1, 2, 3].map(num => bgImage.replace(/face[\d]*/, `face${num}`)).join(", "),
+    toolboxCS.backgroundImage,
+    "The backgroundImage should use face.png three times."
+  );
+  Assert.equal(
+    rootCS.backgroundPosition,
+    "100% 0%",
+    "The backgroundPosition should use the default value for root."
+  );
+  Assert.equal(
+    toolboxCS.backgroundPosition,
+    "100% 0%",
+    "The backgroundPosition should use the default value for navigator-toolbox."
+  );
+  Assert.equal(
+    rootCS.backgroundRepeat,
+    "no-repeat",
+    "The backgroundRepeat should use the default values for root."
+  );
+  Assert.equal(
+    toolboxCS.backgroundRepeat,
+    "repeat-x, repeat-y, repeat",
+    "The backgroundRepeat should use the three values provided for navigator-toolbox."
+  );
+
+  await extension.unload();
+
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+});
+
+add_task(async function test_additional_images_check() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "face.png",
+        },
+        colors: {
+          frame: FRAME_COLOR,
+          tab_background_text: TAB_BACKGROUND_TEXT_COLOR,
+        },
+        properties: {
+          additional_backgrounds_tiling: ["repeat-x", "repeat-y", "repeat"],
+        },
+      },
+    },
+    files: {
+      "face.png": imageBufferFromDataURI(ENCODED_IMAGE_DATA),
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  let toolbox = document.querySelector("#navigator-toolbox");
+
+  Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+  Assert.equal(
+    docEl.getAttribute("lwthemetextcolor"),
+    "bright",
+    "LWT text color attribute should be set"
+  );
+
+  let rootCS = window.getComputedStyle(docEl);
+  let toolboxCS = window.getComputedStyle(toolbox);
+  let bgImage = rootCS.backgroundImage.split(",")[0];
+  Assert.ok(
+    bgImage.includes("face.png"),
+    `The backgroundImage should use face.png. Actual value is: ${bgImage}`
+  );
+  Assert.equal(
+    "none",
+    toolboxCS.backgroundImage,
+    "The backgroundImage should not use face.png."
+  );
+  Assert.equal(
+    rootCS.backgroundPosition,
+    "100% 0%",
+    "The backgroundPosition should use the default value."
+  );
+  Assert.equal(
+    rootCS.backgroundRepeat,
+    "no-repeat",
+    "The backgroundPosition should use only one (default) value."
+  );
+
+  await extension.unload();
+
+  Assert.ok(!docEl.hasAttribute("lwtheme"), "LWT attribute should not be set");
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors.js b/toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors.js
new file mode 100644
index 0000000000..3e5d789709
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors.js
@@ -0,0 +1,157 @@
+"use strict";
+
+// This test checks whether the new tab page color properties work.
+
+/**
+ * Test whether the selected browser has the new tab page theme applied
+ * @param {Object} theme that is applied
+ * @param {boolean} isBrightText whether the brighttext attribute should be set
+ */
+async function test_ntp_theme(theme, isBrightText) {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme,
+    },
+  });
+
+  let browser = gBrowser.selectedBrowser;
+
+  let { originalBackground, originalColor } = await SpecialPowers.spawn(
+    browser,
+    [],
+    function() {
+      let doc = content.document;
+      ok(
+        !doc.body.hasAttribute("lwt-newtab"),
+        "New tab page should not have lwt-newtab attribute"
+      );
+      ok(
+        !doc.body.hasAttribute("lwt-newtab-brighttext"),
+        `New tab page should not have lwt-newtab-brighttext attribute`
+      );
+
+      return {
+        originalBackground: content.getComputedStyle(doc.body).backgroundColor,
+        originalColor: content.getComputedStyle(
+          doc.querySelector(".outer-wrapper")
+        ).color,
+      };
+    }
+  );
+
+  await extension.startup();
+
+  Services.ppmm.sharedData.flush();
+
+  await SpecialPowers.spawn(
+    browser,
+    [
+      {
+        isBrightText,
+        background: hexToCSS(theme.colors.ntp_background),
+        color: hexToCSS(theme.colors.ntp_text),
+      },
+    ],
+    function({ isBrightText, background, color }) {
+      let doc = content.document;
+      ok(
+        doc.body.hasAttribute("lwt-newtab"),
+        "New tab page should have lwt-newtab attribute"
+      );
+      is(
+        doc.body.hasAttribute("lwt-newtab-brighttext"),
+        isBrightText,
+        `New tab page should${
+          !isBrightText ? " not" : ""
+        } have lwt-newtab-brighttext attribute`
+      );
+
+      is(
+        content.getComputedStyle(doc.body).backgroundColor,
+        background,
+        "New tab page background should be set."
+      );
+      is(
+        content.getComputedStyle(doc.querySelector(".outer-wrapper")).color,
+        color,
+        "New tab page text color should be set."
+      );
+    }
+  );
+
+  await extension.unload();
+
+  Services.ppmm.sharedData.flush();
+
+  await SpecialPowers.spawn(
+    browser,
+    [
+      {
+        originalBackground,
+        originalColor,
+      },
+    ],
+    function({ originalBackground, originalColor }) {
+      let doc = content.document;
+      ok(
+        !doc.body.hasAttribute("lwt-newtab"),
+        "New tab page should not have lwt-newtab attribute"
+      );
+      ok(
+        !doc.body.hasAttribute("lwt-newtab-brighttext"),
+        `New tab page should not have lwt-newtab-brighttext attribute`
+      );
+
+      is(
+        content.getComputedStyle(doc.body).backgroundColor,
+        originalBackground,
+        "New tab page background should be reset."
+      );
+      is(
+        content.getComputedStyle(doc.querySelector(".outer-wrapper")).color,
+        originalColor,
+        "New tab page text color should be reset."
+      );
+    }
+  );
+}
+
+add_task(async function test_support_ntp_colors() {
+  // BrowserTestUtils.withNewTab waits for about:newtab to load
+  // so we disable preloading before running the test.
+  SpecialPowers.setBoolPref("browser.newtab.preload", false);
+  registerCleanupFunction(() => {
+    SpecialPowers.clearUserPref("browser.newtab.preload");
+  });
+  NewTabPagePreloading.removePreloadedBrowser(window);
+  for (let url of ["about:newtab", "about:home", "about:welcome"]) {
+    info("Opening url: " + url);
+    await BrowserTestUtils.withNewTab({ gBrowser, url }, async browser => {
+      await test_ntp_theme(
+        {
+          colors: {
+            frame: ACCENT_COLOR,
+            tab_background_text: TEXT_COLOR,
+            ntp_background: "#add8e6",
+            ntp_text: "#00008b",
+          },
+        },
+        false,
+        url
+      );
+
+      await test_ntp_theme(
+        {
+          colors: {
+            frame: ACCENT_COLOR,
+            tab_background_text: TEXT_COLOR,
+            ntp_background: "#00008b",
+            ntp_text: "#add8e6",
+          },
+        },
+        true,
+        url
+      );
+    });
+  }
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors_perwindow.js b/toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors_perwindow.js
new file mode 100644
index 0000000000..bf204632ec
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors_perwindow.js
@@ -0,0 +1,249 @@
+"use strict";
+
+// This test checks whether the new tab page color properties work per-window.
+
+/**
+ * Test whether a given browser has the new tab page theme applied
+ * @param {Object} browser to test against
+ * @param {Object} theme that is applied
+ * @param {boolean} isBrightText whether the brighttext attribute should be set
+ * @returns {Promise} The task as a promise
+ */
+function test_ntp_theme(browser, theme, isBrightText) {
+  Services.ppmm.sharedData.flush();
+  return SpecialPowers.spawn(
+    browser,
+    [
+      {
+        isBrightText,
+        background: hexToCSS(theme.colors.ntp_background),
+        color: hexToCSS(theme.colors.ntp_text),
+      },
+    ],
+    function({ isBrightText, background, color }) {
+      let doc = content.document;
+      ok(
+        doc.body.hasAttribute("lwt-newtab"),
+        "New tab page should have lwt-newtab attribute"
+      );
+      is(
+        doc.body.hasAttribute("lwt-newtab-brighttext"),
+        isBrightText,
+        `New tab page should${
+          !isBrightText ? " not" : ""
+        } have lwt-newtab-brighttext attribute`
+      );
+
+      is(
+        content.getComputedStyle(doc.body).backgroundColor,
+        background,
+        "New tab page background should be set."
+      );
+      is(
+        content.getComputedStyle(doc.querySelector(".outer-wrapper")).color,
+        color,
+        "New tab page text color should be set."
+      );
+    }
+  );
+}
+
+/**
+ * Test whether a given browser has the default theme applied
+ * @param {Object} browser to test against
+ * @param {string} url being tested
+ * @returns {Promise} The task as a promise
+ */
+function test_ntp_default_theme(browser, url) {
+  Services.ppmm.sharedData.flush();
+  if (url === "about:welcome") {
+    return SpecialPowers.spawn(
+      browser,
+      [
+        {
+          background: hexToCSS("#EDEDF0"),
+          color: hexToCSS("#0C0C0D"),
+        },
+      ],
+      function({ background, color }) {
+        let doc = content.document;
+        ok(
+          !doc.body.hasAttribute("lwt-newtab"),
+          "About:welcome page should not have lwt-newtab attribute"
+        );
+        ok(
+          !doc.body.hasAttribute("lwt-newtab-brighttext"),
+          `About:welcome page should not have lwt-newtab-brighttext attribute`
+        );
+
+        is(
+          content.getComputedStyle(doc.body).backgroundColor,
+          background,
+          "About:welcome page background should be reset."
+        );
+        is(
+          content.getComputedStyle(doc.querySelector(".outer-wrapper")).color,
+          color,
+          "About:welcome page text color should be reset."
+        );
+      }
+    );
+  }
+  return SpecialPowers.spawn(
+    browser,
+    [
+      {
+        background: hexToCSS("#F9F9FA"),
+        color: hexToCSS("#0C0C0D"),
+      },
+    ],
+    function({ background, color }) {
+      let doc = content.document;
+      ok(
+        !doc.body.hasAttribute("lwt-newtab"),
+        "New tab page should not have lwt-newtab attribute"
+      );
+      ok(
+        !doc.body.hasAttribute("lwt-newtab-brighttext"),
+        `New tab page should not have lwt-newtab-brighttext attribute`
+      );
+
+      is(
+        content.getComputedStyle(doc.body).backgroundColor,
+        background,
+        "New tab page background should be reset."
+      );
+      is(
+        content.getComputedStyle(doc.querySelector(".outer-wrapper")).color,
+        color,
+        "New tab page text color should be reset."
+      );
+    }
+  );
+}
+
+add_task(async function test_per_window_ntp_theme() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+    },
+    async background() {
+      function promiseWindowChecked() {
+        return new Promise(resolve => {
+          let listener = msg => {
+            if (msg == "checked-window") {
+              browser.test.onMessage.removeListener(listener);
+              resolve();
+            }
+          };
+          browser.test.onMessage.addListener(listener);
+        });
+      }
+
+      function removeWindow(winId) {
+        return new Promise(resolve => {
+          let listener = removedWinId => {
+            if (removedWinId == winId) {
+              browser.windows.onRemoved.removeListener(listener);
+              resolve();
+            }
+          };
+          browser.windows.onRemoved.addListener(listener);
+          browser.windows.remove(winId);
+        });
+      }
+
+      async function checkWindow(theme, isBrightText, winId) {
+        let windowChecked = promiseWindowChecked();
+        browser.test.sendMessage("check-window", {
+          theme,
+          isBrightText,
+          winId,
+        });
+        await windowChecked;
+      }
+
+      const darkTextTheme = {
+        colors: {
+          frame: "#add8e6",
+          tab_background_text: "#000",
+          ntp_background: "#add8e6",
+          ntp_text: "#000",
+        },
+      };
+
+      const brightTextTheme = {
+        colors: {
+          frame: "#00008b",
+          tab_background_text: "#add8e6",
+          ntp_background: "#00008b",
+          ntp_text: "#add8e6",
+        },
+      };
+
+      let { id: winId } = await browser.windows.getCurrent();
+      // We are opening about:blank instead of the default homepage,
+      // because using the default homepage results in intermittent
+      // test failures on debug builds due to browser window leaks.
+      let { id: secondWinId } = await browser.windows.create({
+        url: "about:blank",
+      });
+
+      browser.test.log("Test that single window update works");
+      await browser.theme.update(winId, darkTextTheme);
+      await checkWindow(darkTextTheme, false, winId);
+      await checkWindow(null, false, secondWinId);
+
+      browser.test.log("Test that applying different themes on both windows");
+      await browser.theme.update(secondWinId, brightTextTheme);
+      await checkWindow(darkTextTheme, false, winId);
+      await checkWindow(brightTextTheme, true, secondWinId);
+
+      browser.test.log("Test resetting the theme on one window");
+      await browser.theme.reset(winId);
+      await checkWindow(null, false, winId);
+      await checkWindow(brightTextTheme, true, secondWinId);
+
+      await removeWindow(secondWinId);
+      await checkWindow(null, false, winId);
+      browser.test.notifyPass("perwindow-ntp-theme");
+    },
+  });
+
+  extension.onMessage(
+    "check-window",
+    async ({ theme, isBrightText, winId }) => {
+      let win = Services.wm.getOuterWindowWithId(winId);
+      win.NewTabPagePreloading.removePreloadedBrowser(win);
+      // These pages were initially chosen because LightweightThemeChild.jsm
+      // treats them specially.
+      for (let url of ["about:newtab", "about:home", "about:welcome"]) {
+        info("Opening url: " + url);
+        await BrowserTestUtils.withNewTab(
+          { gBrowser: win.gBrowser, url },
+          async browser => {
+            if (theme) {
+              await test_ntp_theme(browser, theme, isBrightText);
+            } else {
+              await test_ntp_default_theme(browser, url);
+            }
+          }
+        );
+      }
+      extension.sendMessage("checked-window");
+    }
+  );
+
+  // BrowserTestUtils.withNewTab waits for about:newtab to load
+  // so we disable preloading before running the test.
+  await SpecialPowers.setBoolPref("browser.newtab.preload", false);
+  await SpecialPowers.setBoolPref("browser.aboutwelcome.enabled", true);
+  registerCleanupFunction(() => {
+    SpecialPowers.clearUserPref("browser.newtab.preload");
+    SpecialPowers.clearUserPref("browser.aboutwelcome.enabled");
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("perwindow-ntp-theme");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_persistence.js b/toolkit/components/extensions/test/browser/browser_ext_themes_persistence.js
new file mode 100644
index 0000000000..bc72609acd
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_persistence.js
@@ -0,0 +1,58 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes are persisted and applied
+// on newly opened windows.
+
+add_task(async function test_multiple_windows() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = window.document.documentElement;
+  let style = window.getComputedStyle(docEl);
+
+  Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+  Assert.equal(
+    docEl.getAttribute("lwthemetextcolor"),
+    "bright",
+    "LWT text color attribute should be set"
+  );
+  Assert.ok(
+    style.backgroundImage.includes("image1.png"),
+    "Expected background image"
+  );
+
+  // Now we'll open a new window to see if the theme is also applied there.
+  let window2 = await BrowserTestUtils.openNewBrowserWindow();
+  docEl = window2.document.documentElement;
+  style = window2.getComputedStyle(docEl);
+
+  Assert.ok(docEl.hasAttribute("lwtheme"), "LWT attribute should be set");
+  Assert.equal(
+    docEl.getAttribute("lwthemetextcolor"),
+    "bright",
+    "LWT text color attribute should be set"
+  );
+  Assert.ok(
+    style.backgroundImage.includes("image1.png"),
+    "Expected background image"
+  );
+
+  await BrowserTestUtils.closeWindow(window2);
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_reset.js b/toolkit/components/extensions/test/browser/browser_ext_themes_reset.js
new file mode 100644
index 0000000000..d8b3b14073
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_reset.js
@@ -0,0 +1,112 @@
+"use strict";
+
+add_task(async function theme_reset_global_static_theme() {
+  let global_theme_extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: "#123456",
+          tab_background_text: "#fedcba",
+        },
+      },
+    },
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+    },
+    async background() {
+      await browser.theme.reset();
+      let theme_after_reset = await browser.theme.getCurrent();
+
+      browser.test.assertEq(
+        "#123456",
+        theme_after_reset.colors.frame,
+        "Theme from other extension should not be cleared upon reset()"
+      );
+
+      let theme = {
+        colors: {
+          frame: "#CF723F",
+        },
+      };
+
+      await browser.theme.update(theme);
+      await browser.theme.reset();
+      let final_reset_theme = await browser.theme.getCurrent();
+
+      browser.test.assertEq(
+        JSON.stringify({ colors: null, images: null, properties: null }),
+        JSON.stringify(final_reset_theme),
+        "Should reset when extension had replaced the global theme"
+      );
+      browser.test.sendMessage("done");
+    },
+  });
+  await global_theme_extension.startup();
+  await extension.startup();
+  await extension.awaitMessage("done");
+
+  await global_theme_extension.unload();
+  await extension.unload();
+});
+
+add_task(async function theme_reset_by_windowId() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+    },
+    async background() {
+      let theme = {
+        colors: {
+          frame: "#CF723F",
+        },
+      };
+
+      let { id: winId } = await browser.windows.getCurrent();
+      await browser.theme.update(winId, theme);
+      let update_theme = await browser.theme.getCurrent(winId);
+
+      browser.test.onMessage.addListener(async () => {
+        let current_theme = await browser.theme.getCurrent(winId);
+        browser.test.assertEq(
+          update_theme.colors.frame,
+          current_theme.colors.frame,
+          "Should not be reset by a reset(windowId) call from another extension"
+        );
+
+        browser.test.sendMessage("done");
+      });
+
+      browser.test.sendMessage("ready", winId);
+    },
+  });
+
+  let anotherExtension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+    },
+    background() {
+      browser.test.onMessage.addListener(async winId => {
+        await browser.theme.reset(winId);
+        browser.test.sendMessage("done");
+      });
+    },
+  });
+
+  await extension.startup();
+  let winId = await extension.awaitMessage("ready");
+
+  await anotherExtension.startup();
+
+  // theme.reset should be ignored if the theme was set by another extension.
+  anotherExtension.sendMessage(winId);
+  await anotherExtension.awaitMessage("done");
+
+  extension.sendMessage();
+  await extension.awaitMessage("done");
+
+  await anotherExtension.unload();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_sanitization.js b/toolkit/components/extensions/test/browser/browser_ext_themes_sanitization.js
new file mode 100644
index 0000000000..36658cd5b4
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_sanitization.js
@@ -0,0 +1,175 @@
+"use strict";
+
+// This test checks color sanitization in various situations
+
+add_task(async function test_sanitization_invalid() {
+  // This test checks that invalid values are sanitized
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          bookmark_text: "ntimsfavoriteblue",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let navbar = document.querySelector("#nav-bar");
+  Assert.equal(
+    window.getComputedStyle(navbar).color,
+    "rgb(0, 0, 0)",
+    "All invalid values should always compute to black."
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_sanitization_css_variables() {
+  // This test checks that CSS variables are sanitized
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          bookmark_text: "var(--arrowpanel-dimmed)",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let navbar = document.querySelector("#nav-bar");
+  Assert.equal(
+    window.getComputedStyle(navbar).color,
+    "rgb(0, 0, 0)",
+    "All CSS variables should always compute to black."
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_sanitization_important() {
+  // This test checks that the sanitizer cannot be fooled with !important
+  let stylesheetAttr = `href="data:text/css,*{color:red!important}" type="text/css"`;
+  let stylesheet = document.createProcessingInstruction(
+    "xml-stylesheet",
+    stylesheetAttr
+  );
+  let load = BrowserTestUtils.waitForEvent(stylesheet, "load");
+  document.insertBefore(stylesheet, document.documentElement);
+  await load;
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          bookmark_text: "green",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let navbar = document.querySelector("#nav-bar");
+  Assert.equal(
+    window.getComputedStyle(navbar).color,
+    "rgb(255, 0, 0)",
+    "Sheet applies"
+  );
+
+  stylesheet.remove();
+
+  Assert.equal(
+    window.getComputedStyle(navbar).color,
+    "rgb(0, 128, 0)",
+    "Shouldn't be able to fool the color sanitizer with !important"
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_sanitization_transparent() {
+  // This test checks whether transparent values are applied properly
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_top_separator: "transparent",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let navbar = document.querySelector("#nav-bar");
+  Assert.ok(
+    window.getComputedStyle(navbar).boxShadow.includes("rgba(0, 0, 0, 0)"),
+    "Top separator should be transparent"
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_sanitization_transparent_frame_color() {
+  // This test checks whether transparent frame color falls back to white.
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: "transparent",
+          tab_background_text: TEXT_COLOR,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let docEl = document.documentElement;
+  Assert.equal(
+    window.getComputedStyle(docEl).backgroundColor,
+    "rgb(255, 255, 255)",
+    "Accent color should be white"
+  );
+
+  await extension.unload();
+});
+
+add_task(
+  async function test_sanitization_transparent_tab_background_text_color() {
+    // This test checks whether transparent textcolor falls back to black.
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        theme: {
+          colors: {
+            frame: ACCENT_COLOR,
+            tab_background_text: "transparent",
+          },
+        },
+      },
+    });
+
+    await extension.startup();
+
+    let docEl = document.documentElement;
+    Assert.equal(
+      window.getComputedStyle(docEl).color,
+      "rgb(0, 0, 0)",
+      "Text color should be black"
+    );
+
+    await extension.unload();
+  }
+);
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_separators.js b/toolkit/components/extensions/test/browser/browser_ext_themes_separators.js
new file mode 100644
index 0000000000..4266a982d8
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_separators.js
@@ -0,0 +1,69 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the separator colors are applied properly.
+
+add_task(async function test_support_separator_properties() {
+  const SEPARATOR_TOP_COLOR = "#ff00ff";
+  const SEPARATOR_VERTICAL_COLOR = "#f0000f";
+  const SEPARATOR_FIELD_COLOR = "#9400ff";
+  const SEPARATOR_BOTTOM_COLOR = "#3366cc";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_top_separator: SEPARATOR_TOP_COLOR,
+          toolbar_vertical_separator: SEPARATOR_VERTICAL_COLOR,
+          toolbar_field_separator: SEPARATOR_FIELD_COLOR,
+          toolbar_bottom_separator: SEPARATOR_BOTTOM_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let navbar = document.querySelector("#nav-bar");
+  Assert.ok(
+    window
+      .getComputedStyle(navbar)
+      .boxShadow.includes(`rgb(${hexToRGB(SEPARATOR_TOP_COLOR).join(", ")})`),
+    "Top separator color properly set"
+  );
+
+  let mainWin = document.querySelector("#main-window");
+  Assert.equal(
+    window
+      .getComputedStyle(mainWin)
+      .getPropertyValue("--urlbar-separator-color"),
+    `rgb(${hexToRGB(SEPARATOR_FIELD_COLOR).join(", ")})`,
+    "Toolbar field separator color properly set"
+  );
+
+  let panelUIButton = document.querySelector("#PanelUI-button");
+  Assert.ok(
+    window
+      .getComputedStyle(panelUIButton)
+      .getPropertyValue("border-image-source")
+      .includes(`rgb(${hexToRGB(SEPARATOR_VERTICAL_COLOR).join(", ")})`),
+    "Vertical separator color properly set"
+  );
+
+  let toolbox = document.querySelector("#navigator-toolbox");
+  Assert.equal(
+    window.getComputedStyle(toolbox).borderBottomColor,
+    `rgb(${hexToRGB(SEPARATOR_BOTTOM_COLOR).join(", ")})`,
+    "Bottom separator color properly set"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_sidebars.js b/toolkit/components/extensions/test/browser/browser_ext_themes_sidebars.js
new file mode 100644
index 0000000000..3d814d1082
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_sidebars.js
@@ -0,0 +1,274 @@
+"use strict";
+
+// This test checks whether the sidebar color properties work.
+
+/**
+ * Test whether the selected browser has the sidebar theme applied
+ * @param {Object} theme that is applied
+ * @param {boolean} isBrightText whether the brighttext attribute should be set
+ */
+async function test_sidebar_theme(theme, isBrightText) {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme,
+    },
+  });
+
+  const sidebarBox = document.getElementById("sidebar-box");
+  const content = SidebarUI.browser.contentWindow;
+  const root = content.document.documentElement;
+
+  ok(
+    !sidebarBox.hasAttribute("lwt-sidebar"),
+    "Sidebar box should not have lwt-sidebar attribute"
+  );
+  ok(
+    !root.hasAttribute("lwt-sidebar"),
+    "Sidebar should not have lwt-sidebar attribute"
+  );
+  ok(
+    !root.hasAttribute("lwt-sidebar-brighttext"),
+    "Sidebar should not have lwt-sidebar-brighttext attribute"
+  );
+  ok(
+    !root.hasAttribute("lwt-sidebar-highlight"),
+    "Sidebar should not have lwt-sidebar-highlight attribute"
+  );
+
+  const rootCS = content.getComputedStyle(root);
+  const originalBackground = rootCS.backgroundColor;
+  const originalColor = rootCS.color;
+
+  // ::-moz-tree-row(selected, focus) computed style can't be accessed, so we create a fake one.
+  const highlightCS = {
+    get backgroundColor() {
+      // Standardize to rgb like other computed style.
+      let color = rootCS.getPropertyValue(
+        "--lwt-sidebar-highlight-background-color"
+      );
+      let [r, g, b] = color
+        .replace("rgba(", "")
+        .split(",")
+        .map(channel => parseInt(channel, 10));
+      return `rgb(${r}, ${g}, ${b})`;
+    },
+
+    get color() {
+      let color = rootCS.getPropertyValue("--lwt-sidebar-highlight-text-color");
+      let [r, g, b] = color
+        .replace("rgba(", "")
+        .split(",")
+        .map(channel => parseInt(channel, 10));
+      return `rgb(${r}, ${g}, ${b})`;
+    },
+  };
+  const originalHighlightBackground = highlightCS.backgroundColor;
+  const originalHighlightColor = highlightCS.color;
+
+  await extension.startup();
+
+  Services.ppmm.sharedData.flush();
+
+  const actualBackground = hexToCSS(theme.colors.sidebar) || originalBackground;
+  const actualColor = hexToCSS(theme.colors.sidebar_text) || originalColor;
+  const actualHighlightBackground =
+    hexToCSS(theme.colors.sidebar_highlight) || originalHighlightBackground;
+  const actualHighlightColor =
+    hexToCSS(theme.colors.sidebar_highlight_text) || originalHighlightColor;
+  const isCustomHighlight = !!theme.colors.sidebar_highlight_text;
+  const isCustomSidebar = !!theme.colors.sidebar_text;
+
+  is(
+    sidebarBox.hasAttribute("lwt-sidebar"),
+    isCustomSidebar,
+    `Sidebar box should${
+      !isCustomSidebar ? " not" : ""
+    } have lwt-sidebar attribute`
+  );
+  is(
+    root.hasAttribute("lwt-sidebar"),
+    isCustomSidebar,
+    `Sidebar should${!isCustomSidebar ? " not" : ""} have lwt-sidebar attribute`
+  );
+  is(
+    root.hasAttribute("lwt-sidebar-brighttext"),
+    isBrightText,
+    `Sidebar should${
+      !isBrightText ? " not" : ""
+    } have lwt-sidebar-brighttext attribute`
+  );
+  is(
+    root.hasAttribute("lwt-sidebar-highlight"),
+    isCustomHighlight,
+    `Sidebar should${
+      !isCustomHighlight ? " not" : ""
+    } have lwt-sidebar-highlight attribute`
+  );
+
+  if (isCustomSidebar) {
+    const sidebarBoxCS = window.getComputedStyle(sidebarBox);
+    is(
+      sidebarBoxCS.backgroundColor,
+      actualBackground,
+      "Sidebar box background should be set."
+    );
+    is(
+      sidebarBoxCS.color,
+      actualColor,
+      "Sidebar box text color should be set."
+    );
+  }
+
+  is(
+    rootCS.backgroundColor,
+    actualBackground,
+    "Sidebar background should be set."
+  );
+  is(rootCS.color, actualColor, "Sidebar text color should be set.");
+
+  is(
+    highlightCS.backgroundColor,
+    actualHighlightBackground,
+    "Sidebar highlight background color should be set."
+  );
+  is(
+    highlightCS.color,
+    actualHighlightColor,
+    "Sidebar highlight text color should be set."
+  );
+
+  await extension.unload();
+
+  Services.ppmm.sharedData.flush();
+
+  ok(
+    !sidebarBox.hasAttribute("lwt-sidebar"),
+    "Sidebar box should not have lwt-sidebar attribute"
+  );
+  ok(
+    !root.hasAttribute("lwt-sidebar"),
+    "Sidebar should not have lwt-sidebar attribute"
+  );
+  ok(
+    !root.hasAttribute("lwt-sidebar-brighttext"),
+    "Sidebar should not have lwt-sidebar-brighttext attribute"
+  );
+  ok(
+    !root.hasAttribute("lwt-sidebar-highlight"),
+    "Sidebar should not have lwt-sidebar-highlight attribute"
+  );
+
+  is(
+    rootCS.backgroundColor,
+    originalBackground,
+    "Sidebar background should be reset."
+  );
+  is(rootCS.color, originalColor, "Sidebar text color should be reset.");
+  is(
+    highlightCS.backgroundColor,
+    originalHighlightBackground,
+    "Sidebar highlight background color should be reset."
+  );
+  is(
+    highlightCS.color,
+    originalHighlightColor,
+    "Sidebar highlight text color should be reset."
+  );
+}
+
+add_task(async function test_support_sidebar_colors() {
+  for (let command of ["viewBookmarksSidebar", "viewHistorySidebar"]) {
+    info("Executing command: " + command);
+
+    await SidebarUI.show(command);
+
+    await test_sidebar_theme(
+      {
+        colors: {
+          sidebar: "#fafad2", // lightgoldenrodyellow
+          sidebar_text: "#2f4f4f", // darkslategrey
+        },
+      },
+      false
+    );
+
+    await test_sidebar_theme(
+      {
+        colors: {
+          sidebar: "#8b4513", // saddlebrown
+          sidebar_text: "#ffa07a", // lightsalmon
+        },
+      },
+      true
+    );
+
+    await test_sidebar_theme(
+      {
+        colors: {
+          sidebar: "#fffafa", // snow
+          sidebar_text: "#663399", // rebeccapurple
+          sidebar_highlight: "#7cfc00", // lawngreen
+          sidebar_highlight_text: "#ffefd5", // papayawhip
+        },
+      },
+      false
+    );
+
+    await test_sidebar_theme(
+      {
+        colors: {
+          sidebar_highlight: "#a0522d", // sienna
+          sidebar_highlight_text: "#fff5ee", // seashell
+        },
+      },
+      false
+    );
+  }
+});
+
+add_task(async function test_support_sidebar_border_color() {
+  const LIGHT_SALMON = "#ffa07a";
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          sidebar_border: LIGHT_SALMON,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  const sidebarHeader = document.getElementById("sidebar-header");
+  const sidebarHeaderCS = window.getComputedStyle(sidebarHeader);
+
+  is(
+    sidebarHeaderCS.borderBottomColor,
+    hexToCSS(LIGHT_SALMON),
+    "Sidebar header border should be colored properly"
+  );
+
+  if (AppConstants.platform !== "linux") {
+    const sidebarSplitter = document.getElementById("sidebar-splitter");
+    const sidebarSplitterCS = window.getComputedStyle(sidebarSplitter);
+
+    is(
+      sidebarSplitterCS.borderInlineEndColor,
+      hexToCSS(LIGHT_SALMON),
+      "Sidebar splitter should be colored properly"
+    );
+
+    SidebarUI.reversePosition();
+
+    is(
+      sidebarSplitterCS.borderInlineStartColor,
+      hexToCSS(LIGHT_SALMON),
+      "Sidebar splitter should be colored properly after switching sides"
+    );
+
+    SidebarUI.reversePosition();
+  }
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_static_onUpdated.js b/toolkit/components/extensions/test/browser/browser_ext_themes_static_onUpdated.js
new file mode 100644
index 0000000000..081322faa3
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_static_onUpdated.js
@@ -0,0 +1,66 @@
+"use strict";
+
+// This test checks whether browser.theme.onUpdated works
+// when a static theme is applied
+
+add_task(async function test_on_updated() {
+  const theme = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  const extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.theme.onUpdated.addListener(updateInfo => {
+        browser.test.sendMessage("theme-updated", updateInfo);
+      });
+    },
+  });
+
+  await extension.startup();
+
+  info("Testing update event on static theme startup");
+  let updatedPromise = extension.awaitMessage("theme-updated");
+  await theme.startup();
+  const { theme: receivedTheme, windowId } = await updatedPromise;
+  Assert.ok(!windowId, "No window id in static theme update event");
+  Assert.ok(
+    receivedTheme.images.theme_frame.includes("image1.png"),
+    "Theme theme_frame image should be applied"
+  );
+  Assert.equal(
+    receivedTheme.colors.frame,
+    ACCENT_COLOR,
+    "Theme frame color should be applied"
+  );
+  Assert.equal(
+    receivedTheme.colors.tab_background_text,
+    TEXT_COLOR,
+    "Theme tab_background_text color should be applied"
+  );
+
+  info("Testing update event on static theme unload");
+  updatedPromise = extension.awaitMessage("theme-updated");
+  await theme.unload();
+  const updateInfo = await updatedPromise;
+  Assert.ok(!windowId, "No window id in static theme update event on unload");
+  Assert.equal(
+    Object.keys(updateInfo.theme),
+    0,
+    "unloading theme sends empty theme in update event"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_tab_line.js b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_line.js
new file mode 100644
index 0000000000..928fa4edee
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_line.js
@@ -0,0 +1,50 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the color of the tab line are applied properly.
+
+add_task(async function test_support_tab_line() {
+  for (let protonTabsEnabled of [true, false]) {
+    SpecialPowers.pushPrefEnv({
+      set: [["browser.proton.tabs.enabled", protonTabsEnabled]],
+    });
+    let newWin = await BrowserTestUtils.openNewWindowWithFlushedXULCacheForMozSupports();
+
+    const TAB_LINE_COLOR = "#9400ff";
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        theme: {
+          colors: {
+            frame: ACCENT_COLOR,
+            tab_background_text: TEXT_COLOR,
+            tab_line: TAB_LINE_COLOR,
+          },
+        },
+      },
+    });
+
+    await extension.startup();
+
+    info("Checking selected tab line color");
+    let selectedTab = newWin.document.querySelector(
+      ".tabbrowser-tab[selected]"
+    );
+    let line = selectedTab.querySelector(".tab-line");
+    if (protonTabsEnabled) {
+      Assert.equal(
+        newWin.getComputedStyle(line).display,
+        "none",
+        "Tab line should not be displayed when Proton is enabled"
+      );
+    } else {
+      Assert.equal(
+        newWin.getComputedStyle(line).backgroundColor,
+        `rgb(${hexToRGB(TAB_LINE_COLOR).join(", ")})`,
+        "Tab line should have theme color"
+      );
+    }
+
+    await extension.unload();
+    await BrowserTestUtils.closeWindow(newWin);
+  }
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_tab_loading.js b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_loading.js
new file mode 100644
index 0000000000..1e402dbcc6
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_loading.js
@@ -0,0 +1,51 @@
+"use strict";
+
+add_task(async function test_support_tab_loading_filling() {
+  const TAB_LOADING_COLOR = "#FF0000";
+
+  // Make sure we use the animating loading icon
+  await SpecialPowers.pushPrefEnv({
+    set: [["ui.prefersReducedMotion", 0]],
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: "#000",
+          toolbar: "#124455",
+          tab_background_text: "#9400ff",
+          tab_loading: TAB_LOADING_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  info("Checking selected tab loading indicator colors");
+
+  let selectedTab = document.querySelector(
+    ".tabbrowser-tab[visuallyselected=true]"
+  );
+
+  selectedTab.setAttribute("busy", "true");
+  selectedTab.setAttribute("progress", "true");
+
+  let throbber = selectedTab.throbber;
+  Assert.equal(
+    window.getComputedStyle(throbber, "::before").fill,
+    `rgb(${hexToRGB(TAB_LOADING_COLOR).join(", ")})`,
+    "Throbber is filled with theme color"
+  );
+
+  selectedTab.removeAttribute("busy");
+  selectedTab.removeAttribute("progress");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_tab_selected.js b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_selected.js
new file mode 100644
index 0000000000..21f3c6d38b
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_selected.js
@@ -0,0 +1,54 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the background color of selected tab are applied correctly.
+
+add_task(async function test_tab_background_color_property() {
+  const TAB_BACKGROUND_COLOR = "#9400ff";
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          tab_selected: TAB_BACKGROUND_COLOR,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  info("Checking selected tab color");
+
+  let openTab = document.querySelector(
+    ".tabbrowser-tab[visuallyselected=true]"
+  );
+  let openTabBackground = openTab.querySelector(".tab-background");
+
+  let selectedTab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "about:blank"
+  );
+  let selectedTabBackground = selectedTab.querySelector(".tab-background");
+
+  let openTabGradient = window
+    .getComputedStyle(openTabBackground)
+    .getPropertyValue("background-image");
+  let selectedTabGradient = window
+    .getComputedStyle(selectedTabBackground)
+    .getPropertyValue("background-image");
+
+  let rgbRegex = /rgb\((\d{1,3}), (\d{1,3}), (\d{1,3})\)/g;
+  let selectedTabColors = selectedTabGradient.match(rgbRegex);
+
+  Assert.equal(
+    selectedTabColors[0],
+    "rgb(" + hexToRGB(TAB_BACKGROUND_COLOR).join(", ") + ")",
+    "Selected tab background color should be set."
+  );
+  Assert.equal(openTabGradient, "none");
+
+  gBrowser.removeTab(selectedTab);
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_tab_separators.js b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_separators.js
new file mode 100644
index 0000000000..722c7dd99c
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_separators.js
@@ -0,0 +1,38 @@
+"use strict";
+
+add_task(async function test_support_tab_separators() {
+  const TAB_SEPARATOR_COLOR = "#FF0000";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: "#000",
+          tab_background_text: "#9400ff",
+          tab_background_separator: TAB_SEPARATOR_COLOR,
+        },
+      },
+    },
+  });
+  await extension.startup();
+
+  info("Checking background tab separator color");
+
+  let tab = BrowserTestUtils.addTab(gBrowser, "about:blank");
+
+  Assert.equal(
+    window.getComputedStyle(tab, "::before").borderLeftColor,
+    `rgb(${hexToRGB(TAB_SEPARATOR_COLOR).join(", ")})`,
+    "Left separator has right color."
+  );
+
+  Assert.equal(
+    window.getComputedStyle(tab, "::after").borderLeftColor,
+    `rgb(${hexToRGB(TAB_SEPARATOR_COLOR).join(", ")})`,
+    "Right separator has right color."
+  );
+
+  gBrowser.removeTab(tab);
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_tab_text.js b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_text.js
new file mode 100644
index 0000000000..d819f3a5f1
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_tab_text.js
@@ -0,0 +1,70 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the text color of the selected tab are applied properly.
+
+add_task(async function test_support_tab_text_property_css_color() {
+  const TAB_TEXT_COLOR = "#9400ff";
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          tab_text: TAB_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  info("Checking selected tab colors");
+  let selectedTab = document.querySelector(".tabbrowser-tab[selected]");
+  Assert.equal(
+    window.getComputedStyle(selectedTab).color,
+    "rgb(" + hexToRGB(TAB_TEXT_COLOR).join(", ") + ")",
+    "Selected tab text color should be set."
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_support_tab_text_chrome_array() {
+  const TAB_TEXT_COLOR = [148, 0, 255];
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: FRAME_COLOR,
+          tab_background_text: TAB_BACKGROUND_TEXT_COLOR,
+          tab_text: TAB_TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  info("Checking selected tab colors");
+  let selectedTab = document.querySelector(".tabbrowser-tab[selected]");
+  Assert.equal(
+    window.getComputedStyle(selectedTab).color,
+    "rgb(" + TAB_TEXT_COLOR.join(", ") + ")",
+    "Selected tab text color should be set."
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_theme_transition.js b/toolkit/components/extensions/test/browser/browser_ext_themes_theme_transition.js
new file mode 100644
index 0000000000..39934200ac
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_theme_transition.js
@@ -0,0 +1,48 @@
+"use strict";
+
+// This test checks whether the applied theme transition effects are applied
+// correctly.
+
+add_task(async function test_theme_transition_effects() {
+  const TOOLBAR = "#f27489";
+  const TEXT_COLOR = "#000000";
+  const TRANSITION_PROPERTY = "background-color";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          tab_background_text: TEXT_COLOR,
+          toolbar: TOOLBAR,
+          bookmark_text: TEXT_COLOR,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  // check transition effect for toolbars
+  let navbar = document.querySelector("#nav-bar");
+  let navbarCS = window.getComputedStyle(navbar);
+
+  Assert.ok(
+    navbarCS
+      .getPropertyValue("transition-property")
+      .includes(TRANSITION_PROPERTY),
+    "Transition property set for #nav-bar"
+  );
+
+  let bookmarksBar = document.querySelector("#PersonalToolbar");
+  setToolbarVisibility(bookmarksBar, true, false, true);
+  let bookmarksBarCS = window.getComputedStyle(bookmarksBar);
+
+  Assert.ok(
+    bookmarksBarCS
+      .getPropertyValue("transition-property")
+      .includes(TRANSITION_PROPERTY),
+    "Transition property set for #PersonalToolbar"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_toolbar_fields.js b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbar_fields.js
new file mode 100644
index 0000000000..cd4d08c38f
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbar_fields.js
@@ -0,0 +1,145 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the background color and the color of the navbar text fields are applied properly.
+
+ChromeUtils.import(
+  "resource://testing-common/CustomizableUITestUtils.jsm",
+  this
+);
+let gCUITestUtils = new CustomizableUITestUtils(window);
+
+add_task(async function setup() {
+  await gCUITestUtils.addSearchBar();
+  registerCleanupFunction(() => {
+    gCUITestUtils.removeSearchBar();
+  });
+});
+
+add_task(async function test_support_toolbar_field_properties() {
+  const TOOLBAR_FIELD_BACKGROUND = "#ff00ff";
+  const TOOLBAR_FIELD_COLOR = "#00ff00";
+  const TOOLBAR_FIELD_BORDER = "#aaaaff";
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_field: TOOLBAR_FIELD_BACKGROUND,
+          toolbar_field_text: TOOLBAR_FIELD_COLOR,
+          toolbar_field_border: TOOLBAR_FIELD_BORDER,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let root = document.documentElement;
+  // Remove the `remotecontrol` attribute since it interferes with the urlbar styling.
+  root.removeAttribute("remotecontrol");
+  registerCleanupFunction(() => {
+    root.setAttribute("remotecontrol", "true");
+  });
+
+  let fields = [
+    document.querySelector("#urlbar-background"),
+    BrowserSearch.searchBar,
+  ].filter(field => {
+    let bounds = field.getBoundingClientRect();
+    return bounds.width > 0 && bounds.height > 0;
+  });
+
+  Assert.equal(fields.length, 2, "Should be testing two elements");
+
+  info(
+    `Checking toolbar background colors and colors for ${fields.length} toolbar fields.`
+  );
+  for (let field of fields) {
+    info(`Testing ${field.id || field.className}`);
+    Assert.equal(
+      window.getComputedStyle(field).backgroundColor,
+      hexToCSS(TOOLBAR_FIELD_BACKGROUND),
+      "Field background should be set."
+    );
+    Assert.equal(
+      window.getComputedStyle(field).color,
+      hexToCSS(TOOLBAR_FIELD_COLOR),
+      "Field color should be set."
+    );
+    testBorderColor(field, TOOLBAR_FIELD_BORDER);
+  }
+
+  await extension.unload();
+});
+
+add_task(async function test_support_toolbar_field_brighttext() {
+  let root = document.documentElement;
+  // Remove the `remotecontrol` attribute since it interferes with the urlbar styling.
+  root.removeAttribute("remotecontrol");
+  registerCleanupFunction(() => {
+    root.setAttribute("remotecontrol", "true");
+  });
+  let urlbar = gURLBar.textbox;
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_field: "#fff",
+          toolbar_field_text: "#000",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  Assert.equal(
+    window.getComputedStyle(urlbar).color,
+    hexToCSS("#000000"),
+    "Color has been set"
+  );
+  Assert.ok(
+    !root.hasAttribute("lwt-toolbar-field-brighttext"),
+    "Brighttext attribute should not be set"
+  );
+
+  await extension.unload();
+
+  extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar_field: "#000",
+          toolbar_field_text: "#fff",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  Assert.equal(
+    window.getComputedStyle(urlbar).color,
+    hexToCSS("#ffffff"),
+    "Color has been set"
+  );
+  Assert.ok(
+    root.hasAttribute("lwt-toolbar-field-brighttext"),
+    "Brighttext attribute should be set"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_toolbar_fields_focus.js b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbar_fields_focus.js
new file mode 100644
index 0000000000..05b6a186d2
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbar_fields_focus.js
@@ -0,0 +1,102 @@
+"use strict";
+
+add_task(async function setup() {
+  // Remove the `remotecontrol` attribute since it interferes with the urlbar styling.
+  document.documentElement.removeAttribute("remotecontrol");
+  registerCleanupFunction(() => {
+    document.documentElement.setAttribute("remotecontrol", "true");
+  });
+});
+
+add_task(async function test_toolbar_field_focus() {
+  const TOOLBAR_FIELD_BACKGROUND = "#FF00FF";
+  const TOOLBAR_FIELD_COLOR = "#00FF00";
+  const TOOLBAR_FOCUS_BACKGROUND = "#FF0000";
+  const TOOLBAR_FOCUS_TEXT = "#9400FF";
+  const TOOLBAR_FOCUS_BORDER = "#FFFFFF";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: "#FF0000",
+          tab_background_color: "#ffffff",
+          toolbar_field: TOOLBAR_FIELD_BACKGROUND,
+          toolbar_field_text: TOOLBAR_FIELD_COLOR,
+          toolbar_field_focus: TOOLBAR_FOCUS_BACKGROUND,
+          toolbar_field_text_focus: TOOLBAR_FOCUS_TEXT,
+          toolbar_field_border_focus: TOOLBAR_FOCUS_BORDER,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  info("Checking toolbar field's focus color");
+
+  let urlBar = document.querySelector("#urlbar-background");
+  gURLBar.textbox.setAttribute("focused", "true");
+
+  Assert.equal(
+    window.getComputedStyle(urlBar).backgroundColor,
+    `rgb(${hexToRGB(TOOLBAR_FOCUS_BACKGROUND).join(", ")})`,
+    "Background Color is changed"
+  );
+  Assert.equal(
+    window.getComputedStyle(urlBar).color,
+    `rgb(${hexToRGB(TOOLBAR_FOCUS_TEXT).join(", ")})`,
+    "Text Color is changed"
+  );
+  testBorderColor(urlBar, TOOLBAR_FOCUS_BORDER);
+
+  gURLBar.textbox.removeAttribute("focused");
+
+  Assert.equal(
+    window.getComputedStyle(urlBar).backgroundColor,
+    `rgb(${hexToRGB(TOOLBAR_FIELD_BACKGROUND).join(", ")})`,
+    "Background Color is set back to initial"
+  );
+  Assert.equal(
+    window.getComputedStyle(urlBar).color,
+    `rgb(${hexToRGB(TOOLBAR_FIELD_COLOR).join(", ")})`,
+    "Text Color is set back to initial"
+  );
+  await extension.unload();
+});
+
+add_task(async function test_toolbar_field_focus_low_alpha() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: "#FF0000",
+          tab_background_color: "#ffffff",
+          toolbar_field: "#FF00FF",
+          toolbar_field_text: "#00FF00",
+          toolbar_field_focus: "rgba(0, 0, 255, 0.4)",
+          toolbar_field_text_focus: "red",
+          toolbar_field_border_focus: "#FFFFFF",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+  gURLBar.textbox.setAttribute("focused", "true");
+
+  let urlBar = document.querySelector("#urlbar-background");
+  Assert.equal(
+    window.getComputedStyle(urlBar).backgroundColor,
+    `rgba(0, 0, 255, 0.9)`,
+    "Background color has minimum opacity enforced"
+  );
+  Assert.equal(
+    window.getComputedStyle(urlBar).color,
+    `rgb(255, 255, 255)`,
+    "Text color has been overridden to match background"
+  );
+
+  gURLBar.textbox.removeAttribute("focused");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_colors.js b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_colors.js
new file mode 100644
index 0000000000..f31e0fce8a
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_colors.js
@@ -0,0 +1,56 @@
+"use strict";
+
+/* globals InspectorUtils */
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the button background color properties are applied correctly.
+
+add_task(async function test_button_background_properties() {
+  const BUTTON_BACKGROUND_ACTIVE = "#FFFFFF";
+  const BUTTON_BACKGROUND_HOVER = "#59CBE8";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          button_background_active: BUTTON_BACKGROUND_ACTIVE,
+          button_background_hover: BUTTON_BACKGROUND_HOVER,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let toolbarButton = document.querySelector("#home-button");
+  let toolbarButtonIcon = toolbarButton.icon;
+  let toolbarButtonIconCS = window.getComputedStyle(toolbarButtonIcon);
+
+  InspectorUtils.addPseudoClassLock(toolbarButton, ":hover");
+
+  Assert.equal(
+    toolbarButtonIconCS.getPropertyValue("background-color"),
+    `rgb(${hexToRGB(BUTTON_BACKGROUND_HOVER).join(", ")})`,
+    "Toolbar button hover background is set."
+  );
+
+  InspectorUtils.addPseudoClassLock(toolbarButton, ":active");
+
+  Assert.equal(
+    toolbarButtonIconCS.getPropertyValue("background-color"),
+    `rgb(${hexToRGB(BUTTON_BACKGROUND_ACTIVE).join(", ")})`,
+    "Toolbar button active background is set!"
+  );
+
+  InspectorUtils.clearPseudoClassLocks(toolbarButton);
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_icons.js b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_icons.js
new file mode 100644
index 0000000000..11643412dd
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbarbutton_icons.js
@@ -0,0 +1,107 @@
+"use strict";
+
+// This test checks applied WebExtension themes that attempt to change
+// icon color properties
+
+add_task(async function test_icons_properties() {
+  const ICONS_COLOR = "#001b47";
+  const ICONS_ATTENTION_COLOR = "#44ba77";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          icons: ICONS_COLOR,
+          icons_attention: ICONS_ATTENTION_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let toolbarbutton = document.querySelector("#home-button");
+  Assert.equal(
+    window.getComputedStyle(toolbarbutton).getPropertyValue("fill"),
+    `rgb(${hexToRGB(ICONS_COLOR).join(", ")})`,
+    "Buttons fill color set!"
+  );
+
+  let starButton = document.querySelector("#star-button");
+  starButton.setAttribute("starred", "true");
+
+  let starComputedStyle = window.getComputedStyle(starButton);
+  Assert.equal(
+    starComputedStyle.getPropertyValue(
+      "--lwt-toolbarbutton-icon-fill-attention"
+    ),
+    `rgb(${hexToRGB(ICONS_ATTENTION_COLOR).join(", ")})`,
+    "Variable is properly set"
+  );
+  Assert.equal(
+    starComputedStyle.getPropertyValue("fill"),
+    `rgb(${hexToRGB(ICONS_ATTENTION_COLOR).join(", ")})`,
+    "Starred icon fill is properly set"
+  );
+
+  starButton.removeAttribute("starred");
+
+  await extension.unload();
+});
+
+add_task(async function test_no_icons_properties() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+        },
+      },
+    },
+    files: {
+      "image1.png": BACKGROUND,
+    },
+  });
+
+  await extension.startup();
+
+  let toolbarbutton = document.querySelector("#home-button");
+  let toolbarbuttonCS = window.getComputedStyle(toolbarbutton);
+  Assert.equal(
+    toolbarbuttonCS.getPropertyValue("--lwt-toolbarbutton-icon-fill"),
+    "",
+    "Icon fill should not be set when the value is not specified in the manifest."
+  );
+  let currentColor = toolbarbuttonCS.getPropertyValue("color");
+  Assert.equal(
+    window.getComputedStyle(toolbarbutton).getPropertyValue("fill"),
+    currentColor,
+    "Button fill color should be currentColor when no icon color specified."
+  );
+
+  let starButton = document.querySelector("#star-button");
+  starButton.setAttribute("starred", "true");
+  let starComputedStyle = window.getComputedStyle(starButton);
+  Assert.equal(
+    starComputedStyle.getPropertyValue(
+      "--lwt-toolbarbutton-icon-fill-attention"
+    ),
+    "",
+    "Icon attention fill should not be set when the value is not specified in the manifest."
+  );
+  starButton.removeAttribute("starred");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_toolbars.js b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbars.js
new file mode 100644
index 0000000000..ee31d80888
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_toolbars.js
@@ -0,0 +1,105 @@
+"use strict";
+
+// This test checks whether applied WebExtension themes that attempt to change
+// the background color of toolbars are applied properly.
+
+add_task(async function test_support_toolbar_property() {
+  const TOOLBAR_COLOR = "#ff00ff";
+  const TOOLBAR_TEXT_COLOR = "#9400ff";
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar: TOOLBAR_COLOR,
+          toolbar_text: TOOLBAR_TEXT_COLOR,
+        },
+      },
+    },
+  });
+
+  let toolbox = document.querySelector("#navigator-toolbox");
+  let toolbars = [
+    ...toolbox.querySelectorAll("toolbar:not(#TabsToolbar)"),
+  ].filter(toolbar => {
+    let bounds = toolbar.getBoundingClientRect();
+    return bounds.width > 0 && bounds.height > 0;
+  });
+
+  let transitionPromise = waitForTransition(toolbars[0], "background-color");
+  await extension.startup();
+  await transitionPromise;
+
+  info(`Checking toolbar colors for ${toolbars.length} toolbars.`);
+  for (let toolbar of toolbars) {
+    info(`Testing ${toolbar.id}`);
+    Assert.equal(
+      window.getComputedStyle(toolbar).backgroundColor,
+      hexToCSS(TOOLBAR_COLOR),
+      "Toolbar background color should be set."
+    );
+    Assert.equal(
+      window.getComputedStyle(toolbar).color,
+      hexToCSS(TOOLBAR_TEXT_COLOR),
+      "Toolbar text color should be set."
+    );
+  }
+
+  info("Checking selected tab colors");
+  let selectedTab = document.querySelector(".tabbrowser-tab[selected]");
+  Assert.equal(
+    window.getComputedStyle(selectedTab).color,
+    hexToCSS(TOOLBAR_TEXT_COLOR),
+    "Selected tab text color should be set."
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_bookmark_text_property() {
+  const TOOLBAR_COLOR = [255, 0, 255];
+  const TOOLBAR_TEXT_COLOR = [48, 0, 255];
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        colors: {
+          frame: ACCENT_COLOR,
+          tab_background_text: TEXT_COLOR,
+          toolbar: TOOLBAR_COLOR,
+          bookmark_text: TOOLBAR_TEXT_COLOR,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let toolbox = document.querySelector("#navigator-toolbox");
+  let toolbars = [
+    ...toolbox.querySelectorAll("toolbar:not(#TabsToolbar)"),
+  ].filter(toolbar => {
+    let bounds = toolbar.getBoundingClientRect();
+    return bounds.width > 0 && bounds.height > 0;
+  });
+
+  info(`Checking toolbar colors for ${toolbars.length} toolbars.`);
+  for (let toolbar of toolbars) {
+    info(`Testing ${toolbar.id}`);
+    Assert.equal(
+      window.getComputedStyle(toolbar).color,
+      rgbToCSS(TOOLBAR_TEXT_COLOR),
+      "bookmark_text should be an alias for toolbar_text"
+    );
+  }
+
+  info("Checking selected tab colors");
+  let selectedTab = document.querySelector(".tabbrowser-tab[selected]");
+  Assert.equal(
+    window.getComputedStyle(selectedTab).color,
+    rgbToCSS(TOOLBAR_TEXT_COLOR),
+    "Selected tab text color should be set."
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_warnings.js b/toolkit/components/extensions/test/browser/browser_ext_themes_warnings.js
new file mode 100644
index 0000000000..64155006d9
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_warnings.js
@@ -0,0 +1,143 @@
+"use strict";
+
+const { AddonSettings } = ChromeUtils.import(
+  "resource://gre/modules/addons/AddonSettings.jsm"
+);
+
+// This test checks that theme warnings are properly emitted.
+
+function waitForConsole(task, message) {
+  // eslint-disable-next-line no-async-promise-executor
+  return new Promise(async resolve => {
+    SimpleTest.monitorConsole(resolve, [
+      {
+        message: new RegExp(message),
+      },
+    ]);
+    await task();
+    SimpleTest.endMonitorConsole();
+  });
+}
+
+add_task(async function setup() {
+  SimpleTest.waitForExplicitFinish();
+});
+
+add_task(async function test_static_theme() {
+  for (const property of ["colors", "images", "properties"]) {
+    const extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        theme: {
+          [property]: {
+            such_property: "much_wow",
+          },
+        },
+      },
+    });
+    await waitForConsole(
+      extension.startup,
+      `Unrecognized theme property found: ${property}.such_property`
+    );
+    await extension.unload();
+  }
+});
+
+add_task(async function test_dynamic_theme() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["theme"],
+    },
+    background() {
+      browser.test.onMessage.addListener((msg, details) => {
+        if (msg === "update-theme") {
+          browser.theme.update(details).then(() => {
+            browser.test.sendMessage("theme-updated");
+          });
+        } else {
+          browser.theme.reset().then(() => {
+            browser.test.sendMessage("theme-reset");
+          });
+        }
+      });
+    },
+  });
+
+  await extension.startup();
+
+  for (const property of ["colors", "images", "properties"]) {
+    extension.sendMessage("update-theme", {
+      [property]: {
+        such_property: "much_wow",
+      },
+    });
+    await waitForConsole(
+      () => extension.awaitMessage("theme-updated"),
+      `Unrecognized theme property found: ${property}.such_property`
+    );
+  }
+
+  await extension.unload();
+});
+
+add_task(async function test_experiments_enabled() {
+  info("Testing that experiments are handled correctly on nightly and deved");
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        properties: {
+          such_property: "much_wow",
+          unknown_property: "very_unknown",
+        },
+      },
+      theme_experiment: {
+        properties: {
+          such_property: "--such-property",
+        },
+      },
+    },
+  });
+  if (!AddonSettings.EXPERIMENTS_ENABLED) {
+    await waitForConsole(
+      extension.startup,
+      "This extension is not allowed to run theme experiments"
+    );
+  } else {
+    await waitForConsole(
+      extension.startup,
+      "Unrecognized theme property found: properties.unknown_property"
+    );
+  }
+  await extension.unload();
+});
+
+add_task(async function test_experiments_disabled() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.experiments.enabled", false]],
+  });
+
+  info(
+    "Testing that experiments are handled correctly when experiements pref is disabled"
+  );
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      theme: {
+        properties: {
+          such_property: "much_wow",
+        },
+      },
+      theme_experiment: {
+        properties: {
+          such_property: "--such-property",
+        },
+      },
+    },
+  });
+  await waitForConsole(
+    extension.startup,
+    "This extension is not allowed to run theme experiments"
+  );
+  await extension.unload();
+  await SpecialPowers.popPrefEnv();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_thumbnails_bg_extension.js b/toolkit/components/extensions/test/browser/browser_ext_thumbnails_bg_extension.js
new file mode 100644
index 0000000000..96a2216067
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_thumbnails_bg_extension.js
@@ -0,0 +1,94 @@
+"use strict";
+
+/* import-globals-from ../../../thumbnails/test/head.js */
+loadTestSubscript("../../../thumbnails/test/head.js");
+
+// The service that creates thumbnails of webpages in the background loads a
+// web page in the background (with several features disabled). Extensions
+// should be able to observe requests, but not run content scripts.
+add_task(async function test_thumbnails_background_visibility_to_extensions() {
+  const iframeUrl = "http://example.com/?iframe";
+  const testPageUrl = bgTestPageURL({ iframe: iframeUrl });
+  // ^ testPageUrl is http://mochi.test:8888/.../thumbnails_background.sjs?...
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          // ":8888" omitted due to bug 1362809.
+          matches: [
+            "http://mochi.test/*/thumbnails_background.sjs*",
+            "http://example.com/?iframe*",
+          ],
+          js: ["contentscript.js"],
+          run_at: "document_start",
+          all_frames: true,
+        },
+      ],
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "http://example.com/*",
+        "http://mochi.test/*",
+      ],
+    },
+    files: {
+      "contentscript.js": () => {
+        // Content scripts are not expected to be run in the page of the
+        // thumbnail service, so this should never execute.
+        new Image().src = "http://example.com/?unexpected-content-script";
+        browser.test.fail("Content script ran in thumbs, unexpectedly.");
+      },
+    },
+    background() {
+      let requests = [];
+      browser.webRequest.onBeforeRequest.addListener(
+        ({ url, tabId, frameId, type }) => {
+          browser.test.assertEq(-1, tabId, "Thumb page is not a tab");
+          // We want to know if frameId is 0 or non-negative (or possibly -1).
+          if (type === "sub_frame") {
+            browser.test.assertTrue(frameId > 0, `frame ${frameId} for ${url}`);
+          } else {
+            browser.test.assertEq(0, frameId, `frameId for ${type} ${url}`);
+          }
+          requests.push({ type, url });
+        },
+        {
+          types: ["main_frame", "sub_frame", "image"],
+          urls: ["*://*/*"],
+        },
+        ["blocking"]
+      );
+      browser.test.onMessage.addListener(msg => {
+        browser.test.assertEq("get-results", msg, "expected message");
+        browser.test.sendMessage("webRequest-results", requests);
+      });
+    },
+  });
+
+  await extension.startup();
+
+  ok(!thumbnailExists(testPageUrl), "Thumbnail should not be cached yet.");
+
+  await bgCapture(testPageUrl);
+  ok(thumbnailExists(testPageUrl), "Thumbnail should be cached after capture");
+  removeThumbnail(testPageUrl);
+
+  extension.sendMessage("get-results");
+  Assert.deepEqual(
+    await extension.awaitMessage("webRequest-results"),
+    [
+      {
+        type: "main_frame",
+        url: testPageUrl,
+      },
+      {
+        type: "sub_frame",
+        url: iframeUrl,
+      },
+    ],
+    "Expected requests via webRequest"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_webRequest_redirect_mozextension.js b/toolkit/components/extensions/test/browser/browser_ext_webRequest_redirect_mozextension.js
new file mode 100644
index 0000000000..674a10a5ef
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_webRequest_redirect_mozextension.js
@@ -0,0 +1,48 @@
+"use strict";
+
+// See: https://bugzilla.mozilla.org/show_bug.cgi?id=1573456
+add_task(async function test_mozextension_page_loaded_in_extension_process() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "https://example.com/*",
+      ],
+      web_accessible_resources: ["test.html"],
+    },
+    files: {
+      "test.html": '<!DOCTYPE html><script src="test.js"></script>',
+      "test.js": () => {
+        browser.test.assertTrue(
+          browser.webRequest,
+          "webRequest API should be available"
+        );
+
+        browser.test.sendMessage("test_done");
+      },
+    },
+    background: () => {
+      browser.webRequest.onBeforeRequest.addListener(
+        () => {
+          return {
+            redirectUrl: browser.runtime.getURL("test.html"),
+          };
+        },
+        { urls: ["*://*/redir"] },
+        ["blocking"]
+      );
+    },
+  });
+  await extension.startup();
+
+  let tab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "https://example.com/redir"
+  );
+
+  await extension.awaitMessage("test_done");
+
+  await extension.unload();
+  BrowserTestUtils.removeTab(tab);
+});
diff --git a/toolkit/components/extensions/test/browser/browser_ext_windows_popup_title.js b/toolkit/components/extensions/test/browser/browser_ext_windows_popup_title.js
new file mode 100644
index 0000000000..21ef6bf460
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/browser_ext_windows_popup_title.js
@@ -0,0 +1,61 @@
+"use strict";
+
+// Check that extension popup windows contain the name of the extension
+// as well as the title of the loaded document, but not the URL.
+add_task(async function test_popup_title() {
+  const name = "custom_title_number_9_please";
+  const docTitle = "popup-test-title";
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      name,
+      permissions: ["tabs"],
+    },
+
+    async background() {
+      let popup;
+
+      // Called after the popup loads
+      browser.runtime.onMessage.addListener(async ({ docTitle }) => {
+        const { id } = await popup;
+        const { title } = await browser.windows.get(id);
+        browser.windows.remove(id);
+
+        browser.test.assertTrue(
+          title.includes(name),
+          "popup title must include extension name"
+        );
+        browser.test.assertTrue(
+          title.includes(docTitle),
+          "popup title must include extension document title"
+        );
+        browser.test.assertFalse(
+          title.includes("moz-extension:"),
+          "popup title must not include extension URL"
+        );
+
+        browser.test.notifyPass("popup-window-title");
+      });
+
+      popup = browser.windows.create({
+        url: "/index.html",
+        type: "popup",
+      });
+    },
+    files: {
+      "index.html": `<!doctype html>
+        <meta charset="utf-8">
+        <title>${docTitle}</title>,
+        <script src="index.js"></script>
+      `,
+      "index.js": `addEventListener(
+          "load",
+          () => browser.runtime.sendMessage({docTitle: document.title})
+         );`,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("popup-window-title");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/browser/data/test-download.txt b/toolkit/components/extensions/test/browser/data/test-download.txt
new file mode 100644
index 0000000000..f416e0e291
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/data/test-download.txt
@@ -0,0 +1 @@
+test download content
diff --git a/toolkit/components/extensions/test/browser/data/test_downloads_referrer.html b/toolkit/components/extensions/test/browser/data/test_downloads_referrer.html
new file mode 100644
index 0000000000..85410abfcd
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/data/test_downloads_referrer.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>Test downloads referrer</title>
+  </head>
+  <body>
+    <a href="test-download.txt" class="test-link">test link</a>
+  </body>
+</html>
diff --git a/toolkit/components/extensions/test/browser/head.js b/toolkit/components/extensions/test/browser/head.js
new file mode 100644
index 0000000000..0dd1a1666c
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/head.js
@@ -0,0 +1,103 @@
+/* exported ACCENT_COLOR, BACKGROUND, ENCODED_IMAGE_DATA, FRAME_COLOR, TAB_TEXT_COLOR,
+   TEXT_COLOR, TAB_BACKGROUND_TEXT_COLOR, imageBufferFromDataURI, hexToCSS, hexToRGB, testBorderColor,
+   waitForTransition, loadTestSubscript */
+
+"use strict";
+
+const BACKGROUND =
+  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0" +
+  "DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";
+const ENCODED_IMAGE_DATA =
+  "iVBORw0KGgoAAAANSUhEUgAAABkAAAAZCAYAAADE6YVjAAAABGdBTUEAALGPC/xhBQAAAAFzUkdCAK7OHOkAAAAgY0h" +
+  "STQAAeiYAAICEAAD6AAAAgOgAAHUwAADqYAAAOpgAABdwnLpRPAAAAAZiS0dEAP8A/wD/oL2nkwAAAAlwSFlzAAAdhwAAHYcBj+XxZQAAB5dJREFUSMd" +
+  "91vmTlEcZB/Bvd7/vO+/ce83O3gfLDUsC4VgIghBUEo2GM9GCFTaQBEISA1qIEVNQ4aggJDGIgAGTlFUKKcqKQpVHaQyny7FrCMiywp4ze+/Mzs67M/P" +
+  "O+3a3v5jdWo32H/B86vv0U083weecV3+0C8lkEh6PhzS3tuLkieMSAKo3fW9Mb1eoUtM0jemerukLllzrbGlKheovUpeqkmt113hPfx/27tyFF7+/bbg" +
+  "e+U9g20s7kEwmMXXGNLrp2fWi4V5z/tFjJ3fWX726INbfU2xx0yelkJAKdJf3Xl5+2QcPTpv2U0JZR+u92+xvly5ygKDm20/hlX17/jvB6VNnIKXEOyd" +
+  "O0iFh4PLVy0XV1U83Vk54QI7JK+bl+UE5vjRfTCzJ5eWBTFEayBLjisvljKmzwmtWrVkEAPNmVrEZkyfh+fU1n59k//7X4Fbz8MK2DRSAWLNq/Yc36y9" +
+  "+3UVMsyAYVPMy/MTvdBKvriJhphDq6xa9vf0i1GMwPVhM5s9bsLw/EvtN2kywwnw/nzBuLDZs2z4auXGjHuvWbmBQdT5v7qytn165fLCyyGtXTR6j5GV" +
+  "kIsvlBCwTVNgQhMKCRDQ2iIbmJv7BpU+Ykl02UFOzdt6gkbzTEQ5Rl2KL3W8eGUE+/ssFXK+rJQ8vWigLgjk5z9ZsvpOniJzVi+ZKTUhCuATTKCjhoLA" +
+  "hhQAsjrSZBJcm7rZ22O+ev6mMmTLj55eu1T+jU8GOH/kJf2TZCiifIQsXfwEbN2yktxoaeYbf93DKSORMnTOZE0aZaVlQGYVKJCgjEJSCcgLB0xDERjI" +
+  "NFBUEaXmuB20t95eEutr0xrufpo4eepMAkMPIxx+dx9at25EWQNXsh77q0Bzwen0ShEF32HCrCpjksAWHFAKqokFhgEJt2DKJeFoQv8eDuz3duaseXZY" +
+  "dixthaQ+NRlRCcKO+FgCweP68wswMF/yZWcTkNpLJFAZEGi6XC07NCUIIoqaNSLQfFALCEpCSEL/bK/wuw+12sKlDQzKs6k5yZt+rI+2aNKUSNdUbSSQ" +
+  "Wh2mJP46rGPeYrjtkY0M7jFgciUQCiqqgrCAfBTle3G9rR1NHN3SnDq9Lg49QlBQEcbfbQCKZlhQEDkXBih27RpDOrmacfP8YB4CfHT7uNXrCMFM2FdD" +
+  "BVQ5TE/A5HbDSJoSpQXAbXm8A4b5+gKrwulU4KKEBnwuzHpiQu+n1jQoQsM+9cYQMT9fvf/FLBYTaDqdzbfgft95PKzbPyQqwnlAXGkJtGIgNYnJpMfw" +
+  "OghLG0GJE0ZdiaOnsQ16OD6XZLkiRROdAgud5sxk8ridsy/pQU1VlOIkZN6QtAGnx0FA0AtXvIA4C5OX4kOWbiLRhQBDApTmgJuLwEonMgBvjgpmgjIE" +
+  "hhX7DAIVKNeqE05/dJbgEgRy5eOJ1ieXr1gJA7ZNLTrVVlAZLyopLJAUlHsrAMrwwrRQ4t6E5VHgSBExjcGpO0JQNizCE05a41dhOi+cXXVm144e1AHD" +
+  "1vXfFMOLy+KSHEDoEJLZ8s+ZWKpUusWwpFKiMUQ4jbiAaj8Hp9oExBsMCUpEIfD6JLKZjKJVGV3RIZGdm0qxA5qmz+/cgMhBVuuMRewRRGF7fe4BYHMg" +
+  "N5LxdV3vhy1EjrrjA5GAyTuKpFHricfS0dSDNCQRPoSyQgSSPI+UBEtwShiWUQEHw5mMvbz4JRcXvDr3B3dBG1sq5X53GlMcX4JWVTyvRQcOumDD2vfK" +
+  "cjOqiQDZPGBF2ryUEnjRhJlP4d6/BiQ1TABPKiyQhgtzvjPCJlQ/OGRwauqESSUPX68U3Vi4fGeH83Hwc3bYHBWUV0m0k4HB6z7aGu6sznDos00R3exg" +
+  "l5ZMwc+FMaJoKKxHFnbo6DMYiELBlqLOXDBq8dsvuPTfKALpwdbX42iMLsHjLd0Zv4RNvvY1wZxdZunyVDGZm6D/47sv12RqbmOPVhG5LGnAH4S8sgu7" +
+  "1oK/pn2BWAoYw0dDbaTd19iqlZROejwzEjqgMSuXUifak8jF49JnNI0kAoGrBfET7+uXOrS+y5ta21JzZsw7faW45XJaXxSvyAtTpkOi483fwtAWP1wt" +
+  "vrhvd/VFx+26zojr9Les2PnfaTNu4cuGvvKe9BVv3/RgARiNTpk/Hod17MWikxcqzzfhK/+1jL2xc+YQAX1ISDHLV7WTpQQaLcASzPEiB41ZrmEeHkrT" +
+  "Q49uz/aXn+iilLKXq/MmlS0e/jFcuX4SmaQAAKSXlnIvVy1aQ6EBMFgRyCznDpfGFwdKqirF2tu5SdIeGrkiP+KS5yb7dHtIKsnI++kP9rS8RQvjmxxe" +
+  "jePxD2HHwwP9FdCllurGhUbx14CAbiMc4Y2qVJqwLbo0qfpdLSilILB4Xg0mT6h7vnSWzZn9RoaynobWF3K6rk1NmzMWZ83/+37+V4a1cVg5JACYF45b" +
+  "FGVVWOFS2V1HUCjOdBqW0Q9fYb7N9/tcSptnldjpott8rFEXBO+f+NKrWMHL9Wu1nSUAIAaUUa59aAyE43E4X3bD8W6K5K6x1h1snRaMDJDuQf7+vrzf" +
+  "eG+mgfrcLHh3C79bx6wttGEqERiH/AjPohWMouv2ZAAAAAElFTkSuQmCC";
+const ACCENT_COLOR = "#a14040";
+const TEXT_COLOR = "#fac96e";
+// For testing aliases of the colors above:
+const FRAME_COLOR = [71, 105, 91];
+const TAB_BACKGROUND_TEXT_COLOR = [207, 221, 192, 0.9];
+
+function hexToRGB(hex) {
+  if (!hex) {
+    return null;
+  }
+  hex = parseInt(hex.indexOf("#") > -1 ? hex.substring(1) : hex, 16);
+  return [hex >> 16, (hex & 0x00ff00) >> 8, hex & 0x0000ff];
+}
+
+function rgbToCSS(rgb) {
+  return `rgb(${rgb.join(", ")})`;
+}
+
+function hexToCSS(hex) {
+  if (!hex) {
+    return null;
+  }
+  return rgbToCSS(hexToRGB(hex));
+}
+
+function imageBufferFromDataURI(encodedImageData) {
+  let decodedImageData = atob(encodedImageData);
+  return Uint8Array.from(decodedImageData, byte => byte.charCodeAt(0)).buffer;
+}
+
+function waitForTransition(element, propertyName) {
+  return BrowserTestUtils.waitForEvent(
+    element,
+    "transitionend",
+    false,
+    event => {
+      return event.target == element && event.propertyName == propertyName;
+    }
+  );
+}
+
+function testBorderColor(element, expected) {
+  let computedStyle = window.getComputedStyle(element);
+  Assert.equal(
+    computedStyle.borderLeftColor,
+    hexToCSS(expected),
+    "Element left border color should be set."
+  );
+  Assert.equal(
+    computedStyle.borderRightColor,
+    hexToCSS(expected),
+    "Element right border color should be set."
+  );
+  Assert.equal(
+    computedStyle.borderTopColor,
+    hexToCSS(expected),
+    "Element top border color should be set."
+  );
+  Assert.equal(
+    computedStyle.borderBottomColor,
+    hexToCSS(expected),
+    "Element bottom border color should be set."
+  );
+}
+
+function loadTestSubscript(filePath) {
+  Services.scriptloader.loadSubScript(new URL(filePath, gTestPath).href, this);
+}
diff --git a/toolkit/components/extensions/test/browser/head_serviceworker.js b/toolkit/components/extensions/test/browser/head_serviceworker.js
new file mode 100644
index 0000000000..012dcfe284
--- /dev/null
+++ b/toolkit/components/extensions/test/browser/head_serviceworker.js
@@ -0,0 +1,123 @@
+"use strict";
+
+/* exported assert_background_serviceworker_pref_enabled,
+ *          getBackgroundServiceWorkerRegistration,
+ *          getServiceWorkerInfo, getServiceWorkerState,
+ *          waitForServiceWorkerRegistrationsRemoved, waitForServiceWorkerTerminated
+ */
+
+async function assert_background_serviceworker_pref_enabled() {
+  is(
+    WebExtensionPolicy.backgroundServiceWorkerEnabled,
+    true,
+    "Expect extensions.backgroundServiceWorker.enabled to be true"
+  );
+}
+
+// Return the name of the enum corresponding to the worker's state (ex: "STATE_ACTIVATED")
+// because nsIServiceWorkerInfo doesn't currently provide a comparable string-returning getter.
+function getServiceWorkerState(workerInfo) {
+  const map = Object.keys(workerInfo)
+    .filter(k => k.startsWith("STATE_"))
+    .reduce((map, name) => {
+      map.set(workerInfo[name], name);
+      return map;
+    }, new Map());
+  return map.has(workerInfo.state)
+    ? map.get(workerInfo.state)
+    : "state: ${workerInfo.state}";
+}
+
+function getServiceWorkerInfo(swRegInfo) {
+  const {
+    evaluatingWorker,
+    installingWorker,
+    waitingWorker,
+    activeWorker,
+  } = swRegInfo;
+  return evaluatingWorker || installingWorker || waitingWorker || activeWorker;
+}
+
+async function waitForServiceWorkerTerminated(swRegInfo) {
+  info(`Wait all ${swRegInfo.scope} workers to be terminated`);
+
+  try {
+    await BrowserTestUtils.waitForCondition(
+      () => !getServiceWorkerInfo(swRegInfo)
+    );
+  } catch (err) {
+    const workerInfo = getServiceWorkerInfo(swRegInfo);
+    if (workerInfo) {
+      ok(
+        false,
+        `Error while waiting for workers for scope ${swRegInfo.scope} to be terminated. ` +
+          `Found a worker in state: ${getServiceWorkerState(workerInfo)}`
+      );
+      return;
+    }
+
+    throw err;
+  }
+}
+
+function getBackgroundServiceWorkerRegistration(extension) {
+  const policy = WebExtensionPolicy.getByHostname(extension.uuid);
+  const expectedSWScope = policy.getURL("/");
+  const expectedScriptURL = policy.extension.backgroundWorkerScript || "";
+
+  ok(
+    expectedScriptURL.startsWith(expectedSWScope),
+    `Extension does include a valid background.service_worker: ${expectedScriptURL}`
+  );
+
+  const swm = Cc["@mozilla.org/serviceworkers/manager;1"].getService(
+    Ci.nsIServiceWorkerManager
+  );
+
+  let swReg;
+  let regs = swm.getAllRegistrations();
+
+  for (let i = 0; i < regs.length; i++) {
+    let reg = regs.queryElementAt(i, Ci.nsIServiceWorkerRegistrationInfo);
+    if (reg.scriptSpec === expectedScriptURL) {
+      swReg = reg;
+      break;
+    }
+  }
+
+  ok(swReg, `Found service worker registration for ${expectedScriptURL}`);
+
+  is(
+    swReg.scope,
+    expectedSWScope,
+    "The extension background worker registration has the expected scope URL"
+  );
+
+  return swReg;
+}
+
+async function waitForServiceWorkerRegistrationsRemoved(extension) {
+  info(`Wait ${extension.id} service worker registration to be deleted`);
+  const swm = Cc["@mozilla.org/serviceworkers/manager;1"].getService(
+    Ci.nsIServiceWorkerManager
+  );
+  let baseURI = Services.io.newURI(`moz-extension://${extension.uuid}/`);
+  let principal = Services.scriptSecurityManager.createContentPrincipal(
+    baseURI,
+    {}
+  );
+
+  await BrowserTestUtils.waitForCondition(() => {
+    let regs = swm.getAllRegistrations();
+
+    for (let i = 0; i < regs.length; i++) {
+      let reg = regs.queryElementAt(i, Ci.nsIServiceWorkerRegistrationInfo);
+      if (principal.equals(reg.principal)) {
+        return false;
+      }
+    }
+
+    info(`All ${extension.id} service worker registrations are gone`);
+    return true;
+  }, `All ${extension.id} service worker registrations should be deleted`);
+}
diff --git a/toolkit/components/extensions/test/marionette/data/extension-with-bg-sw/manifest.json b/toolkit/components/extensions/test/marionette/data/extension-with-bg-sw/manifest.json
new file mode 100644
index 0000000000..5ed13a1b18
--- /dev/null
+++ b/toolkit/components/extensions/test/marionette/data/extension-with-bg-sw/manifest.json
@@ -0,0 +1,11 @@
+{
+  "manifest_version": 2,
+  "name": "Test Extension with Background Service Worker",
+  "version": "1",
+  "applications": {
+    "gecko": { "id": "extension-with-bg-sw@test" }
+  },
+  "background": {
+    "service_worker": "sw.js"
+  }
+}
\ No newline at end of file
diff --git a/toolkit/components/extensions/test/marionette/data/extension-with-bg-sw/sw.js b/toolkit/components/extensions/test/marionette/data/extension-with-bg-sw/sw.js
new file mode 100644
index 0000000000..2282e6a64b
--- /dev/null
+++ b/toolkit/components/extensions/test/marionette/data/extension-with-bg-sw/sw.js
@@ -0,0 +1,3 @@
+"use strict";
+
+dump("extension-with-bg-sw: sw.js loaded");
diff --git a/toolkit/components/extensions/test/marionette/manifest.ini b/toolkit/components/extensions/test/marionette/manifest.ini
new file mode 100644
index 0000000000..78006ccf1e
--- /dev/null
+++ b/toolkit/components/extensions/test/marionette/manifest.ini
@@ -0,0 +1 @@
+[test_extension_serviceworkers_purged_on_pref_disabled.py]
\ No newline at end of file
diff --git a/toolkit/components/extensions/test/marionette/test_extension_serviceworkers_purged_on_pref_disabled.py b/toolkit/components/extensions/test/marionette/test_extension_serviceworkers_purged_on_pref_disabled.py
new file mode 100644
index 0000000000..64e376adf0
--- /dev/null
+++ b/toolkit/components/extensions/test/marionette/test_extension_serviceworkers_purged_on_pref_disabled.py
@@ -0,0 +1,82 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from marionette_driver import Wait
+from marionette_driver.addons import Addons
+from marionette_harness import MarionetteTestCase
+
+import os
+
+EXT_ID = "extension-with-bg-sw@test"
+EXT_DIR_PATH = "extension-with-bg-sw"
+PREF_BG_SW_ENABLED = "extensions.backgroundServiceWorker.enabled"
+
+
+class PurgeExtensionServiceWorkersOnPrefDisabled(MarionetteTestCase):
+    def setUp(self):
+        super(PurgeExtensionServiceWorkersOnPrefDisabled, self).setUp()
+        self.test_extension_id = EXT_ID
+        # Flip the "mirror: once" pref and restart Firefox to be able
+        # to run the extension successfully.
+        self.marionette.set_pref(PREF_BG_SW_ENABLED, True)
+        self.marionette.restart(in_app=True)
+
+    def tearDown(self):
+        self.marionette.restart(clean=True)
+        super(PurgeExtensionServiceWorkersOnPrefDisabled, self).tearDown()
+
+    def test_unregistering_service_worker_when_clearing_data(self):
+        self.install_extension_with_service_worker()
+
+        # Flip the pref to false and restart again to verify that the
+        # service worker registration has been removed as expected.
+        self.marionette.set_pref(PREF_BG_SW_ENABLED, False)
+        self.marionette.restart(in_app=True)
+        self.assertFalse(self.is_extension_service_worker_registered)
+
+    def install_extension_with_service_worker(self):
+        addons = Addons(self.marionette)
+        test_extension_path = os.path.join(
+            os.path.dirname(self.filepath), "data", EXT_DIR_PATH
+        )
+        addons.install(test_extension_path, temp=True)
+        self.test_extension_base_url = self.get_extension_url()
+        Wait(self.marionette).until(
+            lambda _: self.is_extension_service_worker_registered,
+            message="Wait the extension service worker to be registered",
+        )
+
+    def get_extension_url(self, path="/"):
+        with self.marionette.using_context("chrome"):
+            return self.marionette.execute_script(
+                """
+              let policy = WebExtensionPolicy.getByID(arguments[0]);
+              return policy.getURL(arguments[1])
+            """,
+                script_args=(self.test_extension_id, path),
+            )
+
+    @property
+    def is_extension_service_worker_registered(self):
+        with self.marionette.using_context("chrome"):
+            return self.marionette.execute_script(
+                """
+                let serviceWorkerManager = Cc["@mozilla.org/serviceworkers/manager;1"].getService(
+                    Ci.nsIServiceWorkerManager
+                );
+
+                let serviceWorkers = serviceWorkerManager.getAllRegistrations();
+                for (let i = 0; i < serviceWorkers.length; i++) {
+                    let sw = serviceWorkers.queryElementAt(
+                        i,
+                        Ci.nsIServiceWorkerRegistrationInfo
+                    );
+                    if (sw.scope == arguments[0]) {
+                        return true;
+                    }
+                }
+                return false;
+            """,
+                script_args=(self.test_extension_base_url,),
+            )
diff --git a/toolkit/components/extensions/test/mochitest/.eslintrc.js b/toolkit/components/extensions/test/mochitest/.eslintrc.js
new file mode 100644
index 0000000000..a776405c9d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/.eslintrc.js
@@ -0,0 +1,12 @@
+"use strict";
+
+module.exports = {
+  env: {
+    browser: true,
+    webextensions: true,
+  },
+
+  rules: {
+    "no-shadow": 0,
+  },
+};
diff --git a/toolkit/components/extensions/test/mochitest/chrome.ini b/toolkit/components/extensions/test/mochitest/chrome.ini
new file mode 100644
index 0000000000..209f11b864
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/chrome.ini
@@ -0,0 +1,37 @@
+[DEFAULT]
+support-files =
+  chrome_cleanup_script.js
+  head.js
+  head_cookies.js
+  file_image_good.png
+  file_image_great.png
+  file_sample.html
+  file_with_images.html
+  webrequest_chromeworker.js
+  webrequest_test.jsm
+prefs =
+  security.mixed_content.upgrade_display_content=false
+tags = webextensions in-process-webextensions
+
+# NO NEW TESTS.  mochitest-chrome does not run under e10s, avoid adding new
+# tests here unless absolutely necessary.
+
+[test_chrome_ext_contentscript_data_uri.html]
+[test_chrome_ext_contentscript_telemetry.html]
+skip-if = (os == 'linux' && bits == 64) #Bug 1393920
+[test_chrome_ext_contentscript_unrecognizedprop_warning.html]
+[test_chrome_ext_downloads_open.html]
+[test_chrome_ext_downloads_saveAs.html]
+skip-if = (verify && !debug && (os == 'win')) || (os == 'android')
+[test_chrome_ext_downloads_uniquify.html]
+[test_chrome_ext_permissions.html]
+skip-if = os == 'android' # Bug 1350559
+[test_chrome_ext_trackingprotection.html]
+[test_chrome_ext_webnavigation_resolved_urls.html]
+[test_chrome_ext_webrequest_background_events.html]
+[test_chrome_ext_webrequest_host_permissions.html]
+skip-if = verify
+[test_chrome_ext_webrequest_mozextension.html]
+skip-if = true # Bug 1404172
+[test_chrome_native_messaging_paths.html]
+skip-if = os != "mac" && os != "linux"
diff --git a/toolkit/components/extensions/test/mochitest/chrome_cleanup_script.js b/toolkit/components/extensions/test/mochitest/chrome_cleanup_script.js
new file mode 100644
index 0000000000..397996b15c
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/chrome_cleanup_script.js
@@ -0,0 +1,66 @@
+"use strict";
+
+/* global addMessageListener, sendAsyncMessage */
+
+const { AppConstants } = ChromeUtils.import(
+  "resource://gre/modules/AppConstants.jsm"
+);
+const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+let listener = msg => {
+  void (msg instanceof Ci.nsIConsoleMessage);
+  dump(`Console message: ${msg}\n`);
+};
+
+Services.console.registerListener(listener);
+
+let getBrowserApp, getTabBrowser;
+if (AppConstants.MOZ_BUILD_APP === "mobile/android") {
+  getBrowserApp = win => win.BrowserApp;
+  getTabBrowser = tab => tab.browser;
+} else {
+  getBrowserApp = win => win.gBrowser;
+  getTabBrowser = tab => tab.linkedBrowser;
+}
+
+function* iterBrowserWindows() {
+  for (let win of Services.wm.getEnumerator("navigator:browser")) {
+    if (!win.closed && getBrowserApp(win)) {
+      yield win;
+    }
+  }
+}
+
+let initialTabs = new Map();
+for (let win of iterBrowserWindows()) {
+  initialTabs.set(win, new Set(getBrowserApp(win).tabs));
+}
+
+addMessageListener("check-cleanup", extensionId => {
+  Services.console.unregisterListener(listener);
+
+  let results = {
+    extraWindows: [],
+    extraTabs: [],
+  };
+
+  for (let win of iterBrowserWindows()) {
+    if (initialTabs.has(win)) {
+      let tabs = initialTabs.get(win);
+
+      for (let tab of getBrowserApp(win).tabs) {
+        if (!tabs.has(tab)) {
+          results.extraTabs.push(getTabBrowser(tab).currentURI.spec);
+        }
+      }
+    } else {
+      results.extraWindows.push(
+        Array.from(win.gBrowser.tabs, tab => getTabBrowser(tab).currentURI.spec)
+      );
+    }
+  }
+
+  initialTabs = null;
+
+  sendAsyncMessage("cleanup-results", results);
+});
diff --git a/toolkit/components/extensions/test/mochitest/chrome_head.js b/toolkit/components/extensions/test/mochitest/chrome_head.js
new file mode 100644
index 0000000000..3918c74e44
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/chrome_head.js
@@ -0,0 +1 @@
+"use strict";
diff --git a/toolkit/components/extensions/test/mochitest/file_WebNavigation_page1.html b/toolkit/components/extensions/test/mochitest/file_WebNavigation_page1.html
new file mode 100644
index 0000000000..663ebc6112
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_WebNavigation_page1.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+
+<html>
+<body>
+
+<iframe src="file_WebNavigation_page2.html" width="200" height="200"></iframe>
+
+<form>
+</form>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_WebNavigation_page2.html b/toolkit/components/extensions/test/mochitest/file_WebNavigation_page2.html
new file mode 100644
index 0000000000..cc1acc83d6
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_WebNavigation_page2.html
@@ -0,0 +1,7 @@
+<!DOCTYPE HTML>
+
+<html>
+<body>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_WebNavigation_page3.html b/toolkit/components/extensions/test/mochitest/file_WebNavigation_page3.html
new file mode 100644
index 0000000000..a0a26a2e9d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_WebNavigation_page3.html
@@ -0,0 +1,9 @@
+<!DOCTYPE HTML>
+
+<html>
+<body>
+
+<a id="elt" href="file_WebNavigation_page3.html#ref">click me</a>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_WebRequest_page3.html b/toolkit/components/extensions/test/mochitest/file_WebRequest_page3.html
new file mode 100644
index 0000000000..24c7a42986
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_WebRequest_page3.html
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+<script>
+"use strict";
+</script>
+</head>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_contains_iframe.html b/toolkit/components/extensions/test/mochitest/file_contains_iframe.html
new file mode 100644
index 0000000000..2b9344f463
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_contains_iframe.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<iframe src="http://example.org/tests/toolkit/components/extensions/test/mochitest/file_contains_img.html">
+</iframe>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_contains_img.html b/toolkit/components/extensions/test/mochitest/file_contains_img.html
new file mode 100644
index 0000000000..c1112acbd8
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_contains_img.html
@@ -0,0 +1,11 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<img src="file_image_good.png"/>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab.html b/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab.html
new file mode 100644
index 0000000000..6c1675cb47
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab.html
@@ -0,0 +1,11 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+  <meta charset="utf-8">
+</head>
+<body>
+  <iframe id="emptyframe"></iframe>
+  <iframe id="regularframe" src="http://test1.example.com/"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab2.html b/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab2.html
new file mode 100644
index 0000000000..3b102b3d67
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab2.html
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+  <meta charset="utf-8">
+</head>
+<body>
+  <iframe srcdoc="<iframe src='http://test1.example.com/'&gt;</iframe&gt;"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_contentscript_iframe.html b/toolkit/components/extensions/test/mochitest/file_contentscript_iframe.html
new file mode 100644
index 0000000000..dda5169d69
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_contentscript_iframe.html
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+  <meta charset="utf-8">
+</head>
+<body>
+  <iframe id="frame" src="http://test2.example.com/"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_green.html b/toolkit/components/extensions/test/mochitest/file_green.html
new file mode 100644
index 0000000000..20755c5b56
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_green.html
@@ -0,0 +1,3 @@
+<meta charset=utf-8>
+<title>Super green test page</title>
+<body style="background: #0f0">
diff --git a/toolkit/components/extensions/test/mochitest/file_image_bad.png b/toolkit/components/extensions/test/mochitest/file_image_bad.png
new file mode 100644
index 0000000000..4c3be50847
Binary files /dev/null and b/toolkit/components/extensions/test/mochitest/file_image_bad.png differ
diff --git a/toolkit/components/extensions/test/mochitest/file_image_good.png b/toolkit/components/extensions/test/mochitest/file_image_good.png
new file mode 100644
index 0000000000..769c636340
Binary files /dev/null and b/toolkit/components/extensions/test/mochitest/file_image_good.png differ
diff --git a/toolkit/components/extensions/test/mochitest/file_image_great.png b/toolkit/components/extensions/test/mochitest/file_image_great.png
new file mode 100644
index 0000000000..769c636340
Binary files /dev/null and b/toolkit/components/extensions/test/mochitest/file_image_great.png differ
diff --git a/toolkit/components/extensions/test/mochitest/file_image_redirect.png b/toolkit/components/extensions/test/mochitest/file_image_redirect.png
new file mode 100644
index 0000000000..4c3be50847
Binary files /dev/null and b/toolkit/components/extensions/test/mochitest/file_image_redirect.png differ
diff --git a/toolkit/components/extensions/test/mochitest/file_indexedDB.html b/toolkit/components/extensions/test/mochitest/file_indexedDB.html
new file mode 100644
index 0000000000..65b7e0ad2f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_indexedDB.html
@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <script>
+"use strict";
+
+const objectStoreName = "Objects";
+
+let test = {key: 0, value: "test"};
+
+let request = indexedDB.open("WebExtensionTest", 1);
+request.onupgradeneeded = event => {
+  let db = event.target.result;
+  let objectStore = db.createObjectStore(objectStoreName,
+                                         {autoIncrement: 0});
+  request = objectStore.add(test.value, test.key);
+  request.onsuccess = event => {
+    db.close();
+    window.postMessage("indexedDBCreated", "*");
+  };
+};
+    </script>
+  </head>
+  <body>
+    This is a test page.
+  </body>
+<html>
diff --git a/toolkit/components/extensions/test/mochitest/file_mixed.html b/toolkit/components/extensions/test/mochitest/file_mixed.html
new file mode 100644
index 0000000000..f3c7dda580
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_mixed.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<div id="test">Sample text</div>
+<img id="bad-image" src="http://example.com/tests/toolkit/components/extensions/test/mochitest/file_image_bad.png" />
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_redirect_cors_bypass.html b/toolkit/components/extensions/test/mochitest/file_redirect_cors_bypass.html
new file mode 100644
index 0000000000..b8fda2369a
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_redirect_cors_bypass.html
@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>1450965 Skip Cors Check for Early WebExtention Redirects</title>
+</head>
+<body>
+  <pre id="c">
+    Fetching ...
+  </pre>
+  <script>
+    "use strict";
+    let c = document.querySelector("#c");
+    const channel = new BroadcastChannel("test_bus");
+    function l(t) { c.innerText += `${t}\n`; }
+
+    fetch("https://example.org/tests/toolkit/components/extensions/test/mochitest/file_cors_blocked.txt")
+      .then(r => r.text())
+      .then(t => {
+        // This Request should have been redirected to /file_sample.txt in
+        // onBeforeRequest. So the text should be 'Sample'
+        l(`Loaded: ${t}`);
+        channel.postMessage(t);
+      }).catch(e => {
+        // The Redirect Failed, most likly due to a CORS Error
+        l(`e`);
+        channel.postMessage(e.toString());
+      });
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_redirect_data_uri.html b/toolkit/components/extensions/test/mochitest/file_redirect_data_uri.html
new file mode 100644
index 0000000000..fe8e5bea44
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_redirect_data_uri.html
@@ -0,0 +1,9 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1434357: Allow Web Request API to redirect to data: URI</title>
+</head>
+<body>
+  <div id="testdiv">foo</div>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_remote_frame.html b/toolkit/components/extensions/test/mochitest/file_remote_frame.html
new file mode 100644
index 0000000000..f1b9240092
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_remote_frame.html
@@ -0,0 +1,20 @@
+<!DOCTYPE>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <script>
+      "use strict";
+      var response = {
+        tabs: false,
+        cookie: document.cookie,
+      };
+      try {
+        browser.tabs.create({url: "file_sample.html"});
+        response.tabs = true;
+      } catch (e) {
+        // ok
+      }
+      window.parent.postMessage(response, "*");
+    </script>
+  </head>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_sample.html b/toolkit/components/extensions/test/mochitest/file_sample.html
new file mode 100644
index 0000000000..a20e49a1f0
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_sample.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<div id="test">Sample text</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_sample.txt b/toolkit/components/extensions/test/mochitest/file_sample.txt
new file mode 100644
index 0000000000..c02cd532b1
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_sample.txt
@@ -0,0 +1 @@
+Sample
\ No newline at end of file
diff --git a/toolkit/components/extensions/test/mochitest/file_sample.txt^headers^ b/toolkit/components/extensions/test/mochitest/file_sample.txt^headers^
new file mode 100644
index 0000000000..cb762eff80
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_sample.txt^headers^
@@ -0,0 +1 @@
+Access-Control-Allow-Origin: *
diff --git a/toolkit/components/extensions/test/mochitest/file_script_bad.js b/toolkit/components/extensions/test/mochitest/file_script_bad.js
new file mode 100644
index 0000000000..c425122c71
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_script_bad.js
@@ -0,0 +1,3 @@
+"use strict";
+
+window.failure = true;
diff --git a/toolkit/components/extensions/test/mochitest/file_script_good.js b/toolkit/components/extensions/test/mochitest/file_script_good.js
new file mode 100644
index 0000000000..14e959aa5c
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_script_good.js
@@ -0,0 +1,12 @@
+"use strict";
+
+window.success = window.success ? window.success + 1 : 1;
+
+{
+  let scripts = document.getElementsByTagName("script");
+  let url = new URL(scripts[scripts.length - 1].src);
+  let flag = url.searchParams.get("q");
+  if (flag) {
+    window.postMessage(flag, "*");
+  }
+}
diff --git a/toolkit/components/extensions/test/mochitest/file_script_redirect.js b/toolkit/components/extensions/test/mochitest/file_script_redirect.js
new file mode 100644
index 0000000000..c425122c71
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_script_redirect.js
@@ -0,0 +1,3 @@
+"use strict";
+
+window.failure = true;
diff --git a/toolkit/components/extensions/test/mochitest/file_script_xhr.js b/toolkit/components/extensions/test/mochitest/file_script_xhr.js
new file mode 100644
index 0000000000..ad01f74253
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_script_xhr.js
@@ -0,0 +1,9 @@
+"use strict";
+
+var request = new XMLHttpRequest();
+request.open(
+  "get",
+  "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/xhr_resource",
+  false
+);
+request.send();
diff --git a/toolkit/components/extensions/test/mochitest/file_serviceWorker.html b/toolkit/components/extensions/test/mochitest/file_serviceWorker.html
new file mode 100644
index 0000000000..d2b99769cc
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_serviceWorker.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <script>
+      "use strict";
+
+      navigator.serviceWorker.register("serviceWorker.js").then(() => {
+        window.postMessage("serviceWorkerRegistered", "*");
+      });
+    </script>
+  </head>
+  <body>
+    This is a test page.
+  </body>
+<html>
diff --git a/toolkit/components/extensions/test/mochitest/file_simple_sandboxed_frame.html b/toolkit/components/extensions/test/mochitest/file_simple_sandboxed_frame.html
new file mode 100644
index 0000000000..909a1f9e36
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_simple_sandboxed_frame.html
@@ -0,0 +1,23 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script>
+"use strict";
+
+let req = new XMLHttpRequest();
+req.open("GET", "/xhr_sandboxed");
+req.send();
+
+let sandbox = document.createElement("iframe");
+sandbox.setAttribute("sandbox", "allow-scripts");
+sandbox.setAttribute("src", "file_simple_sandboxed_subframe.html");
+document.documentElement.appendChild(sandbox);
+</script>
+<img src="file_image_great.png"/>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_simple_sandboxed_subframe.html b/toolkit/components/extensions/test/mochitest/file_simple_sandboxed_subframe.html
new file mode 100644
index 0000000000..a0a437d0eb
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_simple_sandboxed_subframe.html
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_simple_xhr.html b/toolkit/components/extensions/test/mochitest/file_simple_xhr.html
new file mode 100644
index 0000000000..f6ef67277d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_simple_xhr.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script>
+"use strict";
+
+let req = new XMLHttpRequest();
+req.open("GET", "http://example.org/example.txt");
+req.send();
+</script>
+<img src="file_image_good.png"/>
+<iframe src="file_simple_xhr_frame.html"/>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_simple_xhr_frame.html b/toolkit/components/extensions/test/mochitest/file_simple_xhr_frame.html
new file mode 100644
index 0000000000..7f38247ac0
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_simple_xhr_frame.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script>
+"use strict";
+
+let req = new XMLHttpRequest();
+req.open("GET", "/xhr_resource");
+req.send();
+</script>
+<img src="file_image_bad.png"/>
+<iframe src="file_simple_xhr_frame2.html"/>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_simple_xhr_frame2.html b/toolkit/components/extensions/test/mochitest/file_simple_xhr_frame2.html
new file mode 100644
index 0000000000..6174a0b402
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_simple_xhr_frame2.html
@@ -0,0 +1,23 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script>
+"use strict";
+
+let req = new XMLHttpRequest();
+req.open("GET", "/xhr_resource_2");
+req.send();
+
+let sandbox = document.createElement("iframe");
+sandbox.setAttribute("sandbox", "allow-scripts");
+sandbox.setAttribute("src", "file_simple_sandboxed_frame.html");
+document.documentElement.appendChild(sandbox);
+</script>
+<img src="file_image_redirect.png"/>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_streamfilter.txt b/toolkit/components/extensions/test/mochitest/file_streamfilter.txt
new file mode 100644
index 0000000000..56cdd85e1d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_streamfilter.txt
@@ -0,0 +1 @@
+Middle
diff --git a/toolkit/components/extensions/test/mochitest/file_style_bad.css b/toolkit/components/extensions/test/mochitest/file_style_bad.css
new file mode 100644
index 0000000000..8dbc8dc7a4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_style_bad.css
@@ -0,0 +1,3 @@
+#test {
+  color: green !important;
+}
diff --git a/toolkit/components/extensions/test/mochitest/file_style_good.css b/toolkit/components/extensions/test/mochitest/file_style_good.css
new file mode 100644
index 0000000000..46f9774b5f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_style_good.css
@@ -0,0 +1,3 @@
+#test {
+  color: red;
+}
diff --git a/toolkit/components/extensions/test/mochitest/file_style_redirect.css b/toolkit/components/extensions/test/mochitest/file_style_redirect.css
new file mode 100644
index 0000000000..8dbc8dc7a4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_style_redirect.css
@@ -0,0 +1,3 @@
+#test {
+  color: green !important;
+}
diff --git a/toolkit/components/extensions/test/mochitest/file_tabs_permission_page1.html b/toolkit/components/extensions/test/mochitest/file_tabs_permission_page1.html
new file mode 100644
index 0000000000..63f503ad3c
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_tabs_permission_page1.html
@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+    <title>The Title</title>
+</head>
+<body>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_tabs_permission_page2.html b/toolkit/components/extensions/test/mochitest/file_tabs_permission_page2.html
new file mode 100644
index 0000000000..87ac7a2f64
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_tabs_permission_page2.html
@@ -0,0 +1,11 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+    <title>Another Title</title>
+    <link href="file_image_great.png" rel="icon" type="image/png" />
+</head>
+<body>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_third_party.html b/toolkit/components/extensions/test/mochitest/file_third_party.html
new file mode 100644
index 0000000000..fc5a326297
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_third_party.html
@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script>
+
+"use strict"
+
+let url = new URL(location);
+let img = new Image();
+img.src = `http://${url.searchParams.get("domain")}/tests/toolkit/components/extensions/test/mochitest/file_image_bad.png`;
+document.body.appendChild(img);
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_to_drawWindow.html b/toolkit/components/extensions/test/mochitest/file_to_drawWindow.html
new file mode 100644
index 0000000000..6ebd54d9a3
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_to_drawWindow.html
@@ -0,0 +1,9 @@
+<!doctype html>
+<html>
+<head>
+  <meta charset="utf-8">
+</head>
+<body style="background: #ff9">
+  &nbsp;
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect.html b/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect.html
new file mode 100644
index 0000000000..cba3043f71
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect.html
@@ -0,0 +1,9 @@
+<!DOCTYPE HTML>
+
+<html>
+  <head>
+    <meta http-equiv="refresh" content="1;dummy_page.html">
+  </head>
+  <body>
+  </body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect_httpHeaders.html b/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect_httpHeaders.html
new file mode 100644
index 0000000000..c5b436979f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect_httpHeaders.html
@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+
+<html>
+  <head>
+  </head>
+  <body>
+  </body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect_httpHeaders.html^headers^ b/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect_httpHeaders.html^headers^
new file mode 100644
index 0000000000..574a392a15
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_clientRedirect_httpHeaders.html^headers^
@@ -0,0 +1 @@
+Refresh: 1;url=dummy_page.html
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_frameClientRedirect.html b/toolkit/components/extensions/test/mochitest/file_webNavigation_frameClientRedirect.html
new file mode 100644
index 0000000000..d360bcbb13
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_frameClientRedirect.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+
+<html>
+<body>
+
+<iframe src="file_webNavigation_clientRedirect.html" width="200" height="200"></iframe>
+
+<form>
+</form>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_frameRedirect.html b/toolkit/components/extensions/test/mochitest/file_webNavigation_frameRedirect.html
new file mode 100644
index 0000000000..06dbd43741
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_frameRedirect.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+
+<html>
+<body>
+
+<iframe src="redirection.sjs" width="200" height="200"></iframe>
+
+<form>
+</form>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe.html b/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe.html
new file mode 100644
index 0000000000..307990714b
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+
+<html>
+<body>
+
+<iframe src="file_webNavigation_manualSubframe_page1.html" width="200" height="200"></iframe>
+
+<form>
+</form>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe_page1.html b/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe_page1.html
new file mode 100644
index 0000000000..55bb7aa6ae
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe_page1.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+
+<html>
+  <body>
+    <h1>page1</h1>
+    <a href="file_webNavigation_manualSubframe_page2.html">page2</a>
+  </body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe_page2.html b/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe_page2.html
new file mode 100644
index 0000000000..8f589f8bbd
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_webNavigation_manualSubframe_page2.html
@@ -0,0 +1,7 @@
+<!DOCTYPE html>
+
+<html>
+  <body>
+    <h1>page2</h1>
+  </body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_with_about_blank.html b/toolkit/components/extensions/test/mochitest/file_with_about_blank.html
new file mode 100644
index 0000000000..af51c2e52a
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_with_about_blank.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html>
+<head>
+  <meta charset="utf-8">
+</head>
+<body>
+  <iframe id="a_b" src="about:blank"></iframe>
+  <iframe srcdoc="galactica actual" src="adama"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_with_images.html b/toolkit/components/extensions/test/mochitest/file_with_images.html
new file mode 100644
index 0000000000..6a3c090be2
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_with_images.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html>
+<head>
+  <meta charset="utf-8">
+</head>
+<body>
+  <img src="https://example.com/chrome/toolkit/components/extensions/test/mochitest/file_image_good.png">
+  <img src="http://mochi.test:8888/chrome/toolkit/components/extensions/test/mochitest/file_image_great.png">
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/file_with_xorigin_frame.html b/toolkit/components/extensions/test/mochitest/file_with_xorigin_frame.html
new file mode 100644
index 0000000000..d0d2f02e2d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/file_with_xorigin_frame.html
@@ -0,0 +1,6 @@
+<!DOCTYPE HTML>
+<meta charset="utf-8">
+
+<img src="file_image_great.png"/>
+Load a cross-origin iframe from example.net <p>
+<iframe src="http://example.net/tests/toolkit/components/extensions/test/mochitest/file_sample.html"></iframe>
diff --git a/toolkit/components/extensions/test/mochitest/head.js b/toolkit/components/extensions/test/mochitest/head.js
new file mode 100644
index 0000000000..2d26de34c7
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/head.js
@@ -0,0 +1,123 @@
+"use strict";
+
+/* exported AppConstants, Assert */
+
+var { AppConstants } = SpecialPowers.Cu.import(
+  "resource://gre/modules/AppConstants.jsm",
+  {}
+);
+
+let remote = SpecialPowers.getBoolPref("extensions.webextensions.remote");
+if (remote) {
+  // We don't want to reset this at the end of the test, so that we don't have
+  // to spawn a new extension child process for each test unit.
+  SpecialPowers.setIntPref("dom.ipc.keepProcessesAlive.extension", 1);
+}
+
+{
+  let chromeScript = SpecialPowers.loadChromeScript(
+    SimpleTest.getTestFileURL("chrome_cleanup_script.js")
+  );
+
+  SimpleTest.registerCleanupFunction(async () => {
+    await new Promise(resolve => setTimeout(resolve, 0));
+
+    chromeScript.sendAsyncMessage("check-cleanup");
+
+    let results = await chromeScript.promiseOneMessage("cleanup-results");
+    chromeScript.destroy();
+
+    if (results.extraWindows.length || results.extraTabs.length) {
+      ok(
+        false,
+        `Test left extra windows or tabs: ${JSON.stringify(results)}\n`
+      );
+    }
+  });
+}
+
+let Assert = {
+  // Cut-down version based on Assert.jsm. Only supports regexp and objects as
+  // the expected variables.
+  rejects(promise, expected, msg) {
+    return promise.then(
+      () => {
+        ok(false, msg);
+      },
+      actual => {
+        let matched = false;
+        if (Object.prototype.toString.call(expected) == "[object RegExp]") {
+          if (expected.test(actual)) {
+            matched = true;
+          }
+        } else if (actual instanceof expected) {
+          matched = true;
+        }
+
+        if (matched) {
+          ok(true, msg);
+        } else {
+          ok(false, `Unexpected exception for "${msg}": ${actual}`);
+        }
+      }
+    );
+  },
+};
+
+/* exported waitForLoad */
+
+function waitForLoad(win) {
+  return new Promise(resolve => {
+    win.addEventListener(
+      "load",
+      function() {
+        resolve();
+      },
+      { capture: true, once: true }
+    );
+  });
+}
+
+/* exported loadChromeScript */
+function loadChromeScript(fn) {
+  let wrapper = `
+const {Services} = Cu.import("resource://gre/modules/Services.jsm", {});
+(${fn.toString()})();`;
+
+  return SpecialPowers.loadChromeScript(new Function(wrapper));
+}
+
+/* exported consoleMonitor */
+let consoleMonitor = {
+  start(messages) {
+    this.chromeScript = SpecialPowers.loadChromeScript(
+      SimpleTest.getTestFileURL("mochitest_console.js")
+    );
+    this.chromeScript.sendAsyncMessage("consoleStart", messages);
+  },
+
+  async finished() {
+    let done = this.chromeScript.promiseOneMessage("consoleDone").then(done => {
+      this.chromeScript.destroy();
+      return done;
+    });
+    this.chromeScript.sendAsyncMessage("waitForConsole");
+    let test = await done;
+    ok(test.ok, test.message);
+  },
+};
+/* exported waitForState */
+
+function waitForState(sw, state) {
+  return new Promise(resolve => {
+    if (sw.state === state) {
+      return resolve();
+    }
+    sw.addEventListener("statechange", function onStateChange() {
+      if (sw.state === state) {
+        sw.removeEventListener("statechange", onStateChange);
+        resolve();
+      }
+    });
+  });
+}
diff --git a/toolkit/components/extensions/test/mochitest/head_cookies.js b/toolkit/components/extensions/test/mochitest/head_cookies.js
new file mode 100644
index 0000000000..610c800c94
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/head_cookies.js
@@ -0,0 +1,287 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* exported testCookies */
+/* import-globals-from head.js */
+
+async function testCookies(options) {
+  // Changing the options object is a bit of a hack, but it allows us to easily
+  // pass an expiration date to the background script.
+  options.expiry = Date.now() / 1000 + 3600;
+
+  async function background(backgroundOptions) {
+    // Ask the parent scope to change some cookies we may or may not have
+    // permission for.
+    let awaitChanges = new Promise(resolve => {
+      browser.test.onMessage.addListener(msg => {
+        browser.test.assertEq("cookies-changed", msg, "browser.test.onMessage");
+        resolve();
+      });
+    });
+
+    let changed = [];
+    browser.cookies.onChanged.addListener(event => {
+      changed.push(`${event.cookie.name}:${event.cause}`);
+    });
+    browser.test.sendMessage("change-cookies");
+
+    // Try to access some cookies in various ways.
+    let { url, domain, secure } = backgroundOptions;
+
+    let failures = 0;
+    let tallyFailure = error => {
+      failures++;
+    };
+
+    try {
+      await awaitChanges;
+
+      let cookie = await browser.cookies.get({ url, name: "foo" });
+      browser.test.assertEq(
+        backgroundOptions.shouldPass,
+        cookie != null,
+        "should pass == get cookie"
+      );
+
+      let cookies = await browser.cookies.getAll({ domain });
+      if (backgroundOptions.shouldPass) {
+        browser.test.assertEq(2, cookies.length, "expected number of cookies");
+      } else {
+        browser.test.assertEq(0, cookies.length, "expected number of cookies");
+      }
+
+      await Promise.all([
+        browser.cookies
+          .set({
+            url,
+            domain,
+            secure,
+            name: "foo",
+            value: "baz",
+            expirationDate: backgroundOptions.expiry,
+          })
+          .catch(tallyFailure),
+        browser.cookies
+          .set({
+            url,
+            domain,
+            secure,
+            name: "bar",
+            value: "quux",
+            expirationDate: backgroundOptions.expiry,
+          })
+          .catch(tallyFailure),
+        browser.cookies.remove({ url, name: "deleted" }),
+      ]);
+
+      if (backgroundOptions.shouldPass) {
+        // The order of eviction events isn't guaranteed, so just check that
+        // it's there somewhere.
+        let evicted = changed.indexOf("evicted:evicted");
+        if (evicted < 0) {
+          browser.test.fail("got no eviction event");
+        } else {
+          browser.test.succeed("got eviction event");
+          changed.splice(evicted, 1);
+        }
+
+        browser.test.assertEq(
+          "x:explicit,x:overwrite,x:explicit,x:explicit,foo:overwrite,foo:explicit,bar:explicit,deleted:explicit",
+          changed.join(","),
+          "expected changes"
+        );
+      } else {
+        browser.test.assertEq("", changed.join(","), "expected no changes");
+      }
+
+      if (!(backgroundOptions.shouldPass || backgroundOptions.shouldWrite)) {
+        browser.test.assertEq(2, failures, "Expected failures");
+      } else {
+        browser.test.assertEq(0, failures, "Expected no failures");
+      }
+
+      browser.test.notifyPass("cookie-permissions");
+    } catch (error) {
+      browser.test.fail(`Error: ${error} :: ${error.stack}`);
+      browser.test.notifyFail("cookie-permissions");
+    }
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: options.permissions,
+    },
+
+    background: `(${background})(${JSON.stringify(options)})`,
+  });
+
+  let stepOne = loadChromeScript(() => {
+    const { addMessageListener, sendAsyncMessage } = this;
+    addMessageListener("options", options => {
+      let domain = options.domain.replace(/^\.?/, ".");
+      // This will be evicted after we add a fourth cookie.
+      Services.cookies.add(
+        domain,
+        "/",
+        "evicted",
+        "bar",
+        options.secure,
+        false,
+        false,
+        options.expiry,
+        {},
+        Ci.nsICookie.SAMESITE_NONE,
+        options.url.startsWith("https")
+          ? Ci.nsICookie.SCHEME_HTTPS
+          : Ci.nsICookie.SCHEME_HTTP
+      );
+      // This will be modified by the background script.
+      Services.cookies.add(
+        domain,
+        "/",
+        "foo",
+        "bar",
+        options.secure,
+        false,
+        false,
+        options.expiry,
+        {},
+        Ci.nsICookie.SAMESITE_NONE,
+        options.url.startsWith("https")
+          ? Ci.nsICookie.SCHEME_HTTPS
+          : Ci.nsICookie.SCHEME_HTTP
+      );
+      // This will be deleted by the background script.
+      Services.cookies.add(
+        domain,
+        "/",
+        "deleted",
+        "bar",
+        options.secure,
+        false,
+        false,
+        options.expiry,
+        {},
+        Ci.nsICookie.SAMESITE_NONE,
+        options.url.startsWith("https")
+          ? Ci.nsICookie.SCHEME_HTTPS
+          : Ci.nsICookie.SCHEME_HTTP
+      );
+      sendAsyncMessage("done");
+    });
+  });
+  stepOne.sendAsyncMessage("options", options);
+  await stepOne.promiseOneMessage("done");
+  stepOne.destroy();
+
+  await extension.startup();
+
+  await extension.awaitMessage("change-cookies");
+
+  let stepTwo = loadChromeScript(() => {
+    const { addMessageListener, sendAsyncMessage } = this;
+    addMessageListener("options", options => {
+      let domain = options.domain.replace(/^\.?/, ".");
+
+      Services.cookies.add(
+        domain,
+        "/",
+        "x",
+        "y",
+        options.secure,
+        false,
+        false,
+        options.expiry,
+        {},
+        Ci.nsICookie.SAMESITE_NONE,
+        options.url.startsWith("https")
+          ? Ci.nsICookie.SCHEME_HTTPS
+          : Ci.nsICookie.SCHEME_HTTP
+      );
+      Services.cookies.add(
+        domain,
+        "/",
+        "x",
+        "z",
+        options.secure,
+        false,
+        false,
+        options.expiry,
+        {},
+        Ci.nsICookie.SAMESITE_NONE,
+        options.url.startsWith("https")
+          ? Ci.nsICookie.SCHEME_HTTPS
+          : Ci.nsICookie.SCHEME_HTTP
+      );
+      Services.cookies.remove(domain, "x", "/", {});
+      sendAsyncMessage("done");
+    });
+  });
+  stepTwo.sendAsyncMessage("options", options);
+  await stepTwo.promiseOneMessage("done");
+  stepTwo.destroy();
+
+  extension.sendMessage("cookies-changed");
+
+  await extension.awaitFinish("cookie-permissions");
+  await extension.unload();
+
+  let stepThree = loadChromeScript(() => {
+    const { addMessageListener, sendAsyncMessage, assert } = this;
+    let cookieSvc = Services.cookies;
+
+    function getCookies(host) {
+      let cookies = [];
+      for (let cookie of cookieSvc.getCookiesFromHost(host, {})) {
+        cookies.push(cookie);
+      }
+      return cookies.sort((a, b) => a.name.localeCompare(b.name));
+    }
+
+    addMessageListener("options", options => {
+      let cookies = getCookies(options.domain);
+
+      if (options.shouldPass) {
+        assert.equal(cookies.length, 2, "expected two cookies for host");
+
+        assert.equal(cookies[0].name, "bar", "correct cookie name");
+        assert.equal(cookies[0].value, "quux", "correct cookie value");
+
+        assert.equal(cookies[1].name, "foo", "correct cookie name");
+        assert.equal(cookies[1].value, "baz", "correct cookie value");
+      } else if (options.shouldWrite) {
+        // Note: |shouldWrite| applies only when |shouldPass| is false.
+        // This is necessary because, unfortunately, websites (and therefore web
+        // extensions) are allowed to write some cookies which they're not allowed
+        // to read.
+        assert.equal(cookies.length, 3, "expected three cookies for host");
+
+        assert.equal(cookies[0].name, "bar", "correct cookie name");
+        assert.equal(cookies[0].value, "quux", "correct cookie value");
+
+        assert.equal(cookies[1].name, "deleted", "correct cookie name");
+
+        assert.equal(cookies[2].name, "foo", "correct cookie name");
+        assert.equal(cookies[2].value, "baz", "correct cookie value");
+      } else {
+        assert.equal(cookies.length, 2, "expected two cookies for host");
+
+        assert.equal(cookies[0].name, "deleted", "correct second cookie name");
+
+        assert.equal(cookies[1].name, "foo", "correct cookie name");
+        assert.equal(cookies[1].value, "bar", "correct cookie value");
+      }
+
+      for (let cookie of cookies) {
+        cookieSvc.remove(cookie.host, cookie.name, "/", {});
+      }
+      // Make sure we don't silently poison subsequent tests if something goes wrong.
+      assert.equal(getCookies(options.domain).length, 0, "cookies cleared");
+      sendAsyncMessage("done");
+    });
+  });
+  stepThree.sendAsyncMessage("options", options);
+  await stepThree.promiseOneMessage("done");
+  stepThree.destroy();
+}
diff --git a/toolkit/components/extensions/test/mochitest/head_notifications.js b/toolkit/components/extensions/test/mochitest/head_notifications.js
new file mode 100644
index 0000000000..0c8cf24350
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/head_notifications.js
@@ -0,0 +1,169 @@
+"use strict";
+
+/* exported MockAlertsService */
+
+function mockServicesChromeScript() {
+  const MOCK_ALERTS_CID = Components.ID(
+    "{48068bc2-40ab-4904-8afd-4cdfb3a385f3}"
+  );
+  const ALERTS_SERVICE_CONTRACT_ID = "@mozilla.org/alerts-service;1";
+
+  const { setTimeout } = ChromeUtils.import(
+    "resource://gre/modules/Timer.jsm",
+    {}
+  );
+  const registrar = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
+
+  let activeNotifications = Object.create(null);
+
+  const mockAlertsService = {
+    showPersistentNotification: function(persistentData, alert, alertListener) {
+      this.showAlert(alert, alertListener);
+    },
+
+    showAlert: function(alert, listener) {
+      activeNotifications[alert.name] = {
+        listener: listener,
+        cookie: alert.cookie,
+        title: alert.title,
+      };
+
+      // fake async alert show event
+      if (listener) {
+        setTimeout(function() {
+          listener.observe(null, "alertshow", alert.cookie);
+        }, 100);
+      }
+    },
+
+    showAlertNotification: function(
+      imageUrl,
+      title,
+      text,
+      textClickable,
+      cookie,
+      alertListener,
+      name
+    ) {
+      this.showAlert(
+        {
+          name: name,
+          cookie: cookie,
+          title: title,
+        },
+        alertListener
+      );
+    },
+
+    closeAlert: function(name) {
+      let alertNotification = activeNotifications[name];
+      if (alertNotification) {
+        if (alertNotification.listener) {
+          alertNotification.listener.observe(
+            null,
+            "alertfinished",
+            alertNotification.cookie
+          );
+        }
+        delete activeNotifications[name];
+      }
+    },
+
+    QueryInterface: ChromeUtils.generateQI(["nsIAlertsService"]),
+
+    createInstance: function(outer, iid) {
+      if (outer != null) {
+        throw Components.Exception("", Cr.NS_ERROR_NO_AGGREGATION);
+      }
+      return this.QueryInterface(iid);
+    },
+  };
+
+  registrar.registerFactory(
+    MOCK_ALERTS_CID,
+    "alerts service",
+    ALERTS_SERVICE_CONTRACT_ID,
+    mockAlertsService
+  );
+
+  function clickNotifications(doClose) {
+    // Until we need to close a specific notification, just click them all.
+    for (let [name, notification] of Object.entries(activeNotifications)) {
+      let { listener, cookie } = notification;
+      listener.observe(null, "alertclickcallback", cookie);
+      if (doClose) {
+        mockAlertsService.closeAlert(name);
+      }
+    }
+  }
+
+  function closeAllNotifications() {
+    for (let alertName of Object.keys(activeNotifications)) {
+      mockAlertsService.closeAlert(alertName);
+    }
+  }
+
+  const { addMessageListener, sendAsyncMessage } = this;
+
+  addMessageListener("mock-alert-service:unregister", () => {
+    closeAllNotifications();
+    activeNotifications = null;
+    registrar.unregisterFactory(MOCK_ALERTS_CID, mockAlertsService);
+    sendAsyncMessage("mock-alert-service:unregistered");
+  });
+
+  addMessageListener(
+    "mock-alert-service:click-notifications",
+    clickNotifications
+  );
+
+  addMessageListener(
+    "mock-alert-service:close-notifications",
+    closeAllNotifications
+  );
+
+  sendAsyncMessage("mock-alert-service:registered");
+}
+
+const MockAlertsService = {
+  async register() {
+    if (this._chromeScript) {
+      throw new Error("MockAlertsService already registered");
+    }
+    this._chromeScript = SpecialPowers.loadChromeScript(
+      mockServicesChromeScript
+    );
+    await this._chromeScript.promiseOneMessage("mock-alert-service:registered");
+  },
+  async unregister() {
+    if (!this._chromeScript) {
+      throw new Error("MockAlertsService not registered");
+    }
+    this._chromeScript.sendAsyncMessage("mock-alert-service:unregister");
+    return this._chromeScript
+      .promiseOneMessage("mock-alert-service:unregistered")
+      .then(() => {
+        this._chromeScript.destroy();
+        this._chromeScript = null;
+      });
+  },
+  async clickNotifications() {
+    // Most implementations of the nsIAlertsService automatically close upon click.
+    await this._chromeScript.sendAsyncMessage(
+      "mock-alert-service:click-notifications",
+      true
+    );
+  },
+  async clickNotificationsWithoutClose() {
+    // The implementation on macOS does not automatically close the notification.
+    await this._chromeScript.sendAsyncMessage(
+      "mock-alert-service:click-notifications",
+      false
+    );
+  },
+  async closeNotifications() {
+    await this._chromeScript.sendAsyncMessage(
+      "mock-alert-service:close-notifications"
+    );
+  },
+};
diff --git a/toolkit/components/extensions/test/mochitest/head_unlimitedStorage.js b/toolkit/components/extensions/test/mochitest/head_unlimitedStorage.js
new file mode 100644
index 0000000000..73b98b68ae
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/head_unlimitedStorage.js
@@ -0,0 +1,50 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* exported checkSitePermissions */
+
+const { Services } = SpecialPowers;
+const { NetUtil } = SpecialPowers.Cu.import(
+  "resource://gre/modules/NetUtil.jsm",
+  {}
+);
+
+function checkSitePermissions(uuid, expectedPermAction, assertMessage) {
+  if (!uuid) {
+    throw new Error(
+      "checkSitePermissions should not be called with an undefined uuid"
+    );
+  }
+
+  const baseURI = NetUtil.newURI(`moz-extension://${uuid}/`);
+  const principal = Services.scriptSecurityManager.createContentPrincipal(
+    baseURI,
+    {}
+  );
+
+  const sitePermissions = {
+    webextUnlimitedStorage: Services.perms.testPermissionFromPrincipal(
+      principal,
+      "WebExtensions-unlimitedStorage"
+    ),
+    indexedDB: Services.perms.testPermissionFromPrincipal(
+      principal,
+      "indexedDB"
+    ),
+    persistentStorage: Services.perms.testPermissionFromPrincipal(
+      principal,
+      "persistent-storage"
+    ),
+  };
+
+  for (const [sitePermissionName, actualPermAction] of Object.entries(
+    sitePermissions
+  )) {
+    is(
+      actualPermAction,
+      expectedPermAction,
+      `The extension "${sitePermissionName}" SitePermission ${assertMessage} as expected`
+    );
+  }
+}
diff --git a/toolkit/components/extensions/test/mochitest/head_webrequest.js b/toolkit/components/extensions/test/mochitest/head_webrequest.js
new file mode 100644
index 0000000000..f6c6530e41
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/head_webrequest.js
@@ -0,0 +1,482 @@
+"use strict";
+
+let commonEvents = {
+  onBeforeRequest: [{ urls: ["<all_urls>"] }, ["blocking"]],
+  onBeforeSendHeaders: [
+    { urls: ["<all_urls>"] },
+    ["blocking", "requestHeaders"],
+  ],
+  onSendHeaders: [{ urls: ["<all_urls>"] }, ["requestHeaders"]],
+  onBeforeRedirect: [{ urls: ["<all_urls>"] }],
+  onHeadersReceived: [
+    { urls: ["<all_urls>"] },
+    ["blocking", "responseHeaders"],
+  ],
+  // Auth tests will need to set their own events object
+  // "onAuthRequired":      [{urls: ["<all_urls>"]}, ["blocking", "responseHeaders"]],
+  onResponseStarted: [{ urls: ["<all_urls>"] }],
+  onCompleted: [{ urls: ["<all_urls>"] }, ["responseHeaders"]],
+  onErrorOccurred: [{ urls: ["<all_urls>"] }],
+};
+
+function background(events) {
+  const IP_PATTERN = /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/;
+
+  let expect;
+  let ignore;
+  let defaultOrigin;
+  let watchAuth = Object.keys(events).includes("onAuthRequired");
+  let expectedIp = null;
+
+  browser.test.onMessage.addListener((msg, expected) => {
+    if (msg !== "set-expected") {
+      return;
+    }
+    expect = expected.expect;
+    defaultOrigin = expected.origin;
+    ignore = expected.ignore;
+    let promises = [];
+    // Initialize some stuff we'll need in the tests.
+    for (let entry of Object.values(expect)) {
+      // a place for the test infrastructure to store some state.
+      entry.test = {};
+      // Each entry in expected gets a Promise that will be resolved in the
+      // last event for that entry.  This will either be onCompleted, or the
+      // last entry if an events list was provided.
+      promises.push(
+        new Promise(resolve => {
+          entry.test.resolve = resolve;
+        })
+      );
+      // If events was left undefined, we're expecting all normal events we're
+      // listening for, exclude onBeforeRedirect and onErrorOccurred
+      if (entry.events === undefined) {
+        entry.events = Object.keys(events).filter(
+          name => name != "onErrorOccurred" && name != "onBeforeRedirect"
+        );
+      }
+      if (entry.optional_events === undefined) {
+        entry.optional_events = [];
+      }
+    }
+    // When every expected entry has finished our test is done.
+    Promise.all(promises).then(() => {
+      browser.test.sendMessage("done");
+    });
+    browser.test.sendMessage("continue");
+  });
+
+  // Retrieve the per-file/test expected values.
+  function getExpected(details) {
+    let url = new URL(details.url);
+    let filename = url.pathname.split("/").pop();
+    if (ignore && ignore.includes(filename)) {
+      return;
+    }
+    let expected = expect[filename];
+    if (!expected) {
+      browser.test.fail(`unexpected request ${filename}`);
+      return;
+    }
+    // Save filename for redirect verification.
+    expected.test.filename = filename;
+    return expected;
+  }
+
+  // Process any test header modifications that can happen in request or response phases.
+  // If a test includes headers, it needs a complete header object, no undefined
+  // objects even if empty:
+  // request: {
+  //   add: {"HeaderName": "value",},
+  //   modify: {"HeaderName": "value",},
+  //   remove: ["HeaderName",],
+  // },
+  // response: {
+  //   add: {"HeaderName": "value",},
+  //   modify: {"HeaderName": "value",},
+  //   remove: ["HeaderName",],
+  // },
+  function processHeaders(phase, expected, details) {
+    // This should only happen once per phase [request|response].
+    browser.test.assertFalse(
+      !!expected.test[phase],
+      `First processing of headers for ${phase}`
+    );
+    expected.test[phase] = true;
+
+    let headers = details[`${phase}Headers`];
+    browser.test.assertTrue(
+      Array.isArray(headers),
+      `${phase}Headers array present`
+    );
+
+    let { add, modify, remove } = expected.headers[phase];
+
+    for (let name in add) {
+      browser.test.assertTrue(
+        !headers.find(h => h.name === name),
+        `header ${name} to be added not present yet in ${phase}Headers`
+      );
+      let header = { name: name };
+      if (name.endsWith("-binary")) {
+        header.binaryValue = Array.from(add[name], c => c.charCodeAt(0));
+      } else {
+        header.value = add[name];
+      }
+      headers.push(header);
+    }
+
+    let modifiedAny = false;
+    for (let header of headers) {
+      if (header.name.toLowerCase() in modify) {
+        header.value = modify[header.name.toLowerCase()];
+        modifiedAny = true;
+      }
+    }
+    browser.test.assertTrue(
+      modifiedAny,
+      `at least one ${phase}Headers element to modify`
+    );
+
+    let deletedAny = false;
+    for (let j = headers.length; j-- > 0; ) {
+      if (remove.includes(headers[j].name.toLowerCase())) {
+        headers.splice(j, 1);
+        deletedAny = true;
+      }
+    }
+    browser.test.assertTrue(
+      deletedAny,
+      `at least one ${phase}Headers element to delete`
+    );
+
+    return headers;
+  }
+
+  // phase is request or response.
+  function checkHeaders(phase, expected, details) {
+    if (!/^https?:/.test(details.url)) {
+      return;
+    }
+
+    let headers = details[`${phase}Headers`];
+    browser.test.assertTrue(
+      Array.isArray(headers),
+      `valid ${phase}Headers array`
+    );
+
+    let { add, modify, remove } = expected.headers[phase];
+    for (let name in add) {
+      let value = headers.find(h => h.name.toLowerCase() === name.toLowerCase())
+        .value;
+      browser.test.assertEq(
+        value,
+        add[name],
+        `header ${name} correctly injected in ${phase}Headers`
+      );
+    }
+
+    for (let name in modify) {
+      let value = headers.find(h => h.name.toLowerCase() === name.toLowerCase())
+        .value;
+      browser.test.assertEq(
+        value,
+        modify[name],
+        `header ${name} matches modified value`
+      );
+    }
+
+    for (let name of remove) {
+      let found = headers.find(
+        h => h.name.toLowerCase() === name.toLowerCase()
+      );
+      browser.test.assertFalse(
+        !!found,
+        `deleted header ${name} still found in ${phase}Headers`
+      );
+    }
+  }
+
+  let listeners = {
+    onBeforeRequest(expected, details, result) {
+      // Save some values to test request consistency in later events.
+      browser.test.assertTrue(
+        details.tabId !== undefined,
+        `tabId ${details.tabId}`
+      );
+      browser.test.assertTrue(
+        details.requestId !== undefined,
+        `requestId ${details.requestId}`
+      );
+      // Validate requestId if it's already set, this happens with redirects.
+      if (expected.test.requestId !== undefined) {
+        browser.test.assertEq(
+          "string",
+          typeof expected.test.requestId,
+          `requestid ${expected.test.requestId} is string`
+        );
+        browser.test.assertEq(
+          "string",
+          typeof details.requestId,
+          `requestid ${details.requestId} is string`
+        );
+        browser.test.assertEq(
+          "number",
+          typeof parseInt(details.requestId, 10),
+          "parsed requestid is number"
+        );
+        browser.test.assertEq(
+          expected.test.requestId,
+          details.requestId,
+          "redirects will keep the same requestId"
+        );
+      } else {
+        // Save any values we want to validate in later events.
+        expected.test.requestId = details.requestId;
+        expected.test.tabId = details.tabId;
+      }
+      // Tests we don't need to do every event.
+      browser.test.assertTrue(
+        details.type.toUpperCase() in browser.webRequest.ResourceType,
+        `valid resource type ${details.type}`
+      );
+      if (details.type == "main_frame") {
+        browser.test.assertEq(
+          0,
+          details.frameId,
+          "frameId is zero when type is main_frame, see bug 1329299"
+        );
+      }
+    },
+    onBeforeSendHeaders(expected, details, result) {
+      if (expected.headers && expected.headers.request) {
+        result.requestHeaders = processHeaders("request", expected, details);
+      }
+      if (expected.redirect) {
+        browser.test.log(`${name} redirect request`);
+        result.redirectUrl = details.url.replace(
+          expected.test.filename,
+          expected.redirect
+        );
+      }
+    },
+    onBeforeRedirect() {},
+    onSendHeaders(expected, details, result) {
+      if (expected.headers && expected.headers.request) {
+        checkHeaders("request", expected, details);
+      }
+    },
+    onResponseStarted() {},
+    onHeadersReceived(expected, details, result) {
+      let expectedStatus = expected.status || 200;
+      // If authentication is being requested we don't fail on the status code.
+      if (watchAuth && [401, 407].includes(details.statusCode)) {
+        expectedStatus = details.statusCode;
+      }
+      browser.test.assertEq(
+        expectedStatus,
+        details.statusCode,
+        `expected HTTP status received for ${details.url} ${details.statusLine}`
+      );
+      if (expected.headers && expected.headers.response) {
+        result.responseHeaders = processHeaders("response", expected, details);
+      }
+    },
+    onAuthRequired(expected, details, result) {
+      result.authCredentials = expected.authInfo;
+    },
+    onCompleted(expected, details, result) {
+      // If we have already completed a GET request for this url,
+      // and it was found, we expect for the response to come fromCache.
+      // expected.cached may be undefined, force boolean.
+      if (typeof expected.cached === "boolean") {
+        let expectCached =
+          expected.cached &&
+          details.method === "GET" &&
+          details.statusCode != 404;
+        browser.test.assertEq(
+          expectCached,
+          details.fromCache,
+          "fromCache is correct"
+        );
+      }
+      // We can only tell IPs for non-cached HTTP requests.
+      if (!details.fromCache && /^https?:/.test(details.url)) {
+        browser.test.assertTrue(
+          IP_PATTERN.test(details.ip),
+          `IP for ${details.url} looks IP-ish: ${details.ip}`
+        );
+
+        // We can't easily predict the IP ahead of time, so just make
+        // sure they're all consistent.
+        expectedIp = expectedIp || details.ip;
+        browser.test.assertEq(
+          expectedIp,
+          details.ip,
+          `correct ip for ${details.url}`
+        );
+      }
+      if (expected.headers && expected.headers.response) {
+        checkHeaders("response", expected, details);
+      }
+    },
+    onErrorOccurred(expected, details, result) {
+      if (expected.error) {
+        if (Array.isArray(expected.error)) {
+          browser.test.assertTrue(
+            expected.error.includes(details.error),
+            "expected error message received in onErrorOccurred"
+          );
+        } else {
+          browser.test.assertEq(
+            expected.error,
+            details.error,
+            "expected error message received in onErrorOccurred"
+          );
+        }
+      }
+    },
+  };
+
+  function getListener(name) {
+    return details => {
+      let result = {};
+      browser.test.log(`${name} ${details.requestId} ${details.url}`);
+      let expected = getExpected(details);
+      if (!expected) {
+        return result;
+      }
+      let expectedEvent = expected.events[0] == name;
+      if (expectedEvent) {
+        expected.events.shift();
+      } else {
+        // e10s vs. non-e10s errors can end with either onCompleted or onErrorOccurred
+        expectedEvent = expected.optional_events.includes(name);
+      }
+      browser.test.assertTrue(expectedEvent, `received ${name}`);
+      browser.test.assertEq(
+        expected.type,
+        details.type,
+        "resource type is correct"
+      );
+      browser.test.assertEq(
+        expected.origin || defaultOrigin,
+        details.originUrl,
+        "origin is correct"
+      );
+
+      if (name != "onBeforeRequest") {
+        // On events after onBeforeRequest, check the previous values.
+        browser.test.assertEq(
+          expected.test.requestId,
+          details.requestId,
+          "correct requestId"
+        );
+        browser.test.assertEq(
+          expected.test.tabId,
+          details.tabId,
+          "correct tabId"
+        );
+      }
+      try {
+        listeners[name](expected, details, result);
+      } catch (e) {
+        browser.test.fail(`unexpected webrequest failure ${name} ${e}`);
+      }
+
+      if (expected.cancel && expected.cancel == name) {
+        browser.test.log(`${name} cancel request`);
+        browser.test.sendMessage("cancelled");
+        result.cancel = true;
+      }
+      // If we've used up all the events for this test, resolve the promise.
+      // If something wrong happens and more events come through, there will be
+      // failures.
+      if (expected.events.length <= 0) {
+        expected.test.resolve();
+      }
+      return result;
+    };
+  }
+
+  for (let [name, args] of Object.entries(events)) {
+    browser.test.log(`adding listener for ${name}`);
+    try {
+      browser.webRequest[name].addListener(getListener(name), ...args);
+    } catch (e) {
+      browser.test.assertTrue(
+        /\brequestBody\b/.test(e.message),
+        "Request body is unsupported"
+      );
+
+      // RequestBody is disabled in release builds.
+      if (!/\brequestBody\b/.test(e.message)) {
+        throw e;
+      }
+
+      args.splice(args.indexOf("requestBody"), 1);
+      browser.webRequest[name].addListener(getListener(name), ...args);
+    }
+  }
+}
+
+/* exported makeExtension */
+
+function makeExtension(events = commonEvents) {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background: `(${background})(${JSON.stringify(events)})`,
+  });
+}
+
+/* exported addStylesheet */
+
+function addStylesheet(file) {
+  let link = document.createElement("link");
+  link.setAttribute("rel", "stylesheet");
+  link.setAttribute("href", file);
+  document.body.appendChild(link);
+}
+
+/* exported addLink */
+
+function addLink(file) {
+  let a = document.createElement("a");
+  a.setAttribute("href", file);
+  a.setAttribute("target", "_blank");
+  a.setAttribute("rel", "opener");
+  document.body.appendChild(a);
+  return a;
+}
+
+/* exported addImage */
+
+function addImage(file) {
+  let img = document.createElement("img");
+  img.setAttribute("src", file);
+  document.body.appendChild(img);
+}
+
+/* exported addScript */
+
+function addScript(file) {
+  let script = document.createElement("script");
+  script.setAttribute("type", "text/javascript");
+  script.setAttribute("src", file);
+  document
+    .getElementsByTagName("head")
+    .item(0)
+    .appendChild(script);
+}
+
+/* exported addFrame */
+
+function addFrame(file) {
+  let frame = document.createElement("iframe");
+  frame.setAttribute("width", "200");
+  frame.setAttribute("height", "200");
+  frame.setAttribute("src", file);
+  document.body.appendChild(frame);
+}
diff --git a/toolkit/components/extensions/test/mochitest/hsts.sjs b/toolkit/components/extensions/test/mochitest/hsts.sjs
new file mode 100644
index 0000000000..636f331882
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/hsts.sjs
@@ -0,0 +1,8 @@
+function handleRequest(request, response) {
+  let page = "<!DOCTYPE html><html><body><p>HSTS page</p></body></html>";
+  response.setStatusLine(request.httpVersion, "200", "OK");
+  response.setHeader("Strict-Transport-Security", "max-age=60");
+  response.setHeader("Content-Type", "text/html", false);
+  response.setHeader("Content-Length", page.length + "", false);
+  response.write(page);
+}
diff --git a/toolkit/components/extensions/test/mochitest/mochitest-common.ini b/toolkit/components/extensions/test/mochitest/mochitest-common.ini
new file mode 100644
index 0000000000..2e32a951e2
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/mochitest-common.ini
@@ -0,0 +1,206 @@
+[DEFAULT]
+support-files =
+  chrome_cleanup_script.js
+  file_WebNavigation_page1.html
+  file_WebNavigation_page2.html
+  file_WebNavigation_page3.html
+  file_WebRequest_page3.html
+  file_contains_img.html
+  file_contains_iframe.html
+  file_green.html
+  file_contentscript_activeTab.html
+  file_contentscript_activeTab2.html
+  file_contentscript_iframe.html
+  file_image_bad.png
+  file_image_good.png
+  file_image_great.png
+  file_image_redirect.png
+  file_indexedDB.html
+  file_mixed.html
+  file_remote_frame.html
+  file_sample.html
+  file_sample.txt
+  file_sample.txt^headers^
+  file_script_bad.js
+  file_script_good.js
+  file_script_redirect.js
+  file_script_xhr.js
+  file_serviceWorker.html
+  file_simple_sandboxed_frame.html
+  file_simple_sandboxed_subframe.html
+  file_simple_xhr.html
+  file_simple_xhr_frame.html
+  file_simple_xhr_frame2.html
+  file_streamfilter.txt
+  file_style_bad.css
+  file_style_good.css
+  file_style_redirect.css
+  file_third_party.html
+  file_to_drawWindow.html
+  file_webNavigation_clientRedirect.html
+  file_webNavigation_clientRedirect_httpHeaders.html
+  file_webNavigation_clientRedirect_httpHeaders.html^headers^
+  file_webNavigation_frameClientRedirect.html
+  file_webNavigation_frameRedirect.html
+  file_webNavigation_manualSubframe.html
+  file_webNavigation_manualSubframe_page1.html
+  file_webNavigation_manualSubframe_page2.html
+  file_with_about_blank.html
+  file_with_xorigin_frame.html
+  head.js
+  head_cookies.js
+  head_notifications.js
+  head_unlimitedStorage.js
+  head_webrequest.js
+  hsts.sjs
+  mochitest_console.js
+  oauth.html
+  redirect_auto.sjs
+  redirection.sjs
+  return_headers.sjs
+  serviceWorker.js
+  slow_response.sjs
+  webrequest_worker.js
+  !/dom/tests/mochitest/geolocation/network_geolocation.sjs
+  !/toolkit/components/passwordmgr/test/authenticate.sjs
+  file_redirect_data_uri.html
+  file_redirect_cors_bypass.html
+  file_tabs_permission_page1.html
+  file_tabs_permission_page2.html
+prefs =
+  security.mixed_content.upgrade_display_content=false
+  browser.chrome.guess_favicon=true
+
+[test_ext_activityLog.html]
+skip-if =
+    os == 'android'
+    tsan  # Times out on TSan, bug 1612707
+    xorigin  # Inconsistent pass/fail in opt and debug
+[test_ext_async_clipboard.html]
+skip-if = toolkit == 'android' || tsan # near-permafail after landing bug 1270059: Bug 1523131. tsan: bug 1612707
+[test_ext_background_canvas.html]
+[test_ext_background_page.html]
+skip-if = (toolkit == 'android') # android doesn't have devtools
+[test_ext_browsingData_indexedDB.html]
+[test_ext_browsingData_localStorage.html]
+[test_ext_browsingData_pluginData.html]
+[test_ext_browsingData_serviceWorkers.html]
+[test_ext_browsingData_settings.html]
+[test_ext_canvas_resistFingerprinting.html]
+[test_ext_clipboard.html]
+skip-if = os == 'android'
+[test_ext_clipboard_image.html]
+skip-if = headless # Bug 1405872
+[test_ext_contentscript_about_blank.html]
+skip-if = os == 'android' # bug 1369440
+[test_ext_contentscript_activeTab.html]
+skip-if = os == 'android' || fission
+[test_ext_contentscript_cache.html]
+skip-if = (os == 'linux' && debug) || (toolkit == 'android' && debug) # bug 1348241
+fail-if = xorigin # TypeError: can't access property "staticScripts", ext is undefined - Should not throw any errors
+[test_ext_contentscript_canvas.html]
+skip-if = (os == 'android') || (verify && debug && (os == 'linux')) # Bug 1617062
+[test_ext_contentscript_devtools_metadata.html]
+[test_ext_contentscript_fission_frame.html]
+[test_ext_contentscript_incognito.html]
+skip-if = os == 'android' # Android does not support multiple windows.
+[test_ext_contentscript_permission.html]
+skip-if = tsan # Times out on TSan, bug 1612707
+[test_ext_cookies.html]
+skip-if = os == 'android' || tsan # Times out on TSan intermittently, bug 1615184; not supported on Android yet
+[test_ext_cookies_containers.html]
+[test_ext_cookies_expiry.html]
+[test_ext_cookies_first_party.html]
+[test_ext_cookies_incognito.html]
+skip-if = os == 'android' # Bug 1513544 Android does not support multiple windows.
+[test_ext_cookies_permissions_bad.html]
+[test_ext_cookies_permissions_good.html]
+[test_ext_downloads_download.html]
+[test_ext_embeddedimg_iframe_frameAncestors.html]
+[test_ext_exclude_include_globs.html]
+[test_ext_external_messaging.html]
+[test_ext_generate.html]
+[test_ext_geolocation.html]
+skip-if = os == 'android' # Android support Bug 1336194
+[test_ext_identity.html]
+skip-if = os == 'android' || tsan # unsupported. tsan: bug 1612707
+[test_ext_idle.html]
+skip-if = tsan # Times out on TSan, bug 1612707
+[test_ext_inIncognitoContext_window.html]
+skip-if = os == 'android' # Android does not support multiple windows.
+[test_ext_listener_proxies.html]
+[test_ext_new_tab_processType.html]
+skip-if = verify && debug && (os == 'linux' || os == 'mac')
+[test_ext_notifications.html]
+skip-if = os == 'android' # Not supported on Android yet
+[test_ext_protocolHandlers.html]
+skip-if = (toolkit == 'android') # bug 1342577
+[test_ext_redirect_jar.html]
+skip-if = os == 'win' && (debug || asan) # Bug 1563440
+[test_ext_request_urlClassification.html]
+skip-if = os == 'android' # Bug 1615427
+[test_ext_runtime_connect.html]
+[test_ext_runtime_connect_twoway.html]
+[test_ext_runtime_connect2.html]
+[test_ext_runtime_disconnect.html]
+[test_ext_sendmessage_doublereply.html]
+[test_ext_sendmessage_frameId.html]
+[test_ext_sendmessage_no_receiver.html]
+[test_ext_sendmessage_reply.html]
+[test_ext_sendmessage_reply2.html]
+skip-if = os == 'android'
+[test_ext_storage_manager_capabilities.html]
+skip-if = xorigin # JavaScript Error: "SecurityError: Permission denied to access property "wrappedJSObject" on cross-origin object" {file: "https://example.com/tests/SimpleTest/TestRunner.js" line: 157}
+scheme=https
+[test_ext_storage_smoke_test.html]
+[test_ext_streamfilter_multiple.html]
+skip-if =
+  !debug # Bug 1628642
+  os == 'linux' # Bug 1628642
+[test_ext_streamfilter_processswitch.html]
+[test_ext_subframes_privileges.html]
+skip-if = os == 'android' || verify # bug 1489771
+[test_ext_tabs_captureTab.html]
+[test_ext_tabs_query_popup.html]
+[test_ext_tabs_permissions.html]
+[test_ext_tabs_sendMessage.html]
+[test_ext_test.html]
+[test_ext_unlimitedStorage.html]
+skip-if = os == 'android'
+[test_ext_unlimitedStorage_legacy_persistent_indexedDB.html]
+# IndexedDB persistent storage mode is not allowed on Fennec from a non-chrome privileged code
+# (it has only been enabled for apps and privileged code). See Bug 1119462 for additional info.
+skip-if = os == 'android'
+[test_ext_web_accessible_resources.html]
+skip-if = (os == 'android' && debug) || fission || (os  == "linux" && bits == 64) # bug 1397615, bug 1588284, bug 1618231
+[test_ext_web_accessible_incognito.html]
+skip-if = (os == 'android') || fission # Crashes intermittently: @ mozilla::dom::BrowsingContext::CreateFromIPC(mozilla::dom::BrowsingContext::IPCInitializer&&, mozilla::dom::BrowsingContextGroup*, mozilla::dom::ContentParent*), bug 1588284, bug 1397615 and bug 1513544
+[test_ext_webnavigation.html]
+skip-if = (os == 'android' && debug) # bug 1397615
+[test_ext_webnavigation_filters.html]
+skip-if = (os == 'android' && debug) || (verify && (os == 'linux' || os == 'mac')) # bug 1397615
+[test_ext_webnavigation_incognito.html]
+skip-if = os == 'android' # bug 1513544
+[test_ext_webrequest_and_proxy_filter.html]
+[test_ext_webrequest_auth.html]
+skip-if = os == 'android'
+[test_ext_webrequest_background_events.html]
+[test_ext_webrequest_basic.html]
+skip-if =
+    os == 'android' && debug  # bug 1397615
+    tsan  # bug 1612707
+    xorigin  # JavaScript Error: "SecurityError: Permission denied to access property "wrappedJSObject" on cross-origin object" {file: "http://mochi.false-test:8888/tests/SimpleTest/TestRunner.js" line: 157}]
+[test_ext_webrequest_errors.html]
+skip-if = tsan
+[test_ext_webrequest_filter.html]
+skip-if = os == 'android' && debug || tsan # bug 1452348. tsan: bug 1612707
+[test_ext_webrequest_frameId.html]
+skip-if = (webrender && os == 'linux') # Bug 1482983 caused by Bug 1480951
+[test_ext_webrequest_hsts.html]
+skip-if = os == 'android' || os == 'linux' || os == 'mac' #Bug 1605515
+[test_ext_webrequest_upgrade.html]
+[test_ext_webrequest_upload.html]
+skip-if = os == 'android' # Currently fails in emulator tests
+[test_ext_webrequest_redirect_bypass_cors.html]
+[test_ext_webrequest_redirect_data_uri.html]
+[test_ext_window_postMessage.html]
diff --git a/toolkit/components/extensions/test/mochitest/mochitest-remote.ini b/toolkit/components/extensions/test/mochitest/mochitest-remote.ini
new file mode 100644
index 0000000000..2828eb2182
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/mochitest-remote.ini
@@ -0,0 +1,8 @@
+[DEFAULT]
+tags = webextensions remote-webextensions
+skip-if = !e10s || (os == 'android') # Bug 1620091: disable on android until extension process is done
+prefs =
+    extensions.webextensions.remote=true
+
+[test_verify_remote_mode.html]
+[include:mochitest-common.ini]
diff --git a/toolkit/components/extensions/test/mochitest/mochitest.ini b/toolkit/components/extensions/test/mochitest/mochitest.ini
new file mode 100644
index 0000000000..4612cac657
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/mochitest.ini
@@ -0,0 +1,12 @@
+[DEFAULT]
+tags = webextensions in-process-webextensions
+prefs =
+    extensions.webextensions.remote=false
+dupe-manifest = true
+
+[test_verify_non_remote_mode.html]
+[test_ext_storage_cleanup.html]
+# Bug 1426514 storage_cleanup: clearing localStorage fails with oop
+
+[include:mochitest-common.ini]
+skip-if = os == 'win' # Windows WebExtensions always run OOP
diff --git a/toolkit/components/extensions/test/mochitest/mochitest_console.js b/toolkit/components/extensions/test/mochitest/mochitest_console.js
new file mode 100644
index 0000000000..e4be8acd69
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/mochitest_console.js
@@ -0,0 +1,53 @@
+"use strict";
+
+const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+const { addMessageListener, sendAsyncMessage } = this;
+
+// Much of the console monitoring code is copied from TestUtils but simplified
+// to our needs.
+function monitorConsole(msgs) {
+  function msgMatches(msg, pat) {
+    for (let k in pat) {
+      if (!(k in msg)) {
+        return false;
+      }
+      if (pat[k] instanceof RegExp && typeof msg[k] === "string") {
+        if (!pat[k].test(msg[k])) {
+          return false;
+        }
+      } else if (msg[k] !== pat[k]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  let counter = 0;
+  function listener(msg) {
+    if (msgMatches(msg, msgs[counter])) {
+      counter++;
+    }
+  }
+  addMessageListener("waitForConsole", () => {
+    sendAsyncMessage("consoleDone", {
+      ok: counter >= msgs.length,
+      message: `monitorConsole | messages left expected at least ${msgs.length} got ${counter}`,
+    });
+    Services.console.unregisterListener(listener);
+  });
+
+  Services.console.registerListener(listener);
+}
+
+addMessageListener("consoleStart", messages => {
+  for (let msg of messages) {
+    // Message might be a RegExp object from a different compartment, but
+    // instanceof RegExp will fail.  If we have an object, lets just make
+    // sure.
+    let message = msg.message;
+    if (typeof message == "object" && !(message instanceof RegExp)) {
+      msg.message = new RegExp(message);
+    }
+  }
+  monitorConsole(messages);
+});
diff --git a/toolkit/components/extensions/test/mochitest/oauth.html b/toolkit/components/extensions/test/mochitest/oauth.html
new file mode 100644
index 0000000000..8b9b1d65ec
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/oauth.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <script>
+  "use strict";
+
+  onload = () => {
+    let url = new URL(location);
+    if (url.searchParams.get("post")) {
+      let server_redirect = `${url.searchParams.get("server_uri")}?redirect_uri=${encodeURIComponent(url.searchParams.get("redirect_uri"))}`;
+      let form = document.forms.testform;
+      form.setAttribute("action", server_redirect);
+      form.submit();
+    } else {
+      let end = new URL(url.searchParams.get("redirect_uri"));
+      end.searchParams.set("access_token", "here ya go");
+      location.href = end.href;
+    }
+  };
+  </script>
+</head>
+<body>
+  <form name="testform" action="" method="POST">
+  </form>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/redirect_auto.sjs b/toolkit/components/extensions/test/mochitest/redirect_auto.sjs
new file mode 100644
index 0000000000..27d249f022
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/redirect_auto.sjs
@@ -0,0 +1,21 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+Components.utils.importGlobalProperties(["URLSearchParams", "URL"]);
+
+function handleRequest(request, response) {
+  let params = new URLSearchParams(request.queryString);
+  if (params.has("no_redirect")) {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.write("ok");
+  } else {
+    if (request.method == "POST") {
+      response.setStatusLine(request.httpVersion, 303, "Redirected");
+    } else {
+      response.setStatusLine(request.httpVersion, 302, "Moved Temporarily");
+    }
+    let url = new URL(params.get("redirect_uri") || params.get("default_redirect"));
+    url.searchParams.set("access_token", "here ya go");
+    response.setHeader("Location", url.href);
+  }
+}
diff --git a/toolkit/components/extensions/test/mochitest/redirection.sjs b/toolkit/components/extensions/test/mochitest/redirection.sjs
new file mode 100644
index 0000000000..370ecd213f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/redirection.sjs
@@ -0,0 +1,4 @@
+function handleRequest(aRequest, aResponse) {
+  aResponse.setStatusLine(aRequest.httpVersion, 302);
+  aResponse.setHeader("Location", "./dummy_page.html");
+}
diff --git a/toolkit/components/extensions/test/mochitest/return_headers.sjs b/toolkit/components/extensions/test/mochitest/return_headers.sjs
new file mode 100644
index 0000000000..54e2e5fb4d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/return_headers.sjs
@@ -0,0 +1,20 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ft=javascript sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* exported handleRequest */
+
+function handleRequest(request, response) {
+  response.setHeader("Content-Type", "text/plain", false);
+
+  let headers = {};
+  // Why on earth is this a nsISimpleEnumerator...
+  let enumerator = request.headers;
+  while (enumerator.hasMoreElements()) {
+    let header = enumerator.getNext().data;
+    headers[header.toLowerCase()] = request.getHeader(header);
+  }
+
+  response.write(JSON.stringify(headers));
+}
+
diff --git a/toolkit/components/extensions/test/mochitest/serviceWorker.js b/toolkit/components/extensions/test/mochitest/serviceWorker.js
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/toolkit/components/extensions/test/mochitest/slow_response.sjs b/toolkit/components/extensions/test/mochitest/slow_response.sjs
new file mode 100644
index 0000000000..290d6ca1de
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/slow_response.sjs
@@ -0,0 +1,55 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80 ft=javascript: */
+"use strict";
+
+/* eslint-disable no-unused-vars */
+
+Cu.import("resource://gre/modules/AppConstants.jsm");
+
+const DELAY = AppConstants.DEBUG ? 4000 : 800;
+
+let nsTimer = Components.Constructor("@mozilla.org/timer;1", "nsITimer", "initWithCallback");
+
+let timer;
+function delay() {
+  return new Promise(resolve => {
+    timer = nsTimer(resolve, DELAY, Ci.nsITimer.TYPE_ONE_SHOT);
+  });
+}
+
+const PARTS = [
+  `<!DOCTYPE html>
+    <html lang="en">
+    <head>
+      <meta charset="UTF-8">
+      <title></title>
+    </head>
+    <body>`,
+  "Lorem ipsum dolor sit amet, <br>",
+  "consectetur adipiscing elit, <br>",
+  "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. <br>",
+  "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. <br>",
+  "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. <br>",
+  "Excepteur sint occaecat cupidatat non proident, <br>",
+  "sunt in culpa qui officia deserunt mollit anim id est laborum.<br>",
+  `
+    </body>
+    </html>`,
+];
+
+async function handleRequest(request, response) {
+  response.processAsync();
+
+  response.setHeader("Content-Type", "text/html", false);
+  response.setHeader("Cache-Control", "no-cache", false);
+
+  await delay();
+
+  for (let part of PARTS) {
+    response.write(`${part}\n`);
+    await delay();
+  }
+
+  response.finish();
+}
+
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_data_uri.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_data_uri.html
new file mode 100644
index 0000000000..42950c50ec
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_data_uri.html
@@ -0,0 +1,104 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Test content script matching a data: URI</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/contents/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script>
+"use strict";
+
+add_task(async function test_contentscript_data_uri() {
+  const target = ExtensionTestUtils.loadExtension({
+    files: {
+      "page.html": `<!DOCTYPE html>
+        <meta charset="utf-8">
+        <iframe id="inherited" src="data:text/html;charset=utf-8,inherited"></iframe>
+      `,
+    },
+    background() {
+      browser.test.sendMessage("page", browser.runtime.getURL("page.html"));
+    },
+  });
+
+  const scripts = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webNavigation"],
+      content_scripts: [{
+        all_frames: true,
+        matches: ["<all_urls>"],
+        run_at: "document_start",
+        css: ["all_urls.css"],
+        js: ["all_urls.js"],
+      }],
+    },
+    files: {
+      "all_urls.css": `
+        body { background: yellow; }
+      `,
+      "all_urls.js": function() {
+        document.body.style.color = "red";
+        browser.test.assertTrue(location.protocol !== "data:",
+                                `Matched document not a data URI: ${location.href}`);
+      },
+    },
+    background() {
+      browser.webNavigation.onCompleted.addListener(({url, frameId}) => {
+        browser.test.log(`Document loading complete: ${url}`);
+        if (frameId === 0) {
+          browser.test.sendMessage("tab-ready", url);
+        }
+      });
+    },
+  });
+
+  await target.startup();
+  await scripts.startup();
+
+  // Test extension page with a data: iframe.
+  const page = await target.awaitMessage("page");
+
+  // Hold on to the tab by the browser, as extension loads are COOP loads, and
+  // will break WindowProxy references.
+  let win = window.open();
+  const browserFrame = win.browsingContext.embedderElement;
+  win.location.href = page;
+
+  await scripts.awaitMessage("tab-ready");
+  win = browserFrame.contentWindow;
+  is(win.location.href, page, "Extension page loaded into a tab");
+  is(win.document.readyState, "complete", "Page finished loading");
+
+  const iframe = win.document.getElementById("inherited").contentWindow;
+  is(iframe.document.readyState, "complete", "iframe finished loading");
+
+  const style1 = iframe.getComputedStyle(iframe.document.body);
+  is(style1.color, "rgb(0, 0, 0)", "iframe text color is unmodified");
+  is(style1.backgroundColor, "rgba(0, 0, 0, 0)", "iframe background unmodified");
+
+  // Test extension tab navigated to a data: URI.
+  const data = "data:text/html;charset=utf-8,also-inherits";
+  win.location.href = data;
+
+  await scripts.awaitMessage("tab-ready");
+  win = browserFrame.contentWindow;
+  is(win.location.href, data, "Extension tab navigated to a data: URI");
+  is(win.document.readyState, "complete", "Tab finished loading");
+
+  const style2 = win.getComputedStyle(win.document.body);
+  is(style2.color, "rgb(0, 0, 0)", "Tab text color is unmodified");
+  is(style2.backgroundColor, "rgba(0, 0, 0, 0)", "Tab background unmodified");
+
+  win.close();
+  await target.unload();
+  await scripts.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_telemetry.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_telemetry.html
new file mode 100644
index 0000000000..198b8e85cf
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_telemetry.html
@@ -0,0 +1,64 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Test for telemetry for content script injection</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/contents/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script>
+"use strict";
+
+const HISTOGRAM = "WEBEXT_CONTENT_SCRIPT_INJECTION_MS";
+
+add_task(async function test_contentscript_telemetry() {
+  // Turn on telemetry and reset it to the previous state once the test is completed.
+  const telemetryCanRecordBase = SpecialPowers.Services.telemetry.canRecordBase;
+  SpecialPowers.Services.telemetry.canRecordBase = true;
+  SimpleTest.registerCleanupFunction(() => {
+    SpecialPowers.Services.telemetry.canRecordBase = telemetryCanRecordBase;
+  });
+
+  function background() {
+    browser.test.onMessage.addListener(() => {
+      browser.tabs.executeScript({code: 'browser.test.sendMessage("content-script-run");'});
+    });
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: ["<all_urls>"],
+    },
+    background,
+  };
+
+  let win = window.open("http://example.com/");
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  let histogram = SpecialPowers.Services.telemetry.getHistogramById(HISTOGRAM);
+  histogram.clear();
+  is(histogram.snapshot().sum, 0,
+     `No data recorded for histogram: ${HISTOGRAM}.`);
+
+  await extension.startup();
+  is(histogram.snapshot().sum, 0,
+     `No data recorded for histogram after startup: ${HISTOGRAM}.`);
+
+  extension.sendMessage();
+  await extension.awaitMessage("content-script-run");
+
+  let histogramSum = histogram.snapshot().sum;
+  ok(histogramSum > 0,
+     `Data recorded for first extension for histogram: ${HISTOGRAM}.`);
+
+  win.close();
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_unrecognizedprop_warning.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_unrecognizedprop_warning.html
new file mode 100644
index 0000000000..40403dea2b
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_contentscript_unrecognizedprop_warning.html
@@ -0,0 +1,80 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script unrecognized property on manifest</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const BASE = "http://mochi.test:8888/chrome/toolkit/components/extensions/test/mochitest";
+
+add_task(async function test_contentscript() {
+  function background() {
+    browser.runtime.onMessage.addListener(async (msg) => {
+      if (msg == "loaded") {
+        // NOTE: we're removing the tab from here because doing a win.close()
+        // from the chrome test code is raising a "TypeError: can't access
+        // dead object" exception.
+        let tabs = await browser.tabs.query({active: true, currentWindow: true});
+        await browser.tabs.remove(tabs[0].id);
+
+        browser.test.notifyPass("content-script-loaded");
+      }
+    });
+  }
+
+  function contentScript() {
+    chrome.runtime.sendMessage("loaded");
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          "matches": ["http://mochi.test/*/file_sample.html"],
+          "js": ["content_script.js"],
+          "run_at": "document_idle",
+          "unrecognized_property": "with-a-random-value",
+        },
+      ],
+    },
+    background,
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  SimpleTest.waitForExplicitFinish();
+  let waitForConsole = new Promise(resolve => {
+    SimpleTest.monitorConsole(resolve, [{
+      message: /Reading manifest: Warning processing content_scripts.*.unrecognized_property: An unexpected property was found/,
+    }]);
+  });
+
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  await extension.startup();
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+
+  window.open(`${BASE}/file_sample.html`);
+
+  await Promise.all([extension.awaitFinish("content-script-loaded")]);
+  info("test page loaded");
+
+  await extension.unload();
+
+  SimpleTest.endMonitorConsole();
+  await waitForConsole;
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_open.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_open.html
new file mode 100644
index 0000000000..530937c1ac
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_open.html
@@ -0,0 +1,114 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for permissions</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_downloads_open_permission() {
+  function backgroundScript() {
+    browser.test.assertEq(browser.downloads.open, undefined,
+                          "`downloads.open` permission is required.");
+    browser.test.notifyPass("downloads tests");
+  }
+
+  let extensionData = {
+    background: backgroundScript,
+    manifest: {
+      permissions: ["downloads"],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitFinish("downloads tests");
+  await extension.unload();
+});
+
+add_task(async function test_downloads_open_requires_user_interaction() {
+  async function backgroundScript() {
+    await browser.test.assertRejects(
+      browser.downloads.open(10),
+      "downloads.open may only be called from a user input handler",
+      "The error is informative.");
+
+    browser.test.notifyPass("downloads tests");
+  }
+
+  let extensionData = {
+    background: backgroundScript,
+    manifest: {
+      permissions: ["downloads", "downloads.open"],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitFinish("downloads tests");
+  await extension.unload();
+});
+
+add_task(async function downloads_open_invalid_id() {
+  async function pageScript() {
+    window.addEventListener("keypress", async function handler() {
+      try {
+        await browser.downloads.open(10);
+        browser.test.sendMessage("download-open.result", {success: true});
+      } catch (e) {
+        browser.test.sendMessage("download-open.result", {
+          success: false,
+          error: e.message,
+        });
+      }
+      window.removeEventListener("keypress", handler);
+    });
+
+    browser.test.sendMessage("page-ready");
+  }
+
+  let extensionData = {
+    background() {
+      browser.test.sendMessage("ready", browser.runtime.getURL("page.html"));
+    },
+    files: {
+      "foo.txt": "It's the file called foo.txt.",
+      "page.html": `<html><head>
+        <script src="page.js"><\/script>
+      </head></html>`,
+      "page.js": pageScript,
+    },
+    manifest: {
+      permissions: ["downloads", "downloads.open"],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let url = await extension.awaitMessage("ready");
+  let win = window.open();
+  let browserFrame = win.browsingContext.embedderElement;
+  win.location.href = url;
+  await extension.awaitMessage("page-ready");
+
+  synthesizeKey("a", {}, browserFrame.contentWindow);
+  let result = await extension.awaitMessage("download-open.result");
+
+  is(result.success, false, "Opening download fails.");
+  is(result.error, "Invalid download id 10", "The error is informative.");
+
+
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_saveAs.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_saveAs.html
new file mode 100644
index 0000000000..64cfcfd289
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_saveAs.html
@@ -0,0 +1,257 @@
+<!doctype html>
+<html>
+<head>
+  <title>Test downloads.download() saveAs option</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const {FileUtils} = ChromeUtils.import("resource://gre/modules/FileUtils.jsm");
+
+const PROMPTLESS_DOWNLOAD_PREF = "browser.download.useDownloadDir";
+
+const DOWNLOAD_FILENAME = "file_download.nonext.txt";
+const DEFAULT_SUBDIR = "subdir";
+
+// We need to be able to distinguish files downloaded by the file picker from
+// files downloaded without it.
+let pickerDir;
+let pbPickerDir; // for incognito downloads
+let defaultDir;
+
+add_task(async function setup() {
+  // Reset DownloadLastDir preferences in case other tests set them.
+  SpecialPowers.Services.obs.notifyObservers(
+    null,
+    "browser:purge-session-history"
+  );
+
+  // Set up temporary directories.
+  let downloadDir = FileUtils.getDir("TmpD", ["downloads"]);
+  pickerDir = downloadDir.clone();
+  pickerDir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  info(`Using file picker download directory ${pickerDir.path}`);
+  pbPickerDir = downloadDir.clone();
+  pbPickerDir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  info(`Using private browsing file picker download directory ${pbPickerDir.path}`);
+  defaultDir = downloadDir.clone();
+  defaultDir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  info(`Using default download directory ${defaultDir.path}`);
+  let subDir = defaultDir.clone();
+  subDir.append(DEFAULT_SUBDIR);
+  subDir.create(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+  isnot(pickerDir.path, defaultDir.path,
+        "Should be able to distinguish between files saved with or without the file picker");
+  isnot(pickerDir.path, pbPickerDir.path,
+        "Should be able to distinguish between files saved in and out of private browsing mode");
+
+  await SpecialPowers.pushPrefEnv({"set": [
+    ["browser.download.folderList", 2],
+    ["browser.download.dir", defaultDir.path],
+  ]});
+
+  SimpleTest.registerCleanupFunction(async () => {
+    await SpecialPowers.popPrefEnv();
+    pickerDir.remove(true);
+    pbPickerDir.remove(true);
+    defaultDir.remove(true); // This also removes DEFAULT_SUBDIR.
+  });
+});
+
+add_task(async function test_downloads_saveAs() {
+  const pickerFile = pickerDir.clone();
+  pickerFile.append(DOWNLOAD_FILENAME);
+
+  const pbPickerFile = pbPickerDir.clone();
+  pbPickerFile.append(DOWNLOAD_FILENAME);
+
+  const defaultFile = defaultDir.clone();
+  defaultFile.append(DOWNLOAD_FILENAME);
+
+  const {MockFilePicker} = SpecialPowers;
+  MockFilePicker.init(window);
+
+  function mockFilePickerCallback(expectedStartingDir, pickedFile) {
+    return fp => {
+      // Assert that the downloads API correctly sets the starting directory.
+      ok(fp.displayDirectory.equals(expectedStartingDir), "Got the expected FilePicker displayDirectory");
+
+      // Assert that the downloads API configures both default properties.
+      is(fp.defaultString, DOWNLOAD_FILENAME, "Got the expected FilePicker defaultString");
+      is(fp.defaultExtension, "txt", "Got the expected FilePicker defaultExtension");
+
+      MockFilePicker.setFiles([pickedFile]);
+    };
+  }
+
+  function background() {
+    const url = URL.createObjectURL(new Blob(["file content"]));
+    browser.test.onMessage.addListener(async (filename, saveAs, isPrivate) => {
+      try {
+        let options = {
+          url,
+          filename,
+          incognito: isPrivate,
+        };
+        // Only define the saveAs option if the argument was actually set
+        if (saveAs !== undefined) {
+          options.saveAs = saveAs;
+        }
+        let id = await browser.downloads.download(options);
+        browser.downloads.onChanged.addListener(delta => {
+          if (delta.id == id && delta.state.current === "complete") {
+            browser.test.sendMessage("done", {ok: true, id});
+          }
+        });
+      } catch ({message}) {
+        browser.test.sendMessage("done", {ok: false, message});
+      }
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  const manifest = {
+    background,
+    incognitoOverride: "spanning",
+    manifest: {permissions: ["downloads"]},
+  };
+  const extension = ExtensionTestUtils.loadExtension(manifest);
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  // options should have the following properties:
+  //   saveAs (Boolean or undefined)
+  //   isPrivate (Boolean)
+  //   fileName (string)
+  //   expectedStartingDir (nsIFile)
+  //   destinationFile (nsIFile)
+  async function testExpectFilePicker(options) {
+    ok(!options.destinationFile.exists(), "the file should have been cleaned up properly previously");
+
+    MockFilePicker.showCallback = mockFilePickerCallback(
+      options.expectedStartingDir,
+      options.destinationFile
+    );
+    MockFilePicker.returnValue = MockFilePicker.returnOK;
+
+    extension.sendMessage(options.fileName, options.saveAs, options.isPrivate);
+    let result = await extension.awaitMessage("done");
+    ok(result.ok, `downloads.download() works with saveAs=${options.saveAs}`);
+
+    ok(options.destinationFile.exists(), "the file exists.");
+    is(options.destinationFile.fileSize, 12, "downloaded file is the correct size");
+    options.destinationFile.remove(false);
+    MockFilePicker.reset();
+
+    // Test the user canceling the save dialog.
+    MockFilePicker.returnValue = MockFilePicker.returnCancel;
+
+    extension.sendMessage(options.fileName, options.saveAs, options.isPrivate);
+    result = await extension.awaitMessage("done");
+
+    ok(!result.ok, "download rejected if the user cancels the dialog");
+    is(result.message, "Download canceled by the user", "with the correct message");
+    ok(!options.destinationFile.exists(), "file was not downloaded");
+    MockFilePicker.reset();
+  }
+
+  async function testNoFilePicker(saveAs) {
+    ok(!defaultFile.exists(), "the file should have been cleaned up properly previously");
+
+    extension.sendMessage(DOWNLOAD_FILENAME, saveAs, false);
+    let result = await extension.awaitMessage("done");
+    ok(result.ok, `downloads.download() works with saveAs=${saveAs}`);
+
+    ok(defaultFile.exists(), "the file exists.");
+    is(defaultFile.fileSize, 12, "downloaded file is the correct size");
+    defaultFile.remove(false);
+  }
+
+  info("Testing that saveAs=true uses the file picker as expected");
+  let expectedStartingDir = defaultDir;
+  let fpOptions = {
+    saveAs: true,
+    isPrivate: false,
+    fileName: DOWNLOAD_FILENAME,
+    expectedStartingDir: expectedStartingDir,
+    destinationFile: pickerFile,
+  };
+  await testExpectFilePicker(fpOptions);
+
+  info("Testing that saveas=true reuses last file picker directory");
+  fpOptions.expectedStartingDir = pickerDir;
+  await testExpectFilePicker(fpOptions);
+
+  info("Testing that saveAs=true in PB reuses last directory");
+  let nonPBStartingDir = fpOptions.expectedStartingDir;
+  fpOptions.isPrivate = true;
+  fpOptions.destinationFile = pbPickerFile;
+  await testExpectFilePicker(fpOptions);
+
+  info("Testing that saveAs=true in PB uses a separate last directory");
+  fpOptions.expectedStartingDir = pbPickerDir;
+  await testExpectFilePicker(fpOptions);
+
+  info("Testing that saveAs=true in Permanent PB mode ignores the incognito option");
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.privatebrowsing.autostart", true]],
+  });
+  fpOptions.isPrivate = false;
+  fpOptions.expectedStartingDir = pbPickerDir;
+  await testExpectFilePicker(fpOptions);
+
+  info("Testing that saveas=true reuses the non-PB last directory after private download");
+  await SpecialPowers.popPrefEnv();
+  fpOptions.isPrivate = false;
+  fpOptions.expectedStartingDir = nonPBStartingDir;
+  fpOptions.destinationFile = pickerFile;
+  await testExpectFilePicker(fpOptions);
+
+  info("Testing that saveAs=true does not reuse last directory when filename contains a path separator");
+  fpOptions.fileName = DEFAULT_SUBDIR + "/" + DOWNLOAD_FILENAME;
+  let destinationFile = defaultDir.clone();
+  destinationFile.append(DEFAULT_SUBDIR);
+  fpOptions.expectedStartingDir = destinationFile.clone();
+  destinationFile.append(DOWNLOAD_FILENAME);
+  fpOptions.destinationFile = destinationFile;
+  await testExpectFilePicker(fpOptions);
+
+  info("Testing that saveAs=false does not use the file picker");
+  fpOptions.saveAs = false;
+  await testNoFilePicker(fpOptions.saveAs);
+
+  // When saveAs is not set, the behavior should be determined by the Firefox
+  // pref that normally determines whether the "Save As" prompt should be
+  // displayed.
+  info(`Testing that the file picker is used when saveAs is not specified ` +
+       `but ${PROMPTLESS_DOWNLOAD_PREF} is disabled`);
+  fpOptions.saveAs = undefined;
+  await SpecialPowers.pushPrefEnv({"set": [
+    [PROMPTLESS_DOWNLOAD_PREF, false],
+  ]});
+  await testExpectFilePicker(fpOptions);
+
+  info(`Testing that the file picker is NOT used when saveAs is not ` +
+       `specified but ${PROMPTLESS_DOWNLOAD_PREF} is enabled`);
+  await SpecialPowers.popPrefEnv();
+  await SpecialPowers.pushPrefEnv({"set": [
+    [PROMPTLESS_DOWNLOAD_PREF, true],
+  ]});
+  await testNoFilePicker(fpOptions.saveAs);
+
+  await extension.unload();
+  MockFilePicker.cleanup();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_uniquify.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_uniquify.html
new file mode 100644
index 0000000000..b5fedee7ec
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_downloads_uniquify.html
@@ -0,0 +1,116 @@
+<!doctype html>
+<html>
+<head>
+  <title>Test downloads.download() uniquify option</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const {FileUtils} = ChromeUtils.import("resource://gre/modules/FileUtils.jsm");
+
+let directory;
+
+add_task(async function setup() {
+  directory = FileUtils.getDir("TmpD", ["downloads"]);
+  directory.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  info(`Using download directory ${directory.path}`);
+
+  await SpecialPowers.pushPrefEnv({"set": [
+    ["browser.download.folderList", 2],
+    ["browser.download.dir", directory.path],
+  ]});
+
+  SimpleTest.registerCleanupFunction(async () => {
+    await SpecialPowers.popPrefEnv();
+    directory.remove(true);
+  });
+});
+
+add_task(async function test_downloads_uniquify() {
+  const file = directory.clone();
+  file.append("file_download.txt");
+
+  const unique = directory.clone();
+  unique.append("file_download(1).txt");
+
+  const {MockFilePicker} = SpecialPowers;
+  MockFilePicker.init(window);
+  MockFilePicker.returnValue = MockFilePicker.returnOK;
+
+  MockFilePicker.showCallback = fp => {
+    let file = directory.clone();
+    file.append(fp.defaultString);
+    MockFilePicker.setFiles([file]);
+  };
+
+  function background() {
+    const url = URL.createObjectURL(new Blob(["file content"]));
+    browser.test.onMessage.addListener(async (filename, saveAs) => {
+      try {
+        let id = await browser.downloads.download({
+          url,
+          filename,
+          saveAs,
+          conflictAction: "uniquify",
+        });
+        browser.downloads.onChanged.addListener(delta => {
+          if (delta.id == id && delta.state.current === "complete") {
+            browser.test.sendMessage("done", {ok: true, id});
+          }
+        });
+      } catch ({message}) {
+        browser.test.sendMessage("done", {ok: false, message});
+      }
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  const manifest = {background, manifest: {permissions: ["downloads"]}};
+  const extension = ExtensionTestUtils.loadExtension(manifest);
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  async function testUniquify(saveAs) {
+    info(`Testing conflictAction:"uniquify" with saveAs=${saveAs}`);
+
+    ok(!file.exists(), "downloaded file should have been cleaned up before test ran");
+    ok(!unique.exists(), "uniquified file should have been cleaned up before test ran");
+
+    // Test download without uniquify and create a conflicting file so we can
+    // test with uniquify.
+    extension.sendMessage("file_download.txt", saveAs);
+    let result = await extension.awaitMessage("done");
+    ok(result.ok, "downloads.download() works with saveAs");
+
+    ok(file.exists(), "the file exists.");
+    is(file.fileSize, 12, "downloaded file is the correct size");
+
+    // Now that a conflicting file exists, test the uniquify behavior
+    extension.sendMessage("file_download.txt", saveAs);
+    result = await extension.awaitMessage("done");
+    ok(result.ok, "downloads.download() works with saveAs and uniquify");
+
+    ok(unique.exists(), "the file exists.");
+    is(unique.fileSize, 12, "downloaded file is the correct size");
+
+    file.remove(false);
+    unique.remove(false);
+  }
+  await testUniquify(true);
+  await testUniquify(false);
+
+  await extension.unload();
+  MockFilePicker.cleanup();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_permissions.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_permissions.html
new file mode 100644
index 0000000000..47761784b1
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_permissions.html
@@ -0,0 +1,176 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for permissions</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function makeTest(manifestPermissions, optionalPermissions, checkFetch = true) {
+  return async function() {
+    function pageScript() {
+      /* global PERMISSIONS */
+      /* eslint-disable mozilla/balanced-listeners */
+      window.addEventListener("keypress", () => {
+        browser.permissions.request(PERMISSIONS).then(result => {
+          browser.test.sendMessage("request.result", result);
+        }, {once: true});
+      });
+      /* eslint-enable mozilla/balanced-listeners */
+
+      browser.test.onMessage.addListener(async msg => {
+        if (msg == "set-cookie") {
+          try {
+            await browser.cookies.set({
+              url: "http://example.com/",
+              name: "COOKIE",
+              value: "NOM NOM",
+            });
+            browser.test.sendMessage("set-cookie.result", {success: true});
+          } catch (err) {
+            dump(`set cookie failed with ${err.message}\n`);
+            browser.test.sendMessage("set-cookie.result",
+                                     {success: false, message: err.message});
+          }
+        } else if (msg == "remove") {
+          browser.permissions.remove(PERMISSIONS).then(result => {
+            browser.test.sendMessage("remove.result", result);
+          });
+        }
+      });
+
+      browser.test.sendMessage("page-ready");
+    }
+
+    let extension = ExtensionTestUtils.loadExtension({
+      background() {
+        browser.test.sendMessage("ready", browser.runtime.getURL("page.html"));
+      },
+
+      manifest: {
+        permissions: manifestPermissions,
+        optional_permissions: [...(optionalPermissions.permissions || []),
+                               ...(optionalPermissions.origins || [])],
+
+        content_scripts: [{
+          matches: ["http://mochi.test/*/file_sample.html"],
+          js: ["content_script.js"],
+        }],
+      },
+
+      files: {
+        "content_script.js": async () => {
+          let url = new URL(window.location.pathname, "http://example.com/");
+          fetch(url, {}).then(response => {
+            browser.test.sendMessage("fetch.result", response.ok);
+          }).catch(err => {
+            browser.test.sendMessage("fetch.result", false);
+          });
+        },
+
+        "page.html": `<html><head>
+          <script src="page.js"><\/script>
+        </head></html>`,
+
+        "page.js": `const PERMISSIONS = ${JSON.stringify(optionalPermissions)}; (${pageScript})();`,
+      },
+    });
+
+    await extension.startup();
+
+    function call(method) {
+      extension.sendMessage(method);
+      return extension.awaitMessage(`${method}.result`);
+    }
+
+    let base = window.location.href.replace(/^chrome:\/\/mochitests\/content/,
+                                            "http://mochi.test:8888");
+    let file = new URL("file_sample.html", base);
+
+    async function testContentScript() {
+      let win = window.open(file);
+      let result = await extension.awaitMessage("fetch.result");
+      win.close();
+      return result;
+    }
+
+    let url = await extension.awaitMessage("ready");
+    let win = window.open();
+    let browserFrame = win.browsingContext.embedderElement;
+    win.location.href = url;
+    await extension.awaitMessage("page-ready");
+
+    // Using the cookies API from an extension page should fail
+    let result = await call("set-cookie");
+    is(result.success, false, "setting cookie failed");
+    if (manifestPermissions.includes("cookies")) {
+      ok(/^Permission denied/.test(result.message),
+         "setting cookie failed with an appropriate error due to missing host permission");
+    } else {
+      ok(/browser\.cookies is undefined/.test(result.message),
+         "setting cookie failed since cookies API is not present");
+    }
+
+    // Making a cross-origin request from a content script should fail
+    if (checkFetch) {
+      result = await testContentScript();
+      is(result, false, "fetch() failed from content script due to lack of host permission");
+    }
+
+    synthesizeKey("a", {}, browserFrame.contentWindow);
+    result = await extension.awaitMessage("request.result");
+    is(result, true, "permissions.request() succeeded");
+
+    // Using the cookies API from an extension page should succeed
+    result = await call("set-cookie");
+    is(result.success, true, "setting cookie succeeded");
+
+    // Making a cross-origin request from a content script should succeed
+    if (checkFetch) {
+      result = await testContentScript();
+      is(result, true, "fetch() succeeded from content script due to lack of host permission");
+    }
+
+    // Now revoke our permissions
+    result = await call("remove");
+
+    // The cookies API should once again fail
+    result = await call("set-cookie");
+    is(result.success, false, "setting cookie failed");
+
+    // As should the cross-origin request from a content script
+    if (checkFetch) {
+      result = await testContentScript();
+      is(result, false, "fetch() failed from content script due to lack of host permission");
+    }
+
+    await extension.unload();
+  };
+}
+
+add_task(function setup() {
+  // Don't bother with prompts in this test.
+  return SpecialPowers.pushPrefEnv({
+    set: [["extensions.webextOptionalPermissionPrompts", false]],
+  });
+});
+
+const ORIGIN = "*://example.com/";
+add_task(makeTest([], {
+  permissions: ["cookies"],
+  origins: [ORIGIN],
+}));
+
+add_task(makeTest(["cookies"], {origins: [ORIGIN]}));
+add_task(makeTest([ORIGIN], {permissions: ["cookies"]}, false));
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_trackingprotection.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_trackingprotection.html
new file mode 100644
index 0000000000..580ea5e793
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_trackingprotection.html
@@ -0,0 +1,98 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+var {UrlClassifierTestUtils} = ChromeUtils.import("resource://testing-common/UrlClassifierTestUtils.jsm");
+
+function tp_background(expectFail = true) {
+  fetch("https://tracking.example.com/example.txt").then(() => {
+    browser.test.assertTrue(!expectFail, "fetch received");
+    browser.test.sendMessage("done");
+  }, () => {
+    browser.test.assertTrue(expectFail, "fetch failure");
+    browser.test.sendMessage("done");
+  });
+}
+
+async function test_permission(permissions, expectFail) {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions,
+    },
+    background: `(${tp_background})(${expectFail})`,
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+}
+
+add_task(async function setup() {
+  await UrlClassifierTestUtils.addTestTrackers();
+  await SpecialPowers.pushPrefEnv({
+    set: [["privacy.trackingprotection.enabled", true]],
+  });
+});
+
+// Fetch would be blocked with these tests
+add_task(async function() { await test_permission([], true); });
+add_task(async function() { await test_permission(["http://*/"], true); });
+add_task(async function() { await test_permission(["http://*.example.com/"], true); });
+add_task(async function() { await test_permission(["http://localhost/*"], true); });
+// Fetch will not be blocked if the extension has host permissions.
+add_task(async function() { await test_permission(["<all_urls>"], false); });
+add_task(async function() { await test_permission(["*://tracking.example.com/*"], false); });
+
+add_task(async function test_contentscript() {
+  function contentScript() {
+    fetch("https://tracking.example.com/example.txt").then(() => {
+      browser.test.notifyPass("fetch received");
+    }, () => {
+      browser.test.notifyFail("fetch failure");
+    });
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: ["*://tracking.example.com/*"],
+      content_scripts: [
+        {
+          "matches": ["http://mochi.test/*/file_sample.html"],
+          "js": ["content_script.js"],
+          "run_at": "document_start",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  };
+  const url = "http://mochi.test:8888/chrome/toolkit/components/extensions/test/mochitest/file_sample.html";
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+  let win = window.open(url);
+  await extension.awaitFinish();
+  win.close();
+  await extension.unload();
+});
+
+add_task(async function teardown() {
+  UrlClassifierTestUtils.cleanupTestTrackers();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_webnavigation_resolved_urls.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webnavigation_resolved_urls.html
new file mode 100644
index 0000000000..a06709d807
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webnavigation_resolved_urls.html
@@ -0,0 +1,81 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function webnav_unresolved_uri_on_expected_URI_scheme() {
+  function background() {
+    let checkURLs;
+
+    browser.webNavigation.onCompleted.addListener(async msg => {
+      if (checkURLs.length) {
+        let expectedURL = checkURLs.shift();
+        browser.test.assertEq(expectedURL, msg.url, "Got the expected URL");
+        await browser.tabs.remove(msg.tabId);
+        browser.test.sendMessage("next");
+      }
+    });
+
+    browser.test.onMessage.addListener((name, urls) => {
+      if (name == "checkURLs") {
+        checkURLs = urls;
+      }
+    });
+
+    browser.test.sendMessage("ready", browser.runtime.getURL("/tab.html"));
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: [
+        "webNavigation",
+      ],
+    },
+    background,
+    files: {
+      "tab.html": `<!DOCTYPE html>
+        <html>
+          <head>
+           <meta charset="utf-8">
+          </head>
+        </html>
+      `,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  let checkURLs = [
+    "resource://gre/modules/Services.jsm",
+    "chrome://mochikit/content/tests/SimpleTest/SimpleTest.js",
+    "about:mozilla",
+  ];
+
+  let tabURL = await extension.awaitMessage("ready");
+  checkURLs.push(tabURL);
+
+  extension.sendMessage("checkURLs", checkURLs);
+
+  for (let url of checkURLs) {
+    window.open(url);
+    await extension.awaitMessage("next");
+  }
+
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_background_events.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_background_events.html
new file mode 100644
index 0000000000..a9dfb0a902
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_background_events.html
@@ -0,0 +1,94 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const {webrequest_test} = ChromeUtils.import(SimpleTest.getTestFileURL("webrequest_test.jsm"));
+let {testFetch, testXHR} = webrequest_test;
+
+// Here we test that any requests originating from a system principal are not
+// accessible through WebRequest.  text_ext_webrequest_background_events tests
+// non-system principal requests.
+
+let testExtension = {
+  manifest: {
+    permissions: [
+      "webRequest",
+      "<all_urls>",
+    ],
+  },
+  background() {
+    let eventNames = [
+      "onBeforeRequest",
+      "onBeforeSendHeaders",
+      "onSendHeaders",
+      "onHeadersReceived",
+      "onResponseStarted",
+      "onCompleted",
+    ];
+
+    function listener(name, details) {
+      // If we get anything, we failed.  Removing the system principal check
+      // in ext-webrequest triggers this failure.
+      browser.test.fail(`received ${name}`);
+    }
+
+    for (let name of eventNames) {
+      browser.webRequest[name].addListener(
+        listener.bind(null, name),
+        {urls: ["https://example.com/*"]}
+      );
+    }
+  },
+};
+
+add_task(async function test_webRequest_chromeworker_events() {
+  let extension = ExtensionTestUtils.loadExtension(testExtension);
+  await extension.startup();
+  await new Promise(resolve => {
+    let worker = new ChromeWorker("webrequest_chromeworker.js");
+    worker.onmessage = event => {
+      ok("chrome worker fetch finished");
+      resolve();
+    };
+    worker.postMessage("go");
+  });
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_chromepage_events() {
+  let extension = ExtensionTestUtils.loadExtension(testExtension);
+  await extension.startup();
+  await new Promise(resolve => {
+    fetch("https://example.com/example.txt").then(() => {
+      ok("test page loaded");
+      resolve();
+    });
+  });
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_jsm_events() {
+  let extension = ExtensionTestUtils.loadExtension(testExtension);
+  await extension.startup();
+  await testFetch("https://example.com/example.txt").then(() => {
+    ok("fetch page loaded");
+  });
+  await testXHR("https://example.com/example.txt").then(() => {
+    ok("xhr page loaded");
+  });
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_host_permissions.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_host_permissions.html
new file mode 100644
index 0000000000..19c812f59f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_host_permissions.html
@@ -0,0 +1,89 @@
+<!doctype html>
+<html>
+<head>
+  <title>Test webRequest checks host permissions</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_webRequest_host_permissions() {
+  function background() {
+    function png(details) {
+      browser.test.sendMessage("png", details.url);
+    }
+    browser.webRequest.onBeforeRequest.addListener(png, {urls: ["*://*/*.png"]});
+    browser.test.sendMessage("ready");
+  }
+
+  const all = ExtensionTestUtils.loadExtension({background, manifest: {permissions: ["webRequest", "<all_urls>"]}});
+  const example = ExtensionTestUtils.loadExtension({background, manifest: {permissions: ["webRequest", "https://example.com/"]}});
+  const mochi_test = ExtensionTestUtils.loadExtension({background, manifest: {permissions: ["webRequest", "http://mochi.test/"]}});
+
+  await all.startup();
+  await example.startup();
+  await mochi_test.startup();
+
+  await all.awaitMessage("ready");
+  await example.awaitMessage("ready");
+  await mochi_test.awaitMessage("ready");
+
+  const win1 = window.open("https://example.com/chrome/toolkit/components/extensions/test/mochitest/file_with_images.html");
+  let urls = [await all.awaitMessage("png"),
+              await all.awaitMessage("png")];
+  ok(urls.some(url => url.endsWith("good.png")), "<all_urls> permission gets to see good.png");
+  ok((await example.awaitMessage("png")).endsWith("good.png"), "example permission sees same-origin example.com image");
+  ok(urls.some(url => url.endsWith("great.png")), "<all_urls> permission also sees great.png");
+
+  // Clear the in-memory image cache, it can prevent listeners from receiving events.
+  const imgTools = SpecialPowers.Cc["@mozilla.org/image/tools;1"].getService(SpecialPowers.Ci.imgITools);
+  imgTools.getImgCacheForDocument(win1.document).clearCache(false);
+  win1.close();
+
+  const win2 = window.open("http://mochi.test:8888/chrome/toolkit/components/extensions/test/mochitest/file_with_images.html");
+  urls = [await all.awaitMessage("png"),
+          await all.awaitMessage("png")];
+  ok(urls.some(url => url.endsWith("good.png")), "<all_urls> permission gets to see good.png");
+  ok((await mochi_test.awaitMessage("png")).endsWith("great.png"), "mochi.test permission sees same-origin mochi.test image");
+  ok(urls.some(url => url.endsWith("great.png")), "<all_urls> permission also sees great.png");
+  win2.close();
+
+  await all.unload();
+  await example.unload();
+  await mochi_test.unload();
+});
+
+add_task(async function test_webRequest_filter_permissions_warning() {
+  const manifest = {
+    permissions: ["webRequest", "http://example.com/"],
+  };
+
+  async function background() {
+    await browser.webRequest.onBeforeRequest.addListener(() => {}, {urls: ["http://example.org/"]});
+    browser.test.notifyPass();
+  }
+
+  const extension = ExtensionTestUtils.loadExtension({manifest, background});
+
+  const warning = new Promise(resolve => {
+    SimpleTest.monitorConsole(resolve, [{message: /filter doesn't overlap with host permissions/}]);
+  });
+
+  await extension.startup();
+  await extension.awaitFinish();
+
+  SimpleTest.endMonitorConsole();
+  await warning;
+
+  await extension.unload();
+});
+
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_mozextension.html b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_mozextension.html
new file mode 100644
index 0000000000..4c19359d8b
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_webrequest_mozextension.html
@@ -0,0 +1,193 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test moz-extension protocol use</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+let peakAchu;
+add_task(async function setup() {
+  peakAchu = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "<all_urls>",
+      ],
+    },
+    background() {
+      // ID for the extension in the tests.  Try to observe it to ensure we cannot.
+      browser.webRequest.onBeforeRequest.addListener(details => {
+        browser.test.notifyFail(`PeakAchu onBeforeRequest ${details.url}`);
+      }, {urls: ["<all_urls>", "moz-extension://*/*"]});
+
+      browser.test.onMessage.addListener((msg, extensionUrl) => {
+        browser.test.log(`spying for ${extensionUrl}`);
+        browser.webRequest.onBeforeRequest.addListener(details => {
+          browser.test.notifyFail(`PeakAchu onBeforeRequest ${details.url}`);
+        }, {urls: [extensionUrl]});
+      });
+    },
+  });
+  await peakAchu.startup();
+});
+
+add_task(async function test_webRequest_no_mozextension_permission() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "tabs",
+        "moz-extension://c9e007e0-e518-ed4c-8202-83849981dd21/*",
+        "moz-extension://*/*",
+      ],
+    },
+    background() {
+      browser.test.notifyPass("loaded");
+    },
+  });
+
+  let messages = [
+    {message: /processing permissions\.2: Value "moz-extension:\/\/c9e007e0-e518-ed4c-8202-83849981dd21\/\*"/},
+    {message: /processing permissions\.3: Value "moz-extension:\/\/\*\/\*"/},
+  ];
+
+  let waitForConsole = new Promise(resolve => {
+    SimpleTest.monitorConsole(resolve, messages);
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("loaded");
+  await extension.unload();
+
+  SimpleTest.endMonitorConsole();
+  await waitForConsole;
+});
+
+add_task(async function test_webRequest_mozextension_fetch() {
+  function background() {
+    let page = browser.extension.getURL("fetched.html");
+    browser.webRequest.onBeforeRequest.addListener(details => {
+      browser.test.assertEq(details.url, page, "got correct url in onBeforeRequest");
+      browser.test.sendMessage("request-started");
+    }, {urls: [browser.extension.getURL("*")]}, ["blocking"]);
+    browser.webRequest.onCompleted.addListener(details => {
+      browser.test.assertEq(details.url, page, "got correct url in onCompleted");
+      browser.test.sendMessage("request-complete");
+    }, {urls: [browser.extension.getURL("*")]});
+
+    browser.test.onMessage.addListener((msg, data) => {
+      fetch(page).then(() => {
+        browser.test.notifyPass("fetch success");
+        browser.test.sendMessage("done");
+      }, () => {
+        browser.test.fail("fetch failed");
+        browser.test.sendMessage("done");
+      });
+    });
+    browser.test.sendMessage("extensionUrl", browser.extension.getURL("*"));
+  }
+
+  // Use webrequest to monitor moz-extension:// requests
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "tabs",
+        "<all_urls>",
+      ],
+    },
+    files: {
+      "fetched.html": `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+          </head>
+          <body>
+            <h1>moz-extension file</h1>
+          </body>
+        </html>
+      `.trim(),
+    },
+    background,
+  });
+
+  await extension.startup();
+  // send the url for this extension to the monitoring extension
+  peakAchu.sendMessage("extensionUrl", await extension.awaitMessage("extensionUrl"));
+
+  extension.sendMessage("testFetch");
+  await extension.awaitMessage("request-started");
+  await extension.awaitMessage("request-complete");
+  await extension.awaitMessage("done");
+
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_mozextension_tab_query() {
+  function background() {
+    browser.test.sendMessage("extensionUrl", browser.extension.getURL("*"));
+    let page = browser.extension.getURL("tab.html");
+
+    async function onUpdated(tabId, tabInfo, tab) {
+      if (tabInfo.status !== "complete") {
+        return;
+      }
+      browser.test.log(`tab created ${tabId} ${JSON.stringify(tabInfo)} ${tab.url}`);
+      let tabs = await browser.tabs.query({url: browser.extension.getURL("*")});
+      browser.test.assertEq(1, tabs.length, "got one tab");
+      browser.test.assertEq(tabs.length && tabs[0].id, tab.id, "got the correct tab");
+      browser.test.assertEq(tabs.length && tabs[0].url, page, "got correct url in tab");
+      browser.tabs.remove(tabId);
+      browser.tabs.onUpdated.removeListener(onUpdated);
+      browser.test.sendMessage("tabs-done");
+    }
+    browser.tabs.onUpdated.addListener(onUpdated);
+    browser.tabs.create({url: page});
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "tabs",
+        "<all_urls>",
+      ],
+    },
+    files: {
+      "tab.html": `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+          </head>
+          <body>
+            <h1>moz-extension file</h1>
+          </body>
+        </html>
+      `.trim(),
+    },
+    background,
+  });
+
+  await extension.startup();
+  peakAchu.sendMessage("extensionUrl", await extension.awaitMessage("extensionUrl"));
+  await extension.awaitMessage("tabs-done");
+  await extension.unload();
+});
+
+add_task(async function teardown() {
+  await peakAchu.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_chrome_native_messaging_paths.html b/toolkit/components/extensions/test/mochitest/test_chrome_native_messaging_paths.html
new file mode 100644
index 0000000000..78359747ce
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_native_messaging_paths.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const {OS} = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+// Test that the default paths searched for native host manifests
+// are the ones we expect.
+add_task(async function test_default_paths() {
+  let expectUser, expectGlobal;
+  switch (AppConstants.platform) {
+    case "macosx": {
+      expectUser = OS.Path.join(OS.Constants.Path.homeDir,
+                                "Library/Application Support/Mozilla");
+      expectGlobal = "/Library/Application Support/Mozilla";
+
+      break;
+    }
+
+    case "linux": {
+      expectUser = OS.Path.join(OS.Constants.Path.homeDir, ".mozilla");
+
+      const libdir = AppConstants.HAVE_USR_LIB64_DIR ? "lib64" : "lib";
+      expectGlobal = OS.Path.join("/usr", libdir, "mozilla");
+      break;
+    }
+
+    default:
+      // Fixed filesystem paths are only defined for MacOS and Linux,
+      // there's nothing to test on other platforms.
+      ok(false, `This test does not apply on ${AppConstants.platform}`);
+      break;
+  }
+
+  let userDir = Services.dirsvc.get("XREUserNativeManifests", Ci.nsIFile).path;
+  is(userDir, expectUser, "user-specific native messaging directory is correct");
+
+  let globalDir = Services.dirsvc.get("XRESysNativeManifests", Ci.nsIFile).path;
+  is(globalDir, expectGlobal, "system-wide native messaing directory is correct");
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_activityLog.html b/toolkit/components/extensions/test/mochitest/test_ext_activityLog.html
new file mode 100644
index 0000000000..ce4689540d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_activityLog.html
@@ -0,0 +1,390 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension activityLog test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_api() {
+  let URL =
+    "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_sample.html";
+
+  // Test that an unspecified extension is not logged by the watcher extension.
+  let unlogged = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+    manifest: {
+      applications: { gecko: { id: "unlogged@tests.mozilla.org" } },
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background() {
+      // This privileged test extension should not affect the webRequest
+      // data received by non-privileged extensions (See Bug 1576272).
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          return { cancel: false };
+        },
+        { urls: ["http://mochi.test/*/file_sample.html"] },
+        ["blocking"]
+      );
+    },
+  });
+  await unlogged.startup();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "watched@tests.mozilla.org" } },
+      permissions: [
+        "tabs",
+        "tabHide",
+        "storage",
+        "webRequest",
+        "webRequestBlocking",
+        "<all_urls>",
+      ],
+      content_scripts: [
+        {
+          matches: ["http://mochi.test/*/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+    },
+    files: {
+      "content_script.js": () => {
+        browser.test.sendMessage("content_script");
+      },
+      "registered_script.js": () => {
+        browser.test.sendMessage("registered_script");
+      },
+    },
+    async background() {
+      let listen = () => {};
+      async function runTest() {
+        // Test activity for a child function call.
+        browser.test.assertEq(
+          undefined,
+          browser.activityLog,
+          "activityLog requires permission"
+        );
+
+        // Test a child event manager.
+        browser.storage.onChanged.addListener(listen);
+        browser.storage.onChanged.removeListener(listen);
+
+        // Test a parent event manager.
+        let webRequestListener = details => {
+          browser.webRequest.onBeforeRequest.removeListener(webRequestListener);
+          return { cancel: false };
+        };
+        browser.webRequest.onBeforeRequest.addListener(
+          webRequestListener,
+          { urls: ["http://mochi.test/*/file_sample.html"] },
+          ["blocking"]
+        );
+
+        // A manifest based content script is already
+        // registered, we do a dynamic registration here.
+        await browser.contentScripts.register({
+          js: [{ file: "registered_script.js" }],
+          matches: ["http://mochi.test/*/file_sample.html"],
+          runAt: "document_start",
+        });
+        browser.test.sendMessage("ready");
+      }
+      browser.test.onMessage.addListener((msg, data) => {
+        // Logging has started here so this listener is logged, but the
+        // call adding it was not.  We do an additional onMessage.addListener
+        // call in the test function to validate child based event managers.
+        if (msg == "runtest") {
+          browser.test.assertTrue(true, msg);
+          runTest();
+        }
+        if (msg == "hideTab") {
+          browser.tabs.hide(data);
+        }
+      });
+      browser.test.sendMessage("url", browser.extension.getURL(""));
+    },
+  });
+
+  async function backgroundScript(expectedUrl, extensionUrl) {
+    let expecting = [
+      // Test child-only api_call.
+      {
+        type: "api_call",
+        name: "test.assertTrue",
+        data: { args: [true, "runtest"] },
+      },
+
+      // Test child-only api_call.
+      {
+        type: "api_call",
+        name: "test.assertEq",
+        data: {
+          args: [undefined, undefined, "activityLog requires permission"],
+        },
+      },
+      // Test child addListener calls.
+      {
+        type: "api_call",
+        name: "storage.onChanged.addListener",
+        data: {
+          args: [],
+        },
+      },
+      {
+        type: "api_call",
+        name: "storage.onChanged.removeListener",
+        data: {
+          args: [],
+        },
+      },
+      // Test parent addListener calls.
+      {
+        type: "api_call",
+        name: "webRequest.onBeforeRequest.addListener",
+        data: {
+          args: [
+            {
+              incognito: null,
+              tabId: null,
+              types: null,
+              urls: ["http://mochi.test/*/file_sample.html"],
+              windowId: null,
+            },
+            ["blocking"],
+          ],
+        },
+      },
+      // Test an api that makes use of callParentAsyncFunction.
+      {
+        type: "api_call",
+        name: "contentScripts.register",
+        data: {
+          args: [
+            {
+              allFrames: null,
+              css: null,
+              excludeGlobs: null,
+              excludeMatches: null,
+              includeGlobs: null,
+              js: [
+                {
+                  file: `${extensionUrl}registered_script.js`,
+                },
+              ],
+              matchAboutBlank: null,
+              matches: ["http://mochi.test/*/file_sample.html"],
+              runAt: "document_start",
+            },
+          ],
+        },
+      },
+      // Test child api_event calls.
+      {
+        type: "api_event",
+        name: "test.onMessage",
+        data: { args: ["runtest"] },
+      },
+      {
+        type: "api_call",
+        name: "test.sendMessage",
+        data: { args: ["ready"] },
+      },
+      // Test parent api_event calls.
+      {
+        type: "api_call",
+        name: "webRequest.onBeforeRequest.removeListener",
+        data: {
+          args: [],
+        },
+      },
+      {
+        type: "api_event",
+        name: "webRequest.onBeforeRequest",
+        data: {
+          args: [
+            {
+              url: expectedUrl,
+              method: "GET",
+              type: "main_frame",
+              frameId: 0,
+              parentFrameId: -1,
+              incognito: false,
+              thirdParty: false,
+              ip: null,
+              frameAncestors: [],
+              urlClassification: { firstParty: [], thirdParty: [] },
+              requestSize: 0,
+              responseSize: 0,
+            },
+          ],
+          result: {
+            cancel: false,
+          },
+        },
+      },
+      // Test manifest based content script.
+      {
+        type: "content_script",
+        name: "content_script.js",
+        data: { url: expectedUrl, tabId: 1 },
+      },
+      // registered script test
+      {
+        type: "content_script",
+        name: `${extensionUrl}registered_script.js`,
+        data: { url: expectedUrl, tabId: 1 },
+      },
+      {
+        type: "api_call",
+        name: "test.sendMessage",
+        data: { args: ["registered_script"], tabId: 1 },
+      },
+      {
+        type: "api_call",
+        name: "test.sendMessage",
+        data: { args: ["content_script"], tabId: 1 },
+      },
+      // Child api call
+      {
+        type: "api_call",
+        name: "tabs.hide",
+        data: { args: ["__TAB_ID"] },
+      },
+      {
+        type: "api_event",
+        name: "test.onMessage",
+        data: { args: ["hideTab", "__TAB_ID"] },
+      },
+    ];
+    browser.test.assertTrue(browser.activityLog, "activityLog is privileged");
+
+    // Slightly less than a normal deep equal, we want to know that the values
+    // in our expected data are the same in the actual data, but we don't care
+    // if actual data has additional data or if data is in the same order in objects.
+    // This allows us to ignore keys that may be variable, or that are set in
+    // the api with an undefined value.
+    function deepEquivalent(a, b) {
+      if (a === b) {
+        return true;
+      }
+      if (
+        typeof a != "object" ||
+        typeof b != "object" ||
+        a === null ||
+        b === null
+      ) {
+        return false;
+      }
+      for (let k in a) {
+        if (!deepEquivalent(a[k], b[k])) {
+          return false;
+        }
+      }
+      return true;
+    }
+
+    let tab;
+    let handler = async details => {
+      browser.test.log(`onExtensionActivity ${JSON.stringify(details)}`);
+      let test = expecting.shift();
+      if (!test) {
+        browser.test.notifyFail(`no test for ${details.name}`);
+      }
+
+      // On multiple runs, tabId will be different.  Set the current
+      // tabId where we need it.
+      if (test.data.tabId !== undefined) {
+        test.data.tabId = tab.id;
+      }
+      if (test.data.args !== undefined) {
+        test.data.args = test.data.args.map(value =>
+          value === "__TAB_ID" ? tab.id : value
+        );
+      }
+
+      browser.test.assertEq(test.type, details.type, "type matches");
+      if (test.type == "content_script") {
+        browser.test.assertTrue(
+          details.name.includes(test.name),
+          "content script name matches"
+        );
+      } else {
+        browser.test.assertEq(test.name, details.name, "name matches");
+      }
+
+      browser.test.assertTrue(
+        deepEquivalent(test.data, details.data),
+        `expected ${JSON.stringify(
+          test.data
+        )} included in actual ${JSON.stringify(details.data)}`
+      );
+      if (!expecting.length) {
+        await browser.tabs.remove(tab.id);
+        browser.test.notifyPass("activity");
+      }
+    };
+    browser.activityLog.onExtensionActivity.addListener(
+      handler,
+      "watched@tests.mozilla.org"
+    );
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg === "opentab") {
+        tab = await browser.tabs.create({ url: expectedUrl });
+        browser.test.sendMessage("tabid", tab.id);
+      }
+      if (msg === "done") {
+        browser.activityLog.onExtensionActivity.removeListener(
+          handler,
+          "watched@tests.mozilla.org"
+        );
+      }
+    });
+  }
+
+  await extension.startup();
+  let extensionUrl = await extension.awaitMessage("url");
+
+  let logger = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+    manifest: {
+      applications: { gecko: { id: "watcher@tests.mozilla.org" } },
+      permissions: ["activityLog"],
+    },
+    background: `(${backgroundScript})("${URL}", "${extensionUrl}")`,
+  });
+  await logger.startup();
+  extension.sendMessage("runtest");
+  await extension.awaitMessage("ready");
+  logger.sendMessage("opentab");
+  let id = await logger.awaitMessage("tabid");
+
+  await Promise.all([
+    extension.awaitMessage("content_script"),
+    extension.awaitMessage("registered_script"),
+  ]);
+
+  extension.sendMessage("hideTab", id);
+  await logger.awaitFinish("activity");
+
+  // Stop watching because we get extra calls on extension shutdown
+  // such as listener removal.
+  logger.sendMessage("done");
+
+  await extension.unload();
+  await unlogged.unload();
+  await logger.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_all_apis.js b/toolkit/components/extensions/test/mochitest/test_ext_all_apis.js
new file mode 100644
index 0000000000..62933bf008
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_all_apis.js
@@ -0,0 +1,181 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+// Tests whether not too many APIs are visible by default.
+// This file is used by test_ext_all_apis.html in browser/ and mobile/android/,
+// which may modify the following variables to add or remove expected APIs.
+/* globals expectedContentApisTargetSpecific */
+/* globals expectedBackgroundApisTargetSpecific */
+
+// Generates a list of expectations.
+function generateExpectations(list) {
+  return list
+    .reduce((allApis, path) => {
+      return allApis.concat(`browser.${path}`, `chrome.${path}`);
+    }, [])
+    .sort();
+}
+
+let expectedCommonApis = [
+  "extension.getURL",
+  "extension.inIncognitoContext",
+  "extension.lastError",
+  "i18n.detectLanguage",
+  "i18n.getAcceptLanguages",
+  "i18n.getMessage",
+  "i18n.getUILanguage",
+  "runtime.OnInstalledReason",
+  "runtime.OnRestartRequiredReason",
+  "runtime.PlatformArch",
+  "runtime.PlatformOs",
+  "runtime.RequestUpdateCheckStatus",
+  "runtime.getManifest",
+  "runtime.connect",
+  "runtime.getURL",
+  "runtime.id",
+  "runtime.lastError",
+  "runtime.onConnect",
+  "runtime.onMessage",
+  "runtime.sendMessage",
+  // browser.test is only available in xpcshell or when
+  // Cu.isInAutomation is true.
+  "test.assertEq",
+  "test.assertFalse",
+  "test.assertRejects",
+  "test.assertThrows",
+  "test.assertTrue",
+  "test.fail",
+  "test.log",
+  "test.notifyFail",
+  "test.notifyPass",
+  "test.onMessage",
+  "test.sendMessage",
+  "test.succeed",
+  "test.withHandlingUserInput",
+];
+
+let expectedContentApis = [
+  ...expectedCommonApis,
+  ...expectedContentApisTargetSpecific,
+];
+
+let expectedBackgroundApis = [
+  ...expectedCommonApis,
+  ...expectedBackgroundApisTargetSpecific,
+  "contentScripts.register",
+  "experiments.APIChildScope",
+  "experiments.APIEvent",
+  "experiments.APIParentScope",
+  "extension.ViewType",
+  "extension.getBackgroundPage",
+  "extension.getViews",
+  "extension.isAllowedFileSchemeAccess",
+  "extension.isAllowedIncognitoAccess",
+  // Note: extensionTypes is not visible in Chrome.
+  "extensionTypes.CSSOrigin",
+  "extensionTypes.ImageFormat",
+  "extensionTypes.RunAt",
+  "management.ExtensionDisabledReason",
+  "management.ExtensionInstallType",
+  "management.ExtensionType",
+  "management.getSelf",
+  "management.uninstallSelf",
+  "permissions.getAll",
+  "permissions.contains",
+  "permissions.request",
+  "permissions.remove",
+  "permissions.onAdded",
+  "permissions.onRemoved",
+  "runtime.getBackgroundPage",
+  "runtime.getBrowserInfo",
+  "runtime.getPlatformInfo",
+  "runtime.onConnectExternal",
+  "runtime.onInstalled",
+  "runtime.onMessageExternal",
+  "runtime.onStartup",
+  "runtime.onUpdateAvailable",
+  "runtime.openOptionsPage",
+  "runtime.reload",
+  "runtime.setUninstallURL",
+  "theme.getCurrent",
+  "theme.onUpdated",
+  "types.LevelOfControl",
+  "types.SettingScope",
+];
+
+function sendAllApis() {
+  function isEvent(key, val) {
+    if (!/^on[A-Z]/.test(key)) {
+      return false;
+    }
+    let eventKeys = [];
+    for (let prop in val) {
+      eventKeys.push(prop);
+    }
+    eventKeys = eventKeys.sort().join();
+    return eventKeys === "addListener,hasListener,removeListener";
+  }
+  function mayRecurse(key, val) {
+    if (Object.keys(val).filter(k => !/^[A-Z\-0-9_]+$/.test(k)).length === 0) {
+      // Don't recurse on constants and empty objects.
+      return false;
+    }
+    return !isEvent(key, val);
+  }
+
+  let results = [];
+  function diveDeeper(path, obj) {
+    for (let key in obj) {
+      let val = obj[key];
+      if (typeof val == "object" && val !== null && mayRecurse(key, val)) {
+        diveDeeper(`${path}.${key}`, val);
+      } else if (val !== undefined) {
+        results.push(`${path}.${key}`);
+      }
+    }
+  }
+  diveDeeper("browser", browser);
+  diveDeeper("chrome", chrome);
+  browser.test.sendMessage("allApis", results.sort());
+}
+
+add_task(async function test_enumerate_content_script_apis() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://mochi.test/*/file_sample.html"],
+          js: ["contentscript.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+    files: {
+      "contentscript.js": sendAllApis,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+  let actualApis = await extension.awaitMessage("allApis");
+  win.close();
+  let expectedApis = generateExpectations(expectedContentApis);
+  isDeeply(actualApis, expectedApis, "content script APIs");
+
+  await extension.unload();
+});
+
+add_task(async function test_enumerate_background_script_apis() {
+  let extensionData = {
+    background: sendAllApis,
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let actualApis = await extension.awaitMessage("allApis");
+  let expectedApis = generateExpectations(expectedBackgroundApis);
+  isDeeply(actualApis, expectedApis, "background script APIs");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_async_clipboard.html b/toolkit/components/extensions/test/mochitest/test_ext_async_clipboard.html
new file mode 100644
index 0000000000..ffa421e042
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_async_clipboard.html
@@ -0,0 +1,376 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Async Clipboard permissions tests</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+
+<script>
+"use strict";
+
+// Bug 1479956 - On android-debug verify this test times out
+SimpleTest.requestLongerTimeout(2);
+
+/* globals clipboardWriteText, clipboardWrite, clipboardReadText, clipboardRead */
+function shared() {
+  this.clipboardWriteText = function(txt) {
+    return navigator.clipboard.writeText(txt);
+  };
+
+  this.clipboardWrite = function(dt) {
+    return navigator.clipboard.write(dt);
+  };
+
+  this.clipboardReadText = function() {
+    return navigator.clipboard.readText();
+  };
+
+  this.clipboardRead = function() {
+    return navigator.clipboard.read();
+  };
+}
+
+/**
+ * Clear the clipboard.
+ *
+ * This is needed because Services.clipboard.emptyClipboard() does not clear the actual system clipboard.
+ */
+function clearClipboard() {
+  if (AppConstants.platform == "android") {
+    // On android, this clears the actual system clipboard
+    SpecialPowers.Services.clipboard.emptyClipboard(SpecialPowers.Services.clipboard.kGlobalClipboard);
+    return;
+  }
+  // Need to do this hack on other platforms to clear the actual system clipboard
+  let transf = SpecialPowers.Cc["@mozilla.org/widget/transferable;1"]
+    .createInstance(SpecialPowers.Ci.nsITransferable);
+  transf.init(null);
+  // Empty transferables may cause crashes, so just add an unknown type.
+  const TYPE = "text/x-moz-place-empty";
+  transf.addDataFlavor(TYPE);
+  transf.setTransferData(TYPE, {}, 0);
+  SpecialPowers.Services.clipboard.setData(transf, null, SpecialPowers.Services.clipboard.kGlobalClipboard);
+}
+
+add_task(async function setup() {
+  await SpecialPowers.pushPrefEnv({"set": [
+    ["dom.events.asyncClipboard", true],
+    ["dom.events.asyncClipboard.dataTransfer", true],
+  ]});
+});
+
+// Test that without enough permissions, we are NOT allowed to use writeText, write, read or readText in background script
+add_task(async function test_background_async_clipboard_no_permissions() {
+  function backgroundScript() {
+    let dt = new DataTransfer();
+    dt.items.add("Howdy", "text/plain");
+    browser.test.assertRejects(clipboardRead(), undefined, "Read should be denied without permission");
+    browser.test.assertRejects(clipboardWrite(dt), undefined, "Write should be denied without permission");
+    browser.test.assertRejects(clipboardWriteText("blabla"), undefined, "WriteText should be denied without permission");
+    browser.test.assertRejects(clipboardReadText(), undefined, "ReadText should be denied without permission");
+    browser.test.sendMessage("ready");
+  }
+  let extensionData = {
+    background: [shared, backgroundScript],
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  await extension.unload();
+});
+
+// Test that without enough permissions, we are NOT allowed to use writeText, write, read or readText in content script
+add_task(async function test_contentscript_async_clipboard_no_permission() {
+  function contentScript() {
+    let dt = new DataTransfer();
+    dt.items.add("Howdy", "text/plain");
+    browser.test.assertRejects(clipboardRead(), undefined, "Read should be denied without permission");
+    browser.test.assertRejects(clipboardWrite(dt), undefined, "Write should be denied without permission");
+    browser.test.assertRejects(clipboardWriteText("blabla"), undefined, "WriteText should be denied without permission");
+    browser.test.assertRejects(clipboardReadText(), undefined, "ReadText should be denied without permission");
+    browser.test.sendMessage("ready");
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["https://example.com/*/file_sample.html"],
+      }],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+  await extension.awaitMessage("ready");
+  win.close();
+  await extension.unload();
+});
+
+// Test that with enough permissions, we are allowed to use writeText  in content script
+add_task(async function test_contentscript_clipboard_permission_writetext() {
+  function contentScript() {
+    let str = "HI";
+    clipboardWriteText(str).then(function() {
+      // nothing here
+      browser.test.sendMessage("ready");
+    }, function(err) {
+      browser.test.fail("WriteText promise rejected");
+      browser.test.sendMessage("ready");
+    }); // clipboardWriteText
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["https://example.com/*/file_sample.html"],
+      }],
+      permissions: [
+        "clipboardWrite",
+        "clipboardRead",
+      ],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+  await extension.awaitMessage("ready");
+  const actual = SpecialPowers.getClipboardData("text/unicode");
+  is(actual, "HI", "right string copied by write");
+  win.close();
+  await extension.unload();
+});
+
+// Test that with enough permissions, we are allowed to use readText in content script
+add_task(async function test_contentscript_clipboard_permission_readtext() {
+  function contentScript() {
+    let str = "HI";
+    clipboardReadText().then(function(strData) {
+      if (strData == str) {
+        browser.test.succeed("Successfully read from clipboard");
+      } else {
+        browser.test.fail("ReadText read the wrong thing from clipboard:" + strData);
+      }
+      browser.test.sendMessage("ready");
+    }, function(err) {
+      browser.test.fail("ReadText promise rejected");
+      browser.test.sendMessage("ready");
+    }); // clipboardReadText
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["https://example.com/*/file_sample.html"],
+      }],
+      permissions: [
+        "clipboardWrite",
+        "clipboardRead",
+      ],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+  await SimpleTest.promiseClipboardChange("HI", () => {
+    SpecialPowers.clipboardCopyString("HI");
+  }, "text/unicode");
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+  await extension.awaitMessage("ready");
+  win.close();
+  await extension.unload();
+});
+
+// Test that with enough permissions, we are allowed to use write in content script
+add_task(async function test_contentscript_clipboard_permission_write() {
+  function contentScript() {
+    let str = "HI";
+    let dt = new DataTransfer();
+    dt.items.add(str, "text/plain");
+    clipboardWrite(dt).then(function() {
+      // nothing here
+      browser.test.sendMessage("ready");
+    }, function(err) { // clipboardWrite promise error function
+      browser.test.fail("Write promise rejected");
+      browser.test.sendMessage("ready");
+    }); // clipboard write
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["https://example.com/*/file_sample.html"],
+      }],
+      permissions: [
+        "clipboardWrite",
+        "clipboardRead",
+      ],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+  await extension.awaitMessage("ready");
+  const actual = SpecialPowers.getClipboardData("text/unicode");
+  is(actual, "HI", "right string copied by write");
+  win.close();
+  await extension.unload();
+});
+
+// Test that with enough permissions, we are allowed to use read in content script
+add_task(async function test_contentscript_clipboard_permission_read() {
+  function contentScript() {
+    clipboardRead().then(function(dt) {
+      let s = dt.getData("text/plain");
+      if (s == "HELLO") {
+        browser.test.succeed("Read promise successfully read the right thing");
+      } else {
+        browser.test.fail("Read read the wrong string from clipboard:" + s);
+      }
+      browser.test.sendMessage("ready");
+    }, function(err) { // clipboardRead promise error function
+      browser.test.fail("Read promise rejected");
+      browser.test.sendMessage("ready");
+    }); // clipboard read
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["https://example.com/*/file_sample.html"],
+      }],
+      permissions: [
+        "clipboardWrite",
+        "clipboardRead",
+      ],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+  await SimpleTest.promiseClipboardChange("HELLO", () => {
+    SpecialPowers.clipboardCopyString("HELLO");
+  }, "text/unicode");
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+  await extension.awaitMessage("ready");
+  win.close();
+  await extension.unload();
+});
+
+// Test that performing readText(...) when the clipboard is empty returns an empty string
+add_task(async function test_contentscript_clipboard_nocontents_readtext() {
+  function contentScript() {
+    clipboardReadText().then(function(strData) {
+      if (strData == "") {
+        browser.test.succeed("ReadText successfully read correct thing from an empty clipboard");
+      } else {
+        browser.test.fail("ReadText should have read an empty string, but read:" + strData);
+      }
+      browser.test.sendMessage("ready");
+    }, function(err) {
+      browser.test.fail("ReadText promise rejected: " + err);
+      browser.test.sendMessage("ready");
+    });
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["https://example.com/*/file_sample.html"],
+      }],
+      permissions: [
+        "clipboardRead",
+      ],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+
+  await SimpleTest.promiseClipboardChange("", () => {
+    clearClipboard();
+  }, "text/x-moz-place-empty");
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+  await extension.awaitMessage("ready");
+  win.close();
+  await extension.unload();
+});
+
+// Test that performing read(...) when the clipboard is empty returns an empty data transfer
+add_task(async function test_contentscript_clipboard_nocontents_read() {
+  function contentScript() {
+    clipboardRead().then(function(dataT) {
+      // On macOS if we clear the clipboard and read from it, there will be
+      // no items in the data transfer object.
+      // On linux with e10s enabled clearing of the clipboard does not happen in
+      // the same way as it does on other platforms. So when we clear  the clipboard
+      // and read from it, the data transfer object contains an item of type
+      // text/plain and kind string, but we can't call getAsString on it to verify
+      // that at least it is an empty string because the callback never gets invoked.
+      if (!dataT.items.length ||
+        (dataT.items.length == 1 && dataT.items[0].type == "text/plain" &&
+         dataT.items[0].kind == "string")) {
+        browser.test.succeed("Read promise successfully resolved");
+      } else {
+        browser.test.fail("Read read the wrong thing from clipboard, " +
+          "data transfer has this many items:" + dataT.items.length);
+      }
+      browser.test.sendMessage("ready");
+    }, function(err) {
+      browser.test.fail("Read promise rejected: " + err);
+      browser.test.sendMessage("ready");
+    });
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["https://example.com/*/file_sample.html"],
+      }],
+      permissions: [
+        "clipboardRead",
+      ],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+
+  await SimpleTest.promiseClipboardChange("", () => {
+    clearClipboard();
+  }, "text/x-moz-place-empty");
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+  await extension.awaitMessage("ready");
+  win.close();
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_background_canvas.html b/toolkit/components/extensions/test/mochitest/test_ext_background_canvas.html
new file mode 100644
index 0000000000..8b6fba25bb
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_background_canvas.html
@@ -0,0 +1,50 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for background page canvas rendering</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_background_canvas() {
+  function background() {
+    try {
+      let canvas = document.createElement("canvas");
+
+      let context = canvas.getContext("2d");
+
+      // This ensures that we have a working PresShell, and can successfully
+      // calculate font metrics.
+      context.font = "8pt fixed";
+
+      browser.test.notifyPass("background-canvas");
+    } catch (e) {
+      browser.test.fail(`Error: ${e} :: ${e.stack}`);
+      browser.test.notifyFail("background-canvas");
+    }
+  }
+
+  let extensionData = {
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "background_canvas@tests.mozilla.org" } },
+    },
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+  await extension.awaitFinish("background-canvas");
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_background_page.html b/toolkit/components/extensions/test/mochitest/test_ext_background_page.html
new file mode 100644
index 0000000000..9cafd8a61a
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_background_page.html
@@ -0,0 +1,84 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <title>WebExtension test</title>
+    <meta charset="utf-8">
+    <script src="/tests/SimpleTest/SimpleTest.js"></script>
+    <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+    <script src="head.js" type="text/javascript"></script>
+    <link href="/tests/SimpleTest/test.css" rel="stylesheet"/>
+  </head>
+  <body>
+
+    <script type="text/javascript">
+      "use strict";
+
+      /* eslint-disable mozilla/balanced-listeners */
+
+      add_task(async function testAlertNotShownInBackgroundWindow() {
+        let extension = ExtensionTestUtils.loadExtension({
+          background: function () {
+            alert("I am an alert in the background.");
+
+            browser.test.notifyPass("alertCalled");
+          }
+        });
+
+        let consoleOpened = loadChromeScript(() => {
+          const {sendAsyncMessage, assert} = this;
+          assert.ok(!Services.wm.getEnumerator("alert:alert").hasMoreElements(), "Alerts should not be present at the start of the test.");
+
+          Services.obs.addObserver(function observer() {
+            sendAsyncMessage("web-console-created");
+            Services.obs.removeObserver(observer, "web-console-created");
+          }, "web-console-created");
+        });
+        let opened = consoleOpened.promiseOneMessage("web-console-created");
+
+        consoleMonitor.start([
+          {
+            message: /alert\(\) is not supported in background windows/
+          }, {
+            message: /I am an alert in the background/
+          }
+        ]);
+
+        await extension.startup();
+        await extension.awaitFinish("alertCalled");
+
+        let chromeScript = loadChromeScript(async () => {
+          const {assert} = this;
+          assert.ok(!Services.wm.getEnumerator("alert:alert").hasMoreElements(), "Alerts should not be present after calling alert().");
+        });
+        chromeScript.destroy();
+
+        await consoleMonitor.finished();
+
+        await opened;
+        consoleOpened.destroy();
+
+        chromeScript = loadChromeScript(async () => {
+          const {sendAsyncMessage} = this;
+          let {require} = ChromeUtils.import ("resource://devtools/shared/Loader.jsm");
+          require("devtools/client/framework/devtools-browser");
+          let {BrowserConsoleManager} = require("devtools/client/webconsole/browser-console-manager");
+
+          // And then double check that we have an actual browser console.
+          let haveConsole = !!BrowserConsoleManager.getBrowserConsole();
+
+          if (haveConsole) {
+            await BrowserConsoleManager.toggleBrowserConsole();
+          }
+          sendAsyncMessage("done", haveConsole);
+        });
+
+        let consoleShown = await chromeScript.promiseOneMessage("done");
+        ok(consoleShown, "console was shown");
+        chromeScript.destroy();
+
+        await extension.unload();
+      });
+    </script>
+
+  </body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_browsingData_indexedDB.html b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_indexedDB.html
new file mode 100644
index 0000000000..f7d36633db
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_indexedDB.html
@@ -0,0 +1,161 @@
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test browsingData.remove indexedDB</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function testIndexedDB() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["privacy.userContext.enabled", true]],
+  });
+
+  async function background() {
+    const PAGE =
+      "/tests/toolkit/components/extensions/test/mochitest/file_indexedDB.html";
+
+    let tabs = [];
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg == "cleanup") {
+        await Promise.all(tabs.map(tabId => browser.tabs.remove(tabId)));
+        browser.test.sendMessage("done");
+        return;
+      }
+
+      await browser.browsingData.remove(msg, { indexedDB: true });
+      browser.test.sendMessage("indexedDBRemoved");
+    });
+
+    // Create two tabs.
+    let tab = await browser.tabs.create({ url: `http://mochi.test:8888${PAGE}` });
+    tabs.push(tab.id);
+
+    tab = await browser.tabs.create({ url: `http://example.com${PAGE}` });
+    tabs.push(tab.id);
+
+    // Create tab with cookieStoreId "firefox-container-1"
+    tab = await browser.tabs.create({ url: `http://example.net${PAGE}`, cookieStoreId: 'firefox-container-1' });
+    tabs.push(tab.id);
+  }
+
+  function contentScript() {
+    // eslint-disable-next-line mozilla/balanced-listeners
+    window.addEventListener(
+      "message",
+      msg => {
+        browser.test.sendMessage("indexedDBCreated");
+      },
+      true
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background,
+    manifest: {
+      applications: { gecko: { id: "indexedDb@tests.mozilla.org" } },
+      permissions: ["browsingData", "tabs", "cookies"],
+      content_scripts: [
+        {
+          matches: [
+            "http://mochi.test/*/file_indexedDB.html",
+            "http://example.com/*/file_indexedDB.html",
+            "http://example.net/*/file_indexedDB.html",
+          ],
+          js: ["script.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+    files: {
+      "script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("indexedDBCreated");
+  await extension.awaitMessage("indexedDBCreated");
+  await extension.awaitMessage("indexedDBCreated");
+
+  function getUsage() {
+    return new Promise(resolve => {
+      let qms = SpecialPowers.Services.qms;
+      let cb = SpecialPowers.wrapCallback(request => resolve(request.result));
+      qms.getUsage(cb);
+    });
+  }
+
+  async function getOrigins() {
+    let origins = [];
+    let result = await getUsage();
+    for (let i = 0; i < result.length; ++i) {
+      if (result[i].usage === 0) {
+        continue;
+      }
+      if (
+        result[i].origin.startsWith("http://mochi.test") ||
+        result[i].origin.startsWith("http://example.com") ||
+        result[i].origin.startsWith("http://example.net")
+      ) {
+        origins.push(result[i].origin);
+      }
+    }
+    return origins.sort();
+  }
+
+  let origins = await getOrigins();
+  is(origins.length, 3, "IndexedDB databases have been populated.");
+
+  // Deleting private browsing mode data is silently ignored.
+  extension.sendMessage({ cookieStoreId: "firefox-private" });
+  await extension.awaitMessage("indexedDBRemoved");
+
+  origins = await getOrigins();
+  is(origins.length, 3, "All indexedDB remains after clearing firefox-private");
+
+  // Delete by hostname
+  extension.sendMessage({ hostnames: ["example.com"] });
+  await extension.awaitMessage("indexedDBRemoved");
+
+  origins = await getOrigins();
+  is(origins.length, 2, "IndexedDB data only for only two domains left");
+  ok(origins[0].startsWith("http://example.net"), "example.net not deleted");
+  ok(origins[1].startsWith("http://mochi.test"), "mochi.test not deleted");
+
+  // TODO: Bug 1643740
+  if (AppConstants.platform != "android") {
+    // Delete by cookieStoreId
+    extension.sendMessage({ cookieStoreId: "firefox-container-1" });
+    await extension.awaitMessage("indexedDBRemoved");
+
+    origins = await getOrigins();
+    is(origins.length, 1, "IndexedDB data only for only one domain");
+    ok(origins[0].startsWith("http://mochi.test"), "mochi.test not deleted");
+  }
+
+  // Delete all
+  extension.sendMessage({});
+  await extension.awaitMessage("indexedDBRemoved");
+
+  origins = await getOrigins();
+  is(origins.length, 0, "All IndexedDB data has been removed.");
+
+  await extension.sendMessage("cleanup");
+  await extension.awaitMessage("done");
+
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_browsingData_localStorage.html b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_localStorage.html
new file mode 100644
index 0000000000..cf6c420366
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_localStorage.html
@@ -0,0 +1,322 @@
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test browsingData.remove indexedDB</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function setup() {
+  // make sure userContext is enabled.
+  return SpecialPowers.pushPrefEnv({
+    set: [["privacy.userContext.enabled", true]],
+  });
+});
+
+add_task(async function testLocalStorage() {
+  async function background() {
+    function waitForTabs() {
+      return new Promise(resolve => {
+        let tabs = {};
+
+        let listener = async (msg, { tab }) => {
+          if (msg !== "content-script-ready") {
+            return;
+          }
+
+          tabs[tab.url] = tab;
+          if (Object.keys(tabs).length == 3) {
+            browser.runtime.onMessage.removeListener(listener);
+            resolve(tabs);
+          }
+        };
+        browser.runtime.onMessage.addListener(listener);
+      });
+    }
+
+    function sendMessageToTabs(tabs, message) {
+      return Promise.all(
+        Object.values(tabs).map(tab => {
+          return browser.tabs.sendMessage(tab.id, message);
+        })
+      );
+    }
+
+    let tabs = await waitForTabs();
+
+    browser.test.assertRejects(
+      browser.browsingData.removeLocalStorage({ since: Date.now() }),
+      "Firefox does not support clearing localStorage with 'since'.",
+      "Expected error received when using unimplemented parameter 'since'."
+    );
+
+    await sendMessageToTabs(tabs, "resetLocalStorage");
+    await browser.browsingData.removeLocalStorage({
+      hostnames: ["example.com"],
+    });
+    await browser.tabs.sendMessage(tabs["http://example.com/"].id, "checkLocalStorageCleared");
+    await browser.tabs.sendMessage(tabs["http://example.net/"].id, "checkLocalStorageSet");
+
+    if (
+      SpecialPowers.Services.domStorageManager.nextGenLocalStorageEnabled ===
+      false
+    ) {
+      // This assertion fails when localStorage is using the legacy
+      // implementation (See Bug 1595431).
+      browser.test.log("Skipped assertion on nextGenLocalStorageEnabled=false");
+    } else {
+      await browser.tabs.sendMessage(tabs["http://test1.example.com/"].id, "checkLocalStorageSet");
+    }
+
+    await sendMessageToTabs(tabs, "resetLocalStorage");
+    await sendMessageToTabs(tabs, "checkLocalStorageSet");
+    await browser.browsingData.removeLocalStorage({});
+    await sendMessageToTabs(tabs, "checkLocalStorageCleared");
+
+    await sendMessageToTabs(tabs, "resetLocalStorage");
+    await sendMessageToTabs(tabs, "checkLocalStorageSet");
+    await browser.browsingData.remove({}, { localStorage: true });
+    await sendMessageToTabs(tabs, "checkLocalStorageCleared");
+
+    // Can only delete cookieStoreId with LSNG enabled.
+    if (SpecialPowers.Services.domStorageManager.nextGenLocalStorageEnabled) {
+      await sendMessageToTabs(tabs, "resetLocalStorage");
+      await sendMessageToTabs(tabs, "checkLocalStorageSet");
+      await browser.browsingData.removeLocalStorage({
+        cookieStoreId: "firefox-container-1",
+      });
+      await browser.tabs.sendMessage(tabs["http://example.com/"].id, "checkLocalStorageSet");
+      await browser.tabs.sendMessage(tabs["http://example.net/"].id, "checkLocalStorageSet");
+
+      // TODO: containers support is lacking on GeckoView (Bug 1643740)
+      if (!navigator.userAgent.includes("Android")) {
+        await browser.tabs.sendMessage(tabs["http://test1.example.com/"].id, "checkLocalStorageCleared");
+      }
+
+      await sendMessageToTabs(tabs, "resetLocalStorage");
+      await sendMessageToTabs(tabs, "checkLocalStorageSet");
+      // Hostname doesn't match, so nothing cleared.
+      await browser.browsingData.removeLocalStorage({
+        cookieStoreId: "firefox-container-1",
+        hostnames: ["example.net"],
+      });
+      await sendMessageToTabs(tabs, "checkLocalStorageSet");
+
+      await sendMessageToTabs(tabs, "resetLocalStorage");
+      await sendMessageToTabs(tabs, "checkLocalStorageSet");
+      // Deleting private browsing mode data is silently ignored.
+      await browser.browsingData.removeLocalStorage({
+        cookieStoreId: "firefox-private",
+      });
+      await sendMessageToTabs(tabs, "checkLocalStorageSet");
+    } else {
+      await browser.test.assertRejects(
+        browser.browsingData.removeLocalStorage({
+          cookieStoreId: "firefox-container-1",
+        }),
+        "removeLocalStorage with cookieStoreId requires LSNG"
+      );
+    }
+
+    // Cleanup (checkLocalStorageCleared creates empty LS databases).
+    await browser.browsingData.removeLocalStorage({});
+
+    browser.test.notifyPass("done");
+  }
+
+  function contentScript() {
+    browser.runtime.onMessage.addListener(msg => {
+      if (msg === "resetLocalStorage") {
+        localStorage.clear();
+        localStorage.setItem("test", "test");
+      } else if (msg === "checkLocalStorageSet") {
+        browser.test.assertEq(
+          "test",
+          localStorage.getItem("test"),
+          `checkLocalStorageSet: ${location.href}`
+        );
+      } else if (msg === "checkLocalStorageCleared") {
+        browser.test.assertEq(
+          null,
+          localStorage.getItem("test"),
+          `checkLocalStorageCleared: ${location.href}`
+        );
+      }
+    });
+    browser.runtime.sendMessage("content-script-ready");
+  }
+
+  // This extension is responsible for opening tabs with a specified
+  // cookieStoreId, we use a separate extension to make sure that browsingData
+  // works without the cookies permission.
+  let openTabsExtension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      name: "Open tabs",
+      applications: { gecko: { id: "open-tabs@tests.mozilla.org" }, },
+      permissions: ["cookies"],
+    },
+    async background() {
+      const TABS = [
+        { url: "http://example.com" },
+        { url: "http://example.net" },
+        {
+          url: "http://test1.example.com",
+          cookieStoreId: 'firefox-container-1',
+        },
+      ];
+
+      function awaitLoad(tabId) {
+        return new Promise(resolve => {
+          browser.tabs.onUpdated.addListener(function listener(tabId_, changed, tab) {
+            if (tabId == tabId_ && changed.status == "complete") {
+              browser.tabs.onUpdated.removeListener(listener);
+              resolve();
+            }
+          });
+        });
+      }
+
+      let tabs = [];
+      let loaded = [];
+      for (let options of TABS) {
+        let tab = await browser.tabs.create(options);
+        loaded.push(awaitLoad(tab.id));
+        tabs.push(tab);
+      }
+
+      await Promise.all(loaded);
+
+      browser.test.onMessage.addListener(async msg => {
+        if (msg === "cleanup") {
+          const tabIds = tabs.map(tab => tab.id);
+          let removedTabs = 0;
+          browser.tabs.onRemoved.addListener(tabId => {
+            browser.test.log(`Removing tab ${tabId}.`);
+            if (tabIds.includes(tabId)) {
+              removedTabs++;
+              if (removedTabs == tabIds.length) {
+                browser.test.sendMessage("done");
+              }
+            }
+          });
+          await browser.tabs.remove(tabIds);
+        }
+      });
+    }
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background,
+    manifest: {
+      name: "Test Extension",
+      applications: { gecko: { id: "localStorage@tests.mozilla.org" } },
+      permissions: ["browsingData", "tabs"],
+      content_scripts: [
+        {
+          matches: [
+            "http://example.com/",
+            "http://example.net/",
+            "http://test1.example.com/",
+          ],
+          js: ["content-script.js"],
+          run_at: "document_end",
+        },
+      ],
+    },
+    files: {
+      "content-script.js": contentScript,
+    },
+  });
+
+  await openTabsExtension.startup();
+
+  await extension.startup();
+  await extension.awaitFinish("done");
+  await extension.unload();
+
+  await openTabsExtension.sendMessage("cleanup");
+  await openTabsExtension.awaitMessage("done");
+  await openTabsExtension.unload();
+});
+
+// Verify that browsingData.removeLocalStorage doesn't break on data stored
+// in about:newtab or file principals.
+add_task(async function test_browserData_on_aboutnewtab_and_file_data() {
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    async background() {
+      await browser.browsingData.removeLocalStorage({}).catch(err => {
+        browser.test.fail(`${err} :: ${err.stack}`);
+      });
+      browser.test.sendMessage("done");
+    },
+    manifest: {
+      applications: { gecko: { id: "indexed-db-file@test.mozilla.org" } },
+      permissions: ["browsingData"],
+    },
+  });
+
+  await new Promise(resolve => {
+    const chromeScript = SpecialPowers.loadChromeScript(async () => {
+      const { SiteDataTestUtils } = ChromeUtils.import(
+        "resource://testing-common/SiteDataTestUtils.jsm"
+      );
+      await SiteDataTestUtils.addToIndexedDB("about:newtab");
+      await SiteDataTestUtils.addToIndexedDB("file:///fake/file");
+      // eslint-disable-next-line no-undef
+      sendAsyncMessage("done");
+    });
+
+    chromeScript.addMessageListener("done", () => {
+      chromeScript.destroy();
+      resolve();
+    });
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_browserData_should_not_remove_extension_data() {
+  if (!SpecialPowers.getBoolPref("dom.storage.next_gen")) {
+    // When LSNG isn't enabled, the browsingData API does still clear
+    // all the extensions localStorage if called without a list of specific
+    // origins to clear.
+    info("Test skipped because LSNG is currently disabled");
+    return;
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    async background() {
+      window.localStorage.setItem("key", "value");
+      await browser.browsingData.removeLocalStorage({}).catch(err => {
+        browser.test.fail(`${err} :: ${err.stack}`);
+      });
+      browser.test.sendMessage("done", window.localStorage.getItem("key"));
+    },
+    manifest: {
+      applications: { gecko: { id: "extension-data@tests.mozilla.org" } },
+      permissions: ["browsingData"],
+    },
+  });
+
+  await extension.startup();
+  const lsValue = await extension.awaitMessage("done");
+  is(lsValue, "value", "Got the expected localStorage data");
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_browsingData_pluginData.html b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_pluginData.html
new file mode 100644
index 0000000000..ff75ca7b9f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_pluginData.html
@@ -0,0 +1,71 @@
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test browsingData.remove indexedDB</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+// NB: Since plugins are disabled, there is never any data to clear.
+// We are really testing that these operations are no-ops.
+
+add_task(async function testPluginData() {
+  async function background() {
+    const REFERENCE_DATE = Date.now();
+    const TEST_CASES = [
+      // Clear plugin data with no since value.
+      {},
+      // Clear pluginData with recent since value.
+      { since: REFERENCE_DATE - 20000 },
+      // Clear pluginData with old since value.
+      { since: REFERENCE_DATE - 1000000 },
+      // Clear pluginData for specific hosts.
+      { hostnames: ["bar.com", "baz.com"] },
+      // Clear pluginData for no hosts.
+      { hostnames: [] },
+    ];
+
+    for (let method of ["removePluginData", "remove"]) {
+      for (let options of TEST_CASES) {
+        browser.test.log(`Testing ${method} with ${JSON.stringify(options)}`);
+        if (method == "removePluginData") {
+          await browser.browsingData.removePluginData(options);
+        } else {
+          await browser.browsingData.remove(options, { pluginData: true });
+        }
+      }
+    }
+
+    browser.test.sendMessage("done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background,
+    manifest: {
+      applications: { gecko: { id: "remove-plugin@tests.mozilla.org" } },
+      permissions: ["tabs", "browsingData"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+
+  // This test has no assertions because it's only meant to check that we don't
+  // throw when calling removePluginData and remove with pluginData: true.
+  ok(true, "dummy check");
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_browsingData_serviceWorkers.html b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_serviceWorkers.html
new file mode 100644
index 0000000000..a97a62a0f4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_serviceWorkers.html
@@ -0,0 +1,141 @@
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test browsingData.remove indexedDB</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const { TestUtils } = SpecialPowers.Cu.import("resource://testing-common/TestUtils.jsm");
+
+add_task(async function setup() {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["dom.serviceWorkers.exemptFromPerDomainMax", true],
+      ["dom.serviceWorkers.enabled", true],
+      ["dom.serviceWorkers.testing.enabled", true],
+    ],
+  });
+});
+
+add_task(async function testServiceWorkers() {
+  async function background() {
+    const PAGE =
+      "/tests/toolkit/components/extensions/test/mochitest/file_serviceWorker.html";
+
+    browser.runtime.onMessage.addListener(msg => {
+      browser.test.sendMessage("serviceWorkerRegistered");
+    });
+
+    let tabs = [];
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg == "cleanup") {
+        await browser.tabs.remove(tabs.map(tab => tab.id));
+        browser.test.sendMessage("done");
+        return;
+      }
+
+      await browser.browsingData.remove(
+        { hostnames: msg.hostnames },
+        { serviceWorkers: true }
+      );
+      browser.test.sendMessage("serviceWorkersRemoved");
+    });
+
+    // Create two serviceWorkers.
+    let tab = await browser.tabs.create({ url: `http://mochi.test:8888${PAGE}` });
+    tabs.push(tab);
+
+    tab = await browser.tabs.create({ url: `http://example.com${PAGE}` });
+    tabs.push(tab);
+  }
+
+  function contentScript() {
+    // eslint-disable-next-line mozilla/balanced-listeners
+    window.addEventListener(
+      "message",
+      msg => {
+        if (msg.data == "serviceWorkerRegistered") {
+          browser.runtime.sendMessage("serviceWorkerRegistered");
+        }
+      },
+      true
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background,
+    manifest: {
+      applications: { gecko: { id: "service-workers@tests.mozilla.org" } },
+      permissions: ["browsingData", "tabs"],
+      content_scripts: [
+        {
+          matches: [
+            "http://mochi.test/*/file_serviceWorker.html",
+            "http://example.com/*/file_serviceWorker.html",
+          ],
+          js: ["script.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+    files: {
+      "script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("serviceWorkerRegistered");
+  await extension.awaitMessage("serviceWorkerRegistered");
+
+  // Even though we await the registrations by waiting for the messages,
+  // sometimes the serviceWorkers are still not registered at this point.
+  async function getRegistrations(count) {
+    await TestUtils.waitForCondition(
+      async () => (await SpecialPowers.registeredServiceWorkers()).length === count,
+      `Wait for ${count} service workers to be registered`
+    );
+    return SpecialPowers.registeredServiceWorkers();
+  }
+
+  let serviceWorkers = await getRegistrations(2);
+  is(serviceWorkers.length, 2, "ServiceWorkers have been registered.");
+
+  extension.sendMessage({ hostnames: ["example.com"] });
+  await extension.awaitMessage("serviceWorkersRemoved");
+
+  serviceWorkers = await getRegistrations(1);
+  is(
+    serviceWorkers.length,
+    1,
+    "ServiceWorkers for example.com have been removed."
+  );
+
+  let { scriptSpec } = serviceWorkers[0];
+  dump(`Service worker spec: ${scriptSpec}`);
+  ok(scriptSpec.startsWith("http://mochi.test:8888/"),
+     "ServiceWorkers for example.com have been removed.");
+
+  extension.sendMessage({});
+  await extension.awaitMessage("serviceWorkersRemoved");
+
+  serviceWorkers = await getRegistrations(0);
+  is(serviceWorkers.length, 0, "All ServiceWorkers have been removed.");
+
+  extension.sendMessage("cleanup");
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_browsingData_settings.html b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_settings.html
new file mode 100644
index 0000000000..3b1d5e1af9
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_browsingData_settings.html
@@ -0,0 +1,67 @@
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test browsingData.settings</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const SETTINGS_LIST = [
+  "cache",
+  "cookies",
+  "history",
+  "formData",
+  "downloads",
+].sort();
+
+add_task(async function testSettings() {
+  async function background() {
+    browser.browsingData.settings().then(settings => {
+      browser.test.sendMessage("settings", settings);
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background,
+    manifest: {
+      applications: { gecko: { id: "browsingData-settings@tests.mozilla.org" } },
+      permissions: ["browsingData"],
+    },
+  });
+
+  await extension.startup();
+  let settings = await extension.awaitMessage("settings");
+
+  // Verify that we get the keys back we expect.
+  isDeeply(
+    Object.entries(settings.dataToRemove)
+      .filter(([key, value]) => value)
+      .map(([key, value]) => key)
+      .sort(),
+    SETTINGS_LIST,
+    "dataToRemove contains expected properties."
+  );
+  isDeeply(
+    Object.entries(settings.dataRemovalPermitted)
+      .filter(([key, value]) => value)
+      .map(([key, value]) => key)
+      .sort(),
+    SETTINGS_LIST,
+    "dataToRemove contains expected properties."
+  );
+  is("since" in settings.options, true, "options contains |since|");
+
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_canvas_resistFingerprinting.html b/toolkit/components/extensions/test/mochitest/test_ext_canvas_resistFingerprinting.html
new file mode 100644
index 0000000000..7116d03235
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_canvas_resistFingerprinting.html
@@ -0,0 +1,64 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript" src="head_cookies.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function setup() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["privacy.resistFingerprinting", true]],
+  });
+});
+
+add_task(async function test_contentscript() {
+  function contentScript() {
+    let canvas = document.createElement("canvas");
+    canvas.width = canvas.height = "100";
+
+    let ctx = canvas.getContext("2d");
+    ctx.fillStyle = "green";
+    ctx.fillRect(0, 0, 100, 100);
+    let data = ctx.getImageData(0, 0, 100, 100);
+
+    browser.test.sendMessage("data-color", data.data[1]);
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          "matches": ["http://mochi.test/*/file_sample.html"],
+          "js": ["content_script.js"],
+          "run_at": "document_start",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  };
+  const url = "http://mochi.test:8888/chrome/toolkit/components/extensions/test/mochitest/file_sample.html";
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+  let win = window.open(url);
+  let color = await extension.awaitMessage("data-color");
+  is(color, 128, "Got correct pixel data for green");
+  win.close();
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_clipboard.html b/toolkit/components/extensions/test/mochitest/test_ext_clipboard.html
new file mode 100644
index 0000000000..77ac767391
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_clipboard.html
@@ -0,0 +1,210 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Clipboard permissions tests</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+
+<script>
+"use strict";
+
+/* globals doCopy, doPaste */
+function shared() {
+  let field = document.createElement("textarea");
+  document.body.appendChild(field);
+  field.contentEditable = true;
+
+  this.doCopy = function(txt) {
+    field.value = txt;
+    field.select();
+    return document.execCommand("copy");
+  };
+
+  this.doPaste = function() {
+    field.select();
+    return document.execCommand("paste") && field.value;
+  };
+}
+
+add_task(async function test_background_clipboard_permissions() {
+  function backgroundScript() {
+    browser.test.assertEq(false, doCopy("whatever"),
+                          "copy should be denied without permission");
+    browser.test.assertEq(false, doPaste(),
+                          "paste should be denied without permission");
+    browser.test.sendMessage("ready");
+  }
+  let extensionData = {
+    background: [shared, backgroundScript],
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await extension.awaitMessage("ready");
+
+  await extension.unload();
+});
+
+add_task(async function test_background_clipboard_copy() {
+  function backgroundScript() {
+    browser.test.onMessage.addListener(txt => {
+      browser.test.assertEq(true, doCopy(txt),
+        "copy should be allowed with permission");
+    });
+    browser.test.sendMessage("ready");
+  }
+  let extensionData = {
+    background: `(${shared})();(${backgroundScript})();`,
+    manifest: {
+      permissions: [
+        "clipboardWrite",
+      ],
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  const DUMMY_STR = "dummy string to copy";
+  await new Promise(resolve => {
+    SimpleTest.waitForClipboard(DUMMY_STR, () => {
+      extension.sendMessage(DUMMY_STR);
+    }, resolve, resolve);
+  });
+
+  await extension.unload();
+});
+
+add_task(async function test_contentscript_clipboard_permissions() {
+  function contentScript() {
+    browser.test.assertEq(false, doCopy("whatever"),
+                          "copy should be denied without permission");
+    browser.test.assertEq(false, doPaste(),
+                          "paste should be denied without permission");
+    browser.test.sendMessage("ready");
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["http://mochi.test/*/file_sample.html"],
+      }],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+  await extension.awaitMessage("ready");
+  win.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_contentscript_clipboard_copy() {
+  function contentScript() {
+    browser.test.onMessage.addListener(txt => {
+      browser.test.assertEq(true, doCopy(txt),
+                            "copy should be allowed with permission");
+    });
+    browser.test.sendMessage("ready");
+  }
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        js: ["shared.js", "contentscript.js"],
+        matches: ["http://mochi.test/*/file_sample.html"],
+      }],
+      permissions: [
+        "clipboardWrite",
+      ],
+    },
+    files: {
+      "shared.js": shared,
+      "contentscript.js": contentScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+  await extension.awaitMessage("ready");
+
+  const DUMMY_STR = "dummy string to copy in content script";
+  await new Promise(resolve => {
+    SimpleTest.waitForClipboard(DUMMY_STR, () => {
+      extension.sendMessage(DUMMY_STR);
+    }, resolve, resolve);
+  });
+
+  win.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_contentscript_clipboard_paste() {
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "clipboardRead",
+      ],
+      content_scripts: [{
+        matches: ["http://mochi.test/*/file_sample.html"],
+        js: ["shared.js", "content_script.js"],
+      }],
+    },
+    files: {
+      "shared.js": shared,
+      "content_script.js": () => {
+        browser.test.sendMessage("paste", doPaste());
+      },
+    },
+  });
+
+  const STRANGE = "A Strange Thing";
+  SpecialPowers.clipboardCopyString(STRANGE);
+
+  await extension.startup();
+  const win = window.open("file_sample.html");
+
+  const paste = await extension.awaitMessage("paste");
+  is(paste, STRANGE, "the correct string was pasted");
+
+  win.close();
+  await extension.unload();
+});
+
+add_task(async function test_background_clipboard_paste() {
+  function background() {
+    browser.test.sendMessage("paste", doPaste());
+  }
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["clipboardRead"],
+    },
+    background: [shared, background],
+  });
+
+  const STRANGE = "Stranger Things";
+  SpecialPowers.clipboardCopyString(STRANGE);
+
+  await extension.startup();
+
+  const paste = await extension.awaitMessage("paste");
+  is(paste, STRANGE, "the correct string was pasted");
+
+  await extension.unload();
+});
+
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_clipboard_image.html b/toolkit/components/extensions/test/mochitest/test_ext_clipboard_image.html
new file mode 100644
index 0000000000..b5d5f6764a
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_clipboard_image.html
@@ -0,0 +1,262 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Clipboard permissions tests</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+
+<script>
+"use strict";
+/**
+ * This cannot be a xpcshell test, because:
+ * - On Android, copyString of nsIClipboardHelper segfaults because
+ *   widget/android/nsClipboard.cpp calls java::Clipboard::SetText, which is
+ *   unavailable in xpcshell.
+ * - On Windows, the clipboard is unavailable to xpcshell.
+ */
+
+function resetClipboard() {
+  SpecialPowers.clipboardCopyString(
+    "This is the default value of the clipboard in the test.");
+}
+
+async function checkClipboardHasTestImage(imageType) {
+  async function backgroundScript(imageType) {
+    async function verifyImage(img) {
+      // Checks whether the image is a 1x1 red image.
+      browser.test.assertEq(1, img.naturalWidth, "image width should match");
+      browser.test.assertEq(1, img.naturalHeight, "image height should match");
+
+      let canvas = document.createElement("canvas");
+      canvas.width = 1;
+      canvas.height = 1;
+      let ctx = canvas.getContext("2d");
+      ctx.drawImage(img, 0, 0); // Draw without scaling.
+      let [r, g, b, a] = ctx.getImageData(0, 0, 1, 1).data;
+      let expectedColor;
+      if (imageType === "png") {
+        expectedColor = [255, 0, 0];
+      } else if (imageType === "jpeg") {
+        expectedColor = [254, 0, 0];
+      }
+      let {os} = await browser.runtime.getPlatformInfo();
+      if (os === "mac") {
+        // Due to https://bugzil.la/1396587, the pasted image differs from the
+        // original/expected image.
+        // Once that bug is fixed, this whole macOS-only branch can be removed.
+        if (imageType === "png") {
+          expectedColor = [255, 38, 0];
+        } else if (imageType === "jpeg") {
+          expectedColor = [255, 38, 0];
+        }
+      }
+      browser.test.assertEq(expectedColor[0], r, "pixel should be red");
+      browser.test.assertEq(expectedColor[1], g, "pixel should not contain green");
+      browser.test.assertEq(expectedColor[2], b, "pixel should not contain blue");
+      browser.test.assertEq(255, a, "pixel should be opaque");
+    }
+
+    let editable = document.body;
+    editable.contentEditable = true;
+    let file;
+    await new Promise(resolve => {
+      document.addEventListener("paste", function(event) {
+        browser.test.assertEq(1, event.clipboardData.types.length, "expected one type");
+        browser.test.assertEq("Files", event.clipboardData.types[0], "expected type");
+        browser.test.assertEq(1, event.clipboardData.files.length, "expected one file");
+
+        // After returning from the paste event, event.clipboardData is cleaned, so we
+        // have to store the file in a separate variable.
+        file = event.clipboardData.files[0];
+        resolve();
+      }, {once: true});
+
+      document.execCommand("paste"); // requires clipboardWrite permission.
+    });
+
+    // When image data is copied, its first frame is decoded and exported to the
+    // clipboard. The pasted result is always an unanimated PNG file, regardless
+    // of the input.
+    browser.test.assertEq("image/png", file.type, "expected file.type");
+
+    // event.files[0] should be an accurate representation of the input image.
+    {
+      let img = new Image();
+      await new Promise((resolve, reject) => {
+        img.onload = resolve;
+        img.onerror = () => reject(new Error(`Failed to load image ${img.src} of size ${file.size}`));
+        img.src = URL.createObjectURL(file);
+      });
+
+      await verifyImage(img);
+    }
+
+    // This confirms that an image was put on the clipboard.
+    // In contrast, when document.execCommand('copy') + clipboardData.setData
+    // is used, then the 'paste' event will also have the image data (as tested
+    // above), but the contentEditable area will be empty.
+    {
+      let imgs = editable.querySelectorAll("img");
+      browser.test.assertEq(1, imgs.length, "should have pasted one image");
+      await verifyImage(imgs[0]);
+    }
+    browser.test.sendMessage("tested image on clipboard");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})("${imageType}");`,
+    manifest: {
+      permissions: ["clipboardRead"],
+    },
+  });
+  await extension.startup();
+  await extension.awaitMessage("tested image on clipboard");
+  await extension.unload();
+}
+
+add_task(async function test_without_clipboard_permission() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.assertEq(undefined, browser.clipboard,
+                            "clipboard API requires the clipboardWrite permission.");
+      browser.test.notifyPass();
+    },
+    manifest: {
+      permissions: ["clipboardRead"],
+    },
+  });
+  await extension.startup();
+  await extension.awaitFinish();
+  await extension.unload();
+});
+
+add_task(async function test_copy_png() {
+  if (AppConstants.platform === "android") {
+    return; // Android does not support images on the clipboard.
+  }
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      // A 1x1 red PNG image.
+      let b64data = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAABlBMVEX/AAD///9BHTQRAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAACklEQVQImWNgAAAAAgAB9HFkpgAAAABJRU5ErkJggg==";
+      let imageData = Uint8Array.from(atob(b64data), c => c.charCodeAt(0)).buffer;
+      await browser.clipboard.setImageData(imageData, "png");
+      browser.test.sendMessage("Called setImageData with PNG");
+    },
+    manifest: {
+      permissions: ["clipboardWrite"],
+    },
+  });
+
+  resetClipboard();
+
+  await extension.startup();
+  await extension.awaitMessage("Called setImageData with PNG");
+  await extension.unload();
+
+  await checkClipboardHasTestImage("png");
+});
+
+add_task(async function test_copy_jpeg() {
+  if (AppConstants.platform === "android") {
+    return; // Android does not support images on the clipboard.
+  }
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      // A 1x1 red JPEG image, created using: convert xc:red red.jpg.
+      // JPEG is lossy, and the red pixel value is actually #FE0000 instead of
+      // #FF0000 (also seen using: convert red.jpg text:-).
+      let b64data = "/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAMCAgICAgMCAgIDAwMDBAYEBAQEBAgGBgUGCQgKCgkICQkKDA8MCgsOCwkJDRENDg8QEBEQCgwSExIQEw8QEBD/2wBDAQMDAwQDBAgEBAgQCwkLEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBD/wAARCAABAAEDAREAAhEBAxEB/8QAFAABAAAAAAAAAAAAAAAAAAAACP/EABQQAQAAAAAAAAAAAAAAAAAAAAD/xAAVAQEBAAAAAAAAAAAAAAAAAAAHCf/EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAMAwEAAhEDEQA/ADoDFU3/2Q==";
+      let imageData = Uint8Array.from(atob(b64data), c => c.charCodeAt(0)).buffer;
+      await browser.clipboard.setImageData(imageData, "jpeg");
+      browser.test.sendMessage("Called setImageData with JPEG");
+    },
+    manifest: {
+      permissions: ["clipboardWrite"],
+    },
+  });
+
+  resetClipboard();
+
+  await extension.startup();
+  await extension.awaitMessage("Called setImageData with JPEG");
+  await extension.unload();
+
+  await checkClipboardHasTestImage("jpeg");
+});
+
+add_task(async function test_copy_invalid_image() {
+  if (AppConstants.platform === "android") {
+    // Android does not support images on the clipboard.
+    return;
+  }
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      // This is a PNG image.
+      let b64data = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAABlBMVEX/AAD///9BHTQRAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAACklEQVQImWNgAAAAAgAB9HFkpgAAAABJRU5ErkJggg==";
+      let pngImageData = Uint8Array.from(atob(b64data), c => c.charCodeAt(0)).buffer;
+      await browser.test.assertRejects(
+        browser.clipboard.setImageData(pngImageData, "jpeg"),
+        "Data is not a valid jpeg image",
+        "Image data that is not valid for the given type should be rejected.");
+      browser.test.sendMessage("finished invalid image");
+    },
+    manifest: {
+      permissions: ["clipboardWrite"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("finished invalid image");
+  await extension.unload();
+});
+
+add_task(async function test_copy_invalid_image_type() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      // setImageData expects "png" or "jpeg", but we pass "image/png" here.
+      browser.test.assertThrows(
+        () => { browser.clipboard.setImageData(new ArrayBuffer(0), "image/png"); },
+        "Type error for parameter imageType (Invalid enumeration value \"image/png\") for clipboard.setImageData.",
+        "An invalid type for setImageData should be rejected.");
+      browser.test.sendMessage("finished invalid type");
+    },
+    manifest: {
+      permissions: ["clipboardWrite"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("finished invalid type");
+  await extension.unload();
+});
+
+if (AppConstants.platform === "android") {
+  add_task(async function test_setImageData_unsupported_on_android() {
+    let extension = ExtensionTestUtils.loadExtension({
+      async background() {
+        // Android does not support images on the clipboard,
+        // so it should not try to decode an image but fail immediately.
+        await browser.test.assertRejects(
+          browser.clipboard.setImageData(new ArrayBuffer(0), "png"),
+          "Writing images to the clipboard is not supported on Android",
+          "Should get an error when setImageData is called on Android.");
+        browser.test.sendMessage("finished unsupported setImageData");
+      },
+      manifest: {
+        permissions: ["clipboardWrite"],
+      },
+    });
+
+    await extension.startup();
+    await extension.awaitMessage("finished unsupported setImageData");
+    await extension.unload();
+  });
+}
+
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_about_blank.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_about_blank.html
new file mode 100644
index 0000000000..04946ceeaf
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_about_blank.html
@@ -0,0 +1,116 @@
+<!doctype html>
+<html>
+<head>
+  <title>Test content script match_about_blank option</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_contentscript_about_blank() {
+  const manifest = {
+    content_scripts: [
+      {
+        match_about_blank: true,
+        matches: ["http://mochi.test/*/file_with_about_blank.html", "http://example.com/*"],
+        all_frames: true,
+        css: ["all.css"],
+        js: ["all.js"],
+      }, {
+        matches: ["http://mochi.test/*/file_with_about_blank.html"],
+        css: ["mochi_without.css"],
+        js: ["mochi_without.js"],
+        all_frames: true,
+      }, {
+        match_about_blank: true,
+        matches: ["http://mochi.test/*/file_with_about_blank.html"],
+        css: ["mochi_with.css"],
+        js: ["mochi_with.js"],
+        all_frames: true,
+      },
+    ],
+  };
+
+  const files = {
+    "all.js": function() {
+      browser.runtime.sendMessage("all");
+    },
+    "all.css": `
+      body { color: red; }
+    `,
+    "mochi_without.js": function() {
+      browser.runtime.sendMessage("mochi_without");
+    },
+    "mochi_without.css": `
+      body { background: yellow; }
+    `,
+    "mochi_with.js": function() {
+      browser.runtime.sendMessage("mochi_with");
+    },
+    "mochi_with.css": `
+      body { text-align: right; }
+    `,
+  };
+
+  function background() {
+    browser.runtime.onMessage.addListener((script, {url}) => {
+      const kind = url.startsWith("about:") ? url : "top";
+      browser.test.sendMessage("script", [script, kind, url]);
+      browser.test.sendMessage(`${script}:${kind}`);
+    });
+  }
+
+  const PATH = "tests/toolkit/components/extensions/test/mochitest/file_with_about_blank.html";
+  const extension = ExtensionTestUtils.loadExtension({manifest, files, background});
+  await extension.startup();
+
+  let count = 0;
+  extension.onMessage("script", script => {
+    info(`script ran: ${script}`);
+    count++;
+  });
+
+  let win = window.open("http://example.com/" + PATH);
+  await Promise.all([
+    extension.awaitMessage("all:top"),
+    extension.awaitMessage("all:about:blank"),
+    extension.awaitMessage("all:about:srcdoc"),
+  ]);
+  is(count, 3, "exactly 3 scripts ran");
+  win.close();
+
+  win = window.open("http://mochi.test:8888/" + PATH);
+  await Promise.all([
+    extension.awaitMessage("all:top"),
+    extension.awaitMessage("all:about:blank"),
+    extension.awaitMessage("all:about:srcdoc"),
+    extension.awaitMessage("mochi_without:top"),
+    extension.awaitMessage("mochi_with:top"),
+    extension.awaitMessage("mochi_with:about:blank"),
+    extension.awaitMessage("mochi_with:about:srcdoc"),
+  ]);
+
+  let style = win.getComputedStyle(win.document.body);
+  is(style.color, "rgb(255, 0, 0)", "top window text color is red");
+  is(style.backgroundColor, "rgb(255, 255, 0)", "top window background is yellow");
+  is(style.textAlign, "right", "top window text is right-aligned");
+
+  let a_b = win.document.getElementById("a_b");
+  style = a_b.contentWindow.getComputedStyle(a_b.contentDocument.body);
+  is(style.color, "rgb(255, 0, 0)", "about:blank iframe text color is red");
+  is(style.backgroundColor, "rgba(0, 0, 0, 0)", "about:blank iframe background is transparent");
+  is(style.textAlign, "right", "about:blank text is right-aligned");
+
+  is(count, 10, "exactly 7 more scripts ran");
+  win.close();
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_activeTab.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_activeTab.html
new file mode 100644
index 0000000000..306f093fe1
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_activeTab.html
@@ -0,0 +1,371 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+// Create a test extension with the provided function as the background
+// script.  The background script will have a few helpful functions
+// available.
+/* global awaitLoad, gatherFrameSources */
+function makeExtension(background) {
+  // Wait for a webNavigation.onCompleted event where the details for the
+  // loaded page match the attributes of `filter`.
+  function awaitLoad(filter) {
+    return new Promise(resolve => {
+      const listener = details => {
+        if (Object.keys(filter).every(key => details[key] === filter[key])) {
+          browser.webNavigation.onCompleted.removeListener(listener);
+          resolve();
+        }
+      };
+      browser.webNavigation.onCompleted.addListener(listener);
+    });
+  }
+
+  // Return a string with a (sorted) list of the source of all frames
+  // in the given tab into which this extension can inject scripts
+  // (ie all frames for which it has the activeTab permission).
+  // Source is the hostname for frames in http sources, or the full
+  // location href in other documents (eg about: pages)
+  async function gatherFrameSources(tabid) {
+    let result = await browser.tabs.executeScript(tabid, {
+      allFrames: true,
+      matchAboutBlank: true,
+      code: "window.location.hostname || window.location.href;",
+    });
+    return String(result.sort());
+  }
+
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["activeTab", "webNavigation"],
+    },
+    background: `${awaitLoad}\n${gatherFrameSources}\n${ExtensionTestCommon.serializeScript(background)}`,
+  });
+}
+
+// Test that executeScript() fails without the activeTab permission
+// (or any specific origin permissions).
+add_task(async function test_no_activeTab() {
+  let extension = makeExtension(async function background() {
+    const URL = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab.html";
+
+    let [tab] = await Promise.all([
+      browser.tabs.create({url: URL}),
+      awaitLoad({frameId: 0}),
+    ]);
+
+    try {
+      await gatherFrameSources(tab.id);
+      browser.test.fail("executeScript() should fail without activeTab permission");
+    } catch (err) {
+      browser.test.assertTrue(/^Missing host permission/.test(err.message),
+                              "executeScript() without activeTab permission failed");
+    }
+
+    await browser.tabs.remove(tab.id);
+
+    browser.test.notifyPass("no-active-tab");
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("no-active-tab");
+  await extension.unload();
+});
+
+// Test that dynamically created iframes do not get the activeTab permission
+add_task(async function test_dynamic_frames() {
+  let extension = makeExtension(async function background() {
+    const BASE_HOST = "www.example.com";
+
+    let [tab] = await Promise.all([
+      browser.tabs.create({url: `http://${BASE_HOST}/`}),
+      awaitLoad({frameId: 0}),
+    ]);
+
+    function inject() {
+      let nframes = 4;
+      function frameLoaded() {
+        nframes--;
+        if (nframes == 0) {
+          browser.runtime.sendMessage("frames-loaded");
+        }
+      }
+
+      let frame = document.createElement("iframe");
+      frame.addEventListener("load", frameLoaded, {once: true});
+      document.body.appendChild(frame);
+
+      let div = document.createElement("div");
+      div.innerHTML = "<iframe src='http://test1.example.com/'></iframe>";
+      let framelist = div.getElementsByTagName("iframe");
+      browser.test.assertEq(1, framelist.length, "Found 1 frame inside div");
+      framelist[0].addEventListener("load", frameLoaded, {once: true});
+      document.body.appendChild(div);
+
+      let div2 = document.createElement("div");
+      div2.innerHTML = "<iframe srcdoc=\"<iframe src='http://test2.example.com/'&gt;</iframe&gt;\"></iframe>";
+      framelist = div2.getElementsByTagName("iframe");
+      browser.test.assertEq(1, framelist.length, "Found 1 frame inside div");
+      framelist[0].addEventListener("load", frameLoaded, {once: true});
+      document.body.appendChild(div2);
+
+      const URL = "http://www.example.com/tests/toolkit/components/extensions/test/mochitest/file_contentscript_iframe.html";
+
+      let xhr = new XMLHttpRequest();
+      xhr.open("GET", URL);
+      xhr.responseType = "document";
+      xhr.overrideMimeType("text/html");
+
+      xhr.addEventListener("load", () => {
+        if (xhr.readyState != 4) {
+          return;
+        }
+        if (xhr.status != 200) {
+          browser.runtime.sendMessage("error");
+        }
+
+        let frame = xhr.response.getElementById("frame");
+        browser.test.assertTrue(frame, "Found frame in response document");
+        frame.addEventListener("load", frameLoaded, {once: true});
+        document.body.appendChild(frame);
+      }, {once: true});
+      xhr.addEventListener("error", () => {
+        browser.runtime.sendMessage("error");
+      }, {once: true});
+      xhr.send();
+    }
+
+    browser.test.onMessage.addListener(async () => {
+      let loadedPromise = new Promise((resolve, reject) => {
+        let listener = msg => {
+          let unlisten = () => browser.runtime.onMessage.removeListener(listener);
+          if (msg == "frames-loaded") {
+            unlisten();
+            resolve();
+          } else if (msg == "error") {
+            unlisten();
+            reject();
+          }
+        };
+        browser.runtime.onMessage.addListener(listener);
+      });
+
+      await browser.tabs.executeScript(tab.id, {
+        code: `(${inject})();`,
+      });
+
+      await loadedPromise;
+
+      let result = await gatherFrameSources(tab.id);
+      browser.test.assertEq(String([BASE_HOST]), result,
+                            "Script is not injected into dynamically created frames");
+
+      await browser.tabs.remove(tab.id);
+
+      browser.test.notifyPass("dynamic-frames");
+    });
+
+    browser.test.sendMessage("ready", tab.id);
+  });
+
+  await extension.startup();
+
+  let tabId = await extension.awaitMessage("ready");
+  extension.grantActiveTab(tabId);
+
+  extension.sendMessage("go");
+  await extension.awaitFinish("dynamic-frames");
+
+  await extension.unload();
+});
+
+// Test that an iframe created from an <iframe srcdoc> gets the
+// activeTab permission.
+add_task(async function test_srcdoc() {
+  let extension = makeExtension(async function background() {
+    const URL = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab2.html";
+    const OUTER_SOURCE = "about:srcdoc";
+    const PAGE_SOURCE = "mochi.test";
+    const FRAME_SOURCE = "test1.example.com";
+
+    let [tab] = await Promise.all([
+      browser.tabs.create({url: URL}),
+      awaitLoad({frameId: 0}),
+    ]);
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg == "go") {
+        let result = await gatherFrameSources(tab.id);
+        browser.test.assertEq(String([OUTER_SOURCE, PAGE_SOURCE, FRAME_SOURCE]),
+                              result,
+                              "Script is injected into frame created from <iframe srcdoc>");
+
+        await browser.tabs.remove(tab.id);
+
+        browser.test.notifyPass("srcdoc");
+      }
+    });
+
+    browser.test.sendMessage("ready", tab.id);
+  });
+
+  await extension.startup();
+
+  let tabId = await extension.awaitMessage("ready");
+  extension.grantActiveTab(tabId);
+
+  extension.sendMessage("go");
+  await extension.awaitFinish("srcdoc");
+
+  await extension.unload();
+});
+
+// Test that navigating frames by setting the src attribute from the
+// parent page revokes the activeTab permission.
+add_task(async function test_navigate_by_src() {
+  let extension = makeExtension(async function background() {
+    const URL = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab.html";
+    const PAGE_SOURCE = "mochi.test";
+    const EMPTY_SOURCE = "about:blank";
+    const FRAME_SOURCE = "test1.example.com";
+
+    let [tab] = await Promise.all([
+      browser.tabs.create({url: URL}),
+      awaitLoad({frameId: 0}),
+    ]);
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg == "go") {
+        let result = await gatherFrameSources(tab.id);
+        browser.test.assertEq(String([EMPTY_SOURCE, PAGE_SOURCE, FRAME_SOURCE]),
+                              result,
+                              "In original page, script is injected into base page and original frames");
+
+        let loadedPromise = awaitLoad({tabId: tab.id});
+        await browser.tabs.executeScript(tab.id, {
+          code: "document.getElementById('emptyframe').src = 'http://test2.example.com/';",
+        });
+        await loadedPromise;
+
+        result = await gatherFrameSources(tab.id);
+        browser.test.assertEq(String([PAGE_SOURCE, FRAME_SOURCE]), result,
+                              "Script is not injected into initially empty frame after navigation");
+
+        loadedPromise = awaitLoad({tabId: tab.id});
+        await browser.tabs.executeScript(tab.id, {
+          code: "document.getElementById('regularframe').src = 'http://test2.example.com/';",
+        });
+        await loadedPromise;
+
+        result = await gatherFrameSources(tab.id);
+        browser.test.assertEq(String([PAGE_SOURCE]), result,
+                              "Script is not injected into regular frame after navigation");
+
+        await browser.tabs.remove(tab.id);
+        browser.test.notifyPass("test-scripts");
+      }
+    });
+
+    browser.test.sendMessage("ready", tab.id);
+  });
+
+  await extension.startup();
+
+  let tabId = await extension.awaitMessage("ready");
+  extension.grantActiveTab(tabId);
+
+  extension.sendMessage("go");
+  await extension.awaitFinish("test-scripts");
+
+  await extension.unload();
+});
+
+// Test that navigating frames by setting window.location from inside the
+// frame revokes the activeTab permission.
+add_task(async function test_navigate_by_window_location() {
+  let extension = makeExtension(async function background() {
+    const URL = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_contentscript_activeTab.html";
+    const PAGE_SOURCE = "mochi.test";
+    const EMPTY_SOURCE = "about:blank";
+    const FRAME_SOURCE = "test1.example.com";
+
+    let [tab] = await Promise.all([
+      browser.tabs.create({url: URL}),
+      awaitLoad({frameId: 0}),
+    ]);
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg == "go") {
+        let result = await gatherFrameSources(tab.id);
+        browser.test.assertEq(String([EMPTY_SOURCE, PAGE_SOURCE, FRAME_SOURCE]),
+                              result,
+                              "Script initially injected into all frames");
+
+        let nframes = 0;
+        let frames = await browser.webNavigation.getAllFrames({tabId: tab.id});
+        for (let frame of frames) {
+          if (frame.parentFrameId == -1) {
+            continue;
+          }
+
+          let loadPromise = awaitLoad({
+            tabId: tab.id,
+            frameId: frame.frameId,
+          });
+
+          await browser.tabs.executeScript(tab.id, {
+            frameId: frame.frameId,
+            matchAboutBlank: true,
+            code: "window.location.href = 'https://test2.example.com/';",
+          });
+          await loadPromise;
+
+          try {
+            result = await browser.tabs.executeScript(tab.id, {
+              frameId: frame.frameId,
+              matchAboutBlank: true,
+              code: "window.location.hostname;",
+            });
+
+            browser.test.fail("executeScript should have failed on navigated frame");
+          } catch (err) {
+            browser.test.assertEq("Frame not found, or missing host permission", err.message);
+          }
+
+          nframes++;
+        }
+        browser.test.assertEq(2, nframes, "Found 2 frames");
+
+        await browser.tabs.remove(tab.id);
+        browser.test.notifyPass("scripted-navigation");
+      }
+    });
+
+    browser.test.sendMessage("ready", tab.id);
+  });
+
+  await extension.startup();
+
+  let tabId = await extension.awaitMessage("ready");
+  extension.grantActiveTab(tabId);
+
+  extension.sendMessage("go");
+  await extension.awaitFinish("scripted-navigation");
+
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_cache.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_cache.html
new file mode 100644
index 0000000000..e8bb638d95
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_cache.html
@@ -0,0 +1,113 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script caching</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+// This file defines content scripts.
+/* eslint-env mozilla/frame-script */
+
+const BASE = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest";
+
+add_task(async function test_contentscript_cache() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [{
+        "matches": ["http://mochi.test/*/file_sample.html"],
+        "js": ["content_script.js"],
+        "run_at": "document_start",
+      }],
+
+      permissions: ["<all_urls>", "tabs"],
+    },
+
+    async background() {
+      // Force our extension instance to be initialized for the current content process.
+      await browser.tabs.insertCSS({code: ""});
+
+      browser.test.sendMessage("origin", location.origin);
+    },
+
+    files: {
+      "content_script.js": function() {
+        browser.test.sendMessage("content-script-loaded");
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let origin = await extension.awaitMessage("origin");
+  let scriptUrl = `${origin}/content_script.js`;
+
+  let {ExtensionManager} = SpecialPowers.Cu.import("resource://gre/modules/ExtensionChild.jsm", {});
+  let ext = ExtensionManager.extensions.get(extension.id);
+
+  ext.staticScripts.expiryTimeout = 3000;
+  is(ext.staticScripts.size, 0, "Should have no cached scripts");
+
+  let win = window.open(`${BASE}/file_sample.html`);
+  await extension.awaitMessage("content-script-loaded");
+
+  if (AppConstants.platform !== "android") {
+    is(ext.staticScripts.size, 1, "Should have one cached script");
+    ok(ext.staticScripts.has(scriptUrl), "Script cache should contain script URL");
+  }
+
+  let chromeScript, chromeScriptDone;
+  let {appinfo} = SpecialPowers.Services;
+  if (appinfo.processType === appinfo.PROCESS_TYPE_CONTENT) {
+    /* globals addMessageListener, assert */
+    chromeScript = SpecialPowers.loadChromeScript(() => {
+      addMessageListener("check-script-cache", extensionId => {
+        let {ExtensionManager} = ChromeUtils.import("resource://gre/modules/ExtensionChild.jsm", null);
+        let ext = ExtensionManager.extensions.get(extensionId);
+
+        if (ext && ext.staticScripts) {
+          assert.equal(ext.staticScripts.size, 0, "Should have no cached scripts in the parent process");
+        }
+
+        sendAsyncMessage("done");
+      });
+    });
+    chromeScript.sendAsyncMessage("check-script-cache", extension.id);
+    chromeScriptDone = chromeScript.promiseOneMessage("done");
+  }
+
+  SimpleTest.requestFlakyTimeout("Required to test expiry timeout");
+  await new Promise(resolve => setTimeout(resolve, 3000));
+  is(ext.staticScripts.size, 0, "Should have no cached scripts");
+
+  if (chromeScript) {
+    await chromeScriptDone;
+    chromeScript.destroy();
+  }
+
+  win.close();
+
+  win = window.open(`${BASE}/file_sample.html`);
+  await extension.awaitMessage("content-script-loaded");
+
+  is(ext.staticScripts.size, 1, "Should have one cached script");
+  ok(ext.staticScripts.has(scriptUrl));
+
+  SpecialPowers.Services.obs.notifyObservers(null, "memory-pressure", "heap-minimize");
+
+  is(ext.staticScripts.size, 0, "Should have no cached scripts after heap-minimize");
+
+  win.close();
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_canvas.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_canvas.html
new file mode 100644
index 0000000000..c4b6b5a256
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_canvas.html
@@ -0,0 +1,138 @@
+<!doctype html>
+<html>
+<head>
+  <title>Test content script access to canvas drawWindow()</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<script>
+"use strict";
+
+add_task(async function test_drawWindow() {
+  const permissions = [
+    "<all_urls>",
+  ];
+
+  const content_scripts = [{
+    matches: ["https://example.org/*"],
+    js: ["content_script.js"],
+  }];
+
+  const files = {
+    "content_script.js": () => {
+      const canvas = document.createElement("canvas");
+      const ctx = canvas.getContext("2d");
+      try {
+        ctx.drawWindow(window, 0, 0, 10, 10, "red");
+        const {data} = ctx.getImageData(0, 0, 10, 10);
+        browser.test.sendMessage("success", data.slice(0, 3).join());
+      } catch (e) {
+        browser.test.sendMessage("error", e.message);
+      }
+    },
+  };
+
+  const first = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "draw_window_first@tests.mozilla.org" } },
+      permissions,
+      content_scripts
+    },
+    files
+  });
+  const second = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "draw_window_second@tests.mozilla.org" } },
+      content_scripts
+    },
+    files
+  });
+
+  await first.startup();
+  await second.startup();
+
+  const win = window.open("https://example.org/tests/toolkit/components/extensions/test/mochitest/file_to_drawWindow.html");
+
+  const colour = await first.awaitMessage("success");
+  is(colour, "255,255,153", "drawWindow() call was successful: #ff9 == rgb(255,255,153)");
+
+  const error = await second.awaitMessage("error");
+  is(error, "ctx.drawWindow is not a function", "drawWindow() method not awailable without permission");
+
+  win.close();
+  await first.unload();
+  await second.unload();
+});
+
+add_task(async function test_tainted_canvas() {
+  const permissions = [
+    "<all_urls>",
+  ];
+
+  const content_scripts = [{
+    matches: ["https://example.org/*"],
+    js: ["content_script.js"],
+  }];
+
+  const files = {
+    "content_script.js": () => {
+      const canvas = document.createElement("canvas");
+      const ctx = canvas.getContext("2d");
+      const img = new Image();
+
+      img.onload = function() {
+        ctx.drawImage(img, 0, 0);
+        try {
+          const png = canvas.toDataURL();
+          const {data} = ctx.getImageData(0, 0, 10, 10);
+          browser.test.sendMessage("success", {png, colour: data.slice(0, 4).join()});
+        } catch (e) {
+          browser.test.log(`Exception: ${e.message}`);
+          browser.test.sendMessage("error", e.message);
+        }
+      };
+
+      // Cross-origin image from example.com.
+      img.src = "https://example.com/tests/toolkit/components/extensions/test/mochitest/file_image_good.png";
+    },
+  };
+
+  const first = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "draw_window_first@tests.mozilla.org" } },
+      permissions,
+      content_scripts
+    },
+    files
+  });
+  const second = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "draw_window_second@tests.mozilla.org" } },
+      content_scripts
+    },
+    files
+  });
+
+  await first.startup();
+  await second.startup();
+
+  const win = window.open("https://example.org/tests/toolkit/components/extensions/test/mochitest/file_to_drawWindow.html");
+
+  const {png, colour} = await first.awaitMessage("success");
+  ok(png.startsWith("data:image/png;base64,"), "toDataURL() call was successful.");
+  is(colour, "0,0,0,0", "getImageData() returned the correct colour (transparent).");
+
+  const error = await second.awaitMessage("error");
+  is(error, "The operation is insecure.", "toDataURL() throws without permission.");
+
+  win.close();
+  await first.unload();
+  await second.unload();
+});
+
+</script>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_devtools_metadata.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_devtools_metadata.html
new file mode 100644
index 0000000000..f2a2de0e05
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_devtools_metadata.html
@@ -0,0 +1,77 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for Sandbox metadata on WebExtensions ContentScripts</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_contentscript_devtools_sandbox_metadata() {
+  function contentScript() {
+    browser.runtime.sendMessage("contentScript.executed");
+  }
+
+  function background() {
+    browser.runtime.onMessage.addListener((msg) => {
+      if (msg == "contentScript.executed") {
+        browser.test.notifyPass("contentScript.executed");
+      }
+    });
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          "matches": ["http://mochi.test/*/file_sample.html"],
+          "js": ["content_script.js"],
+          "run_at": "document_idle",
+        },
+      ],
+    },
+
+    background,
+    files: {
+      "content_script.js": contentScript,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+
+  let innerWindowID = SpecialPowers.wrap(win).windowGlobalChild.innerWindowId;
+
+  await extension.awaitFinish("contentScript.executed");
+
+  const {ExtensionContent} = SpecialPowers.Cu.import(
+    "resource://gre/modules/ExtensionContent.jsm", {}
+  );
+
+  let res = ExtensionContent.getContentScriptGlobals(win);
+  is(res.length, 1, "Got the expected array of globals");
+  let metadata = SpecialPowers.Cu.getSandboxMetadata(res[0]) || {};
+
+  is(metadata.addonId, extension.id, "Got the expected addonId");
+  is(metadata["inner-window-id"], innerWindowID, "Got the expected inner-window-id");
+
+  await extension.unload();
+  info("extension unloaded");
+
+  res = ExtensionContent.getContentScriptGlobals(win);
+  is(res.length, 0, "No content scripts globals found once the extension is unloaded");
+
+  win.close();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_fission_frame.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_fission_frame.html
new file mode 100644
index 0000000000..702456a798
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_fission_frame.html
@@ -0,0 +1,100 @@
+<!doctype html>
+<head>
+  <title>Test content script in cross-origin frame</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+</head>
+<script>
+"use strict";
+
+add_task(async function test_content_script_cross_origin_frame() {
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [{
+        matches: ["http://example.net/*/file_sample.html"],
+        all_frames: true,
+        js: ["cs.js"],
+      }],
+      permissions: ["http://example.net/"],
+    },
+
+    background() {
+      browser.runtime.onConnect.addListener(port => {
+        port.onMessage.addListener(async num => {
+          let { tab, url, frameId } = port.sender;
+
+          browser.test.assertTrue(frameId > 0, "sender frameId is ok");
+          browser.test.assertTrue(url.endsWith("file_sample.html"), "url is ok");
+
+          let shared = await browser.tabs.executeScript(tab.id, {
+            allFrames: true,
+            code: `window.sharedVal`,
+          });
+          browser.test.assertEq(shared[0], 357, "CS runs in a shared Sandbox");
+
+          let code = "does.not.exist";
+          await browser.test.assertRejects(
+            browser.tabs.executeScript(tab.id, { allFrames: true, code }),
+            /does is not defined/,
+            "Got the expected rejection from tabs.executeScript"
+          );
+
+          code = "() => {}";
+          await browser.test.assertRejects(
+            browser.tabs.executeScript(tab.id, { allFrames: true, code }),
+            /Script .* result is non-structured-clonable data/,
+            "Got the expected rejection from tabs.executeScript"
+          );
+
+          let result = await browser.tabs.sendMessage(tab.id, num);
+          port.postMessage(result);
+          port.disconnect();
+        });
+      });
+    },
+
+    files: {
+      "cs.js"() {
+        let text = document.body.innerText;
+        browser.test.assertEq(text, "Sample text", "CS can access page DOM");
+
+        let manifest = browser.runtime.getManifest();
+        browser.test.assertEq(manifest.version, "1.0");
+        browser.test.assertEq(manifest.name, "Generated extension");
+
+        browser.runtime.onMessage.addListener(async num => {
+          browser.test.log("content script received tabs.sendMessage");
+          return num * 3;
+        })
+
+        let response;
+        window.sharedVal = 357;
+
+        let port = browser.runtime.connect();
+        port.onMessage.addListener(num => {
+          response = num;
+        });
+        port.onDisconnect.addListener(() => {
+          browser.test.assertEq(response, 21, "Got correct response");
+          browser.test.notifyPass();
+        });
+        port.postMessage(7);
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let base = "http://example.org/tests/toolkit/components/extensions/test";
+  let win = window.open(`${base}/mochitest/file_with_xorigin_frame.html`);
+
+  await extension.awaitFinish();
+  win.close();
+
+  await extension.unload();
+});
+
+</script>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_incognito.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_incognito.html
new file mode 100644
index 0000000000..63dd23b151
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_incognito.html
@@ -0,0 +1,105 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script private browsing ID</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ChromeTask.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+async function test_contentscript_incognito() {
+  await SpecialPowers.pushPrefEnv({set: [
+    ["extensions.allowPrivateBrowsingByDefault", false],
+  ]});
+
+  let extension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    manifest: {
+      content_scripts: [
+        {
+          "matches": ["http://mochi.test/*/file_sample.html"],
+          "js": ["content_script.js"],
+        },
+      ],
+    },
+
+    background() {
+      let windowId;
+
+      browser.test.onMessage.addListener(([msg, url]) => {
+        if (msg === "open-window") {
+          browser.windows.create({url, incognito: true}).then(window => {
+            windowId = window.id;
+          });
+        } else if (msg === "close-window") {
+          browser.windows.remove(windowId).then(() => {
+            browser.test.sendMessage("done");
+          });
+        }
+      });
+    },
+
+    files: {
+      "content_script.js": async () => {
+        const COOKIE = "foo=florgheralzps";
+        document.cookie = COOKIE;
+
+        let url = new URL("return_headers.sjs", location.href);
+
+        let responses = [
+          new Promise(resolve => {
+            let xhr = new XMLHttpRequest();
+            xhr.open("GET", url);
+            xhr.onload = () => resolve(JSON.parse(xhr.responseText));
+            xhr.send();
+          }),
+
+          fetch(url, {credentials: "include"}).then(body => body.json()),
+        ];
+
+        try {
+          for (let response of await Promise.all(responses)) {
+            browser.test.assertEq(COOKIE, response.cookie, "Got expected cookie header");
+          }
+          browser.test.notifyPass("cookies");
+        } catch (e) {
+          browser.test.fail(`Error: ${e}`);
+          browser.test.notifyFail("cookies");
+        }
+      },
+    },
+  });
+
+  await extension.startup();
+
+  extension.sendMessage(["open-window", SimpleTest.getTestFileURL("file_sample.html")]);
+
+  await extension.awaitFinish("cookies");
+
+  extension.sendMessage(["close-window"]);
+  await extension.awaitMessage("done");
+
+  await extension.unload();
+}
+
+add_task(async function() {
+  await test_contentscript_incognito();
+});
+
+add_task(async function() {
+  await SpecialPowers.pushPrefEnv({set: [
+    ["network.cookie.cookieBehavior", 3],
+  ]});
+  await test_contentscript_incognito();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_contentscript_permission.html b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_permission.html
new file mode 100644
index 0000000000..e6bc48800c
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_contentscript_permission.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_contentscript() {
+  function background() {
+    browser.test.onMessage.addListener(async url => {
+      let tab = await browser.tabs.create({url});
+
+      let executed = true;
+      try {
+        await browser.tabs.executeScript(tab.id, {code: "true;"});
+      } catch (e) {
+        executed = false;
+      }
+
+      await browser.tabs.remove([tab.id]);
+      browser.test.sendMessage("executed", executed);
+    });
+  }
+
+  let extensionData = {
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "contentscript@tests.mozilla.org" } },
+      permissions: ["<all_urls>"],
+    },
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  extension.sendMessage("https://example.com");
+  let result = await extension.awaitMessage("executed");
+  is(result, true, "Content script can be run in a page without mozAddonManager");
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.webapi.testing", true]],
+  });
+
+  extension.sendMessage("https://example.com");
+  result = await extension.awaitMessage("executed");
+  is(result, false, "Content script cannot be run in a page with mozAddonManager");
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_cookies.html b/toolkit/components/extensions/test/mochitest/test_ext_cookies.html
new file mode 100644
index 0000000000..c9dd05a41c
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_cookies.html
@@ -0,0 +1,366 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_cookies() {
+  await SpecialPowers.pushPrefEnv({set: [
+    ["extensions.allowPrivateBrowsingByDefault", false],
+  ]});
+
+  async function background() {
+    function assertExpected(expected, cookie) {
+      for (let key of Object.keys(cookie)) {
+        browser.test.assertTrue(key in expected, `found property ${key}`);
+        browser.test.assertEq(expected[key], cookie[key], `property value for ${key} is correct`);
+      }
+      browser.test.assertEq(Object.keys(expected).length, Object.keys(cookie).length, "all expected properties found");
+    }
+
+    async function getDocumentCookie(tabId) {
+      let results = await browser.tabs.executeScript(tabId, {
+        code: "document.cookie",
+      });
+      browser.test.assertEq(1, results.length, "executeScript returns one result");
+      return results[0];
+    }
+
+    async function testIpCookie(ipAddress, setHostOnly) {
+      const IP_TEST_HOST = ipAddress;
+      const IP_TEST_URL = `http://${IP_TEST_HOST}/`;
+      const IP_THE_FUTURE = Date.now() + 5 * 60;
+      const IP_STORE_ID = "firefox-default";
+
+      let expectedCookie = {
+        name: "name1",
+        value: "value1",
+        domain: IP_TEST_HOST,
+        hostOnly: true,
+        path: "/",
+        secure: false,
+        httpOnly: false,
+        sameSite: "no_restriction",
+        session: false,
+        expirationDate: IP_THE_FUTURE,
+        storeId: IP_STORE_ID,
+        firstPartyDomain: "",
+      };
+
+      await browser.browsingData.removeCookies({});
+      let ip_cookie = await browser.cookies.set({
+        url: IP_TEST_URL,
+        domain: setHostOnly ? ipAddress : undefined,
+        name: "name1",
+        value: "value1",
+        expirationDate: IP_THE_FUTURE,
+      });
+      assertExpected(expectedCookie, ip_cookie);
+
+      let ip_cookies = await browser.cookies.getAll({name: "name1"});
+      browser.test.assertEq(1, ip_cookies.length, "ip cookie can be added");
+      assertExpected(expectedCookie, ip_cookies[0]);
+
+      ip_cookies = await browser.cookies.getAll({domain: IP_TEST_HOST, name: "name1"});
+      browser.test.assertEq(1, ip_cookies.length, "can get ip cookie by host");
+      assertExpected(expectedCookie, ip_cookies[0]);
+
+      let ip_details = await browser.cookies.remove({url: IP_TEST_URL, name: "name1"});
+      assertExpected({url: IP_TEST_URL, name: "name1", storeId: IP_STORE_ID, firstPartyDomain: ""}, ip_details);
+
+      ip_cookies = await browser.cookies.getAll({name: "name1"});
+      browser.test.assertEq(0, ip_cookies.length, "ip cookie can be removed");
+    }
+
+    async function openPrivateWindowAndTab(TEST_URL) {
+      // Add some random suffix to make sure that we select the right tab.
+      const PRIVATE_TEST_URL = TEST_URL + "?random" + Math.random();
+
+      let tabReadyPromise = new Promise((resolve) => {
+        browser.webNavigation.onDOMContentLoaded.addListener(function listener({tabId}) {
+          browser.webNavigation.onDOMContentLoaded.removeListener(listener);
+          resolve(tabId);
+        }, {
+          url: [{
+            urlPrefix: PRIVATE_TEST_URL,
+          }],
+        });
+      });
+      // This tab is opened for two purposes:
+      // 1. To allow tests to run content scripts in the context of a tab,
+      //    for fetching the value of document.cookie.
+      // 2. TODO Bug 1309637 To work around cookies in incognito windows,
+      //    based on the analysis in comment 8.
+      let {id: windowId} = await browser.windows.create({
+        incognito: true,
+        url: PRIVATE_TEST_URL,
+      });
+      let tabId = await tabReadyPromise;
+      return {windowId, tabId};
+    }
+
+    function changePort(href, port) {
+      let url = new URL(href);
+      url.port = port;
+      return url.href;
+    }
+
+    await testIpCookie("[2a03:4000:6:310e:216:3eff:fe53:99b]", false);
+    await testIpCookie("[2a03:4000:6:310e:216:3eff:fe53:99b]", true);
+    await testIpCookie("192.168.1.1", false);
+    await testIpCookie("192.168.1.1", true);
+
+    const TEST_URL = "http://example.org/";
+    const TEST_SECURE_URL = "https://example.org/";
+    const THE_FUTURE = Date.now() + 5 * 60;
+    const TEST_PATH = "set_path";
+    const TEST_URL_WITH_PATH = TEST_URL + TEST_PATH;
+    const TEST_COOKIE_PATH = `/${TEST_PATH}`;
+    const STORE_ID = "firefox-default";
+    const PRIVATE_STORE_ID = "firefox-private";
+
+    let expected = {
+      name: "name1",
+      value: "value1",
+      domain: "example.org",
+      hostOnly: true,
+      path: "/",
+      secure: false,
+      httpOnly: false,
+      sameSite: "no_restriction",
+      session: false,
+      expirationDate: THE_FUTURE,
+      storeId: STORE_ID,
+      firstPartyDomain: "",
+    };
+
+    // Remove all cookies before starting the test.
+    await browser.browsingData.removeCookies({});
+
+    let cookie = await browser.cookies.set({url: TEST_URL, name: "name1", value: "value1", expirationDate: THE_FUTURE});
+    assertExpected(expected, cookie);
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1"});
+    assertExpected(expected, cookie);
+
+    let cookies = await browser.cookies.getAll({name: "name1"});
+    browser.test.assertEq(1, cookies.length, "one cookie found for matching name");
+    assertExpected(expected, cookies[0]);
+
+    cookies = await browser.cookies.getAll({domain: "example.org"});
+    browser.test.assertEq(1, cookies.length, "one cookie found for matching domain");
+    assertExpected(expected, cookies[0]);
+
+    cookies = await browser.cookies.getAll({domain: "example.net"});
+    browser.test.assertEq(0, cookies.length, "no cookies found for non-matching domain");
+
+    cookies = await browser.cookies.getAll({secure: false});
+    browser.test.assertEq(1, cookies.length, "one non-secure cookie found");
+    assertExpected(expected, cookies[0]);
+
+    cookies = await browser.cookies.getAll({secure: true});
+    browser.test.assertEq(0, cookies.length, "no secure cookies found");
+
+    cookies = await browser.cookies.getAll({storeId: STORE_ID});
+    browser.test.assertEq(1, cookies.length, "one cookie found for valid storeId");
+    assertExpected(expected, cookies[0]);
+
+    cookies = await browser.cookies.getAll({storeId: "invalid_id"});
+    browser.test.assertEq(0, cookies.length, "no cookies found for invalid storeId");
+
+    let details = await browser.cookies.remove({url: TEST_URL, name: "name1"});
+    assertExpected({url: TEST_URL, name: "name1", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1"});
+    browser.test.assertEq(null, cookie, "removed cookie not found");
+
+    // Ports in cookie URLs should be ignored. Every API call uses a different port number for better coverage.
+    cookie = await browser.cookies.set({url: changePort(TEST_URL, 1234), name: "name1", value: "value1", expirationDate: THE_FUTURE});
+    assertExpected(expected, cookie);
+
+    cookie = await browser.cookies.get({url: changePort(TEST_URL, 65535), name: "name1"});
+    assertExpected(expected, cookie);
+
+    cookies = await browser.cookies.getAll({url: TEST_URL});
+    browser.test.assertEq(cookies.length, 1, "Found cookie using getAll without port");
+    assertExpected(expected, cookies[0]);
+
+    cookies = await browser.cookies.getAll({url: changePort(TEST_URL, 1)});
+    browser.test.assertEq(cookies.length, 1, "Found cookie using getAll with port");
+    assertExpected(expected, cookies[0]);
+
+    // .remove should return the URL of the API call, so the port is included in the return value.
+    const TEST_URL_TO_REMOVE = changePort(TEST_URL, 1023);
+    details = await browser.cookies.remove({url: TEST_URL_TO_REMOVE, name: "name1"});
+    assertExpected({url: TEST_URL_TO_REMOVE, name: "name1", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1"});
+    browser.test.assertEq(null, cookie, "removed cookie not found");
+
+    let stores = await browser.cookies.getAllCookieStores();
+    browser.test.assertEq(1, stores.length, "expected number of stores returned");
+    browser.test.assertEq(STORE_ID, stores[0].id, "expected store id returned");
+    browser.test.assertEq(1, stores[0].tabIds.length, "one tabId returned for store");
+    browser.test.assertEq("number", typeof stores[0].tabIds[0], "tabId is a number");
+
+    // TODO bug 1372178: Opening private windows/tabs is not supported on Android
+    if (browser.windows) {
+      let {windowId} = await openPrivateWindowAndTab(TEST_URL);
+      let stores = await browser.cookies.getAllCookieStores();
+
+      browser.test.assertEq(2, stores.length, "expected number of stores returned");
+      browser.test.assertEq(STORE_ID, stores[0].id, "expected store id returned");
+      browser.test.assertEq(1, stores[0].tabIds.length, "one tab returned for store");
+      browser.test.assertEq(PRIVATE_STORE_ID, stores[1].id, "expected private store id returned");
+      browser.test.assertEq(1, stores[0].tabIds.length, "one tab returned for private store");
+
+      await browser.windows.remove(windowId);
+    }
+
+    cookie = await browser.cookies.set({url: TEST_URL, name: "name2", domain: ".example.org", expirationDate: THE_FUTURE});
+    browser.test.assertEq(false, cookie.hostOnly, "cookie is not a hostOnly cookie");
+
+    details = await browser.cookies.remove({url: TEST_URL, name: "name2"});
+    assertExpected({url: TEST_URL, name: "name2", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+    // Create a session cookie.
+    cookie = await browser.cookies.set({url: TEST_URL, name: "name1", value: "value1"});
+    browser.test.assertEq(true, cookie.session, "session cookie set");
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1"});
+    browser.test.assertEq(true, cookie.session, "got session cookie");
+
+    cookies = await browser.cookies.getAll({session: true});
+    browser.test.assertEq(1, cookies.length, "one session cookie found");
+    browser.test.assertEq(true, cookies[0].session, "found session cookie");
+
+    cookies = await browser.cookies.getAll({session: false});
+    browser.test.assertEq(0, cookies.length, "no non-session cookies found");
+
+    details = await browser.cookies.remove({url: TEST_URL, name: "name1"});
+    assertExpected({url: TEST_URL, name: "name1", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1"});
+    browser.test.assertEq(null, cookie, "removed cookie not found");
+
+    cookie = await browser.cookies.set({url: TEST_SECURE_URL, name: "name1", value: "value1", secure: true});
+    browser.test.assertEq(true, cookie.secure, "secure cookie set");
+
+    cookie = await browser.cookies.get({url: TEST_SECURE_URL, name: "name1"});
+    browser.test.assertEq(true, cookie.session, "got secure cookie");
+
+    cookies = await browser.cookies.getAll({secure: true});
+    browser.test.assertEq(1, cookies.length, "one secure cookie found");
+    browser.test.assertEq(true, cookies[0].secure, "found secure cookie");
+
+    cookies = await browser.cookies.getAll({secure: false});
+    browser.test.assertEq(0, cookies.length, "no non-secure cookies found");
+
+    details = await browser.cookies.remove({url: TEST_SECURE_URL, name: "name1"});
+    assertExpected({url: TEST_SECURE_URL, name: "name1", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+    cookie = await browser.cookies.get({url: TEST_SECURE_URL, name: "name1"});
+    browser.test.assertEq(null, cookie, "removed cookie not found");
+
+    cookie = await browser.cookies.set({url: TEST_URL_WITH_PATH, path: TEST_COOKIE_PATH, name: "name1", value: "value1", expirationDate: THE_FUTURE});
+    browser.test.assertEq(TEST_COOKIE_PATH, cookie.path, "created cookie with path");
+
+    cookie = await browser.cookies.get({url: TEST_URL_WITH_PATH, name: "name1"});
+    browser.test.assertEq(TEST_COOKIE_PATH, cookie.path, "got cookie with path");
+
+    cookies = await browser.cookies.getAll({path: TEST_COOKIE_PATH});
+    browser.test.assertEq(1, cookies.length, "one cookie with path found");
+    browser.test.assertEq(TEST_COOKIE_PATH, cookies[0].path, "found cookie with path");
+
+    cookie = await browser.cookies.get({url: TEST_URL + "invalid_path", name: "name1"});
+    browser.test.assertEq(null, cookie, "get with invalid path returns null");
+
+    cookies = await browser.cookies.getAll({path: "/invalid_path"});
+    browser.test.assertEq(0, cookies.length, "getAll with invalid path returns 0 cookies");
+
+    details = await browser.cookies.remove({url: TEST_URL_WITH_PATH, name: "name1"});
+    assertExpected({url: TEST_URL_WITH_PATH, name: "name1", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+    cookie = await browser.cookies.set({url: TEST_URL, name: "name1", value: "value1", httpOnly: true});
+    browser.test.assertEq(true, cookie.httpOnly, "httpOnly cookie set");
+
+    cookie = await browser.cookies.set({url: TEST_URL, name: "name1", value: "value1", httpOnly: false});
+    browser.test.assertEq(false, cookie.httpOnly, "non-httpOnly cookie set");
+
+    details = await browser.cookies.remove({url: TEST_URL, name: "name1"});
+    assertExpected({url: TEST_URL, name: "name1", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+    cookie = await browser.cookies.set({url: TEST_URL});
+    browser.test.assertEq("", cookie.name, "default name set");
+    browser.test.assertEq("", cookie.value, "default value set");
+    browser.test.assertEq(true, cookie.session, "no expiry date created session cookie");
+
+    // TODO bug 1372178: Opening private windows/tabs is not supported on Android
+    if (browser.windows) {
+      let {tabId, windowId} = await openPrivateWindowAndTab(TEST_URL);
+
+      browser.test.assertEq("", await getDocumentCookie(tabId), "initially no cookie");
+
+      let cookie = await browser.cookies.set({url: TEST_URL, name: "store", value: "private", expirationDate: THE_FUTURE, storeId: PRIVATE_STORE_ID});
+      browser.test.assertEq("private", cookie.value, "set the private cookie");
+
+      cookie = await browser.cookies.set({url: TEST_URL, name: "store", value: "default", expirationDate: THE_FUTURE, storeId: STORE_ID});
+      browser.test.assertEq("default", cookie.value, "set the default cookie");
+
+      cookie = await browser.cookies.get({url: TEST_URL, name: "store", storeId: PRIVATE_STORE_ID});
+      browser.test.assertEq("private", cookie.value, "get the private cookie");
+      browser.test.assertEq(PRIVATE_STORE_ID, cookie.storeId, "get the private cookie storeId");
+
+      cookie = await browser.cookies.get({url: TEST_URL, name: "store", storeId: STORE_ID});
+      browser.test.assertEq("default", cookie.value, "get the default cookie");
+      browser.test.assertEq(STORE_ID, cookie.storeId, "get the default cookie storeId");
+
+      browser.test.assertEq("store=private", await getDocumentCookie(tabId), "private document.cookie should be set");
+
+      let details = await browser.cookies.remove({url: TEST_URL, name: "store", storeId: STORE_ID});
+      assertExpected({url: TEST_URL, name: "store", storeId: STORE_ID, firstPartyDomain: ""}, details);
+
+      cookie = await browser.cookies.get({url: TEST_URL, name: "store", storeId: STORE_ID});
+      browser.test.assertEq(null, cookie, "deleted the default cookie");
+
+      details = await browser.cookies.remove({url: TEST_URL, name: "store", storeId: PRIVATE_STORE_ID});
+      assertExpected({url: TEST_URL, name: "store", storeId: PRIVATE_STORE_ID, firstPartyDomain: ""}, details);
+
+      cookie = await browser.cookies.get({url: TEST_URL, name: "store", storeId: PRIVATE_STORE_ID});
+      browser.test.assertEq(null, cookie, "deleted the private cookie");
+
+      browser.test.assertEq("", await getDocumentCookie(tabId), "private document.cookie should be removed");
+
+      await browser.windows.remove(windowId);
+    }
+
+    browser.test.notifyPass("cookies");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    incognitoOverride: "spanning",
+    background,
+    manifest: {
+      applications: { gecko: { id: "cookies@tests.mozilla.org" } },
+      permissions: ["cookies", "*://example.org/", "*://[2a03:4000:6:310e:216:3eff:fe53:99b]/", "*://192.168.1.1/", "webNavigation", "browsingData"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("cookies");
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_cookies_containers.html b/toolkit/components/extensions/test/mochitest/test_ext_cookies_containers.html
new file mode 100644
index 0000000000..db12a97854
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_cookies_containers.html
@@ -0,0 +1,97 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function setup() {
+  // make sure userContext is enabled.
+  await SpecialPowers.pushPrefEnv({"set": [
+    ["privacy.userContext.enabled", true],
+  ]});
+});
+
+add_task(async function test_cookie_containers() {
+  async function background() {
+    // Sometimes there is a cookie without name/value when running tests.
+    let cookiesAtStart = await browser.cookies.getAll({storeId: "firefox-default"});
+
+    function assertExpected(expected, cookie) {
+      for (let key of Object.keys(cookie)) {
+        browser.test.assertTrue(key in expected, `found property ${key}`);
+        browser.test.assertEq(expected[key], cookie[key], `property value for ${key} is correct`);
+      }
+      browser.test.assertEq(Object.keys(expected).length, Object.keys(cookie).length, "all expected properties found");
+    }
+
+    const TEST_URL = "http://example.org/";
+    const THE_FUTURE = Date.now() + 5 * 60;
+
+    let expected = {
+      name: "name1",
+      value: "value1",
+      domain: "example.org",
+      hostOnly: true,
+      path: "/",
+      secure: false,
+      httpOnly: false,
+      sameSite: "no_restriction",
+      session: false,
+      expirationDate: THE_FUTURE,
+      storeId: "firefox-container-1",
+      firstPartyDomain: "",
+    };
+
+    let cookie = await browser.cookies.set({
+      url: TEST_URL, name: "name1", value: "value1",
+      expirationDate: THE_FUTURE, storeId: "firefox-container-1",
+    });
+    browser.test.assertEq("firefox-container-1", cookie.storeId, "the cookie has the correct storeId");
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1"});
+    browser.test.assertEq(null, cookie, "get() without storeId returns null");
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1", storeId: "firefox-container-1"});
+    assertExpected(expected, cookie);
+
+    let cookies = await browser.cookies.getAll({storeId: "firefox-default"});
+    browser.test.assertEq(0, cookiesAtStart.length - cookies.length, "getAll() with default storeId hasn't added cookies");
+
+    cookies = await browser.cookies.getAll({storeId: "firefox-container-1"});
+    browser.test.assertEq(1, cookies.length, "one cookie found for matching domain");
+    assertExpected(expected, cookies[0]);
+
+    let details = await browser.cookies.remove({url: TEST_URL, name: "name1", storeId: "firefox-container-1"});
+    assertExpected({url: TEST_URL, name: "name1", storeId: "firefox-container-1", firstPartyDomain: ""}, details);
+
+    cookie = await browser.cookies.get({url: TEST_URL, name: "name1", storeId: "firefox-container-1"});
+    browser.test.assertEq(null, cookie, "removed cookie not found");
+
+    browser.test.notifyPass("cookies");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["cookies", "*://example.org/"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("cookies");
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_cookies_expiry.html b/toolkit/components/extensions/test/mochitest/test_ext_cookies_expiry.html
new file mode 100644
index 0000000000..fa118f5271
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_cookies_expiry.html
@@ -0,0 +1,72 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension cookies test</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_cookies_expiry() {
+  function background() {
+    let expectedEvents = [];
+
+    browser.cookies.onChanged.addListener(event => {
+      expectedEvents.push(`${event.removed}:${event.cause}`);
+      if (expectedEvents.length === 1) {
+        browser.test.assertEq("true:expired", expectedEvents[0], "expired cookie removed");
+        browser.test.assertEq("first", event.cookie.name, "expired cookie has the expected name");
+        browser.test.assertEq("one", event.cookie.value, "expired cookie has the expected value");
+      } else {
+        browser.test.assertEq("false:explicit", expectedEvents[1], "new cookie added");
+        browser.test.assertEq("first", event.cookie.name, "new cookie has the expected name");
+        browser.test.assertEq("one-again", event.cookie.value, "new cookie has the expected value");
+        browser.test.notifyPass("cookie-expiry");
+      }
+    });
+
+    setTimeout(() => {
+      browser.test.sendMessage("change-cookies");
+    }, 1000);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      "permissions": ["http://example.com/", "cookies"],
+    },
+    background,
+  });
+
+  let chromeScript = loadChromeScript(() => {
+    const {sendAsyncMessage} = this;
+    Services.cookies.add(".example.com", "/", "first", "one", false, false, false, Date.now() / 1000 + 1, {}, Ci.nsICookie.SAMESITE_NONE, Ci.nsICookie.SCHEME_HTTP);
+    sendAsyncMessage("done");
+  });
+  await chromeScript.promiseOneMessage("done");
+  chromeScript.destroy();
+
+  await extension.startup();
+  await extension.awaitMessage("change-cookies");
+
+  chromeScript = loadChromeScript(() => {
+    const {sendAsyncMessage} = this;
+    Services.cookies.add(".example.com", "/", "first", "one-again", false, false, false, Date.now() / 1000 + 10, {}, Ci.nsICookie.SAMESITE_NONE, Ci.nsICookie.SCHEME_HTTP);
+    sendAsyncMessage("done");
+  });
+  await chromeScript.promiseOneMessage("done");
+  chromeScript.destroy();
+
+  await extension.awaitFinish("cookie-expiry");
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_cookies_first_party.html b/toolkit/components/extensions/test/mochitest/test_ext_cookies_first_party.html
new file mode 100644
index 0000000000..7e33f4731d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_cookies_first_party.html
@@ -0,0 +1,316 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+<script src="head.js"></script>
+<script>
+"use strict";
+
+async function background() {
+  const url = "http://ext-cookie-first-party.mochi.test/";
+  const firstPartyDomain = "ext-cookie-first-party.mochi.test";
+  // A first party domain with invalid characters for the file system, which just happens to be a IPv6 address.
+  const firstPartyDomainInvalidChars = "[2606:4700:4700::1111]";
+  const expectedError = "First-Party Isolation is enabled, but the required 'firstPartyDomain' attribute was not set.";
+
+  const assertExpectedCookies = (expected, cookies, message) => {
+    let matches = (cookie, expected) => {
+      if (!cookie || !expected) {
+        return cookie === expected; // true if both are null.
+      }
+      for (let key of Object.keys(expected)) {
+        if (cookie[key] !== expected[key]) {
+          return false;
+        }
+      }
+      return true;
+    };
+    browser.test.assertEq(expected.length, cookies.length, `Got expected number of cookies - ${message}`);
+    if (cookies.length !== expected.length) {
+      return;
+    }
+    for (let expect of expected) {
+      let foundCookies = cookies.filter(cookie => matches(cookie, expect));
+      browser.test.assertEq(1, foundCookies.length,
+                            `Expected cookie ${JSON.stringify(expect)} found - ${message}`);
+    }
+  };
+
+  // Test when FPI is disabled.
+  const test_fpi_disabled = async () => {
+    let cookie, cookies;
+
+    // set
+    cookie = await browser.cookies.set({url, name: "foo1", value: "bar1"});
+    assertExpectedCookies([
+      {name: "foo1", value: "bar1", firstPartyDomain: ""},
+    ], [cookie], "set: FPI off, w/ empty firstPartyDomain, non-FP cookie");
+    cookie = await browser.cookies.set({url, name: "foo2", value: "bar2", firstPartyDomain});
+    assertExpectedCookies([
+      {name: "foo2", value: "bar2", firstPartyDomain},
+    ], [cookie], "set: FPI off, w/ firstPartyDomain, FP cookie");
+
+    // get
+    // When FPI is disabled, missing key/null/undefined is equivalent to "".
+    cookie = await browser.cookies.get({url, name: "foo1"});
+    assertExpectedCookies([
+      {name: "foo1", value: "bar1", firstPartyDomain: ""},
+    ], [cookie], "get: FPI off, w/o firstPartyDomain, non-FP cookie");
+    cookie = await browser.cookies.get({url, name: "foo1", firstPartyDomain: ""});
+    assertExpectedCookies([
+      {name: "foo1", value: "bar1", firstPartyDomain: ""},
+    ], [cookie], "get: FPI off, w/ empty firstPartyDomain, non-FP cookie");
+    cookie = await browser.cookies.get({url, name: "foo1", firstPartyDomain: null});
+    assertExpectedCookies([
+      {name: "foo1", value: "bar1", firstPartyDomain: ""},
+    ], [cookie], "get: FPI off, w/ null firstPartyDomain, non-FP cookie");
+    cookie = await browser.cookies.get({url, name: "foo1", firstPartyDomain: undefined});
+    assertExpectedCookies([
+      {name: "foo1", value: "bar1", firstPartyDomain: ""},
+    ], [cookie], "get: FPI off, w/ undefined firstPartyDomain, non-FP cookie");
+
+    cookie = await browser.cookies.get({url, name: "foo2", firstPartyDomain});
+    assertExpectedCookies([
+      {name: "foo2", value: "bar2", firstPartyDomain},
+    ], [cookie], "get: FPI off, w/ firstPartyDomain, FP cookie");
+    // There is no match for non-FP cookies with name "foo2".
+    cookie = await browser.cookies.get({url, name: "foo2"});
+    assertExpectedCookies([null], [cookie], "get: FPI off, w/o firstPartyDomain, no cookie");
+    cookie = await browser.cookies.get({url, name: "foo2", firstPartyDomain: ""});
+    assertExpectedCookies([null], [cookie], "get: FPI off, w/ empty firstPartyDomain, no cookie");
+    cookie = await browser.cookies.get({url, name: "foo2", firstPartyDomain: null});
+    assertExpectedCookies([null], [cookie], "get: FPI off, w/ null firstPartyDomain, no cookie");
+    cookie = await browser.cookies.get({url, name: "foo2", firstPartyDomain: undefined});
+    assertExpectedCookies([null], [cookie], "get: FPI off, w/ undefined firstPartyDomain, no cookie");
+
+    // getAll
+    for (let extra of [{}, {url}, {domain: firstPartyDomain}]) {
+      const prefix = `getAll(${JSON.stringify(extra)})`;
+      cookies = await browser.cookies.getAll({...extra});
+      assertExpectedCookies([
+        {name: "foo1", value: "bar1", firstPartyDomain: ""},
+      ], cookies, `${prefix}: FPI off, w/o firstPartyDomain, non-FP cookies`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain: ""});
+      assertExpectedCookies([
+        {name: "foo1", value: "bar1", firstPartyDomain: ""},
+      ], cookies, `${prefix}: FPI off, w/ empty firstPartyDomain, non-FP cookies`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain: null});
+      assertExpectedCookies([
+        {name: "foo1", value: "bar1", firstPartyDomain: ""},
+        {name: "foo2", value: "bar2", firstPartyDomain},
+      ], cookies, `${prefix}: FPI off, w/ null firstPartyDomain, all cookies`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain: undefined});
+      assertExpectedCookies([
+        {name: "foo1", value: "bar1", firstPartyDomain: ""},
+        {name: "foo2", value: "bar2", firstPartyDomain},
+      ], cookies, `${prefix}: FPI off, w/ undefined firstPartyDomain, all cookies`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain});
+      assertExpectedCookies([
+        {name: "foo2", value: "bar2", firstPartyDomain},
+      ], cookies, `${prefix}: FPI off, w/ firstPartyDomain, FP cookies`);
+    }
+
+    // remove
+    cookie = await browser.cookies.remove({url, name: "foo1"});
+    assertExpectedCookies([
+      {url, name: "foo1", firstPartyDomain: ""},
+    ], [cookie], "remove: FPI off, w/ empty firstPartyDomain, non-FP cookie");
+    cookie = await browser.cookies.remove({url, name: "foo2", firstPartyDomain});
+    assertExpectedCookies([
+      {url, name: "foo2", firstPartyDomain},
+    ], [cookie], "remove: FPI off, w/ firstPartyDomain, FP cookie");
+
+    // Test if FP cookies set when FPI off can be accessed when FPI on.
+    await browser.cookies.set({url, name: "foo1", value: "bar1"});
+    await browser.cookies.set({url, name: "foo2", value: "bar2", firstPartyDomain});
+
+    browser.test.sendMessage("test_fpi_disabled");
+  };
+
+  // Test when FPI is enabled.
+  const test_fpi_enabled = async () => {
+    let cookie, cookies;
+
+    // set
+    await browser.test.assertRejects(
+      browser.cookies.set({url, name: "foo3", value: "bar3"}),
+      expectedError,
+      "set: FPI on, w/o firstPartyDomain, rejection");
+    cookie = await browser.cookies.set({url, name: "foo4", value: "bar4", firstPartyDomain});
+    assertExpectedCookies([
+      {name: "foo4", value: "bar4", firstPartyDomain},
+    ], [cookie], "set: FPI on, w/ firstPartyDomain, FP cookie");
+
+    // get
+    await browser.test.assertRejects(
+      browser.cookies.get({url, name: "foo3"}),
+      expectedError,
+      "get: FPI on, w/o firstPartyDomain, rejection");
+    await browser.test.assertRejects(
+      browser.cookies.get({url, name: "foo3", firstPartyDomain: null}),
+      expectedError,
+      "get: FPI on, w/ null firstPartyDomain, rejection");
+    await browser.test.assertRejects(
+      browser.cookies.get({url, name: "foo3", firstPartyDomain: undefined}),
+      expectedError,
+      "get: FPI on, w/ undefined firstPartyDomain, rejection");
+    cookie = await browser.cookies.get({url, name: "foo1", firstPartyDomain: ""});
+    assertExpectedCookies([
+      {name: "foo1", value: "bar1", firstPartyDomain: ""},
+    ], [cookie], "get: FPI on, w/ empty firstPartyDomain, non-FP cookie");
+    cookie = await browser.cookies.get({url, name: "foo4", firstPartyDomain});
+    assertExpectedCookies([
+      {name: "foo4", value: "bar4", firstPartyDomain},
+    ], [cookie], "get: FPI on, w/ firstPartyDomain, FP cookie");
+    cookie = await browser.cookies.get({url, name: "foo2", firstPartyDomain});
+    assertExpectedCookies([
+      {name: "foo2", value: "bar2", firstPartyDomain},
+    ], [cookie], "get: FPI on, w/ firstPartyDomain, FP cookie (set when FPI off)");
+
+    // getAll
+    for (let extra of [{}, {url}, {domain: firstPartyDomain}]) {
+      const prefix = `getAll(${JSON.stringify(extra)})`;
+      await browser.test.assertRejects(
+        browser.cookies.getAll({...extra}),
+        expectedError,
+        `${prefix}: FPI on, w/o firstPartyDomain, rejection`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain: ""});
+      assertExpectedCookies([
+        {name: "foo1", value: "bar1", firstPartyDomain: ""},
+      ], cookies, `${prefix}: FPI on, w/ empty firstPartyDomain, non-FP cookies`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain: null});
+      assertExpectedCookies([
+        {name: "foo1", value: "bar1", firstPartyDomain: ""},
+        {name: "foo2", value: "bar2", firstPartyDomain},
+        {name: "foo4", value: "bar4", firstPartyDomain},
+      ], cookies, `${prefix}: FPI on, w/ null firstPartyDomain, all cookies`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain: undefined});
+      assertExpectedCookies([
+        {name: "foo1", value: "bar1", firstPartyDomain: ""},
+        {name: "foo2", value: "bar2", firstPartyDomain},
+        {name: "foo4", value: "bar4", firstPartyDomain},
+      ], cookies, `${prefix}: FPI on, w/ undefined firstPartyDomain, all cookies`);
+      cookies = await browser.cookies.getAll({...extra, firstPartyDomain});
+      assertExpectedCookies([
+        {name: "foo2", value: "bar2", firstPartyDomain},
+        {name: "foo4", value: "bar4", firstPartyDomain},
+      ], cookies, `${prefix}: FPI on, w/ firstPartyDomain, FP cookies`);
+    }
+
+    // remove
+    await browser.test.assertRejects(
+      browser.cookies.remove({url, name: "foo3"}),
+      expectedError,
+      "remove: FPI on, w/o firstPartyDomain, rejection");
+    cookie = await browser.cookies.remove({url, name: "foo4", firstPartyDomain});
+    assertExpectedCookies([
+      {url, name: "foo4", firstPartyDomain},
+    ], [cookie], "remove: FPI on, w/ firstPartyDomain, FP cookie");
+    cookie = await browser.cookies.remove({url, name: "foo2", firstPartyDomain});
+    assertExpectedCookies([
+      {url, name: "foo2", firstPartyDomain},
+    ], [cookie], "remove: FPI on, w/ firstPartyDomain, FP cookie (set when FPI off)");
+
+    // Test if FP cookies set when FPI on can be accessed when FPI off.
+    await browser.cookies.set({url, name: "foo4", value: "bar4", firstPartyDomain});
+
+    browser.test.sendMessage("test_fpi_enabled");
+  };
+
+  // Test FPI with a first party domain with invalid characters for
+  // the file system.
+  const test_fpi_with_invalid_characters = async () => {
+    let cookie;
+
+    // Test setting a cookie with a first party domain with invalid characters
+    // for the file system.
+    cookie = await browser.cookies.set({url, name: "foo5", value: "bar5",
+                                        firstPartyDomain: firstPartyDomainInvalidChars});
+    assertExpectedCookies([
+      {name: "foo5", value: "bar5", firstPartyDomain: firstPartyDomainInvalidChars},
+    ], [cookie], "set: FPI on, w/ firstPartyDomain with invalid characters, FP cookie");
+
+    // Test getting a cookie with a first party domain with invalid characters
+    // for the file system.
+    cookie = await browser.cookies.get({url, name: "foo5",
+                                        firstPartyDomain: firstPartyDomainInvalidChars});
+    assertExpectedCookies([
+      {name: "foo5", value: "bar5", firstPartyDomain: firstPartyDomainInvalidChars},
+    ], [cookie], "get: FPI on, w/ firstPartyDomain with invalid characters, FP cookie");
+
+    // Test removing a cookie with a first party domain with invalid characters
+    // for the file system.
+    cookie = await browser.cookies.remove({url, name: "foo5",
+                                           firstPartyDomain: firstPartyDomainInvalidChars});
+    assertExpectedCookies([
+      {url, name: "foo5", firstPartyDomain: firstPartyDomainInvalidChars},
+    ], [cookie], "remove: FPI on, w/ firstPartyDomain with invalid characters, FP cookie");
+
+    browser.test.sendMessage("test_fpi_with_invalid_characters");
+  };
+
+  // Test when FPI is disabled again, accessing FP cookies set when FPI is enabled.
+  const test_fpd_cookies_on_fpi_disabled = async () => {
+    let cookie, cookies;
+    cookie = await browser.cookies.get({url, name: "foo4", firstPartyDomain});
+    assertExpectedCookies([
+      {name: "foo4", value: "bar4", firstPartyDomain},
+    ], [cookie], "get: FPI off, w/ firstPartyDomain, FP cookie (set when FPI on)");
+    cookie = await browser.cookies.remove({url, name: "foo4", firstPartyDomain});
+    assertExpectedCookies([
+      {url, name: "foo4", firstPartyDomain},
+    ], [cookie], "remove: FPI off, w/ firstPartyDomain, FP cookie (set when FPI on)");
+
+    // Clean up.
+    await browser.cookies.remove({url, name: "foo1"});
+
+    cookies = await browser.cookies.getAll({firstPartyDomain: null});
+    assertExpectedCookies([], cookies, "Test is finishing, all cookies removed");
+
+    browser.test.sendMessage("test_fpd_cookies_on_fpi_disabled");
+  };
+
+  browser.test.onMessage.addListener((message) => {
+    switch (message) {
+      case "test_fpi_disabled": return test_fpi_disabled();
+      case "test_fpi_enabled": return test_fpi_enabled();
+      case "test_fpi_with_invalid_characters": return test_fpi_with_invalid_characters();
+      case "test_fpd_cookies_on_fpi_disabled": return test_fpd_cookies_on_fpi_disabled();
+      default: return browser.test.notifyFail("unknown-message");
+    }
+  });
+}
+
+function enableFirstPartyIsolation() {
+  return SpecialPowers.pushPrefEnv({
+    set: [
+      ["privacy.firstparty.isolate", true],
+    ],
+  });
+}
+
+function disableFirstPartyIsolation() {
+  return SpecialPowers.popPrefEnv();
+}
+
+add_task(async () => {
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["cookies", "*://ext-cookie-first-party.mochi.test/"],
+    },
+  });
+  await extension.startup();
+  extension.sendMessage("test_fpi_disabled");
+  await extension.awaitMessage("test_fpi_disabled");
+  await enableFirstPartyIsolation();
+  extension.sendMessage("test_fpi_enabled");
+  await extension.awaitMessage("test_fpi_enabled");
+  extension.sendMessage("test_fpi_with_invalid_characters");
+  await extension.awaitMessage("test_fpi_with_invalid_characters");
+  await disableFirstPartyIsolation();
+  extension.sendMessage("test_fpd_cookies_on_fpi_disabled");
+  await extension.awaitMessage("test_fpd_cookies_on_fpi_disabled");
+  await extension.unload();
+});
+</script>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_cookies_incognito.html b/toolkit/components/extensions/test/mochitest/test_ext_cookies_incognito.html
new file mode 100644
index 0000000000..a7c6931c06
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_cookies_incognito.html
@@ -0,0 +1,112 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_cookies_incognito_not_allowed() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.allowPrivateBrowsingByDefault", false]],
+  });
+
+  let privateExtension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    async background() {
+      let window = await browser.windows.create({incognito: true});
+      browser.test.onMessage.addListener(async () => {
+        await browser.windows.remove(window.id);
+        browser.test.sendMessage("done");
+      });
+      browser.test.sendMessage("ready");
+    },
+    manifest: {
+      permissions: ["cookies", "*://example.org/"],
+    },
+  });
+  await privateExtension.startup();
+  await privateExtension.awaitMessage("ready");
+
+  async function background() {
+    const storeId = "firefox-private";
+    const url = "http://example.org/";
+
+    // Getting the wrong storeId will fail, otherwise we should finish the test fine.
+    browser.cookies.onChanged.addListener(changeInfo => {
+      let {cookie} = changeInfo;
+      browser.test.assertTrue(cookie.storeId != storeId, "cookie store is correct");
+    });
+
+    browser.test.onMessage.addListener(async () => {
+      let stores = await browser.cookies.getAllCookieStores();
+      let store = stores.find(s => s.incognito);
+      browser.test.assertTrue(!store, "incognito cookie store should not be available");
+      browser.test.notifyPass("cookies");
+    });
+
+    await browser.test.assertRejects(
+      browser.cookies.set({url, name: "test", storeId}),
+      /Extension disallowed access/,
+      "API should reject setting cookie");
+    await browser.test.assertRejects(
+      browser.cookies.get({url, name: "test", storeId}),
+      /Extension disallowed access/,
+      "API should reject getting cookie");
+    await browser.test.assertRejects(
+      browser.cookies.getAll({url, storeId}),
+      /Extension disallowed access/,
+      "API should reject getting cookie");
+    await browser.test.assertRejects(
+      browser.cookies.remove({url, name: "test", storeId}),
+      /Extension disallowed access/,
+      "API should reject getting cookie");
+    await browser.test.assertRejects(
+      browser.cookies.getAll({url, storeId}),
+      /Extension disallowed access/,
+      "API should reject getting cookie");
+
+    browser.test.sendMessage("set-cookies");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["cookies", "*://example.org/"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("set-cookies");
+
+  let chromeScript = SpecialPowers.loadChromeScript(() => {
+    const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+    Services.cookies.add("example.org", "/", "public", `foo${Math.random()}`,
+                         false, false, false, Number.MAX_SAFE_INTEGER, {},
+                         Ci.nsICookie.SAMESITE_NONE);
+    Services.cookies.add("example.org", "/", "private", `foo${Math.random()}`,
+                         false, false, false, Number.MAX_SAFE_INTEGER, {privateBrowsingId: 1},
+                         Ci.nsICookie.SAMESITE_NONE);
+  });
+  extension.sendMessage("test-cookie-store");
+  await extension.awaitFinish("cookies");
+
+  await extension.unload();
+  privateExtension.sendMessage("close");
+  await privateExtension.awaitMessage("done");
+  await privateExtension.unload();
+  chromeScript.destroy();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_cookies_permissions_bad.html b/toolkit/components/extensions/test/mochitest/test_ext_cookies_permissions_bad.html
new file mode 100644
index 0000000000..0bd2852075
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_cookies_permissions_bad.html
@@ -0,0 +1,115 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript" src="head_cookies.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function init() {
+  // We need to trigger a cookie eviction in order to test our batch delete
+  // observer.
+
+  // Set quotaPerHost to maxPerHost - 1, so there is only one cookie
+  // will be evicted everytime.
+  SpecialPowers.setIntPref("network.cookie.quotaPerHost", 2);
+  SpecialPowers.setIntPref("network.cookie.maxPerHost", 3);
+  SimpleTest.registerCleanupFunction(() => {
+    SpecialPowers.clearUserPref("network.cookie.quotaPerHost");
+    SpecialPowers.clearUserPref("network.cookie.maxPerHost");
+  });
+});
+
+add_task(async function test_bad_cookie_permissions() {
+  info("Test non-matching, non-secure domain with non-secure cookie");
+  await testCookies({
+    permissions: ["http://example.com/", "cookies"],
+    url: "http://example.net/",
+    domain: "example.net",
+    secure: false,
+    shouldPass: false,
+    shouldWrite: false,
+  });
+
+  info("Test non-matching, secure domain with non-secure cookie");
+  await testCookies({
+    permissions: ["https://example.com/", "cookies"],
+    url: "https://example.net/",
+    domain: "example.net",
+    secure: false,
+    shouldPass: false,
+    shouldWrite: false,
+  });
+
+  info("Test non-matching, secure domain with secure cookie");
+  await testCookies({
+    permissions: ["https://example.com/", "cookies"],
+    url: "https://example.net/",
+    domain: "example.net",
+    secure: false,
+    shouldPass: false,
+    shouldWrite: false,
+  });
+
+  info("Test matching subdomain with superdomain privileges, secure cookie (http)");
+  await testCookies({
+    permissions: ["http://foo.bar.example.com/", "cookies"],
+    url: "http://foo.bar.example.com/",
+    domain: ".example.com",
+    secure: true,
+    shouldPass: false,
+    shouldWrite: true,
+  });
+
+  info("Test matching, non-secure domain with secure cookie");
+  await testCookies({
+    permissions: ["http://example.com/", "cookies"],
+    url: "http://example.com/",
+    domain: "example.com",
+    secure: true,
+    shouldPass: false,
+    shouldWrite: true,
+  });
+
+  info("Test matching, non-secure host, secure URL");
+  await testCookies({
+    permissions: ["http://example.com/", "cookies"],
+    url: "https://example.com/",
+    domain: "example.com",
+    secure: true,
+    shouldPass: false,
+    shouldWrite: false,
+  });
+
+  info("Test non-matching domain");
+  await testCookies({
+    permissions: ["http://example.com/", "cookies"],
+    url: "http://example.com/",
+    domain: "example.net",
+    secure: false,
+    shouldPass: false,
+    shouldWrite: false,
+  });
+
+  info("Test invalid scheme");
+  await testCookies({
+    permissions: ["ftp://example.com/", "cookies"],
+    url: "ftp://example.com/",
+    domain: "example.com",
+    secure: false,
+    shouldPass: false,
+    shouldWrite: false,
+  });
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_cookies_permissions_good.html b/toolkit/components/extensions/test/mochitest/test_ext_cookies_permissions_good.html
new file mode 100644
index 0000000000..bd76f2b9c0
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_cookies_permissions_good.html
@@ -0,0 +1,89 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript" src="head_cookies.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function init() {
+  // We need to trigger a cookie eviction in order to test our batch delete
+  // observer.
+
+  // Set quotaPerHost to maxPerHost - 1, so there is only one cookie
+  // will be evicted everytime.
+  SpecialPowers.setIntPref("network.cookie.quotaPerHost", 2);
+  SpecialPowers.setIntPref("network.cookie.maxPerHost", 3);
+  SimpleTest.registerCleanupFunction(() => {
+    SpecialPowers.clearUserPref("network.cookie.quotaPerHost");
+    SpecialPowers.clearUserPref("network.cookie.maxPerHost");
+  });
+});
+
+add_task(async function test_good_cookie_permissions() {
+  info("Test matching, non-secure domain with non-secure cookie");
+  await testCookies({
+    permissions: ["http://example.com/", "cookies"],
+    url: "http://example.com/",
+    domain: "example.com",
+    secure: false,
+    shouldPass: true,
+  });
+
+  info("Test matching, secure domain with non-secure cookie");
+  await testCookies({
+    permissions: ["https://example.com/", "cookies"],
+    url: "https://example.com/",
+    domain: "example.com",
+    secure: false,
+    shouldPass: true,
+  });
+
+  info("Test matching, secure domain with secure cookie");
+  await testCookies({
+    permissions: ["https://example.com/", "cookies"],
+    url: "https://example.com/",
+    domain: "example.com",
+    secure: true,
+    shouldPass: true,
+  });
+
+  info("Test matching subdomain with superdomain privileges, secure cookie (https)");
+  await testCookies({
+    permissions: ["https://foo.bar.example.com/", "cookies"],
+    url: "https://foo.bar.example.com/",
+    domain: ".example.com",
+    secure: true,
+    shouldPass: true,
+  });
+
+  info("Test matching subdomain with superdomain privileges, non-secure cookie (https)");
+  await testCookies({
+    permissions: ["https://foo.bar.example.com/", "cookies"],
+    url: "https://foo.bar.example.com/",
+    domain: ".example.com",
+    secure: false,
+    shouldPass: true,
+  });
+
+  info("Test matching subdomain with superdomain privileges, non-secure cookie  (http)");
+  await testCookies({
+    permissions: ["http://foo.bar.example.com/", "cookies"],
+    url: "http://foo.bar.example.com/",
+    domain: ".example.com",
+    secure: false,
+    shouldPass: true,
+  });
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_downloads_download.html b/toolkit/components/extensions/test/mochitest/test_ext_downloads_download.html
new file mode 100644
index 0000000000..ea163db0de
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_downloads_download.html
@@ -0,0 +1,90 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Downloads Test</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+async function background() {
+  const url = "http://mochi.test:8888/tests/mobile/android/components/extensions/test/mochitest/context_tabs_onUpdated_page.html";
+
+  browser.test.assertThrows(
+    () => browser.downloads.download(),
+    /Incorrect argument types for downloads.download/,
+    "Should fail without options"
+  );
+
+  browser.test.assertThrows(
+    () => browser.downloads.download({url: "invalid url"}),
+    /invalid url is not a valid URL/,
+    "Should fail on invalid URL"
+  );
+
+  browser.test.assertThrows(
+    () => browser.downloads.download({}),
+    /Property "url" is required/,
+    "Should fail with no URL"
+  );
+
+  browser.test.assertThrows(
+    () => browser.downloads.download({url, method: "DELETE"}),
+    /Invalid enumeration value "DELETE"/,
+    "Should fail with invalid method"
+  );
+
+  await browser.test.assertRejects(
+    browser.downloads.download({url, headers: [{name: "Host", value: "Banana"}]}),
+    /Forbidden request header name/,
+    "Should fail with a forbidden header"
+  );
+
+  await browser.test.assertRejects(
+    browser.downloads.download({url, filename: "/tmp/file.gif"}),
+    /filename must not be an absolute path/,
+    "Should fail with an absolute file path"
+  );
+
+  await browser.test.assertRejects(
+    browser.downloads.download({url, filename: ""}),
+    /filename must not be empty/,
+    "Should fail with an empty file path"
+  );
+
+  await browser.test.assertRejects(
+    browser.downloads.download({url, filename: "file."}),
+    /filename must not contain illegal characters/,
+    "Should fail with a dot in the filename"
+  );
+
+  await browser.test.assertRejects(
+    browser.downloads.download({url, filename: "../file.gif"}),
+    /filename must not contain back-references/,
+    "Should fail with a file path that contains back-references"
+  );
+
+  browser.test.notifyPass("download.done");
+}
+
+add_task(async function test_invalid_download_parameters() {
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {permissions: ["downloads"]},
+    background,
+  });
+  await extension.startup();
+
+  await extension.awaitFinish("download.done");
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_embeddedimg_iframe_frameAncestors.html b/toolkit/components/extensions/test/mochitest/test_ext_embeddedimg_iframe_frameAncestors.html
new file mode 100644
index 0000000000..d6702da4d3
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_embeddedimg_iframe_frameAncestors.html
@@ -0,0 +1,94 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Test checking webRequest.onBeforeRequest details object</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+let expected = {
+  "file_contains_iframe.html": {
+    type: "main_frame",
+    frameAncestor_length: 0,
+  },
+  "file_contains_img.html": {
+    type: "sub_frame",
+    frameAncestor_length: 1,
+  },
+  "file_image_good.png": {
+    type: "image",
+    frameAncestor_length: 1,
+  }
+};
+
+function checkDetails(details) {
+  let url = new URL(details.url);
+  let filename = url.pathname.split("/").pop();
+  ok(expected.hasOwnProperty(filename), `Should be expecting a request for ${filename}`);
+  let expect = expected[filename];
+  is(expect.type, details.type, `${details.type} type matches`);
+  is(expect.frameAncestor_length, details.frameAncestors.length, "incorrect frameAncestors length");
+  if (filename == "file_contains_img.html") {
+    is(details.frameAncestors[0].frameId, details.parentFrameId,
+    "frameAncestors[0] should match parentFrameId");
+    expected["file_image_good.png"].frameId = details.frameId;
+  } else if (filename == "file_image_good.png") {
+    is(details.frameAncestors[0].frameId, details.parentFrameId,
+       "frameAncestors[0] should match parentFrameId");
+    is(details.frameId, expect.frameId,
+       "frameId for image and iframe should match");
+  }
+}
+
+add_task(async () => {
+  // Clear the image cache, since it gets in the way otherwise.
+  let imgTools = SpecialPowers.Cc["@mozilla.org/image/tools;1"].getService(SpecialPowers.Ci.imgITools);
+  let cache = imgTools.getImgCacheForDocument(document);
+  cache.clearCache(false);
+  await SpecialPowers.spawnChrome([], async () => {
+    Services.cache2.clear();
+  });
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "<all_urls>"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.sendMessage("onBeforeRequest", details);
+        },
+        {
+          urls: [
+          "http://example.org/*/file_contains_img.html",
+          "http://mochi.test/*/file_contains_iframe.html",
+          "*://*/*.png",
+          ],
+        }
+      );
+    },
+  });
+
+  await extension.startup();
+  const FILE_URL = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_contains_iframe.html";
+  let win = window.open(FILE_URL);
+  await new Promise(resolve => win.addEventListener("load", () => resolve(), {once: true}));
+
+  for (let i = 0; i < Object.keys(expected).length; i++) {
+    checkDetails(await extension.awaitMessage("onBeforeRequest"));
+  }
+
+  win.close();
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_exclude_include_globs.html b/toolkit/components/extensions/test/mochitest/test_ext_exclude_include_globs.html
new file mode 100644
index 0000000000..bdf300ec50
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_exclude_include_globs.html
@@ -0,0 +1,91 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_contentscript() {
+  function background() {
+    browser.runtime.onMessage.addListener(([script], sender) => {
+      browser.test.sendMessage("run", {script});
+      browser.test.sendMessage("run-" + script);
+    });
+    browser.test.sendMessage("running");
+  }
+
+  function contentScriptAll() {
+    browser.runtime.sendMessage(["all"]);
+  }
+  function contentScriptIncludesTest1() {
+    browser.runtime.sendMessage(["includes-test1"]);
+  }
+  function contentScriptExcludesTest1() {
+    browser.runtime.sendMessage(["excludes-test1"]);
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          "matches": ["http://example.org/", "http://*.example.org/"],
+          "exclude_globs": [],
+          "include_globs": ["*"],
+          "js": ["content_script_all.js"],
+        },
+        {
+          "matches": ["http://example.org/", "http://*.example.org/"],
+          "include_globs": ["*test1*"],
+          "js": ["content_script_includes_test1.js"],
+        },
+        {
+          "matches": ["http://example.org/", "http://*.example.org/"],
+          "exclude_globs": ["*test1*"],
+          "js": ["content_script_excludes_test1.js"],
+        },
+      ],
+    },
+    background,
+
+    files: {
+      "content_script_all.js": contentScriptAll,
+      "content_script_includes_test1.js": contentScriptIncludesTest1,
+      "content_script_excludes_test1.js": contentScriptExcludesTest1,
+    },
+
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  let ran = 0;
+  extension.onMessage("run", ({script}) => {
+    ran++;
+  });
+
+  await Promise.all([extension.startup(), extension.awaitMessage("running")]);
+  info("extension loaded");
+
+  let win = window.open("http://example.org/");
+  await Promise.all([extension.awaitMessage("run-all"), extension.awaitMessage("run-excludes-test1")]);
+  win.close();
+  is(ran, 2);
+
+  win = window.open("http://test1.example.org/");
+  await Promise.all([extension.awaitMessage("run-all"), extension.awaitMessage("run-includes-test1")]);
+  win.close();
+  is(ran, 4);
+
+  await extension.unload();
+  info("extension unloaded");
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_external_messaging.html b/toolkit/components/extensions/test/mochitest/test_ext_external_messaging.html
new file mode 100644
index 0000000000..ba91989d9c
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_external_messaging.html
@@ -0,0 +1,110 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension external messaging</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function backgroundScript(id, otherId) {
+  browser.runtime.onMessage.addListener((msg, sender) => {
+    browser.test.fail(`Got unexpected message: ${uneval(msg)} ${uneval(sender)}`);
+  });
+
+  browser.runtime.onConnect.addListener(port => {
+    browser.test.fail(`Got unexpected connection: ${uneval(port.sender)}`);
+  });
+
+  browser.runtime.onMessageExternal.addListener((msg, sender) => {
+    browser.test.assertEq(otherId, sender.id, `${id}: Got expected external sender ID`);
+    browser.test.assertEq(`helo-${id}`, msg, "Got expected message");
+
+    browser.test.sendMessage("onMessage-done");
+
+    return Promise.resolve(`ehlo-${otherId}`);
+  });
+
+  browser.runtime.onConnectExternal.addListener(port => {
+    browser.test.assertEq(otherId, port.sender.id, `${id}: Got expected external connecter ID`);
+
+    port.onMessage.addListener(msg => {
+      browser.test.assertEq(`helo-${id}`, msg, "Got expected port message");
+
+      port.postMessage(`ehlo-${otherId}`);
+
+      browser.test.sendMessage("onConnect-done");
+    });
+  });
+
+  browser.test.onMessage.addListener(msg => {
+    if (msg === "go") {
+      browser.runtime.sendMessage(otherId, `helo-${otherId}`).then(result => {
+        browser.test.assertEq(`ehlo-${id}`, result, "Got expected reply");
+        browser.test.sendMessage("sendMessage-done");
+      });
+
+      let port = browser.runtime.connect(otherId);
+      port.postMessage(`helo-${otherId}`);
+
+      port.onMessage.addListener(msg => {
+        port.disconnect();
+
+        browser.test.assertEq(msg, `ehlo-${id}`, "Got expected port reply");
+        browser.test.sendMessage("connect-done");
+      });
+    }
+  });
+}
+
+function makeExtension(id, otherId) {
+  let args = `${JSON.stringify(id)}, ${JSON.stringify(otherId)}`;
+
+  let extensionData = {
+    background: `(${backgroundScript})(${args})`,
+    manifest: {
+      "applications": {"gecko": {id}},
+    },
+  };
+
+  return ExtensionTestUtils.loadExtension(extensionData);
+}
+
+add_task(async function test_contentscript() {
+  const ID1 = "foo-message@mochitest.mozilla.org";
+  const ID2 = "bar-message@mochitest.mozilla.org";
+
+  let extension1 = makeExtension(ID1, ID2);
+  let extension2 = makeExtension(ID2, ID1);
+
+  await Promise.all([extension1.startup(), extension2.startup()]);
+
+  extension1.sendMessage("go");
+  extension2.sendMessage("go");
+
+  await Promise.all([
+    extension1.awaitMessage("sendMessage-done"),
+    extension2.awaitMessage("sendMessage-done"),
+
+    extension1.awaitMessage("onMessage-done"),
+    extension2.awaitMessage("onMessage-done"),
+
+    extension1.awaitMessage("connect-done"),
+    extension2.awaitMessage("connect-done"),
+
+    extension1.awaitMessage("onConnect-done"),
+    extension2.awaitMessage("onConnect-done"),
+  ]);
+
+  await extension1.unload();
+  await extension2.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_generate.html b/toolkit/components/extensions/test/mochitest/test_ext_generate.html
new file mode 100644
index 0000000000..ba88d16ca3
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_generate.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for generating WebExtensions</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function background() {
+  browser.test.log("running background script");
+
+  browser.test.onMessage.addListener((x, y) => {
+    browser.test.assertEq(x, 10, "x is 10");
+    browser.test.assertEq(y, 20, "y is 20");
+
+    browser.test.notifyPass("background test passed");
+  });
+
+  browser.test.sendMessage("running", 1);
+}
+
+let extensionData = {
+  background,
+};
+
+add_task(async function test_background() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  info("load complete");
+  let [, x] = await Promise.all([extension.startup(), extension.awaitMessage("running")]);
+  is(x, 1, "got correct value from extension");
+  info("startup complete");
+  extension.sendMessage(10, 20);
+  await extension.awaitFinish();
+  info("test complete");
+  await extension.unload();
+  info("extension unloaded successfully");
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_geolocation.html b/toolkit/components/extensions/test/mochitest/test_ext_geolocation.html
new file mode 100644
index 0000000000..9f326372bb
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_geolocation.html
@@ -0,0 +1,86 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+<script>
+"use strict";
+
+add_task(async function test_geolocation_nopermission() {
+  let GEO_URL = "http://mochi.test:8888/tests/dom/tests/mochitest/geolocation/network_geolocation.sjs";
+  await SpecialPowers.pushPrefEnv({"set": [["geo.provider.network.url", GEO_URL]]});
+});
+
+add_task(async function test_geolocation() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "geolocation",
+      ],
+    },
+    background() {
+      navigator.geolocation.getCurrentPosition(() => {
+        browser.test.notifyPass("success geolocation call");
+      }, (error) => {
+        browser.test.notifyFail(`geolocation call ${error}`);
+      });
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish();
+  await extension.unload();
+});
+
+add_task(async function test_geolocation_nopermission() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      navigator.geolocation.getCurrentPosition(() => {
+        browser.test.notifyFail("success geolocation call");
+      }, (error) => {
+        browser.test.notifyPass(`geolocation call ${error}`);
+      });
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish();
+  await extension.unload();
+});
+
+add_task(async function test_geolocation_prompt() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.tabs.create({url: "tab.html"});
+    },
+    files: {
+      "tab.html": `<html><head>
+        <meta charset="utf-8">
+        <script src="tab.js"><\/script>
+      </head></html>`,
+      "tab.js": () => {
+        navigator.geolocation.getCurrentPosition(() => {
+          browser.test.notifyPass("success geolocation call");
+        }, (error) => {
+          browser.test.notifyFail(`geolocation call ${error}`);
+        });
+      },
+    },
+  });
+
+  // Bypass the actual prompt, but the prompt result is to allow access.
+  await SpecialPowers.pushPrefEnv({"set": [["geo.prompt.testing", true], ["geo.prompt.testing.allow", true]]});
+  await extension.startup();
+  await extension.awaitFinish();
+  await extension.unload();
+});
+</script>
+</head>
+<body>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_identity.html b/toolkit/components/extensions/test/mochitest/test_ext_identity.html
new file mode 100644
index 0000000000..c40578cd40
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_identity.html
@@ -0,0 +1,390 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for WebExtension Identity</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function setup() {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["extensions.webextensions.identity.redirectDomain", "example.com"],
+      // Disable the network cache first-party partition during this
+      // test (TODO: look more closely to how that is affecting the intermittency
+      // of this test on MacOS, see Bug 1626482).
+      ["privacy.partition.network_state", false],
+    ],
+  });
+});
+
+add_task(async function test_noPermission() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.assertEq(
+        undefined,
+        browser.identity,
+        "No identity api without permission"
+      );
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_getRedirectURL() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "identity@mozilla.org",
+        },
+      },
+      permissions: ["identity", "https://example.com/"],
+    },
+    async background() {
+      let redirect_base =
+        "https://35b64b676900f491c00e7f618d43f7040e88422e.example.com/";
+      await browser.test.assertEq(
+        redirect_base,
+        browser.identity.getRedirectURL(),
+        "redirect url ok"
+      );
+      await browser.test.assertEq(
+        redirect_base,
+        browser.identity.getRedirectURL(""),
+        "redirect url ok"
+      );
+      await browser.test.assertEq(
+        redirect_base + "foobar",
+        browser.identity.getRedirectURL("foobar"),
+        "redirect url ok"
+      );
+      await browser.test.assertEq(
+        redirect_base + "callback",
+        browser.identity.getRedirectURL("/callback"),
+        "redirect url ok"
+      );
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_badAuthURI() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["identity", "https://example.com/"],
+    },
+    async background() {
+      for (let url of [
+        "foobar",
+        "about:addons",
+        "about:blank",
+        "ftp://example.com/test",
+      ]) {
+        await browser.test.assertThrows(
+          () => {
+            browser.identity.launchWebAuthFlow({ interactive: true, url });
+          },
+          /Type error for parameter details/,
+          "details.url is invalid"
+        );
+      }
+
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_badRequestURI() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["identity", "https://example.com/"],
+    },
+    async background() {
+      let base_uri =
+        "https://example.com/tests/toolkit/components/extensions/test/mochitest/";
+      let url = `${base_uri}?redirect_uri=badrobot}`;
+      await browser.test.assertRejects(
+        browser.identity.launchWebAuthFlow({ interactive: true, url }),
+        "redirect_uri is invalid",
+        "invalid redirect url"
+      );
+      url = `${base_uri}?redirect_uri=https://somesite.com`;
+      await browser.test.assertRejects(
+        browser.identity.launchWebAuthFlow({ interactive: true, url }),
+        "redirect_uri not allowed",
+        "invalid redirect url"
+      );
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function background_launchWebAuthFlow_requires_interaction() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["identity", "https://example.com/"],
+    },
+    async background() {
+      let base_uri =
+        "https://example.com/tests/toolkit/components/extensions/test/mochitest/";
+      let url = `${base_uri}?redirect_uri=${browser.identity.getRedirectURL(
+        "redirect"
+      )}`;
+      await browser.test.assertRejects(
+        browser.identity.launchWebAuthFlow({ interactive: false, url }),
+        "Requires user interaction",
+        "Rejects on required user interaction"
+      );
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+function background_launchWebAuthFlow({
+  interactive = false,
+  path = "redirect_auto.sjs",
+  params = {},
+  redirect = true,
+  useRedirectUri = true,
+} = {}) {
+  let uri_path = useRedirectUri ? "identity_cb" : "";
+  let expected_redirect = `https://35b64b676900f491c00e7f618d43f7040e88422e.example.com/${uri_path}`;
+  let base_uri =
+    "https://example.com/tests/toolkit/components/extensions/test/mochitest/";
+  let redirect_uri = browser.identity.getRedirectURL(
+    useRedirectUri ? uri_path : undefined
+  );
+  browser.test.assertEq(
+    expected_redirect,
+    redirect_uri,
+    "expected redirect uri matches hash"
+  );
+  let url = `${base_uri}${path}`;
+  if (useRedirectUri) {
+    params.redirect_uri = redirect_uri;
+  } else {
+    // We kind of fake it with the redirect url that would normally be configured
+    // in the oauth service.  This does still test that the identity service falls back
+    // to the extensions redirect url.
+    params.default_redirect = expected_redirect;
+  }
+  if (!redirect) {
+    params.no_redirect = 1;
+  }
+  let query = [];
+  for (let [param, value] of Object.entries(params)) {
+    query.push(`${param}=${encodeURIComponent(value)}`);
+  }
+  url = `${url}?${query.join("&")}`;
+
+  // Ensure we do not start the actual request for the redirect url.  In the case
+  // of a 303 POST redirect we are getting a request started.
+  let watchRedirectRequest = () => {};
+  if (params.post !== 303) {
+    watchRedirectRequest = details => {
+      if (details.url.startsWith(expected_redirect)) {
+        browser.test.fail(`onBeforeRequest called for redirect url: ${JSON.stringify(details)}`);
+      }
+    };
+
+    browser.webRequest.onBeforeRequest.addListener(
+      watchRedirectRequest,
+      {
+        urls: [
+          "https://35b64b676900f491c00e7f618d43f7040e88422e.example.com/*",
+        ],
+      }
+    );
+  }
+
+  browser.identity
+    .launchWebAuthFlow({ interactive, url })
+    .then(redirectURL => {
+      browser.test.assertTrue(
+        redirectURL.startsWith(redirect_uri),
+        `correct redirect url ${redirectURL}`
+      );
+      if (redirect) {
+        let url = new URL(redirectURL);
+        browser.test.assertEq(
+          "here ya go",
+          url.searchParams.get("access_token"),
+          "Handled auto redirection"
+        );
+      }
+    })
+    .catch(error => {
+      if (redirect) {
+        browser.test.fail(error.message);
+      } else {
+        browser.test.assertEq(
+          "Requires user interaction",
+          error.message,
+          "Auth page loaded, interaction required."
+        );
+      }
+    }).then(() => {
+      browser.webRequest.onBeforeRequest.removeListener(watchRedirectRequest);
+      browser.test.sendMessage("done");
+    });
+}
+
+// Tests the situation where the oauth provider has already granted access and
+// simply redirects the oauth client to provide the access key or code.
+add_task(async function test_autoRedirect() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "identity@mozilla.org",
+        },
+      },
+      permissions: ["webRequest", "identity", "https://*.example.com/*"],
+    },
+    background: `(${background_launchWebAuthFlow})()`,
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_autoRedirect_noRedirectURI() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "identity@mozilla.org",
+        },
+      },
+      permissions: ["webRequest", "identity", "https://*.example.com/*"],
+    },
+    background: `(${background_launchWebAuthFlow})({useRedirectUri: false})`,
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+// Tests the situation where the oauth provider has not granted access and interactive=false
+add_task(async function test_noRedirect() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "identity@mozilla.org",
+        },
+      },
+      permissions: ["webRequest", "identity", "https://*.example.com/*"],
+    },
+    background: `(${background_launchWebAuthFlow})({redirect: false})`,
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+// Tests the situation where the oauth provider must show a window where
+// presumably the user interacts, then the redirect occurs and access key or
+// code is provided.  We bypass any real interaction, but want the window to
+// open and result in a redirect.
+add_task(async function test_interaction() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "identity@mozilla.org",
+        },
+      },
+      permissions: ["webRequest", "identity", "https://*.example.com/*"],
+    },
+    background: `(${background_launchWebAuthFlow})({interactive: true, path: "oauth.html"})`,
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+// Tests the situation where the oauth provider redirects with a 303.
+add_task(async function test_auto303Redirect() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "identity@mozilla.org",
+        },
+      },
+      permissions: ["webRequest", "identity", "https://*.example.com/*"],
+    },
+    background: `(${background_launchWebAuthFlow})({interactive: true, path: "oauth.html", params: {post: 303, server_uri: "redirect_auto.sjs"}})`,
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_loopbackRedirectURI() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "identity@mozilla.org",
+        },
+      },
+      permissions: ["identity"],
+    },
+    async background() {
+      let redirectURL = "http://127.0.0.1/mozoauth2/35b64b676900f491c00e7f618d43f7040e88422e";
+      let actualRedirect = await browser.identity.launchWebAuthFlow({
+        interactive: true,
+        url: `https://example.com/tests/toolkit/components/extensions/test/mochitest/oauth.html?redirect_uri=${encodeURIComponent(redirectURL)}`
+      }).catch(error => {
+        browser.test.fail(error.message)
+      });
+      browser.test.assertTrue(
+        actualRedirect.startsWith(redirectURL),
+        "Expected redirect url to be loopback address"
+      )
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_idle.html b/toolkit/components/extensions/test/mochitest/test_ext_idle.html
new file mode 100644
index 0000000000..381687ee38
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_idle.html
@@ -0,0 +1,68 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function testWithRealIdleService() {
+  function background() {
+    browser.test.onMessage.addListener(async (msg, ...args) => {
+      let detectionInterval = args[0];
+      if (msg == "addListener") {
+        let status = await browser.idle.queryState(detectionInterval);
+        browser.test.assertEq("active", status, "Idle status is active");
+        browser.idle.setDetectionInterval(detectionInterval);
+        browser.idle.onStateChanged.addListener(newState => {
+          browser.test.assertEq("idle", newState, "listener fired with the expected state");
+          browser.test.sendMessage("listenerFired");
+        });
+        browser.test.sendMessage("listenerAdded");
+      } else if (msg == "checkState") {
+        let status = await browser.idle.queryState(detectionInterval);
+        browser.test.assertEq("idle", status, "Idle status is idle");
+        browser.test.notifyPass("idle");
+      }
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["idle"],
+    },
+  });
+
+  await extension.startup();
+
+  let chromeScript = loadChromeScript(() => {
+    const {sendAsyncMessage} = this;
+    const idleService = Cc["@mozilla.org/widget/useridleservice;1"].getService(Ci.nsIUserIdleService);
+    let idleTime = idleService.idleTime;
+    sendAsyncMessage("detectionInterval", Math.max(Math.ceil(idleTime / 1000) + 10, 15));
+  });
+  let detectionInterval = await chromeScript.promiseOneMessage("detectionInterval");
+  chromeScript.destroy();
+
+  info(`Setting interval to ${detectionInterval}`);
+  extension.sendMessage("addListener", detectionInterval);
+  await extension.awaitMessage("listenerAdded");
+  info("Listener added");
+  await extension.awaitMessage("listenerFired");
+  info("Listener fired");
+  extension.sendMessage("checkState", detectionInterval);
+  await extension.awaitFinish("idle");
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_inIncognitoContext_window.html b/toolkit/components/extensions/test/mochitest/test_ext_inIncognitoContext_window.html
new file mode 100644
index 0000000000..5b36902581
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_inIncognitoContext_window.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_in_incognito_context_true() {
+  function background() {
+    browser.runtime.onMessage.addListener(msg => {
+      browser.test.assertEq(true, msg, "inIncognitoContext is true");
+      browser.test.notifyPass("inIncognitoContext");
+    });
+
+    browser.windows.create({url: browser.runtime.getURL("/tab.html"), incognito: true});
+  }
+
+  function tabScript() {
+    browser.runtime.sendMessage(browser.extension.inIncognitoContext);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    files: {
+      "tab.js": tabScript,
+      "tab.html": `<!DOCTYPE html><html><head>
+        <meta charset="utf-8">
+        <script src="tab.js"><\/script>
+      </head></html>`,
+    },
+    incognitoOverride: "spanning",
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("inIncognitoContext");
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_listener_proxies.html b/toolkit/components/extensions/test/mochitest/test_ext_listener_proxies.html
new file mode 100644
index 0000000000..cc161f735f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_listener_proxies.html
@@ -0,0 +1,62 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_listener_proxies() {
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+
+    manifest: {
+      "permissions": ["storage"],
+    },
+
+    async background() {
+      // Test that adding multiple listeners for the same event works as
+      // expected.
+
+      let awaitChanged = () => new Promise(resolve => {
+        browser.storage.onChanged.addListener(function listener() {
+          browser.storage.onChanged.removeListener(listener);
+          resolve();
+        });
+      });
+
+      let promises = [
+        awaitChanged(),
+        awaitChanged(),
+      ];
+
+      function removedListener() {}
+      browser.storage.onChanged.addListener(removedListener);
+      browser.storage.onChanged.removeListener(removedListener);
+
+      promises.push(awaitChanged(), awaitChanged());
+
+      browser.storage.local.set({foo: "bar"});
+
+      await Promise.all(promises);
+
+      browser.test.notifyPass("onchanged-listeners");
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitFinish("onchanged-listeners");
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_new_tab_processType.html b/toolkit/components/extensions/test/mochitest/test_ext_new_tab_processType.html
new file mode 100644
index 0000000000..4561ef1a28
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_new_tab_processType.html
@@ -0,0 +1,152 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Test for opening links in new tabs from extension frames</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function promiseObserved(topic, check) {
+  return new Promise(resolve => {
+    let obs = SpecialPowers.Services.obs;
+
+    function observer(subject, topic, data) {
+      subject = SpecialPowers.wrap(subject);
+      if (check(subject, data)) {
+        obs.removeObserver(observer, topic);
+        resolve({subject, data});
+      }
+    }
+    obs.addObserver(observer, topic);
+  });
+}
+
+add_task(async function test_target_blank_link_no_opener_from_privileged() {
+  const linkURL = "http://example.com/";
+
+  function extension_tab() {
+    document.getElementById("link").click();
+  }
+
+  function content_script() {
+    browser.runtime.sendMessage("content_page_loaded");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "target_blank_link@tests.mozilla.org" } },
+      content_scripts: [{
+        js: ["content_script.js"],
+        matches: ["http://example.com/*"],
+        run_at: "document_idle",
+      }],
+      permissions: ["tabs"],
+    },
+    files: {
+      "page.html": `<!DOCTYPE html>
+        <html>
+          <head><meta charset="utf-8"></html>
+          <body>
+            <a href="${linkURL}" target="_blank" id="link">link</a>
+            <script src="extension_tab.js"><\/script>
+          </body>
+        </html>`,
+      "extension_tab.js": extension_tab,
+      "content_script.js": content_script,
+    },
+    background() {
+      let pageTab;
+      browser.runtime.onMessage.addListener((msg, sender) => {
+        if (sender.tab) {
+          browser.test.sendMessage(msg, sender.tab.url);
+          browser.tabs.remove(sender.tab.id);
+          browser.tabs.remove(pageTab.id);
+        }
+      });
+      pageTab = browser.tabs.create({ url: browser.runtime.getURL("page.html") });
+    },
+  });
+
+  await extension.startup();
+
+  // Make sure page is loaded correctly
+  const url = await extension.awaitMessage("content_page_loaded");
+  is(url, linkURL, "Page URL should match");
+
+  await extension.unload();
+});
+
+add_task(async function test_target_blank_link() {
+  const linkURL = "http://mochi.test:8888/tests/toolkit/";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_security_policy: "script-src 'self' 'unsafe-eval'; object-src 'self';",
+
+      web_accessible_resources: ["iframe.html"],
+    },
+    files: {
+      "iframe.html": `<!DOCTYPE html>
+        <html>
+          <head><meta charset="utf-8"></html>
+          <body>
+            <a href="${linkURL}" target="_blank" id="link" rel="opener">link</a>
+          </body>
+        </html>`,
+    },
+    background() {
+      browser.test.sendMessage("frame_url", browser.runtime.getURL("iframe.html"));
+    },
+  });
+
+  await extension.startup();
+
+  let url = await extension.awaitMessage("frame_url");
+
+  let iframe = document.createElement("iframe");
+  iframe.src = url;
+  document.body.appendChild(iframe);
+  await new Promise(resolve => iframe.addEventListener("load", () => setTimeout(resolve, 0), {once: true}));
+
+  let win = SpecialPowers.wrap(iframe).contentWindow;
+
+  {
+    // Flush layout so that synthesizeMouseAtCenter on a cross-origin iframe
+    // works as expected.
+    document.body.getBoundingClientRect();
+
+    let promise = promiseObserved("document-element-inserted", doc => doc.documentURI === linkURL);
+
+    await SpecialPowers.spawn(iframe, [], async () => {
+      this.content.document.getElementById("link").click();
+    });
+
+    let {subject: doc} = await promise;
+    info("Link opened");
+    doc.defaultView.close();
+    info("Window closed");
+  }
+
+  {
+    let promise = promiseObserved("document-element-inserted", doc => doc.documentURI === linkURL);
+
+    let res = win.eval(`window.open("${linkURL}")`);
+    let {subject: doc} = await promise;
+    is(SpecialPowers.unwrap(res), SpecialPowers.unwrap(doc.defaultView), "window.open worked as expected");
+
+    doc.defaultView.close();
+  }
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_notifications.html b/toolkit/components/extensions/test/mochitest/test_ext_notifications.html
new file mode 100644
index 0000000000..7a91320373
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_notifications.html
@@ -0,0 +1,340 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for notifications</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head_notifications.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+// A 1x1 PNG image.
+// Source: https://commons.wikimedia.org/wiki/File:1x1.png (Public Domain)
+let image = atob("iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAA" +
+                 "ACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=");
+const IMAGE_ARRAYBUFFER = Uint8Array.from(image, byte => byte.charCodeAt(0)).buffer;
+
+add_task(async function setup_mock_alert_service() {
+  await MockAlertsService.register();
+});
+
+add_task(async function test_notification() {
+  async function background() {
+    let opts = {
+      type: "basic",
+      title: "Testing Notification",
+      message: "Carry on",
+    };
+
+    let id = await browser.notifications.create(opts);
+
+    browser.test.sendMessage("running", id);
+    browser.test.notifyPass("background test passed");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    background,
+  });
+  await extension.startup();
+  let x = await extension.awaitMessage("running");
+  is(x, "0", "got correct id from notifications.create");
+  await extension.awaitFinish();
+  await extension.unload();
+});
+
+add_task(async function test_notification_events() {
+  async function background() {
+    let opts = {
+      type: "basic",
+      title: "Testing Notification",
+      message: "Carry on",
+    };
+
+    let createdId = "98";
+
+    // Test an ignored listener.
+    browser.notifications.onButtonClicked.addListener(function() {});
+
+    // We cannot test onClicked listener without a mock
+    // but we can attempt to add a listener.
+    browser.notifications.onClicked.addListener(async function(id) {
+      browser.test.assertEq(createdId, id, "onClicked has the expected ID");
+      browser.test.sendMessage("notification-event", "clicked");
+    });
+
+    browser.notifications.onShown.addListener(async function listener(id) {
+      browser.test.assertEq(createdId, id, "onShown has the expected ID");
+      browser.test.sendMessage("notification-event", "shown");
+    });
+
+    browser.test.onMessage.addListener(async function(msg, expectedCount) {
+      if (msg === "create-again") {
+        let newId = await browser.notifications.create(createdId, opts);
+        browser.test.assertEq(createdId, newId, "create returned the expected id.");
+        browser.test.sendMessage("notification-created-twice");
+      } else if (msg === "check-count") {
+        let notifications = await browser.notifications.getAll();
+        let ids = Object.keys(notifications);
+        browser.test.assertEq(expectedCount, ids.length, `getAll() = ${ids}`);
+        browser.test.sendMessage("check-count-result");
+      }
+    });
+
+    // Test onClosed listener.
+    browser.notifications.onClosed.addListener(function listener(id) {
+      browser.test.assertEq(createdId, id, "onClosed received the expected id.");
+      browser.test.sendMessage("notification-event", "closed");
+    });
+
+    await browser.notifications.create(createdId, opts);
+
+    browser.test.sendMessage("notification-created-once");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  async function waitForNotificationEvent(name) {
+    info(`Waiting for notification event: ${name}`);
+    is(name, await extension.awaitMessage("notification-event"),
+       "Expected notification event");
+  }
+  async function checkNotificationCount(expectedCount) {
+    extension.sendMessage("check-count", expectedCount);
+    await extension.awaitMessage("check-count-result");
+  }
+
+  await extension.awaitMessage("notification-created-once");
+  await waitForNotificationEvent("shown");
+  await checkNotificationCount(1);
+
+  // On most platforms, clicking the notification closes it.
+  // But on macOS, the notification can repeatedly be clicked without closing.
+  await MockAlertsService.clickNotificationsWithoutClose();
+  await waitForNotificationEvent("clicked");
+  await checkNotificationCount(1);
+  await MockAlertsService.clickNotificationsWithoutClose();
+  await waitForNotificationEvent("clicked");
+  await checkNotificationCount(1);
+  await MockAlertsService.clickNotifications();
+  await waitForNotificationEvent("clicked");
+  await waitForNotificationEvent("closed");
+  await checkNotificationCount(0);
+
+  extension.sendMessage("create-again");
+  await extension.awaitMessage("notification-created-twice");
+  await waitForNotificationEvent("shown");
+  await checkNotificationCount(1);
+
+  await MockAlertsService.closeNotifications();
+  await waitForNotificationEvent("closed");
+  await checkNotificationCount(0);
+
+  await extension.unload();
+});
+
+add_task(async function test_notification_clear() {
+  function background() {
+    let opts = {
+      type: "basic",
+      title: "Testing Notification",
+      message: "Carry on",
+    };
+
+    let createdId = "99";
+
+    browser.notifications.onShown.addListener(async id => {
+      browser.test.assertEq(createdId, id, "onShown received the expected id.");
+      let wasCleared = await browser.notifications.clear(id);
+      browser.test.assertTrue(wasCleared, "notifications.clear returned true.");
+    });
+
+    browser.notifications.onClosed.addListener(id => {
+      browser.test.assertEq(createdId, id, "onClosed received the expected id.");
+      browser.test.notifyPass("background test passed");
+    });
+
+    browser.notifications.create(createdId, opts);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    background,
+  });
+
+  await extension.startup();
+  await extension.awaitFinish();
+  await extension.unload();
+});
+
+add_task(async function test_notifications_empty_getAll() {
+  async function background() {
+    let notifications = await browser.notifications.getAll();
+
+    browser.test.assertEq("object", typeof notifications, "getAll() returned an object");
+    browser.test.assertEq(0, Object.keys(notifications).length, "the object has no properties");
+    browser.test.notifyPass("getAll empty");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    background,
+  });
+  await extension.startup();
+  await extension.awaitFinish("getAll empty");
+  await extension.unload();
+});
+
+add_task(async function test_notifications_populated_getAll() {
+  async function background() {
+    let opts = {
+      type: "basic",
+      iconUrl: "a.png",
+      title: "Testing Notification",
+      message: "Carry on",
+    };
+
+    await browser.notifications.create("p1", opts);
+    await browser.notifications.create("p2", opts);
+    let notifications = await browser.notifications.getAll();
+
+    browser.test.assertEq("object", typeof notifications, "getAll() returned an object");
+    browser.test.assertEq(2, Object.keys(notifications).length, "the object has 2 properties");
+
+    for (let notificationId of ["p1", "p2"]) {
+      for (let key of Object.keys(opts)) {
+        browser.test.assertEq(
+          opts[key],
+          notifications[notificationId][key],
+          `the notification has the expected value for option: ${key}`
+        );
+      }
+    }
+
+    browser.test.notifyPass("getAll populated");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    background,
+    files: {
+      "a.png": IMAGE_ARRAYBUFFER,
+    },
+  });
+  await extension.startup();
+  await extension.awaitFinish("getAll populated");
+  await extension.unload();
+});
+
+add_task(async function test_buttons_unsupported() {
+  function background() {
+    let opts = {
+      type: "basic",
+      title: "Testing Notification",
+      message: "Carry on",
+      buttons: [{title: "Button title"}],
+    };
+
+    let exception = {};
+    try {
+      browser.notifications.create(opts);
+    } catch (e) {
+      exception = e;
+    }
+
+    browser.test.assertTrue(
+      String(exception).includes('Property "buttons" is unsupported by Firefox'),
+      "notifications.create with buttons option threw an expected exception"
+    );
+    browser.test.notifyPass("buttons-unsupported");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    background,
+  });
+  await extension.startup();
+  await extension.awaitFinish("buttons-unsupported");
+  await extension.unload();
+});
+
+add_task(async function test_notifications_different_contexts() {
+  async function background() {
+    let opts = {
+      type: "basic",
+      title: "Testing Notification",
+      message: "Carry on",
+    };
+
+    let id = await browser.notifications.create(opts);
+
+    browser.runtime.onMessage.addListener(async (message, sender) => {
+      await browser.tabs.remove(sender.tab.id);
+
+      // We should be able to clear the notification after creating and
+      // destroying the tab.html page.
+      let wasCleared = await browser.notifications.clear(id);
+      browser.test.assertTrue(wasCleared, "The notification was cleared.");
+      browser.test.notifyPass("notifications");
+    });
+
+    browser.tabs.create({url: browser.runtime.getURL("/tab.html")});
+  }
+
+  async function tabScript() {
+    // We should be able to see the notification created in the background page
+    // in this page.
+    let notifications = await browser.notifications.getAll();
+    browser.test.assertEq(1, Object.keys(notifications).length,
+                          "One notification found.");
+    browser.runtime.sendMessage("continue-test");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    background,
+    files: {
+      "tab.js": tabScript,
+      "tab.html": `<!DOCTYPE html><html><head>
+        <meta charset="utf-8">
+        <script src="tab.js"><\/script>
+      </head></html>`,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("notifications");
+  await extension.unload();
+});
+
+add_task(async function teardown_mock_alert_service() {
+  await MockAlertsService.unregister();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_protocolHandlers.html b/toolkit/components/extensions/test/mochitest/test_ext_protocolHandlers.html
new file mode 100644
index 0000000000..10305c8ac0
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_protocolHandlers.html
@@ -0,0 +1,394 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Test for protocol handlers</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+/* eslint-disable mozilla/balanced-listeners */
+/* global addMessageListener, sendAsyncMessage */
+
+function protocolChromeScript() {
+  addMessageListener("setup", () => {
+    let data = {};
+    const protoSvc = Cc["@mozilla.org/uriloader/external-protocol-service;1"]
+                        .getService(Ci.nsIExternalProtocolService);
+    let protoInfo = protoSvc.getProtocolHandlerInfo("ext+foo");
+    data.preferredAction = protoInfo.preferredAction === protoInfo.useHelperApp;
+
+    let handlers = protoInfo.possibleApplicationHandlers;
+    data.handlers = handlers.length;
+
+    let handler = handlers.queryElementAt(0, Ci.nsIHandlerApp);
+    data.isWebHandler = handler instanceof Ci.nsIWebHandlerApp;
+    data.uriTemplate =  handler.uriTemplate;
+
+    // ext+ protocols should be set as default when there is only one
+    data.preferredApplicationHandler = protoInfo.preferredApplicationHandler == handler;
+    data.alwaysAskBeforeHandling = protoInfo.alwaysAskBeforeHandling;
+    const handlerSvc = Cc["@mozilla.org/uriloader/handler-service;1"]
+                          .getService(Ci.nsIHandlerService);
+    handlerSvc.store(protoInfo);
+
+    sendAsyncMessage("handlerData", data);
+  });
+}
+
+add_task(async function test_protocolHandler() {
+  await SpecialPowers.pushPrefEnv({set: [
+    ["extensions.allowPrivateBrowsingByDefault", false],
+    // Disabling the external protocol permission prompt. We don't need it
+    // for this test.
+    ["security.external_protocol_requires_permission", false],
+  ]});
+  let extensionData = {
+    manifest: {
+      "protocol_handlers": [
+        {
+          "protocol": "ext+foo",
+          "name": "a foo protocol handler",
+          "uriTemplate": "foo.html?val=%s",
+        },
+      ],
+    },
+
+    background() {
+      browser.test.onMessage.addListener(async (msg, arg) => {
+        if (msg == "open") {
+          let tab = await browser.tabs.create({url: arg});
+          browser.test.sendMessage("opened", tab.id);
+        } else if (msg == "close") {
+          await browser.tabs.remove(arg);
+          browser.test.sendMessage("closed");
+        }
+      });
+      browser.test.sendMessage("test-url", browser.runtime.getURL("foo.html"));
+    },
+
+    files: {
+      "foo.js": function() {
+        browser.test.sendMessage("test-query", location.search);
+      },
+      "foo.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="foo.js"><\/script>
+          </head>
+        </html>`,
+    },
+  };
+
+  let pb_extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.onMessage.addListener(async (msg, arg) => {
+        if (msg == "open") {
+          let win = await browser.windows.create({ url: arg, incognito: true });
+          browser.test.sendMessage("opened", { windowId: win.id, tabId: win.tabs[0].id });
+        } else if(msg == "nav") {
+          await browser.tabs.update(arg.tabId, { url: arg.url })
+          browser.test.sendMessage("navigated");
+        } else if (msg == "close") {
+          await browser.windows.remove(arg);
+          browser.test.sendMessage("closed");
+        }
+      });
+    },
+    incognitoOverride: "spanning",
+  });
+  await pb_extension.startup();
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let handlerUrl = await extension.awaitMessage("test-url");
+
+  // Ensure that the protocol handler is configured, and set it as default to
+  // bypass the dialog.
+  let chromeScript = SpecialPowers.loadChromeScript(protocolChromeScript);
+
+  let msg = chromeScript.promiseOneMessage("handlerData");
+  chromeScript.sendAsyncMessage("setup");
+  let data = await msg;
+  ok(data.preferredAction, "using a helper application is the preferred action");
+  ok(data.preferredApplicationHandler, "handler was set as default handler");
+  is(data.handlers, 1, "one handler is set");
+  ok(!data.alwaysAskBeforeHandling, "will not show dialog");
+  ok(data.isWebHandler, "the handler is a web handler");
+  is(data.uriTemplate, `${handlerUrl}?val=%s`, "correct url template");
+  chromeScript.destroy();
+
+  extension.sendMessage("open", "ext+foo:test");
+  let id = await extension.awaitMessage("opened");
+
+  let query = await extension.awaitMessage("test-query");
+  is(query, "?val=ext%2Bfoo%3Atest", "test query ok");
+
+  extension.sendMessage("close", id);
+  await extension.awaitMessage("closed");
+
+  // Test the protocol in a private window, watch for the
+  // console error.
+  consoleMonitor.start([{message: /NS_ERROR_FILE_NOT_FOUND/}]);
+
+  // Expect the chooser window to be open, close it.
+  chromeScript = SpecialPowers.loadChromeScript(async () => {
+    const CONTENT_HANDLING_URL = "chrome://mozapps/content/handling/appChooser.xhtml";
+    const {BrowserTestUtils} = ChromeUtils.import("resource://testing-common/BrowserTestUtils.jsm");
+
+    let windowOpen = BrowserTestUtils.domWindowOpenedAndLoaded();
+
+    sendAsyncMessage("listenWindow");
+
+    let window = await windowOpen;
+    let gBrowser = window.gBrowser
+    let tabDialogBox = gBrowser.getTabDialogBox(gBrowser.selectedBrowser);
+    let dialogStack = tabDialogBox.getTabDialogManager()._dialogStack;
+
+    let checkFn = dialogEvent =>
+      dialogEvent.detail.dialog?._openedURL == CONTENT_HANDLING_URL;
+
+    let eventPromise = BrowserTestUtils.waitForEvent(
+      dialogStack,
+      "dialogopen",
+      true,
+      checkFn
+    );
+
+    sendAsyncMessage("listenDialog");
+
+    let event = await eventPromise;
+
+    let { dialog } = event.detail;
+
+    let entry =  dialog._frame.contentDocument.getElementById("items").firstChild;
+    sendAsyncMessage("handling", {name: entry.getAttribute("name"), disabled: entry.disabled});
+
+    dialog.close();
+  });
+
+  // Wait for the chrome script to attach window listener
+  await chromeScript.promiseOneMessage("listenWindow");
+
+  let listenDialog = chromeScript.promiseOneMessage("listenDialog");
+  let windowOpen =  pb_extension.awaitMessage("opened");
+
+  pb_extension.sendMessage("open", "ext+foo:test");
+
+  // Wait for chrome script to attach dialog listener
+  await listenDialog;
+  let {tabId, windowId} = await windowOpen;
+
+  let testData = chromeScript.promiseOneMessage("handling");
+  let navPromise = pb_extension.awaitMessage("navigated");
+  pb_extension.sendMessage("nav", {url: "ext+foo:test", tabId});
+  await navPromise;
+  await consoleMonitor.finished();
+  let entry = await testData;
+
+  is(entry.name, "a foo protocol handler", "entry is correct");
+  ok(entry.disabled, "handler is disabled");
+
+  let promiseClosed = pb_extension.awaitMessage("closed");
+  pb_extension.sendMessage("close", windowId);
+  await promiseClosed;
+  await pb_extension.unload();
+
+  // Shutdown the addon, then ensure the protocol was removed.
+  await extension.unload();
+  chromeScript = SpecialPowers.loadChromeScript(() => {
+    addMessageListener("setup", () => {
+      const protoSvc = Cc["@mozilla.org/uriloader/external-protocol-service;1"]
+                         .getService(Ci.nsIExternalProtocolService);
+      let protoInfo = protoSvc.getProtocolHandlerInfo("ext+foo");
+      sendAsyncMessage("preferredApplicationHandler", !protoInfo.preferredApplicationHandler);
+      let handlers = protoInfo.possibleApplicationHandlers;
+
+      sendAsyncMessage("handlerData", {
+        preferredApplicationHandler: !protoInfo.preferredApplicationHandler,
+        handlers: handlers.length,
+      });
+    });
+  });
+
+  msg = chromeScript.promiseOneMessage("handlerData");
+  chromeScript.sendAsyncMessage("setup");
+  data = await msg;
+  ok(data.preferredApplicationHandler, "no preferred handler is set");
+  is(data.handlers, 0, "no handler is set");
+  chromeScript.destroy();
+});
+
+add_task(async function test_protocolHandler_two() {
+  let extensionData = {
+    manifest: {
+      "protocol_handlers": [
+        {
+          "protocol": "ext+foo",
+          "name": "a foo protocol handler",
+          "uriTemplate": "foo.html?val=%s",
+        },
+        {
+          "protocol": "ext+foo",
+          "name": "another foo protocol handler",
+          "uriTemplate": "foo2.html?val=%s",
+        },
+      ],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  // Ensure that the protocol handler is configured, and set it as default,
+  // but because there are two handlers, the dialog is not bypassed.  We
+  // don't test the actual dialog ui, it's been here forever and works based
+  // on the alwaysAskBeforeHandling value.
+  let chromeScript = SpecialPowers.loadChromeScript(protocolChromeScript);
+
+  let msg = chromeScript.promiseOneMessage("handlerData");
+  chromeScript.sendAsyncMessage("setup");
+  let data = await msg;
+  ok(data.preferredAction, "using a helper application is the preferred action");
+  ok(data.preferredApplicationHandler, "preferred handler is set");
+  is(data.handlers, 2, "two handlers are set");
+  ok(data.alwaysAskBeforeHandling, "will show dialog");
+  ok(data.isWebHandler, "the handler is a web handler");
+  chromeScript.destroy();
+  await extension.unload();
+});
+
+add_task(async function test_protocolHandler_https_target() {
+  let extensionData = {
+    manifest: {
+      "protocol_handlers": [
+        {
+          "protocol": "ext+foo",
+          "name": "http target",
+          "uriTemplate": "https://example.com/foo.html?val=%s",
+        },
+      ],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  ok(true, "https uriTemplate target works");
+  await extension.unload();
+});
+
+add_task(async function test_protocolHandler_http_target() {
+  let extensionData = {
+    manifest: {
+      "protocol_handlers": [
+        {
+          "protocol": "ext+foo",
+          "name": "http target",
+          "uriTemplate": "http://example.com/foo.html?val=%s",
+        },
+      ],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  ok(true, "http uriTemplate target works");
+  await extension.unload();
+});
+
+add_task(async function test_protocolHandler_restricted_protocol() {
+  let extensionData = {
+    manifest: {
+      "protocol_handlers": [
+        {
+          "protocol": "http",
+          "name": "take over the http protocol",
+          "uriTemplate": "http.html?val=%s",
+        },
+      ],
+    },
+  };
+
+  consoleMonitor.start([{message: /processing protocol_handlers\.0\.protocol/}]);
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await Assert.rejects(extension.startup(),
+                       /startup failed/,
+                       "unable to register restricted handler protocol");
+
+  await consoleMonitor.finished();
+});
+
+add_task(async function test_protocolHandler_restricted_uriTemplate() {
+  let extensionData = {
+    manifest: {
+      "protocol_handlers": [
+        {
+          "protocol": "ext+foo",
+          "name": "take over the http protocol",
+          "uriTemplate": "ftp://example.com/file.txt",
+        },
+      ],
+    },
+  };
+
+  consoleMonitor.start([{message: /processing protocol_handlers\.0\.uriTemplate/}]);
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await Assert.rejects(extension.startup(),
+                       /startup failed/,
+                       "unable to register restricted handler uriTemplate");
+
+  await consoleMonitor.finished();
+});
+
+add_task(async function test_protocolHandler_duplicate() {
+  let extensionData = {
+    manifest: {
+      "protocol_handlers": [
+        {
+          "protocol": "ext+foo",
+          "name": "foo protocol",
+          "uriTemplate": "foo.html?val=%s",
+        },
+        {
+          "protocol": "ext+foo",
+          "name": "foo protocol",
+          "uriTemplate": "foo.html?val=%s",
+        },
+      ],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  // Get the count of handlers installed.
+  let chromeScript = SpecialPowers.loadChromeScript(() => {
+    addMessageListener("setup", () => {
+      const protoSvc = Cc["@mozilla.org/uriloader/external-protocol-service;1"]
+                         .getService(Ci.nsIExternalProtocolService);
+      let protoInfo = protoSvc.getProtocolHandlerInfo("ext+foo");
+      let handlers = protoInfo.possibleApplicationHandlers;
+      sendAsyncMessage("handlerData", handlers.length);
+    });
+  });
+
+  let msg = chromeScript.promiseOneMessage("handlerData");
+  chromeScript.sendAsyncMessage("setup");
+  let data = await msg;
+  is(data, 1, "cannot re-register the same handler config");
+  chromeScript.destroy();
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_redirect_jar.html b/toolkit/components/extensions/test/mochitest/test_ext_redirect_jar.html
new file mode 100644
index 0000000000..24dc737982
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_redirect_jar.html
@@ -0,0 +1,92 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script>
+"use strict";
+
+function getExtension() {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      "applications": {
+        "gecko": {
+          "id": "redirect-to-jar@mochi.test",
+        },
+      },
+      "permissions": [
+        "webRequest",
+        "webRequestBlocking",
+        "<all_urls>",
+      ],
+      "web_accessible_resources": [
+        "finished.html",
+      ],
+    },
+    useAddonManager: "temporary",
+    files: {
+      "finished.html": `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+          </head>
+          <body>
+            <h1>redirected!</h1>
+          </body>
+        </html>
+      `,
+    },
+    background: async () => {
+      let redirectUrl = browser.extension.getURL("finished.html");
+      browser.webRequest.onBeforeRequest.addListener(details => {
+        return {redirectUrl};
+      }, {urls: ["*://*/intercept*"]}, ["blocking"]);
+
+      let code = `new Promise(resolve => {
+            var s = document.createElement('iframe');
+            s.src = "/intercept?r=" + Math.random();
+            s.onload = async () => {
+                let url = await window.wrappedJSObject.SpecialPowers.spawn(s, [], () => content.location.href );
+              resolve(['loaded', url]);
+            }
+            s.onerror = () => resolve(['error']);
+            document.documentElement.appendChild(s);
+          });`;
+
+      async function testSubFrameResource(tabId, code) {
+        let [result] = await browser.tabs.executeScript(tabId, { code });
+        return result;
+      }
+
+      let tab = await browser.tabs.create({url: "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_sample.html"});
+      let result = await testSubFrameResource(tab.id, code);
+      browser.test.assertEq("loaded", result[0], "frame 1 loaded");
+      browser.test.assertEq(redirectUrl, result[1], "frame 1 redirected");
+      // If jar caching breaks redirects, this next test will fail (See Bug 1390346).
+      result = await testSubFrameResource(tab.id, code);
+      browser.test.assertEq("loaded", result[0], "frame 2 loaded");
+      browser.test.assertEq(redirectUrl, result[1], "frame 2 redirected");
+      await browser.tabs.remove(tab.id);
+      browser.test.sendMessage("requestsCompleted");
+    },
+  });
+}
+
+add_task(async function test_redirect_to_jar() {
+  let extension = getExtension();
+  await extension.startup();
+  await extension.awaitMessage("requestsCompleted");
+  await extension.unload();
+});
+
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_request_urlClassification.html b/toolkit/components/extensions/test/mochitest/test_ext_request_urlClassification.html
new file mode 100644
index 0000000000..d9a85ad8e4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_request_urlClassification.html
@@ -0,0 +1,129 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for WebRequest urlClassification</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function setup() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["privacy.trackingprotection.enabled", true]],
+  });
+
+  let chromeScript = SpecialPowers.loadChromeScript(async _ => {
+    const {UrlClassifierTestUtils} = ChromeUtils.import("resource://testing-common/UrlClassifierTestUtils.jsm");
+    await UrlClassifierTestUtils.addTestTrackers();
+    sendAsyncMessage("trackersLoaded");
+  });
+  await chromeScript.promiseOneMessage("trackersLoaded");
+  chromeScript.destroy();
+});
+
+add_task(async function test_urlClassification() {
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: {gecko: {id: "classification@mochi.test"}},
+      permissions: ["webRequest", "webRequestBlocking", "proxy", "<all_urls>"],
+    },
+    background() {
+      let expected = {
+        "http://tracking.example.org/": {first: "tracking", thirdParty: false, },
+        "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_third_party.html?domain=tracking.example.org": { thirdParty: false, },
+        "http://tracking.example.org/tests/toolkit/components/extensions/test/mochitest/file_image_bad.png": {third: "tracking", thirdParty: true, },
+        "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_third_party.html?domain=example.net": { thirdParty: false, },
+        "http://example.net/tests/toolkit/components/extensions/test/mochitest/file_image_bad.png": { thirdParty: true, },
+      };
+      function testRequest(details) {
+        let expect = expected[details.url];
+        if (expect) {
+          if (expect.first) {
+            browser.test.assertTrue(details.urlClassification.firstParty.includes("tracking"), "tracking firstParty");
+          } else {
+            browser.test.assertEq(details.urlClassification.firstParty.length, 0, "not tracking firstParty");
+          }
+          if (expect.third) {
+            browser.test.assertTrue(details.urlClassification.thirdParty.includes("tracking"), "tracking thirdParty");
+          } else {
+            browser.test.assertEq(details.urlClassification.thirdParty.length, 0, "not tracking thirdParty");
+          }
+
+          browser.test.assertEq(details.thirdParty, expect.thirdParty, "3rd party flag matches");
+          return true;
+        }
+        return false;
+      }
+
+      browser.proxy.onRequest.addListener(details => {
+        browser.test.log(`proxy.onRequest ${JSON.stringify(details)}`);
+        testRequest(details);
+      }, {urls: ["http://mochi.test/tests/*", "http://tracking.example.org/*", "http://example.net/*"]});
+      browser.webRequest.onBeforeRequest.addListener(async (details) => {
+        browser.test.log(`webRequest.onBeforeRequest ${JSON.stringify(details)}`);
+        testRequest(details);
+      }, {urls: ["http://mochi.test/tests/*", "http://tracking.example.org/*", "http://example.net/*"]}, ["blocking"]);
+      browser.webRequest.onCompleted.addListener(async (details) => {
+        browser.test.log(`webRequest.onCompleted ${JSON.stringify(details)}`);
+        if (testRequest(details)) {
+          browser.test.sendMessage("classification", details.url);
+        }
+      }, {urls: ["http://mochi.test/tests/*", "http://tracking.example.org/*", "http://example.net/*"]});
+    },
+  });
+  await extension.startup();
+
+  // Test first party tracking classification.
+  let url = "http://tracking.example.org/";
+  let win = window.open(url);
+  is(await extension.awaitMessage("classification"), url, "request completed");
+  win.close();
+
+  // Test third party tracking classification, expecting two results.
+  url = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_third_party.html?domain=tracking.example.org";
+  win = window.open(url);
+  is(await extension.awaitMessage("classification"), url);
+  is(await extension.awaitMessage("classification"),
+     "http://tracking.example.org/tests/toolkit/components/extensions/test/mochitest/file_image_bad.png",
+     "request completed");
+  win.close();
+
+  // Test third party tracking classification, expecting two results.
+  url = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_third_party.html?domain=example.net";
+  win = window.open(url);
+  is(await extension.awaitMessage("classification"), url);
+  is(await extension.awaitMessage("classification"),
+     "http://example.net/tests/toolkit/components/extensions/test/mochitest/file_image_bad.png",
+     "request completed");
+  win.close();
+
+  await extension.unload();
+});
+
+add_task(async function teardown() {
+  let chromeScript = SpecialPowers.loadChromeScript(async _ => {
+    // Cleanup cache
+    await new Promise(resolve => {
+      const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+      Services.clearData.deleteData(Ci.nsIClearDataService.CLEAR_ALL, value => resolve());
+    });
+
+    /* global sendAsyncMessage */
+    const {UrlClassifierTestUtils} = ChromeUtils.import("resource://testing-common/UrlClassifierTestUtils.jsm");
+    await UrlClassifierTestUtils.cleanupTestTrackers();
+    sendAsyncMessage("trackersUnloaded");
+  });
+  await chromeScript.promiseOneMessage("trackersUnloaded");
+  chromeScript.destroy();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect.html b/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect.html
new file mode 100644
index 0000000000..c4726092ec
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect.html
@@ -0,0 +1,82 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function background() {
+  browser.runtime.onConnect.addListener(port => {
+    browser.test.assertEq(port.name, "ernie", "port name correct");
+    browser.test.assertTrue(port.sender.url.endsWith("file_sample.html"), "URL correct");
+    browser.test.assertTrue(port.sender.tab.url.endsWith("file_sample.html"), "tab URL correct");
+
+    let expected = "message 1";
+    port.onMessage.addListener(msg => {
+      browser.test.assertEq(msg, expected, "message is expected");
+      if (expected == "message 1") {
+        port.postMessage("message 2");
+        expected = "message 3";
+      } else if (expected == "message 3") {
+        expected = "disconnect";
+        browser.test.notifyPass("runtime.connect");
+      }
+    });
+    port.onDisconnect.addListener(() => {
+      browser.test.assertEq(null, port.error, "No error because port is closed by disconnect() at other end");
+      browser.test.assertEq(expected, "disconnect", "got disconnection at right time");
+    });
+  });
+}
+
+function contentScript() {
+  let port = browser.runtime.connect({name: "ernie"});
+  port.postMessage("message 1");
+  port.onMessage.addListener(msg => {
+    if (msg == "message 2") {
+      port.postMessage("message 3");
+      port.disconnect();
+    }
+  });
+}
+
+let extensionData = {
+  background,
+  manifest: {
+    "permissions": ["tabs"],
+    "content_scripts": [{
+      "matches": ["http://mochi.test/*/file_sample.html"],
+      "js": ["content_script.js"],
+      "run_at": "document_start",
+    }],
+  },
+
+  files: {
+    "content_script.js": contentScript,
+  },
+};
+
+add_task(async function test_contentscript() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+
+  await Promise.all([waitForLoad(win), extension.awaitFinish("runtime.connect")]);
+
+  win.close();
+
+  await extension.unload();
+  info("extension unloaded");
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect2.html b/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect2.html
new file mode 100644
index 0000000000..13b9029c48
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect2.html
@@ -0,0 +1,102 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function backgroundScript(token) {
+  browser.runtime.onMessage.addListener(msg => {
+    browser.test.assertEq(msg, "done");
+    browser.test.notifyPass("sendmessage_reply");
+  });
+
+  browser.runtime.onConnect.addListener(port => {
+    browser.test.assertTrue(port.sender.url.endsWith("file_sample.html"), "sender url correct");
+    browser.test.assertTrue(port.sender.tab.url.endsWith("file_sample.html"), "sender url correct");
+
+    let tabId = port.sender.tab.id;
+    browser.tabs.connect(tabId, {name: token});
+
+    browser.test.assertEq(port.name, token, "token matches");
+    port.postMessage(token + "-done");
+  });
+
+  browser.test.sendMessage("background-ready");
+}
+
+function contentScript(token) {
+  let gotTabMessage = false;
+  let badTabMessage = false;
+  browser.runtime.onConnect.addListener(port => {
+    if (port.name == token) {
+      gotTabMessage = true;
+    } else {
+      badTabMessage = true;
+    }
+    port.disconnect();
+  });
+
+  let port = browser.runtime.connect(null, {name: token});
+  port.onMessage.addListener(function(msg) {
+    if (msg != token + "-done" || !gotTabMessage || badTabMessage) {
+      return; // test failed
+    }
+
+    // FIXME: Removing this line causes the test to fail:
+    // resource://gre/modules/ExtensionUtils.jsm, line 651: NS_ERROR_NOT_INITIALIZED
+    port.disconnect();
+    browser.runtime.sendMessage("done");
+  });
+}
+
+function makeExtension() {
+  let token = Math.random();
+  let extensionData = {
+    background: `(${backgroundScript})("${token}")`,
+    manifest: {
+      "permissions": ["tabs"],
+      "content_scripts": [{
+        "matches": ["http://mochi.test/*/file_sample.html"],
+        "js": ["content_script.js"],
+        "run_at": "document_idle",
+      }],
+    },
+
+    files: {
+      "content_script.js": `(${contentScript})("${token}")`,
+    },
+  };
+  return extensionData;
+}
+
+add_task(async function test_contentscript() {
+  let extension1 = ExtensionTestUtils.loadExtension(makeExtension());
+  let extension2 = ExtensionTestUtils.loadExtension(makeExtension());
+  await Promise.all([extension1.startup(), extension2.startup()]);
+
+  await extension1.awaitMessage("background-ready");
+  await extension2.awaitMessage("background-ready");
+
+  let win = window.open("file_sample.html");
+
+  await Promise.all([waitForLoad(win),
+                     extension1.awaitFinish("sendmessage_reply"),
+                     extension2.awaitFinish("sendmessage_reply")]);
+
+  win.close();
+
+  await extension1.unload();
+  await extension2.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect_twoway.html b/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect_twoway.html
new file mode 100644
index 0000000000..b671cba23d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_runtime_connect_twoway.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+
+<script>
+"use strict";
+
+add_task(async function test_connect_bidirectionally_and_postMessage() {
+  function background() {
+    let onConnectCount = 0;
+    browser.runtime.onConnect.addListener(port => {
+      // 3. onConnect by connect() from CS.
+      browser.test.assertEq("from-cs", port.name);
+      browser.test.assertEq(1, ++onConnectCount,
+                            "BG onConnect should be called once");
+
+      let tabId = port.sender.tab.id;
+      browser.test.assertTrue(tabId, "content script must have a tab ID");
+
+      let port2;
+      let postMessageCount1 = 0;
+      port.onMessage.addListener(msg => {
+        // 11. port.onMessage by port.postMessage in CS.
+        browser.test.assertEq("from CS to port", msg);
+        browser.test.assertEq(1, ++postMessageCount1,
+                              "BG port.onMessage should be called once");
+
+        // 12. should trigger port2.onMessage in CS.
+        port2.postMessage("from BG to port2");
+      });
+
+      // 4. Should trigger onConnect in CS.
+      port2 = browser.tabs.connect(tabId, {name: "from-bg"});
+      let postMessageCount2 = 0;
+      port2.onMessage.addListener(msg => {
+        // 7. onMessage by port2.postMessage in CS.
+        browser.test.assertEq("from CS to port2", msg);
+        browser.test.assertEq(1, ++postMessageCount2,
+                              "BG port2.onMessage should be called once");
+
+        // 8. Should trigger port.onMessage in CS.
+        port.postMessage("from BG to port");
+      });
+    });
+
+    // 1. Notify test runner to create a new tab.
+    browser.test.sendMessage("ready");
+  }
+
+  function contentScript() {
+    let onConnectCount = 0;
+    let port;
+    browser.runtime.onConnect.addListener(port2 => {
+      // 5. onConnect by connect() from BG.
+      browser.test.assertEq("from-bg", port2.name);
+      browser.test.assertEq(1, ++onConnectCount,
+                            "CS onConnect should be called once");
+
+      let postMessageCount2 = 0;
+      port2.onMessage.addListener(msg => {
+        // 12. port2.onMessage by port2.postMessage in BG.
+        browser.test.assertEq("from BG to port2", msg);
+        browser.test.assertEq(1, ++postMessageCount2,
+                              "CS port2.onMessage should be called once");
+
+        // TODO(robwu): Do not explicitly disconnect, it should not be a problem
+        // if we keep the ports open. However, not closing the ports causes the
+        // test to fail with NS_ERROR_NOT_INITIALIZED in ExtensionUtils.jsm, in
+        // Port.prototype.disconnect (nsIMessageSender.sendAsyncMessage).
+        port.disconnect();
+        port2.disconnect();
+        browser.test.notifyPass("ping pong done");
+      });
+      // 6. should trigger port2.onMessage in BG.
+      port2.postMessage("from CS to port2");
+    });
+
+    // 2. should trigger onConnect in BG.
+    port = browser.runtime.connect({name: "from-cs"});
+    let postMessageCount1 = 0;
+    port.onMessage.addListener(msg => {
+      // 9. onMessage by port.postMessage in BG.
+      browser.test.assertEq("from BG to port", msg);
+      browser.test.assertEq(1, ++postMessageCount1,
+                            "CS port.onMessage should be called once");
+
+      // 10. should trigger port.onMessage in BG.
+      port.postMessage("from CS to port");
+    });
+  }
+
+  let extensionData = {
+    background,
+    manifest: {
+      content_scripts: [{
+        js: ["contentscript.js"],
+        matches: ["http://mochi.test/*/file_sample.html"],
+      }],
+    },
+    files: {
+      "contentscript.js": contentScript,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  info("extension loaded");
+
+  await extension.awaitMessage("ready");
+
+  let win = window.open("file_sample.html");
+  await extension.awaitFinish("ping pong done");
+  win.close();
+
+  await extension.unload();
+  info("extension unloaded");
+});
+</script>
+</body>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_runtime_disconnect.html b/toolkit/components/extensions/test/mochitest/test_ext_runtime_disconnect.html
new file mode 100644
index 0000000000..f18190bf8b
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_runtime_disconnect.html
@@ -0,0 +1,77 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function background() {
+  browser.runtime.onConnect.addListener(port => {
+    browser.test.assertEq(port.name, "ernie", "port name correct");
+    port.onDisconnect.addListener(() => {
+      browser.test.assertEq(null, port.error, "The port is implicitly closed without errors when the other context unloads");
+      // Closing an already-disconnected port is a no-op.
+      port.disconnect();
+      port.disconnect();
+      browser.test.sendMessage("disconnected");
+    });
+    browser.test.sendMessage("connected");
+  });
+}
+
+function contentScript() {
+  browser.runtime.connect({name: "ernie"});
+}
+
+let extensionData = {
+  background,
+  manifest: {
+    "permissions": ["tabs"],
+    "content_scripts": [{
+      "matches": ["http://mochi.test/*/file_sample.html"],
+      "js": ["content_script.js"],
+      "run_at": "document_idle",
+    }],
+  },
+
+  files: {
+    "content_script.js": contentScript,
+  },
+};
+
+add_task(async function test_contentscript() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+  await Promise.all([waitForLoad(win), extension.awaitMessage("connected")]);
+  win.close();
+  await extension.awaitMessage("disconnected");
+
+  info("win.close() succeeded");
+
+  win = window.open("file_sample.html");
+  await Promise.all([waitForLoad(win), extension.awaitMessage("connected")]);
+
+  // Add an "unload" listener so that we don't put the window in the
+  // bfcache. This way it gets destroyed immediately upon navigation.
+  win.addEventListener("unload", function() {}); // eslint-disable-line mozilla/balanced-listeners
+
+  win.location = "http://example.com";
+  await extension.awaitMessage("disconnected");
+  win.close();
+
+  await extension.unload();
+  info("extension unloaded");
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_doublereply.html b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_doublereply.html
new file mode 100644
index 0000000000..ffdbc90efb
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_doublereply.html
@@ -0,0 +1,100 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function background() {
+  // Add two listeners that both send replies. We're supposed to ignore all but one
+  // of them. Which one is chosen is non-deterministic.
+
+  browser.runtime.onMessage.addListener((msg, sender, sendReply) => {
+    browser.test.assertTrue(sender.tab.url.endsWith("file_sample.html"), "sender url correct");
+
+    if (msg == "getreply") {
+      sendReply("reply1");
+    }
+  });
+
+  browser.runtime.onMessage.addListener((msg, sender, sendReply) => {
+    browser.test.assertTrue(sender.tab.url.endsWith("file_sample.html"), "sender url correct");
+
+    if (msg == "getreply") {
+      sendReply("reply2");
+    }
+  });
+
+  function sleep(callback, n = 10) {
+    if (n == 0) {
+      callback();
+    } else {
+      setTimeout(function() { sleep(callback, n - 1); }, 0);
+    }
+  }
+
+  let done_count = 0;
+  browser.runtime.onMessage.addListener((msg, sender, sendReply) => {
+    browser.test.assertTrue(sender.tab.url.endsWith("file_sample.html"), "sender url correct");
+
+    if (msg == "done") {
+      done_count++;
+      browser.test.assertEq(done_count, 1, "got exactly one reply");
+
+      // Go through the event loop a few times to make sure we don't get multiple replies.
+      sleep(function() {
+        browser.test.notifyPass("sendmessage_doublereply");
+      });
+    }
+  });
+}
+
+function contentScript() {
+  browser.runtime.sendMessage("getreply", function(resp) {
+    if (resp != "reply1" && resp != "reply2") {
+      return; // test failed
+    }
+    browser.runtime.sendMessage("done");
+  });
+}
+
+let extensionData = {
+  background,
+  manifest: {
+    "permissions": ["tabs"],
+    "content_scripts": [{
+      "matches": ["http://mochi.test/*/file_sample.html"],
+      "js": ["content_script.js"],
+      "run_at": "document_start",
+    }],
+  },
+
+  files: {
+    "content_script.js": contentScript,
+  },
+};
+
+add_task(async function test_contentscript() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+
+  await Promise.all([waitForLoad(win), extension.awaitFinish("sendmessage_doublereply")]);
+
+  win.close();
+
+  await extension.unload();
+  info("extension unloaded");
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_frameId.html b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_frameId.html
new file mode 100644
index 0000000000..ca151b0216
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_frameId.html
@@ -0,0 +1,49 @@
+<!doctype html>
+<head>
+  <title>Test sendMessage frameId</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+</head>
+<script>
+"use strict";
+
+add_task(async function test_sendMessage_frameId() {
+  const html = `<!doctype html><meta charset="utf-8"><script src="script.js"><\/script>`;
+
+  const extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "send_message_frame_id@tests.mozilla.org" } },
+    },
+    background() {
+      browser.runtime.onMessage.addListener((msg, sender) => {
+        browser.test.sendMessage(msg, sender);
+      });
+      browser.tabs.create({url: "tab.html"});
+    },
+    files: {
+      "iframe.html": html,
+      "tab.html": `${html}<iframe src="iframe.html"></iframe>`,
+      "script.js": () => {
+        browser.runtime.sendMessage(window.top === window ? "tab" : "iframe");
+      },
+    },
+  });
+
+  await extension.startup();
+
+  const tab = await extension.awaitMessage("tab");
+  ok(tab.url.endsWith("tab.html"), "Got the message from the tab");
+  is(tab.frameId, 0, "And sender.frameId is zero");
+
+  const iframe = await extension.awaitMessage("iframe");
+  ok(iframe.url.endsWith("iframe.html"), "Got the message from the iframe");
+  is(typeof iframe.frameId, "number", "With sender.frameId of type number");
+  ok(iframe.frameId > 0, "And sender.frameId greater than zero");
+
+  await extension.unload();
+});
+
+</script>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_no_receiver.html b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_no_receiver.html
new file mode 100644
index 0000000000..970de26528
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_no_receiver.html
@@ -0,0 +1,82 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+<script>
+"use strict";
+
+function loadContentScriptExtension(contentScript) {
+  let extensionData = {
+    manifest: {
+      "content_scripts": [{
+        "js": ["contentscript.js"],
+        "matches": ["http://mochi.test/*/file_sample.html"],
+      }],
+    },
+    files: {
+      "contentscript.js": contentScript,
+    },
+  };
+  return ExtensionTestUtils.loadExtension(extensionData);
+}
+
+add_task(async function test_content_script_sendMessage_without_listener() {
+  async function contentScript() {
+    await browser.test.assertRejects(
+      browser.runtime.sendMessage("msg"),
+      "Could not establish connection. Receiving end does not exist.");
+
+    browser.test.notifyPass("sendMessage callback was invoked");
+  }
+
+  let extension = loadContentScriptExtension(contentScript);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+  await extension.awaitFinish("sendMessage callback was invoked");
+  win.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_content_script_chrome_sendMessage_without_listener() {
+  function contentScript() {
+    /* globals chrome */
+    browser.test.assertEq(null, chrome.runtime.lastError, "no lastError before call");
+    let retval = chrome.runtime.sendMessage("msg");
+    browser.test.assertEq(null, chrome.runtime.lastError, "no lastError after call");
+    // TODO(robwu): Fix the implementation and uncomment the next expectation.
+    // When content script APIs are schema-based (bugzil.la/1287007) this bug will be fixed for free.
+    // browser.test.assertEq(undefined, retval, "return value of chrome.runtime.sendMessage without callback");
+    browser.test.assertTrue(retval instanceof Promise, "TODO: chrome.runtime.sendMessage should return undefined, not a promise");
+
+    let isAsyncCall = false;
+    retval = chrome.runtime.sendMessage("msg", reply => {
+      browser.test.assertEq(undefined, reply, "no reply");
+      browser.test.assertTrue(isAsyncCall, "chrome.runtime.sendMessage's callback must be called asynchronously");
+      browser.test.assertEq(undefined, retval, "return value of chrome.runtime.sendMessage with callback");
+      browser.test.assertEq("Could not establish connection. Receiving end does not exist.", chrome.runtime.lastError.message);
+      browser.test.notifyPass("finished chrome.runtime.sendMessage");
+    });
+    isAsyncCall = true;
+  }
+
+  let extension = loadContentScriptExtension(contentScript);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+  await extension.awaitFinish("finished chrome.runtime.sendMessage");
+  win.close();
+
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_reply.html b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_reply.html
new file mode 100644
index 0000000000..a7f6314efd
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_reply.html
@@ -0,0 +1,78 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function background() {
+  browser.runtime.onMessage.addListener((msg, sender, sendReply) => {
+    browser.test.assertTrue(sender.tab.url.endsWith("file_sample.html"), "sender url correct");
+
+    if (msg == 0) {
+      sendReply("reply1");
+    } else if (msg == 1) {
+      window.setTimeout(function() {
+        sendReply("reply2");
+      }, 0);
+      return true;
+    } else if (msg == 2) {
+      browser.test.notifyPass("sendmessage_reply");
+    }
+  });
+}
+
+function contentScript() {
+  browser.runtime.sendMessage(0, function(resp1) {
+    if (resp1 != "reply1") {
+      return; // test failed
+    }
+    browser.runtime.sendMessage(1, function(resp2) {
+      if (resp2 != "reply2") {
+        return; // test failed
+      }
+      browser.runtime.sendMessage(2);
+    });
+  });
+}
+
+let extensionData = {
+  background,
+  manifest: {
+    "permissions": ["tabs"],
+    "content_scripts": [{
+      "matches": ["http://mochi.test/*/file_sample.html"],
+      "js": ["content_script.js"],
+      "run_at": "document_idle",
+    }],
+  },
+
+  files: {
+    "content_script.js": contentScript,
+  },
+};
+
+add_task(async function test_contentscript() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let win = window.open("file_sample.html");
+
+  await Promise.all([waitForLoad(win), extension.awaitFinish("sendmessage_reply")]);
+
+  win.close();
+
+  await extension.unload();
+  info("extension unloaded");
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_reply2.html b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_reply2.html
new file mode 100644
index 0000000000..d3227dbcaf
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_sendmessage_reply2.html
@@ -0,0 +1,204 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+function backgroundScript(token, id, otherId) {
+  browser.runtime.onMessage.addListener((msg, sender, sendReply) => {
+    browser.test.assertEq(id, sender.id, `${id}: Got expected sender ID`);
+
+    if (msg === `content-${token}`) {
+      browser.test.assertTrue(sender.tab.url.endsWith("file_sample.html"),
+                              `${id}: sender url correct`);
+
+      let tabId = sender.tab.id;
+      browser.tabs.sendMessage(tabId, `${token}-contentMessage`);
+
+      sendReply(`${token}-done`);
+    } else if (msg === `tab-${token}`) {
+      browser.runtime.sendMessage(otherId, `${otherId}-tabMessage`);
+      browser.runtime.sendMessage(`${token}-tabMessage`);
+
+      sendReply(`${token}-done`);
+    } else {
+      browser.test.fail(`${id}: Unexpected runtime message received: ${msg} ${uneval(sender)}`);
+    }
+  });
+
+  browser.runtime.onMessageExternal.addListener((msg, sender, sendReply) => {
+    browser.test.assertEq(otherId, sender.id, `${id}: Got expected external sender ID`);
+
+    if (msg === `content-${id}`) {
+      browser.test.assertTrue(sender.tab.url.endsWith("file_sample.html"),
+                              `${id}: external sender url correct`);
+
+      sendReply(`${otherId}-done`);
+    } else if (msg === `tab-${id}`) {
+      sendReply(`${otherId}-done`);
+    } else if (msg !== `${id}-tabMessage`) {
+      browser.test.fail(`${id}: Unexpected runtime external message received: ${msg} ${uneval(sender)}`);
+    }
+  });
+
+  browser.tabs.create({url: "tab.html"});
+}
+
+function contentScript(token, id, otherId) {
+  let gotContentMessage = false;
+  browser.runtime.onMessage.addListener((msg, sender, sendReply) => {
+    browser.test.assertEq(id, sender.id, `${id}: Got expected sender ID`);
+
+    browser.test.assertEq(`${token}-contentMessage`, msg,
+                          `${id}: Correct content script message`);
+    if (msg === `${token}-contentMessage`) {
+      gotContentMessage = true;
+    }
+  });
+
+  Promise.all([
+    browser.runtime.sendMessage(otherId, `content-${otherId}`).then(resp => {
+      browser.test.assertEq(`${id}-done`, resp, `${id}: Correct content script external response token`);
+    }),
+
+    browser.runtime.sendMessage(`content-${token}`).then(resp => {
+      browser.test.assertEq(`${token}-done`, resp, `${id}: Correct content script response token`);
+    }).catch(e => {
+      browser.test.fail(`content-${token} rejected with ${e.message}`);
+    }),
+  ]).then(() => {
+    browser.test.assertTrue(gotContentMessage, `${id}: Got content script message`);
+
+    browser.test.sendMessage("content-script-done");
+  });
+}
+
+async function tabScript(token, id, otherId) {
+  let gotTabMessage = false;
+  browser.runtime.onMessage.addListener((msg, sender, sendReply) => {
+    browser.test.assertEq(id, sender.id, `${id}: Got expected sender ID`);
+
+    if (String(msg).startsWith("content-")) {
+      return;
+    }
+
+    browser.test.assertEq(`${token}-tabMessage`, msg,
+                          `${id}: Correct tab script message`);
+    if (msg === `${token}-tabMessage`) {
+      gotTabMessage = true;
+    }
+  });
+
+  browser.test.sendMessage("tab-script-loaded");
+
+  await new Promise(resolve => {
+    const listener = (msg) => {
+      if (msg !== "run-tab-script") {
+        return;
+      }
+      browser.test.onMessage.removeListener(listener);
+      resolve();
+    };
+    browser.test.onMessage.addListener(listener);
+  });
+
+  Promise.all([
+    browser.runtime.sendMessage(otherId, `tab-${otherId}`).then(resp => {
+      browser.test.assertEq(`${id}-done`, resp, `${id}: Correct tab script external response token`);
+    }),
+
+    browser.runtime.sendMessage(`tab-${token}`).then(resp => {
+      browser.test.assertEq(`${token}-done`, resp, `${id}: Correct tab script response token`);
+    }),
+  ]).then(() => {
+    browser.test.assertTrue(gotTabMessage, `${id}: Got tab script message`);
+
+    window.close();
+
+    browser.test.sendMessage("tab-script-done");
+  });
+}
+
+function makeExtension(id, otherId) {
+  let token = Math.random();
+
+  let args = `${token}, ${JSON.stringify(id)}, ${JSON.stringify(otherId)}`;
+
+  let extensionData = {
+    useAddonManager: "permanent",
+    background: `(${backgroundScript})(${args})`,
+    manifest: {
+      "applications": {"gecko": {id}},
+
+      "permissions": ["tabs"],
+
+
+      "content_scripts": [{
+        "matches": ["http://mochi.test/*/file_sample.html"],
+        "js": ["content_script.js"],
+        "run_at": "document_start",
+      }],
+    },
+
+    files: {
+      "tab.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="tab.js"><\/script>
+          </head>
+        </html>`,
+
+      "tab.js": `(${tabScript})(${args})`,
+
+      "content_script.js": `(${contentScript})(${args})`,
+    },
+  };
+  return extensionData;
+}
+
+add_task(async function test_contentscript() {
+  const ID1 = "sendmessage1@mochitest.mozilla.org";
+  const ID2 = "sendmessage2@mochitest.mozilla.org";
+
+  let extension1 = ExtensionTestUtils.loadExtension(makeExtension(ID1, ID2));
+  let extension2 = ExtensionTestUtils.loadExtension(makeExtension(ID2, ID1));
+
+  await Promise.all([
+    extension1.startup(),
+    extension2.startup(),
+    extension1.awaitMessage("tab-script-loaded"),
+    extension2.awaitMessage("tab-script-loaded"),
+  ]);
+
+  extension1.sendMessage("run-tab-script");
+  extension2.sendMessage("run-tab-script");
+
+  let win = window.open("file_sample.html");
+
+  await waitForLoad(win);
+
+  await Promise.all([
+    extension1.awaitMessage("content-script-done"),
+    extension2.awaitMessage("content-script-done"),
+    extension1.awaitMessage("tab-script-done"),
+    extension2.awaitMessage("tab-script-done"),
+  ]);
+
+  win.close();
+
+  await extension1.unload();
+  await extension2.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_storage_cleanup.html b/toolkit/components/extensions/test/mochitest/test_ext_storage_cleanup.html
new file mode 100644
index 0000000000..e02b016419
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_storage_cleanup.html
@@ -0,0 +1,235 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const {
+  ExtensionStorageIDB,
+} = SpecialPowers.Cu.import("resource://gre/modules/ExtensionStorageIDB.jsm");
+
+const storageTestHelpers = {
+  storageLocal: {
+    async writeData() {
+      await browser.storage.local.set({hello: "world"});
+      browser.test.sendMessage("finished");
+    },
+
+    async readData() {
+      const matchBrowserStorage = await browser.storage.local.get("hello").then(result => {
+        return (Object.keys(result).length == 1 && result.hello == "world");
+      });
+
+      browser.test.sendMessage("results", {matchBrowserStorage});
+    },
+
+    assertResults({results, keepOnUninstall}) {
+      if (keepOnUninstall) {
+        is(results.matchBrowserStorage, true, "browser.storage.local data is still present");
+      } else {
+        is(results.matchBrowserStorage, false, "browser.storage.local data was cleared");
+      }
+    },
+  },
+  webAPIs: {
+    async readData() {
+      let matchLocalStorage = (localStorage.getItem("hello") == "world");
+
+      let idbPromise = new Promise((resolve, reject) => {
+        let req = indexedDB.open("test");
+        req.onerror = e => {
+          reject(new Error(`indexedDB open failed with ${e.errorCode}`));
+        };
+
+        req.onupgradeneeded = e => {
+          // no database, data is not present
+          resolve(false);
+        };
+
+        req.onsuccess = e => {
+          let db = e.target.result;
+          let transaction = db.transaction("store", "readwrite");
+          let addreq = transaction.objectStore("store").get("hello");
+          addreq.onerror = addreqError => {
+            reject(new Error(`read from indexedDB failed with ${addreqError.errorCode}`));
+          };
+          addreq.onsuccess = () => {
+            let match = (addreq.result.value == "world");
+            resolve(match);
+          };
+        };
+      });
+
+      await idbPromise.then(matchIDB => {
+        let result = {matchLocalStorage, matchIDB};
+        browser.test.sendMessage("results", result);
+      });
+    },
+
+    async writeData() {
+      localStorage.setItem("hello", "world");
+
+      let idbPromise = new Promise((resolve, reject) => {
+        let req = indexedDB.open("test");
+        req.onerror = e => {
+          reject(new Error(`indexedDB open failed with ${e.errorCode}`));
+        };
+
+        req.onupgradeneeded = e => {
+          let db = e.target.result;
+          db.createObjectStore("store", {keyPath: "name"});
+        };
+
+        req.onsuccess = e => {
+          let db = e.target.result;
+          let transaction = db.transaction("store", "readwrite");
+          let addreq = transaction.objectStore("store")
+                                  .add({name: "hello", value: "world"});
+          addreq.onerror = addreqError => {
+            reject(new Error(`add to indexedDB failed with ${addreqError.errorCode}`));
+          };
+          addreq.onsuccess = () => {
+            resolve();
+          };
+        };
+      });
+
+      await idbPromise.then(() => {
+        browser.test.sendMessage("finished");
+      });
+    },
+
+    assertResults({results, keepOnUninstall}) {
+      if (keepOnUninstall) {
+        is(results.matchLocalStorage, true, "localStorage data is still present");
+        is(results.matchIDB, true, "indexedDB data is still present");
+      } else {
+        is(results.matchLocalStorage, false, "localStorage data was cleared");
+        is(results.matchIDB, false, "indexedDB data was cleared");
+      }
+    },
+  },
+};
+
+async function test_uninstall({extensionId, writeData, readData, assertResults}) {
+  // Set the pref to prevent cleaning up storage on uninstall in a separate prefEnv
+  // so we can pop it below, leaving flags set in the previous prefEnvs unmodified.
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.webextensions.keepStorageOnUninstall", true]],
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: writeData,
+    manifest: {
+      applications: {gecko: {id: extensionId}},
+      permissions: ["storage"],
+    },
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("finished");
+  await extension.unload();
+
+  // Check that we can still see data we wrote to storage but clear the
+  // "leave storage" flag so our storaged gets cleared on the next uninstall.
+  // This effectively tests the keepUuidOnUninstall logic, which ensures
+  // that when we read storage again and check that it is cleared, that
+  // it is actually a meaningful test!
+  await SpecialPowers.popPrefEnv();
+
+  extension = ExtensionTestUtils.loadExtension({
+    background: readData,
+    manifest: {
+      applications: {gecko: {id: extensionId}},
+      permissions: ["storage"],
+    },
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+  let results = await extension.awaitMessage("results");
+
+  assertResults({results, keepOnUninstall: true});
+
+  await extension.unload();
+
+  // Read again.  This time, our data should be gone.
+  extension = ExtensionTestUtils.loadExtension({
+    background: readData,
+    manifest: {
+      applications: {gecko: {id: extensionId}},
+      permissions: ["storage"],
+    },
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+  results = await extension.awaitMessage("results");
+
+  assertResults({results, keepOnUninstall: false});
+
+  await extension.unload();
+}
+
+
+add_task(async function test_setup_keep_uuid_on_uninstall() {
+  // Use a test-only pref to leave the addonid->uuid mapping around after
+  // uninstall so that we can re-attach to the same storage (this prefEnv
+  // is kept for this entire file and cleared automatically once all the
+  // tests in this file have been executed).
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.webextensions.keepUuidOnUninstall", true]],
+  });
+});
+
+// Test extension indexedDB and localStorage storages get cleaned up when the
+// extension is uninstalled.
+add_task(async function test_uninstall_with_webapi_storages() {
+  await test_uninstall({
+    extensionId: "storage.cleanup-WebAPIStorages@tests.mozilla.org",
+    ...(storageTestHelpers.webAPIs),
+  });
+});
+
+// Test browser.storage.local with JSONFile backend gets cleaned up when the
+// extension is uninstalled.
+add_task(async function test_uninistall_with_storage_local_file_backend() {
+  await SpecialPowers.pushPrefEnv({
+    set: [[ExtensionStorageIDB.BACKEND_ENABLED_PREF, false]],
+  });
+
+  await test_uninstall({
+    extensionId: "storage.cleanup-JSONFileBackend@tests.mozilla.org",
+    ...(storageTestHelpers.storageLocal),
+  });
+
+  await SpecialPowers.popPrefEnv();
+});
+
+// Repeat the cleanup test when the storage.local IndexedDB backend is enabled.
+add_task(async function test_uninistall_with_storage_local_idb_backend() {
+  await SpecialPowers.pushPrefEnv({
+    set: [[ExtensionStorageIDB.BACKEND_ENABLED_PREF, true]],
+  });
+
+  await test_uninstall({
+    extensionId: "storage.cleanup-IDBBackend@tests.mozilla.org",
+    ...(storageTestHelpers.storageLocal),
+  });
+
+  await SpecialPowers.popPrefEnv();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_storage_manager_capabilities.html b/toolkit/components/extensions/test/mochitest/test_ext_storage_manager_capabilities.html
new file mode 100644
index 0000000000..3a02f3fb63
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_storage_manager_capabilities.html
@@ -0,0 +1,126 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test Storage API </title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function setup() {
+  await SpecialPowers.pushPrefEnv({
+    "set": [
+      ["dom.storageManager.enabled", true],
+      ["dom.storageManager.prompt.testing", true],
+      ["dom.storageManager.prompt.testing.allow", true],
+    ],
+  });
+});
+
+add_task(async function test_backgroundScript() {
+  function background() {
+    browser.test.assertTrue(navigator.storage !== undefined, "Has storage api interface");
+
+    // Test estimate.
+    browser.test.assertTrue("estimate" in navigator.storage, "Has estimate function");
+    browser.test.assertEq("function", typeof navigator.storage.estimate, "estimate is function");
+    browser.test.assertTrue(navigator.storage.estimate() instanceof Promise, "estimate returns a promise");
+
+    return browser.test.notifyPass("navigation_storage_api.done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("navigation_storage_api.done");
+  await extension.unload();
+});
+
+add_task(async function test_contentScript() {
+  function contentScript() {
+    // Should not access storage api in non-secure context.
+    browser.test.assertEq(undefined, navigator.storage,
+                          "A page from the unsecure http protocol " +
+                          "doesn't have access to the navigator.storage API");
+
+    return browser.test.notifyPass("navigation_storage_api.done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [{
+        "matches": ["http://example.com/*/file_sample.html"],
+        "js": ["content_script.js"],
+      }],
+    },
+
+    files: {
+      "content_script.js":  `(${contentScript})()`,
+    },
+  });
+
+  await extension.startup();
+
+  // Open an explicit URL for testing Storage API in an insecure context.
+  let win = window.open("http://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html");
+
+  await extension.awaitFinish("navigation_storage_api.done");
+
+  await extension.unload();
+  win.close();
+});
+
+add_task(async function test_contentScriptSecure() {
+  function contentScript() {
+    browser.test.assertTrue(navigator.storage !== undefined, "Has storage api interface");
+
+    // Test estimate.
+    browser.test.assertTrue("estimate" in navigator.storage, "Has estimate function");
+    browser.test.assertEq("function", typeof navigator.storage.estimate, "estimate is function");
+
+    // The promise that estimate function returns belongs to the content page,
+    // but the Promise constructor belongs to the content script sandbox.
+    // Check window.Promise here.
+    browser.test.assertTrue(navigator.storage.estimate() instanceof window.Promise, "estimate returns a promise");
+
+    return browser.test.notifyPass("navigation_storage_api.done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [{
+        "matches": ["https://example.com/*/file_sample.html"],
+        "js": ["content_script.js"],
+      }],
+    },
+
+    files: {
+      "content_script.js":  `(${contentScript})()`,
+    },
+  });
+
+  await extension.startup();
+
+  // Open an explicit URL for testing Storage API in a secure context.
+  let win = window.open("file_sample.html");
+
+  await extension.awaitFinish("navigation_storage_api.done");
+
+  await extension.unload();
+  win.close();
+});
+
+add_task(async function cleanup() {
+  await SpecialPowers.popPrefEnv();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_storage_smoke_test.html b/toolkit/components/extensions/test/mochitest/test_ext_storage_smoke_test.html
new file mode 100644
index 0000000000..b0c7425383
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_storage_smoke_test.html
@@ -0,0 +1,110 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension test</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+// The purpose of this test is making sure that the implementation enabled by
+// default for the storage.local and storage.sync APIs does work across all
+// platforms/builds/apps
+add_task(async function test_storage_smoke_test() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      for (let storageArea of ["sync", "local"]) {
+        let storage = browser.storage[storageArea];
+
+        browser.test.assertTrue(!!storage, `StorageArea ${storageArea} is present.`)
+
+        let data = await storage.get();
+        browser.test.assertEq(0, Object.keys(data).length,
+            `Storage starts out empty for ${storageArea}`);
+
+        data = await storage.get("test");
+        browser.test.assertEq(0, Object.keys(data).length,
+            `Can read non-existent keys for ${storageArea}`);
+
+        await storage.set({
+          "test1": "test-value1",
+          "test2": "test-value2",
+          "test3": "test-value3"
+        });
+
+        browser.test.assertEq(
+            "test-value1",
+            (await storage.get("test1")).test1,
+            `Can set and read back single values for ${storageArea}`);
+
+        browser.test.assertEq(
+            "test-value2",
+            (await storage.get("test2")).test2,
+            `Can set and read back single values for ${storageArea}`);
+
+        data = await storage.get();
+        browser.test.assertEq(3, Object.keys(data).length,
+            `Can set and read back all values for ${storageArea}`);
+        browser.test.assertEq("test-value1", data.test1,
+            `Can set and read back all values for ${storageArea}`);
+        browser.test.assertEq("test-value2", data.test2,
+            `Can set and read back all values for ${storageArea}`);
+        browser.test.assertEq("test-value3", data.test3,
+            `Can set and read back all values for ${storageArea}`);
+
+        data = await storage.get(["test1", "test2"]);
+        browser.test.assertEq(2, Object.keys(data).length,
+            `Can set and read back array of values for ${storageArea}`);
+        browser.test.assertEq("test-value1", data.test1,
+            `Can set and read back array of values for ${storageArea}`);
+        browser.test.assertEq("test-value2", data.test2,
+            `Can set and read back array of values for ${storageArea}`);
+
+        await storage.remove("test1");
+        data = await storage.get(["test1", "test2"]);
+        browser.test.assertEq(1, Object.keys(data).length,
+            `Data can be removed for ${storageArea}`);
+        browser.test.assertEq("test-value2", data.test2,
+            `Data can be removed for ${storageArea}`);
+
+        data = await storage.get({
+          test1: 1,
+          test2: 2,
+        });
+        browser.test.assertEq(2, Object.keys(data).length,
+            `Expected a key-value pair for every property for ${storageArea}`);
+        browser.test.assertEq(1, data.test1,
+            `Use default value if key was deleted for ${storageArea}`);
+        browser.test.assertEq("test-value2", data.test2,
+            `Use stored value if found for ${storageArea}`);
+
+        await storage.clear();
+        data = await storage.get();
+        browser.test.assertEq(0, Object.keys(data).length,
+            `Data is empty after clear for ${storageArea}`);
+      }
+
+      browser.test.sendMessage("done");
+    },
+    // Note: when Android supports sync on the java layer we will need to add
+    // useAddonManager: "permanent" here. Bug 1625257
+    manifest: {
+      permissions: ["storage"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_streamfilter_multiple.html b/toolkit/components/extensions/test/mochitest/test_ext_streamfilter_multiple.html
new file mode 100644
index 0000000000..d1bfbd824b
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_streamfilter_multiple.html
@@ -0,0 +1,91 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Test for multiple extensions trying to filterResponseData on the same request</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const TEST_URL =
+  "http://example.org/tests/toolkit/components/extensions/test/mochitest/file_streamfilter.txt";
+
+add_task(async () => {
+  const firstExtension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        ({ requestId }) => {
+          const filter = browser.webRequest.filterResponseData(requestId);
+          filter.ondata = event => {
+            filter.write(new TextEncoder().encode("Start "));
+            filter.write(event.data);
+            filter.disconnect();
+          };
+        },
+        {
+          urls: [
+            "http://example.org/*/file_streamfilter.txt",
+          ],
+        },
+        ["blocking"]
+      );
+    },
+  });
+
+  const secondExtension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        ({ requestId }) => {
+          const filter = browser.webRequest.filterResponseData(requestId);
+          filter.ondata = event => {
+            filter.write(event.data);
+          };
+          filter.onstop = event => {
+            filter.write(new TextEncoder().encode(" End"));
+            filter.close();
+          };
+        },
+        {
+          urls: [
+            "http://example.org/tests/toolkit/components/extensions/test/mochitest/file_streamfilter.txt",
+          ],
+        },
+        ["blocking"]
+      );
+    },
+  });
+
+  await firstExtension.startup();
+  await secondExtension.startup();
+
+  let iframe = document.createElement("iframe");
+  iframe.src = TEST_URL;
+  document.body.appendChild(iframe);
+  await new Promise(resolve => iframe.addEventListener("load", () => resolve(), {once: true}));
+
+  let content = await SpecialPowers.spawn(iframe, [], async () => {
+    return this.content.document.body.textContent;
+  });
+  SimpleTest.is(content, "Start Middle\n End", "Correctly intercepted page content");
+
+  await firstExtension.unload();
+  await secondExtension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_streamfilter_processswitch.html b/toolkit/components/extensions/test/mochitest/test_ext_streamfilter_processswitch.html
new file mode 100644
index 0000000000..2cf15db4e2
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_streamfilter_processswitch.html
@@ -0,0 +1,73 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Test for using filterResponseData to intercept a cross-origin navigation that will involve a process switch with fission</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const TEST_HOST = "http://example.com/";
+const CROSS_ORIGIN_HOST = "http://example.org/";
+const TEST_PATH =
+  "tests/toolkit/components/extensions/test/mochitest/file_streamfilter.txt";
+
+const TEST_URL = TEST_HOST + TEST_PATH;
+const CROSS_ORIGIN_URL = CROSS_ORIGIN_HOST + TEST_PATH;
+
+add_task(async () => {
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        ({ requestId }) => {
+          const filter = browser.webRequest.filterResponseData(requestId);
+          filter.ondata = event => {
+            filter.write(event.data);
+          };
+          filter.onstop = event => {
+            filter.write(new TextEncoder().encode(" End"));
+            filter.close();
+          };
+        },
+        {
+          urls: [
+            "http://example.org/*/file_streamfilter.txt",
+          ],
+        },
+        ["blocking"]
+      );
+    },
+  });
+
+  await extension.startup();
+
+  let iframe = document.createElement("iframe");
+  iframe.src = TEST_URL;
+  document.body.appendChild(iframe);
+  await new Promise(resolve => iframe.addEventListener("load", () => resolve(), {once: true}));
+
+
+  iframe.src = CROSS_ORIGIN_URL;
+  await new Promise(resolve => iframe.addEventListener("load", () => resolve(), {once: true}));
+
+  let content = await SpecialPowers.spawn(iframe, [], async () => {
+    return this.content.document.body.textContent;
+  });
+  SimpleTest.is(content, "Middle\n End", "Correctly intercepted page content");
+
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_subframes_privileges.html b/toolkit/components/extensions/test/mochitest/test_ext_subframes_privileges.html
new file mode 100644
index 0000000000..f7389236ab
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_subframes_privileges.html
@@ -0,0 +1,340 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>WebExtension test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+/* eslint-disable mozilla/balanced-listeners */
+
+add_task(async function test_webext_tab_subframe_privileges() {
+  function background() {
+    browser.runtime.onMessage.addListener(async ({msg, success, tabId, error}) => {
+      if (msg == "webext-tab-subframe-privileges") {
+        if (success) {
+          await browser.tabs.remove(tabId);
+
+          browser.test.notifyPass(msg);
+        } else {
+          browser.test.log(`Got an unexpected error: ${error}`);
+
+          let tabs = await browser.tabs.query({active: true});
+          await browser.tabs.remove(tabs[0].id);
+
+          browser.test.notifyFail(msg);
+        }
+      }
+    });
+    browser.tabs.create({url: browser.runtime.getURL("/tab.html")});
+  }
+
+  async function tabSubframeScript() {
+    browser.test.assertTrue(browser.tabs != undefined,
+                            "Subframe of a privileged page has access to privileged APIs");
+    if (browser.tabs) {
+      try {
+        let tab = await browser.tabs.getCurrent();
+        browser.runtime.sendMessage({
+          msg: "webext-tab-subframe-privileges",
+          success: true,
+          tabId: tab.id,
+        });
+      } catch (e) {
+        browser.runtime.sendMessage({msg: "webext-tab-subframe-privileges", success: false, error: `${e}`});
+      }
+    } else {
+      browser.runtime.sendMessage({
+        msg: "webext-tab-subframe-privileges",
+        success: false,
+        error: `Privileged APIs missing in WebExtension tab sub-frame`,
+      });
+    }
+  }
+
+  let extensionData = {
+    background,
+    files: {
+      "tab.html": `<!DOCTYPE>
+          <head>
+            <meta charset="utf-8">
+          </head>
+          <body>
+            <iframe src="tab-subframe.html"></iframe>
+          </body>
+        </html>`,
+      "tab-subframe.html": `<!DOCTYPE>
+          <head>
+            <meta charset="utf-8">
+            <script src="tab-subframe.js"><\/script>
+          </head>
+        </html>`,
+      "tab-subframe.js": tabSubframeScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  await extension.awaitFinish("webext-tab-subframe-privileges");
+  await extension.unload();
+});
+
+add_task(async function test_webext_background_subframe_privileges() {
+  function backgroundSubframeScript() {
+    browser.test.assertTrue(browser.tabs != undefined,
+                            "Subframe of a background page has access to privileged APIs");
+    browser.test.notifyPass("webext-background-subframe-privileges");
+  }
+
+  let extensionData = {
+    manifest: {
+      background: {
+        page: "background.html",
+      },
+    },
+    files: {
+      "background.html": `<!DOCTYPE>
+         <head>
+           <meta charset="utf-8">
+         </head>
+         <body>
+           <iframe src="background-subframe.html"></iframe>
+         </body>
+       </html>`,
+      "background-subframe.html": `<!DOCTYPE>
+         <head>
+           <meta charset="utf-8">
+           <script src="background-subframe.js"><\/script>
+         </head>
+       </html>`,
+      "background-subframe.js": backgroundSubframeScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  await extension.awaitFinish("webext-background-subframe-privileges");
+  await extension.unload();
+});
+
+add_task(async function test_webext_contentscript_iframe_subframe_privileges() {
+  function background() {
+    browser.runtime.onMessage.addListener(({name, hasTabsAPI, hasStorageAPI}) => {
+      if (name == "contentscript-iframe-loaded") {
+        browser.test.assertFalse(hasTabsAPI,
+                                 "Subframe of a content script privileged iframes has no access to privileged APIs");
+        browser.test.assertTrue(hasStorageAPI,
+                                "Subframe of a content script privileged iframes has access to content script APIs");
+
+        browser.test.notifyPass("webext-contentscript-subframe-privileges");
+      }
+    });
+  }
+
+  function subframeScript() {
+    browser.runtime.sendMessage({
+      name: "contentscript-iframe-loaded",
+      hasTabsAPI: browser.tabs != undefined,
+      hasStorageAPI: browser.storage != undefined,
+    });
+  }
+
+  function contentScript() {
+    let iframe = document.createElement("iframe");
+    iframe.setAttribute("src", browser.runtime.getURL("/contentscript-iframe.html"));
+    document.body.appendChild(iframe);
+  }
+
+  let extensionData = {
+    background,
+    manifest: {
+      "permissions": ["storage"],
+      "content_scripts": [{
+        "matches": ["http://example.com/*"],
+        "js": ["contentscript.js"],
+      }],
+      web_accessible_resources: [
+        "contentscript-iframe.html",
+      ],
+    },
+    files: {
+      "contentscript.js": contentScript,
+      "contentscript-iframe.html": `<!DOCTYPE>
+         <head>
+           <meta charset="utf-8">
+         </head>
+         <body>
+           <iframe src="contentscript-iframe-subframe.html"></iframe>
+         </body>
+       </html>`,
+      "contentscript-iframe-subframe.html": `<!DOCTYPE>
+         <head>
+           <meta charset="utf-8">
+           <script src="contentscript-iframe-subframe.js"><\/script>
+         </head>
+       </html>`,
+      "contentscript-iframe-subframe.js": subframeScript,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  let win = window.open("http://example.com");
+
+  await extension.awaitFinish("webext-contentscript-subframe-privileges");
+
+  win.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_webext_background_remote_subframe_privileges() {
+  function backgroundSubframeScript() {
+    window.addEventListener("message", evt => {
+      browser.test.assertEq("http://mochi.test:8888", evt.origin, "postmessage origin ok");
+      browser.test.assertFalse(evt.data.tabs, "remote frame cannot access webextension APIs");
+      browser.test.assertEq("cookie=monster", evt.data.cookie, "Expected cookie value");
+      browser.test.notifyPass("webext-background-subframe-privileges");
+    }, {once: true});
+    browser.cookies.set({url: "http://mochi.test:8888", name: "cookie", "value": "monster"});
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: ["cookies", "*://mochi.test/*", "tabs"],
+      background: {
+        page: "background.html",
+      },
+    },
+    files: {
+      "background.html": `<!DOCTYPE>
+         <head>
+           <meta charset="utf-8">
+           <script src="background-subframe.js"><\/script>
+         </head>
+         <body>
+           <iframe src='${SimpleTest.getTestFileURL("file_remote_frame.html")}'></iframe>
+         </body>
+       </html>`,
+      "background-subframe.js": backgroundSubframeScript,
+    },
+  };
+  // Need remote webextensions to be able to load remote content from a background page.
+  if (!SpecialPowers.getBoolPref("extensions.webextensions.remote", true)) {
+    return;
+  }
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  await extension.awaitFinish("webext-background-subframe-privileges");
+  await extension.unload();
+});
+
+// Test a moz-extension:// iframe inside a content iframe in an extension page.
+add_task(async function test_sub_subframe_conduit_verified_env() {
+  let manifest = {
+    content_scripts: [{
+      matches: ["http://mochi.test/*/file_sample.html"],
+      all_frames: true,
+      js: ["cs.js"],
+    }],
+    background: {
+      page: "background.html",
+    },
+    web_accessible_resources: ["iframe.html"],
+  };
+
+  let files = {
+    "iframe.html": `<!DOCTYPE html><meta charset=utf-8> iframe`,
+    "cs.js"() {
+      // A compromised content sandbox shouldn't be able to trick the parent
+      // process into giving it extension privileges by sending false metadata.
+      async function faker(extensionId, envType) {
+        try {
+          let id = envType + "-xyz1234";
+          let wgc = this.content.windowGlobalChild;
+
+          let conduit = wgc.getActor("Conduits").openConduit({}, {
+            id,
+            envType,
+            extensionId,
+            query: ["CreateProxyContext"],
+          });
+
+          return await conduit.queryCreateProxyContext({
+            childId: id,
+            extensionId,
+            envType: "addon_parent",
+            url: this.content.location.href,
+            viewType: "tab",
+          });
+        } catch (e) {
+          return e.message;
+        }
+      }
+
+      let iframe = document.createElement("iframe");
+      iframe.src = browser.runtime.getURL("iframe.html");
+
+      iframe.onload = async () => {
+        for (let envType of ["content_child", "addon_child"]) {
+          let msg = await this.wrappedJSObject.SpecialPowers.spawn(
+              iframe, [browser.runtime.id, envType], faker);
+          browser.test.sendMessage(envType, msg);
+        }
+      };
+      document.body.appendChild(iframe);
+    },
+    "background.html": `<!DOCTYPE html>
+      <meta charset=utf-8>
+      <iframe src="${SimpleTest.getTestFileURL("file_sample.html")}">
+      </iframe>
+      page
+    `,
+  };
+
+  async function expectErrors(ext, log) {
+    let err = await ext.awaitMessage("content_child");
+    is(err, "Bad sender context envType: content_child");
+
+    err = await ext.awaitMessage("addon_child");
+    is(err, "Unknown sender or wrong actor for recvCreateProxyContext");
+  }
+
+  let remote = SpecialPowers.getBoolPref("extensions.webextensions.remote");
+
+  let badProcess = { message: /Bad {[\w-]+} process: web/ };
+  let badPrincipal = { message: /Bad {[\w-]+} principal: http/ };
+  consoleMonitor.start(remote ? [badPrincipal, badProcess] : [badProcess]);
+
+  let extension = ExtensionTestUtils.loadExtension({ manifest, files });
+  await extension.startup();
+
+  if (remote) {
+    info("Need OOP to spoof from a web iframe inside background page.");
+    await expectErrors(extension);
+  }
+
+  info("Try spoofing from the web process.");
+  let win = window.open("./file_sample.html");
+  await expectErrors(extension);
+  win.close();
+
+  await extension.unload();
+  await consoleMonitor.finished();
+  info("Conduit creation logged correct exception(s).");
+});
+
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_tabs_captureTab.html b/toolkit/components/extensions/test/mochitest/test_ext_tabs_captureTab.html
new file mode 100644
index 0000000000..7feb1064ba
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_tabs_captureTab.html
@@ -0,0 +1,301 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Tests tabs.captureTab and tabs.captureVisibleTab</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="text/javascript">
+"use strict";
+
+async function runTest({ html, fullZoom, coords, rect, scale }) {
+  let url = `data:text/html,${encodeURIComponent(html)}#scroll`;
+
+  async function background({ coords, rect, scale, method, fullZoom }) {
+    try {
+      // Wait for the page to load
+      await new Promise(resolve => {
+        browser.webNavigation.onCompleted.addListener(
+          () => resolve(),
+          {url: [{schemes: ["data"]}]});
+      });
+
+      let [tab] = await browser.tabs.query({
+        currentWindow: true,
+        active: true,
+      });
+
+      // TODO: Bug 1665429 - on mobile we ignore zoom for now
+      if (browser.tabs.setZoom) {
+        await browser.tabs.setZoom(tab.id, fullZoom ?? 1);
+      }
+
+      let id = method === "captureVisibleTab" ? tab.windowId : tab.id;
+
+      let [jpeg, png, ...pngs] = await Promise.all([
+        browser.tabs[method](id, { format: "jpeg", quality: 95, rect, scale }),
+        browser.tabs[method](id, { format: "png", quality: 95, rect, scale }),
+        browser.tabs[method](id, { quality: 95, rect, scale }),
+        browser.tabs[method](id, { rect, scale }),
+      ]);
+
+      browser.test.assertTrue(
+        pngs.every(url => url == png),
+        "All PNGs are identical"
+      );
+
+      browser.test.assertTrue(
+        jpeg.startsWith("data:image/jpeg;base64,"),
+        "jpeg is JPEG"
+      );
+      browser.test.assertTrue(
+        png.startsWith("data:image/png;base64,"),
+        "png is PNG"
+      );
+
+      let promises = [jpeg, png].map(
+        url =>
+          new Promise(resolve => {
+            let img = new Image();
+            img.src = url;
+            img.onload = () => resolve(img);
+          })
+      );
+
+      let width = (rect?.width ?? tab.width) * (scale ?? devicePixelRatio);
+      let height = (rect?.height ?? tab.height) * (scale ?? devicePixelRatio);
+
+      [jpeg, png] = await Promise.all(promises);
+      let images = { jpeg, png };
+      for (let format of Object.keys(images)) {
+        let img = images[format];
+
+        // WGP.drawSnapshot() deals in int coordinates, and rounds down.
+        browser.test.assertTrue(
+          Math.abs(width - img.width) <= 1,
+          `${format} ok image width: ${img.width}, expected: ${width}`
+        );
+        browser.test.assertTrue(
+          Math.abs(height - img.height) <= 1,
+          `${format} ok image height ${img.height}, expected: ${height}`
+        );
+
+        let canvas = document.createElement("canvas");
+        canvas.width = img.width;
+        canvas.height = img.height;
+        canvas.mozOpaque = true;
+
+        let ctx = canvas.getContext("2d");
+        ctx.drawImage(img, 0, 0);
+
+        for (let { x, y, color } of coords) {
+          x = (x + img.width) % img.width;
+          y = (y + img.height) % img.height;
+          let imageData = ctx.getImageData(x, y, 1, 1).data;
+
+          if (format == "png") {
+            browser.test.assertEq(
+              `rgba(${color},255)`,
+              `rgba(${[...imageData]})`,
+              `${format} image color is correct at (${x}, ${y})`
+            );
+          } else {
+            // Allow for some deviation in JPEG version due to lossy compression.
+            const SLOP = 3;
+
+            browser.test.log(
+              `Testing ${format} image color at (${x}, ${y}), have rgba(${[
+                ...imageData,
+              ]}), expecting approx. rgba(${color},255)`
+            );
+
+            browser.test.assertTrue(
+              Math.abs(color[0] - imageData[0]) <= SLOP,
+              `${format} image color.red is correct at (${x}, ${y})`
+            );
+            browser.test.assertTrue(
+              Math.abs(color[1] - imageData[1]) <= SLOP,
+              `${format} image color.green is correct at (${x}, ${y})`
+            );
+            browser.test.assertTrue(
+              Math.abs(color[2] - imageData[2]) <= SLOP,
+              `${format} image color.blue is correct at (${x}, ${y})`
+            );
+            browser.test.assertEq(
+              255,
+              imageData[3],
+              `${format} image color.alpha is correct at (${x}, ${y})`
+            );
+          }
+        }
+      }
+
+      browser.test.notifyPass("captureTab");
+    } catch (e) {
+      browser.test.fail(`Error: ${e} :: ${e.stack}`);
+      browser.test.notifyFail("captureTab");
+    }
+  }
+
+  for (let method of ["captureTab", "captureVisibleTab"]) {
+    let options = { coords, rect, scale, method, fullZoom };
+    info(`Testing configuration: ${JSON.stringify(options)}`);
+
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        permissions: ["<all_urls>", "webNavigation"],
+      },
+
+      background: `(${background})(${JSON.stringify(options)})`,
+    });
+
+    await extension.startup();
+
+    let testWindow = window.open(url);
+    await extension.awaitFinish("captureTab");
+
+    testWindow.close();
+    await extension.unload();
+  }
+}
+
+async function testEdgeToEdge({ color, fullZoom }) {
+  let neutral = [0xaa, 0xaa, 0xaa];
+
+  let html = `
+    <!DOCTYPE html>
+    <html lang="en">
+    <head>
+      <meta charset="UTF-8">
+      <meta name="viewport" content="width=device-width, initial-scale=1">
+    </head>
+    <body style="background-color: rgb(${color})">
+      <!-- Fill most of the image with a neutral color to test edge-to-edge scaling. -->
+      <div style="position: absolute;
+                  left: 2px;
+                  right: 2px;
+                  top: 2px;
+                  bottom: 2px;
+                  background: rgb(${neutral});"></div>
+    </body>
+    </html>
+  `;
+
+  // Check the colors of the first and last pixels of the image, to make
+  // sure we capture the entire frame, and scale it correctly.
+  let coords = [
+    { x: 0, y: 0, color },
+    { x: -1, y: -1, color },
+    { x: 300, y: 200, color: neutral },
+  ];
+
+  info(`Test edge to edge color ${color} at fullZoom=${fullZoom}`);
+  await runTest({ html, fullZoom, coords });
+}
+
+add_task(async function testCaptureEdgeToEdge() {
+  await testEdgeToEdge({ color: [0, 0, 0], fullZoom: 1 });
+  await testEdgeToEdge({ color: [0, 0, 0], fullZoom: 2 });
+  await testEdgeToEdge({ color: [0, 0, 0], fullZoom: 0.5 });
+  await testEdgeToEdge({ color: [255, 255, 255], fullZoom: 1 });
+});
+
+const tallDoc = `<!DOCTYPE html>
+  <meta charset=utf-8>
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <div style="background: yellow; width: 50%; height: 500px;"></div>
+  <div id=scroll style="background: red; width: 25%; height: 5000px;"></div>
+  Opened with the #scroll fragment, scrolls the div ^ into view.
+`;
+
+// Test currently visible viewport is captured if scrolling is involved.
+add_task(async function testScrolledViewport() {
+  await runTest({
+    html: tallDoc,
+    coords: [
+      { x: 50, y: 50, color: [255, 0, 0] },
+      { x: 50, y: -50, color: [255, 0, 0] },
+      { x: -50, y: -50, color: [255, 255, 255] },
+    ],
+  });
+});
+
+// Test rect and scale options.
+add_task(async function testRectAndScale() {
+  await runTest({
+    html: tallDoc,
+    rect: { x: 50, y: 50, width: 10, height: 1000 },
+    scale: 4,
+    coords: [
+      { x: 0, y: 0, color: [255, 255, 0] },
+      { x: -1, y: 0, color: [255, 255, 0] },
+      { x: 0, y: -1, color: [255, 0, 0] },
+      { x: -1, y: -1, color: [255, 0, 0] },
+    ],
+  });
+});
+
+// Test OOP iframes are captured, for Fission compatibility.
+add_task(async function testOOPiframe() {
+  await runTest({
+    html: `<!DOCTYPE html>
+      <meta charset=utf-8>
+      <meta name="viewport" content="width=device-width, initial-scale=1">
+      <iframe src="http://example.net/tests/toolkit/components/extensions/test/mochitest/file_green.html"></iframe>
+    `,
+    coords: [
+      { x: 50, y: 50, color: [0, 255, 0] },
+      { x: 50, y: -50, color: [255, 255, 255] },
+      { x: -50, y: 50, color: [255, 255, 255] },
+    ],
+  });
+});
+
+add_task(async function testCaptureTabPermissions() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["tabs"],
+    },
+
+    background() {
+      browser.test.assertEq(
+        undefined,
+        browser.tabs.captureTab,
+        'Extension without "<all_urls>" permission should not have access to captureTab'
+      );
+      browser.test.notifyPass("captureTabPermissions");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("captureTabPermissions");
+  await extension.unload();
+});
+
+add_task(async function testCaptureVisibleTabPermissions() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["tabs"],
+    },
+
+    background() {
+      browser.test.assertEq(
+        undefined,
+        browser.tabs.captureVisibleTab,
+        'Extension without "<all_urls>" permission should not have access to captureVisibleTab'
+      );
+      browser.test.notifyPass("captureVisibleTabPermissions");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("captureVisibleTabPermissions");
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_tabs_permissions.html b/toolkit/components/extensions/test/mochitest/test_ext_tabs_permissions.html
new file mode 100644
index 0000000000..99d8b77f16
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_tabs_permissions.html
@@ -0,0 +1,780 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Tabs permissions test</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+const URL1 =
+  "http://www.example.com/tests/toolkit/components/extensions/test/mochitest/file_tabs_permission_page1.html";
+const URL2 =
+  "http://example.net/tests/toolkit/components/extensions/test/mochitest/file_tabs_permission_page2.html";
+
+const helperExtensionDef = {
+  manifest: {
+    applications: {
+      gecko: {
+        id: "helper@tests.mozilla.org",
+      },
+    },
+    permissions: ["webNavigation", "<all_urls>"],
+  },
+
+  useAddonManager: "permanent",
+
+  async background() {
+    browser.test.onMessage.addListener(async message => {
+      switch (message.subject) {
+        case "createTab": {
+          const tabLoaded = new Promise(resolve => {
+            browser.webNavigation.onCompleted.addListener(function listener(
+              details
+            ) {
+              if (details.url === message.data.url) {
+                browser.webNavigation.onCompleted.removeListener(listener);
+                resolve();
+              }
+            });
+          });
+
+          const tab = await browser.tabs.create({ url: message.data.url });
+          await tabLoaded;
+          browser.test.sendMessage("tabCreated", tab.id);
+          break;
+        }
+
+        case "changeTabURL": {
+          const tabLoaded = new Promise(resolve => {
+            browser.webNavigation.onCompleted.addListener(function listener(
+              details
+            ) {
+              if (details.url === message.data.url) {
+                browser.webNavigation.onCompleted.removeListener(listener);
+                resolve();
+              }
+            });
+          });
+
+          await browser.tabs.update(message.data.tabId, {
+            url: message.data.url,
+          });
+          await tabLoaded;
+          browser.test.sendMessage("tabURLChanged", message.data.tabId);
+          break;
+        }
+
+        case "changeTabHashAndTitle": {
+          const tabChanged = new Promise(resolve => {
+            let hasURLChangeInfo = false,
+              hasTitleChangeInfo = false;
+            browser.tabs.onUpdated.addListener(function listener(
+              tabId,
+              changeInfo,
+              tab
+            ) {
+              if (changeInfo.url?.endsWith(message.data.urlHash)) {
+                hasURLChangeInfo = true;
+              }
+              if (changeInfo.title === message.data.title) {
+                hasTitleChangeInfo = true;
+              }
+              if (hasURLChangeInfo && hasTitleChangeInfo) {
+                browser.tabs.onUpdated.removeListener(listener);
+                resolve();
+              }
+            });
+          });
+
+          await browser.tabs.executeScript(message.data.tabId, {
+            code: `
+              document.location.hash = ${JSON.stringify(message.data.urlHash)};
+              document.title = ${JSON.stringify(message.data.title)};
+            `,
+          });
+          await tabChanged;
+          browser.test.sendMessage("tabHashAndTitleChanged");
+          break;
+        }
+
+        case "removeTab": {
+          await browser.tabs.remove(message.data.tabId);
+          browser.test.sendMessage("tabRemoved");
+          break;
+        }
+
+        default:
+          browser.test.fail(`Received unexpected message: ${message}`);
+      }
+    });
+  },
+};
+
+/*
+ * Test tabs.query function
+ * Check if the correct tabs are queried by url or title based on the granted permissions
+ */
+async function test_query(testCases, permissions) {
+  const helperExtension = ExtensionTestUtils.loadExtension(helperExtensionDef);
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "permissions@tests.mozilla.org",
+        },
+      },
+      permissions,
+    },
+
+    useAddonManager: "permanent",
+
+    async background() {
+      // wait for start message
+      const [testCases, tabIdFromURL1, tabIdFromURL2] = await new Promise(
+        resolve => {
+          browser.test.onMessage.addListener(message => resolve(message));
+        }
+      );
+
+      for (const testCase of testCases) {
+        const query = testCase.query;
+        const matchingTabs = testCase.matchingTabs;
+
+        let tabQuery = await browser.tabs.query(query);
+        // ignore other tabs in the window
+        tabQuery = tabQuery.filter(tab => {
+          return tab.id === tabIdFromURL1 || tab.id === tabIdFromURL2;
+        });
+
+        browser.test.assertEq(matchingTabs, tabQuery.length, `Tabs queried`);
+      }
+      // send end message
+      browser.test.notifyPass("tabs.query");
+    },
+  });
+
+  await helperExtension.startup();
+  await extension.startup();
+
+  helperExtension.sendMessage({
+    subject: "createTab",
+    data: { url: URL1 },
+  });
+  const tabIdFromURL1 = await helperExtension.awaitMessage("tabCreated");
+
+  helperExtension.sendMessage({
+    subject: "createTab",
+    data: { url: URL2 },
+  });
+  const tabIdFromURL2 = await helperExtension.awaitMessage("tabCreated");
+
+  if (permissions.includes("activeTab")) {
+    extension.grantActiveTab(tabIdFromURL2);
+  }
+
+  extension.sendMessage([testCases, tabIdFromURL1, tabIdFromURL2]);
+  await extension.awaitFinish("tabs.query");
+
+  helperExtension.sendMessage({
+    subject: "removeTab",
+    data: { tabId: tabIdFromURL1 },
+  });
+  await helperExtension.awaitMessage("tabRemoved");
+
+  helperExtension.sendMessage({
+    subject: "removeTab",
+    data: { tabId: tabIdFromURL2 },
+  });
+  await helperExtension.awaitMessage("tabRemoved");
+
+  await extension.unload();
+  await helperExtension.unload();
+}
+
+// http://www.example.com host permission
+add_task(function query_with_host_permission_url1() {
+  return test_query(
+    [
+      {
+        query: { url: "*://www.example.com/*" },
+        matchingTabs: 1,
+      },
+      {
+        query: { url: "<all_urls>" },
+        matchingTabs: 1,
+      },
+      {
+        query: { url: ["*://www.example.com/*", "*://example.net/*"] },
+        matchingTabs: 1,
+      },
+      {
+        query: { title: "The Title" },
+        matchingTabs: 1,
+      },
+      {
+        query: { title: "Another Title" },
+        matchingTabs: 0,
+      },
+      {
+        query: {},
+        matchingTabs: 2,
+      },
+    ],
+    ["*://www.example.com/*"]
+  );
+});
+
+// http://example.net host permission
+add_task(function query_with_host_permission_url2() {
+  return test_query(
+    [
+      {
+        query: { url: "*://www.example.com/*" },
+        matchingTabs: 0,
+      },
+      {
+        query: { url: "<all_urls>" },
+        matchingTabs: 1,
+      },
+      {
+        query: { url: ["*://www.example.com/*", "*://example.net/*"] },
+        matchingTabs: 1,
+      },
+      {
+        query: { title: "The Title" },
+        matchingTabs: 0,
+      },
+      {
+        query: { title: "Another Title" },
+        matchingTabs: 1,
+      },
+      {
+        query: {},
+        matchingTabs: 2,
+      },
+    ],
+    ["*://example.net/*"]
+  );
+});
+
+// <all_urls> permission
+add_task(function query_with_host_permission_all_urls() {
+  return test_query(
+    [
+      {
+        query: { url: "*://www.example.com/*" },
+        matchingTabs: 1,
+      },
+      {
+        query: { url: "<all_urls>" },
+        matchingTabs: 2,
+      },
+      {
+        query: { url: ["*://www.example.com/*", "*://example.net/*"] },
+        matchingTabs: 2,
+      },
+      {
+        query: { title: "The Title" },
+        matchingTabs: 1,
+      },
+      {
+        query: { title: "Another Title" },
+        matchingTabs: 1,
+      },
+      {
+        query: {},
+        matchingTabs: 2,
+      },
+    ],
+    ["<all_urls>"]
+  );
+});
+
+// tabs permission
+add_task(function query_with_tabs_permission() {
+  return test_query(
+    [
+      {
+        query: { url: "*://www.example.com/*" },
+        matchingTabs: 1,
+      },
+      {
+        query: { url: "<all_urls>" },
+        matchingTabs: 2,
+      },
+      {
+        query: { url: ["*://www.example.com/*", "*://example.net/*"] },
+        matchingTabs: 2,
+      },
+      {
+        query: { title: "The Title" },
+        matchingTabs: 1,
+      },
+      {
+        query: { title: "Another Title" },
+        matchingTabs: 1,
+      },
+      {
+        query: {},
+        matchingTabs: 2,
+      },
+    ],
+    ["tabs"]
+  );
+});
+
+// activeTab permission
+add_task(function query_with_activeTab_permission() {
+  return test_query(
+    [
+      {
+        query: { url: "*://www.example.com/*" },
+        matchingTabs: 0,
+      },
+      {
+        query: { url: "<all_urls>" },
+        matchingTabs: 1,
+      },
+      {
+        query: { url: ["*://www.example.com/*", "*://example.net/*"] },
+        matchingTabs: 1,
+      },
+      {
+        query: { title: "The Title" },
+        matchingTabs: 0,
+      },
+      {
+        query: { title: "Another Title" },
+        matchingTabs: 1,
+      },
+      {
+        query: {},
+        matchingTabs: 2,
+      },
+    ],
+    ["activeTab"]
+  );
+});
+// no permission
+add_task(function query_without_permission() {
+  return test_query(
+    [
+      {
+        query: { url: "*://www.example.com/*" },
+        matchingTabs: 0,
+      },
+      {
+        query: { url: "<all_urls>" },
+        matchingTabs: 0,
+      },
+      {
+        query: { url: ["*://www.example.com/*", "*://example.net/*"] },
+        matchingTabs: 0,
+      },
+      {
+        query: { title: "The Title" },
+        matchingTabs: 0,
+      },
+      {
+        query: { title: "Another Title" },
+        matchingTabs: 0,
+      },
+      {
+        query: {},
+        matchingTabs: 2,
+      },
+    ],
+    []
+  );
+});
+
+/*
+ * Test tabs.onUpdate and tabs.get function
+ * Check if the changeInfo or tab object contains the restricted properties
+ * url and title only when the right permissions are granted
+ * The tab is updated without causing navigation in order to also test activeTab permission
+ */
+async function test_restricted_properties(
+  permissions,
+  hasRestrictedProperties
+) {
+  const helperExtension = ExtensionTestUtils.loadExtension(helperExtensionDef);
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "permissions@tests.mozilla.org",
+        },
+      },
+      permissions,
+    },
+
+    useAddonManager: "permanent",
+
+    async background() {
+      // wait for test start signal and data
+      const [
+        hasRestrictedProperties,
+        tabId,
+        urlHash,
+        title,
+      ] = await new Promise(resolve => {
+        browser.test.onMessage.addListener(message => {
+          resolve(message);
+        });
+      });
+
+      let hasURLChangeInfo = false,
+        hasTitleChangeInfo = false;
+      function onUpdateListener(tabId, changeInfo, tab) {
+        if (changeInfo.url?.endsWith(urlHash)) {
+          hasURLChangeInfo = true;
+        }
+        if (changeInfo.title === title) {
+          hasTitleChangeInfo = true;
+        }
+      }
+      browser.tabs.onUpdated.addListener(onUpdateListener);
+
+      // wait for test evaluation signal and data
+      await new Promise(resolve => {
+        browser.test.onMessage.addListener(message => {
+          if (message === "collectTestResults") {
+            resolve(message);
+          }
+        });
+        browser.test.sendMessage("waitingForTabPropertyChanges");
+      });
+
+      // check onUpdate changeInfo
+      browser.test.assertEq(
+        hasRestrictedProperties,
+        hasURLChangeInfo,
+        `Has changeInfo property "url"`
+      );
+      browser.test.assertEq(
+        hasRestrictedProperties,
+        hasTitleChangeInfo,
+        `Has changeInfo property "title"`
+      );
+      // check tab properties
+      const tabGet = await browser.tabs.get(tabId);
+      browser.test.assertEq(
+        hasRestrictedProperties,
+        !!tabGet.url?.endsWith(urlHash),
+        `Has tab property "url"`
+      );
+      browser.test.assertEq(
+        hasRestrictedProperties,
+        tabGet.title === title,
+        `Has tab property "title"`
+      );
+      // send end message
+      browser.test.notifyPass("tabs.restricted_properties");
+    },
+  });
+
+  const urlHash = "#ChangedURL";
+  const title = "Changed Title";
+
+  await helperExtension.startup();
+  await extension.startup();
+
+  helperExtension.sendMessage({
+    subject: "createTab",
+    data: { url: URL1 },
+  });
+  const tabId = await helperExtension.awaitMessage("tabCreated");
+
+  if (permissions.includes("activeTab")) {
+    extension.grantActiveTab(tabId);
+  }
+  // send test start signal and data
+  extension.sendMessage([hasRestrictedProperties, tabId, urlHash, title]);
+  await extension.awaitMessage("waitingForTabPropertyChanges");
+
+  helperExtension.sendMessage({
+    subject: "changeTabHashAndTitle",
+    data: {
+      tabId,
+      urlHash,
+      title,
+    },
+  });
+  await helperExtension.awaitMessage("tabHashAndTitleChanged");
+
+  // send end signal and evaluate results
+  extension.sendMessage("collectTestResults");
+  await extension.awaitFinish("tabs.restricted_properties");
+
+  helperExtension.sendMessage({
+    subject: "removeTab",
+    data: { tabId },
+  });
+  await helperExtension.awaitMessage("tabRemoved");
+
+  await extension.unload();
+  await helperExtension.unload();
+}
+
+// http://www.example.com host permission
+add_task(function has_restricted_properties_with_host_permission_url1() {
+  return test_restricted_properties(["*://www.example.com/*"], true);
+});
+// http://example.net host permission
+add_task(function has_restricted_properties_with_host_permission_url2() {
+  return test_restricted_properties(["*://example.net/*"], false);
+});
+// <all_urls> permission
+add_task(function has_restricted_properties_with_host_permission_all_urls() {
+  return test_restricted_properties(["<all_urls>"], true);
+});
+// tabs permission
+add_task(function has_restricted_properties_with_tabs_permission() {
+  return test_restricted_properties(["tabs"], true);
+});
+// activeTab permission
+add_task(function has_restricted_properties_with_activeTab_permission() {
+  return test_restricted_properties(["activeTab"], true);
+}).skip(); // TODO bug 1686080: support changeInfo.url with activeTab
+// no permission
+add_task(function has_restricted_properties_without_permission() {
+  return test_restricted_properties([], false);
+});
+
+
+/*
+ * Test tabs.onUpdate filter functionality
+ * Check if the restricted filter properties only work if the
+ * right permissions are granted
+ */
+async function test_onUpdateFilter(testCases, permissions) {
+  // Filters for onUpdated are not supported on Android.
+  if (AppConstants.platform === "android") {
+    return;
+  }
+
+  const helperExtension = ExtensionTestUtils.loadExtension(helperExtensionDef);
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "permissions@tests.mozilla.org",
+        },
+      },
+      permissions,
+    },
+
+    useAddonManager: "permanent",
+
+    async background() {
+      let listenerGotCalled = false;
+      function onUpdateListener(tabId, changeInfo, tab) {
+        listenerGotCalled = true;
+      }
+
+      browser.test.onMessage.addListener(async message => {
+        switch (message.subject) {
+          case "setup": {
+            browser.tabs.onUpdated.addListener(
+              onUpdateListener,
+              message.data.filter
+            );
+            browser.test.sendMessage("done");
+            break;
+          }
+
+          case "collectTestResults": {
+            browser.test.assertEq(
+              message.data.expectEvent,
+              listenerGotCalled,
+              `Update listener called`
+            );
+            browser.tabs.onUpdated.removeListener(onUpdateListener);
+            listenerGotCalled = false;
+            browser.test.sendMessage("done");
+            break;
+          }
+
+          default:
+            browser.test.fail(`Received unexpected message: ${message}`);
+        }
+      });
+    },
+  });
+
+  await helperExtension.startup();
+  await extension.startup();
+
+  for (const testCase of testCases) {
+    helperExtension.sendMessage({
+      subject: "createTab",
+      data: { url: URL1 },
+    });
+    const tabId = await helperExtension.awaitMessage("tabCreated");
+
+    extension.sendMessage({
+      subject: "setup",
+      data: {
+        filter: testCase.filter,
+      },
+    });
+    await extension.awaitMessage("done");
+
+    helperExtension.sendMessage({
+      subject: "changeTabURL",
+      data: {
+        tabId,
+        url: URL2,
+      },
+    });
+    await helperExtension.awaitMessage("tabURLChanged");
+
+    extension.sendMessage({
+      subject: "collectTestResults",
+      data: {
+        expectEvent: testCase.expectEvent,
+      },
+    });
+    await extension.awaitMessage("done");
+
+    helperExtension.sendMessage({
+      subject: "removeTab",
+      data: { tabId },
+    });
+    await helperExtension.awaitMessage("tabRemoved");
+  }
+
+  await extension.unload();
+  await helperExtension.unload();
+}
+
+// http://mozilla.org host permission
+add_task(function onUpdateFilter_with_host_permission_url3() {
+  return test_onUpdateFilter(
+    [
+      {
+        filter: { urls: ["*://mozilla.org/*"] },
+        expectEvent: false,
+      },
+      {
+        filter: { urls: ["<all_urls>"] },
+        expectEvent: false,
+      },
+      {
+        filter: { urls: ["*://mozilla.org/*", "*://example.net/*"] },
+        expectEvent: false,
+      },
+      {
+        filter: { properties: ["title"] },
+        expectEvent: false,
+      },
+      {
+        filter: {},
+        expectEvent: true,
+      },
+    ],
+    ["*://mozilla.org/*"]
+  );
+});
+
+// http://example.net host permission
+add_task(function onUpdateFilter_with_host_permission_url2() {
+  return test_onUpdateFilter(
+    [
+      {
+        filter: { urls: ["*://mozilla.org/*"] },
+        expectEvent: false,
+      },
+      {
+        filter: { urls: ["<all_urls>"] },
+        expectEvent: true,
+      },
+      {
+        filter: { urls: ["*://mozilla.org/*", "*://example.net/*"] },
+        expectEvent: true,
+      },
+      {
+        filter: { properties: ["title"] },
+        expectEvent: true,
+      },
+      {
+        filter: {},
+        expectEvent: true,
+      },
+    ],
+    ["*://example.net/*"]
+  );
+});
+
+// <all_urls> permission
+add_task(function onUpdateFilter_with_host_permission_all_urls() {
+  return test_onUpdateFilter(
+    [
+      {
+        filter: { urls: ["*://mozilla.org/*"] },
+        expectEvent: false,
+      },
+      {
+        filter: { urls: ["<all_urls>"] },
+        expectEvent: true,
+      },
+      {
+        filter: { urls: ["*://mozilla.org/*", "*://example.net/*"] },
+        expectEvent: true,
+      },
+      {
+        filter: { properties: ["title"] },
+        expectEvent: true,
+      },
+      {
+        filter: {},
+        expectEvent: true,
+      },
+    ],
+    ["<all_urls>"]
+  );
+});
+
+// tabs permission
+add_task(function onUpdateFilter_with_tabs_permission() {
+  return test_onUpdateFilter(
+    [
+      {
+        filter: { urls: ["*://mozilla.org/*"] },
+        expectEvent: false,
+      },
+      {
+        filter: { urls: ["<all_urls>"] },
+        expectEvent: true,
+      },
+      {
+        filter: { urls: ["*://mozilla.org/*", "*://example.net/*"] },
+        expectEvent: true,
+      },
+      {
+        filter: { properties: ["title"] },
+        expectEvent: true,
+      },
+      {
+        filter: {},
+        expectEvent: true,
+      },
+    ],
+    ["tabs"]
+  );
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_tabs_query_popup.html b/toolkit/components/extensions/test/mochitest/test_ext_tabs_query_popup.html
new file mode 100644
index 0000000000..6393114c5f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_tabs_query_popup.html
@@ -0,0 +1,95 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Tabs create Test</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+async function test_query(query) {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "current-window@tests.mozilla.org",
+        }
+      },
+      permissions: ["tabs"],
+      browser_action: {
+        default_popup: "popup.html",
+      },
+    },
+
+    useAddonManager: "permanent",
+
+    background: async function() {
+      let query = await new Promise(resolve => {
+        browser.test.onMessage.addListener(message => {
+          resolve(message);
+        });
+      });
+      let tab = await browser.tabs.create({ url: "http://www.example.com", active: true });
+      browser.runtime.onMessage.addListener(message => {
+        if (message === "popup-loaded") {
+          browser.runtime.sendMessage({ tab, query });
+        }
+      });
+      browser.test.withHandlingUserInput(() =>
+          browser.browserAction.openPopup()
+      );
+    },
+
+    files: {
+      "popup.html": `<!DOCTYPE html><meta charset="utf-8"><script src="popup.js"><\/script>`,
+      "popup.js"() {
+        browser.runtime.onMessage.addListener(async function({ tab, query }) {
+          let tabs = await browser.tabs.query(query);
+          browser.test.assertEq(tabs.length, 1, `Got one tab`);
+          browser.test.assertEq(tabs[0].id, tab.id, "The tab is the right one");
+
+          // Create a new tab and verify that we still see the right result
+          let newTab = await browser.tabs.create({ url: "http://www.example.com", active: true });
+          tabs = await browser.tabs.query(query);
+          browser.test.assertEq(tabs.length, 1, `Got one tab`);
+          browser.test.assertEq(tabs[0].id, newTab.id, "Got the newly-created tab");
+
+          await browser.tabs.remove(newTab.id);
+
+          // Remove the tab and verify that we see the old tab
+          tabs = await browser.tabs.query(query);
+          browser.test.assertEq(tabs.length, 1, `Got one tab`);
+          browser.test.assertEq(tabs[0].id, tab.id, "Got the tab that was active before");
+
+          // Cleanup
+          await browser.tabs.remove(tab.id);
+
+          browser.test.notifyPass("tabs.query");
+        });
+        browser.runtime.sendMessage("popup-loaded");
+      },
+    },
+  });
+
+  await extension.startup();
+  extension.sendMessage(query);
+  await extension.awaitFinish("tabs.query");
+  await extension.unload();
+}
+
+add_task(function test_query_currentWindow_from_popup() {
+  return test_query({ currentWindow: true, active: true });
+});
+
+add_task(function test_query_lastActiveWindow_from_popup() {
+  return test_query({ lastFocusedWindow: true, active: true });
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_tabs_sendMessage.html b/toolkit/components/extensions/test/mochitest/test_ext_tabs_sendMessage.html
new file mode 100644
index 0000000000..293914fe5d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_tabs_sendMessage.html
@@ -0,0 +1,95 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test tabs.sendMessage</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script>
+"use strict";
+
+add_task(async function test_tabs_sendMessage_to_extension_page_frame() {
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: {
+        gecko: { id: "blah@android" },
+      },
+      content_scripts: [{
+        matches: ["http://mochi.test/*/file_sample.html?tabs.sendMessage"],
+        js: ["cs.js"],
+      }],
+      web_accessible_resources: ["page.html", "page.js"],
+    },
+
+    async background() {
+      let tab;
+
+      browser.runtime.onMessage.addListener(async (msg, sender) => {
+        browser.test.assertEq(msg, "page-script-ready");
+        browser.test.assertEq(sender.url, browser.runtime.getURL("page.html"));
+
+        let tabId = sender.tab.id;
+        let response = await browser.tabs.sendMessage(tabId, "tab-sendMessage");
+
+        switch (response) {
+          case "extension-tab":
+            browser.test.assertEq(tab.id, tabId, "Extension tab responded");
+            browser.test.assertEq(sender.frameId, 0, "Response from top level");
+            await browser.tabs.remove(tab.id);
+            browser.test.sendMessage("extension-tab-responded");
+            break;
+
+          case "extension-frame":
+            browser.test.assertTrue(sender.frameId > 0, "Response from iframe");
+            browser.test.sendMessage("extension-frame-responded");
+            break;
+
+          default:
+            browser.test.fail("Unexpected response: " + response);
+        }
+      });
+
+      tab = await browser.tabs.create({ url: "page.html" });
+    },
+
+    files: {
+      "cs.js"() {
+        let iframe = document.createElement("iframe");
+        iframe.src = browser.runtime.getURL("page.html");
+        document.body.append(iframe);
+        browser.test.sendMessage("content-script-done");
+      },
+
+      "page.html": `<!DOCTYPE html>
+        <meta charset=utf-8>
+        <script src=page.js><\/script>
+        Extension page`,
+
+      "page.js"() {
+        browser.runtime.onMessage.addListener(async msg => {
+          browser.test.assertEq(msg, "tab-sendMessage");
+          return window.parent === window ? "extension-tab" : "extension-frame";
+        });
+        browser.runtime.sendMessage("page-script-ready");
+      },
+    }
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("extension-tab-responded");
+
+  let win = window.open("file_sample.html?tabs.sendMessage");
+  await extension.awaitMessage("content-script-done");
+  await extension.awaitMessage("extension-frame-responded");
+  win.close();
+
+  await extension.unload();
+});
+
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_test.html b/toolkit/components/extensions/test/mochitest/test_ext_test.html
new file mode 100644
index 0000000000..9fef13d8d4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_test.html
@@ -0,0 +1,196 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Testing test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+
+<script>
+"use strict";
+
+function loadExtensionAndInterceptTest(extensionData) {
+  let results = [];
+  let testResolve;
+  let testDone = new Promise(resolve => { testResolve = resolve; });
+  let handler = {
+    testResult(...result) {
+      result.pop();
+      results.push(result);
+      SimpleTest.info(`Received test result: ${JSON.stringify(result)}`);
+    },
+
+    testMessage(msg, ...args) {
+      results.push(["test-message", msg, ...args]);
+      SimpleTest.info(`Received message: ${msg} ${JSON.stringify(args)}`);
+      if (msg === "This is the last browser.test call") {
+        testResolve();
+      }
+    },
+  };
+  let extension = SpecialPowers.loadExtension(extensionData, handler);
+  SimpleTest.registerCleanupFunction(() => {
+    if (extension.state == "pending" || extension.state == "running") {
+      SimpleTest.ok(false, "Extension left running at test shutdown");
+      return extension.unload();
+    } else if (extension.state == "unloading") {
+      SimpleTest.ok(false, "Extension not fully unloaded at test shutdown");
+    }
+  });
+  extension.awaitResults = () => testDone.then(() => results);
+  return extension;
+}
+
+function testScript() {
+  // Note: The result of these browser.test calls are intercepted by the test.
+  // See verifyTestResults for the expectations of each browser.test call.
+  browser.test.notifyPass("dot notifyPass");
+  browser.test.notifyFail("dot notifyFail");
+  browser.test.log("dot log");
+  browser.test.fail("dot fail");
+  browser.test.succeed("dot succeed");
+  browser.test.assertTrue(true);
+  browser.test.assertFalse(false);
+  browser.test.assertEq("", "");
+
+  let obj = {};
+  let arr = [];
+  let dom = document.createElement("body");
+  browser.test.assertTrue(obj, "Object truthy");
+  browser.test.assertTrue(arr, "Array truthy");
+  browser.test.assertTrue(dom, "Element truthy");
+  browser.test.assertTrue(true, "True truthy");
+  browser.test.assertTrue(false, "False truthy");
+  browser.test.assertTrue(null, "Null truthy");
+  browser.test.assertTrue(undefined, "Void truthy");
+  browser.test.assertTrue(false, document.createElement("html"));
+
+  browser.test.assertFalse(obj, "Object falsey");
+  browser.test.assertFalse(arr, "Array falsey");
+  browser.test.assertFalse(dom, "Element falsey");
+  browser.test.assertFalse(true, "True falsey");
+  browser.test.assertFalse(false, "False falsey");
+  browser.test.assertFalse(null, "Null falsey");
+  browser.test.assertFalse(undefined, "Void falsey");
+  browser.test.assertFalse(true, document.createElement("head"));
+
+  browser.test.assertEq(obj, obj, "Object equality");
+  browser.test.assertEq(arr, arr, "Array equality");
+  browser.test.assertEq(dom, dom, "Element equality");
+  browser.test.assertEq(null, null, "Null equality");
+  browser.test.assertEq(undefined, undefined, "Void equality");
+
+  browser.test.assertEq({}, {}, "Object reference ineqality");
+  browser.test.assertEq([], [], "Array reference ineqality");
+  browser.test.assertEq(dom, document.createElement("body"), "Element ineqality");
+  browser.test.assertEq(null, undefined, "Null and void ineqality");
+  browser.test.assertEq(true, false, document.createElement("div"));
+
+  obj = {
+    toString() {
+      return "Dynamic toString forbidden";
+    },
+  };
+  browser.test.assertEq(obj, obj, "obj with dynamic toString()");
+  browser.test.assertThrows(
+    () => { throw new Error("dummy"); },
+    /dummy2/,
+    "intentional failure"
+  );
+  browser.test.sendMessage("Ran test at", location.protocol);
+  browser.test.sendMessage("This is the last browser.test call");
+}
+
+function verifyTestResults(results, shortName, expectedProtocol) {
+  let expectations = [
+    ["test-done", true, "dot notifyPass"],
+    ["test-done", false, "dot notifyFail"],
+    ["test-log", true, "dot log"],
+    ["test-result", false, "dot fail"],
+    ["test-result", true, "dot succeed"],
+    ["test-result", true, "undefined"],
+    ["test-result", true, "undefined"],
+    ["test-eq", true, "undefined", "", ""],
+
+    ["test-result", true, "Object truthy"],
+    ["test-result", true, "Array truthy"],
+    ["test-result", true, "Element truthy"],
+    ["test-result", true, "True truthy"],
+    ["test-result", false, "False truthy"],
+    ["test-result", false, "Null truthy"],
+    ["test-result", false, "Void truthy"],
+    ["test-result", false, "[object HTMLHtmlElement]"],
+
+    ["test-result", false, "Object falsey"],
+    ["test-result", false, "Array falsey"],
+    ["test-result", false, "Element falsey"],
+    ["test-result", false, "True falsey"],
+    ["test-result", true, "False falsey"],
+    ["test-result", true, "Null falsey"],
+    ["test-result", true, "Void falsey"],
+    ["test-result", false, "[object HTMLHeadElement]"],
+
+    ["test-eq", true, "Object equality", "[object Object]", "[object Object]"],
+    ["test-eq", true, "Array equality", "", ""],
+    ["test-eq", true, "Element equality", "[object HTMLBodyElement]", "[object HTMLBodyElement]"],
+    ["test-eq", true, "Null equality", "null", "null"],
+    ["test-eq", true, "Void equality", "undefined", "undefined"],
+
+    ["test-eq", false, "Object reference ineqality", "[object Object]", "[object Object] (different)"],
+    ["test-eq", false, "Array reference ineqality", "", " (different)"],
+    ["test-eq", false, "Element ineqality", "[object HTMLBodyElement]", "[object HTMLBodyElement] (different)"],
+    ["test-eq", false, "Null and void ineqality", "null", "undefined"],
+    ["test-eq", false, "[object HTMLDivElement]", "true", "false"],
+
+    ["test-eq", true, "obj with dynamic toString()", "[object Object]", "[object Object]"],
+    ["test-result", false, "Function threw, expecting error to match /dummy2/, got \"dummy\": intentional failure"],
+
+    ["test-message", "Ran test at", expectedProtocol],
+    ["test-message", "This is the last browser.test call"],
+  ];
+
+  expectations.forEach((expectation, i) => {
+    let msg = expectation.slice(2).join(" - ");
+    isDeeply(results[i], expectation, `${shortName} (${msg})`);
+  });
+  is(results[expectations.length], undefined, "No more results");
+}
+
+add_task(async function test_test_in_background() {
+  let extensionData = {
+    background: `(${testScript})()`,
+  };
+
+  let extension = loadExtensionAndInterceptTest(extensionData);
+  await extension.startup();
+  let results = await extension.awaitResults();
+  verifyTestResults(results, "background page", "moz-extension:");
+  await extension.unload();
+});
+
+add_task(async function test_test_in_content_script() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [{
+        matches: ["http://mochi.test/*/file_sample.html"],
+        js: ["contentscript.js"],
+      }],
+    },
+    files: {
+      "contentscript.js": `(${testScript})()`,
+    },
+  };
+
+  let extension = loadExtensionAndInterceptTest(extensionData);
+  await extension.startup();
+  let win = window.open("file_sample.html");
+  let results = await extension.awaitResults();
+  win.close();
+  verifyTestResults(results, "content script", "http:");
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_unlimitedStorage.html b/toolkit/components/extensions/test/mochitest/test_ext_unlimitedStorage.html
new file mode 100644
index 0000000000..b92de8ab4f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_unlimitedStorage.html
@@ -0,0 +1,139 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript" src="head_unlimitedStorage.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+
+"use strict";
+
+async function test_background_storagePersist(EXTENSION_ID) {
+  await SpecialPowers.pushPrefEnv({
+    "set": [
+      ["dom.storageManager.enabled", true],
+      ["dom.storageManager.prompt.testing", false],
+      ["dom.storageManager.prompt.testing.allow", false],
+    ],
+  });
+
+  const extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+
+    manifest: {
+      permissions: ["storage", "unlimitedStorage"],
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+
+    background: async function() {
+      const PROMISE_RACE_TIMEOUT = 8000;
+
+      browser.test.sendMessage("extension-uuid", window.location.host);
+
+      await browser.storage.local.set({testkey: "testvalue"});
+      await browser.test.sendMessage("storage-local-called");
+
+      const requestStoragePersist = async () => {
+        const persistAllowed = await navigator.storage.persist();
+        if (!persistAllowed) {
+          throw new Error("navigator.storage.persist() has been denied");
+        }
+      };
+
+      await Promise.race([
+        requestStoragePersist(),
+        new Promise((resolve, reject) => {
+          setTimeout(() => {
+            reject(new Error("Timeout opening persistent db from background page"));
+          }, PROMISE_RACE_TIMEOUT);
+        }),
+      ]).then(
+        () => {
+          browser.test.notifyPass("indexeddb-storagePersistent-unlimitedStorage-done");
+        },
+        (error) => {
+          browser.test.fail(`error while testing persistent IndexedDB storage: ${error}`);
+          browser.test.notifyFail("indexeddb-storagePersistent-unlimitedStorage-done");
+        }
+      );
+    },
+  });
+
+  await extension.startup();
+
+  const uuid = await extension.awaitMessage("extension-uuid");
+
+  await extension.awaitMessage("storage-local-called");
+
+  let chromeScript = SpecialPowers.loadChromeScript(function test_country_data() {
+    const {addMessageListener, sendAsyncMessage} = this;
+
+    addMessageListener("getPersistedStatus", (uuid) => {
+      const {
+        ExtensionStorageIDB,
+      } = ChromeUtils.import("resource://gre/modules/ExtensionStorageIDB.jsm");
+
+      const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+      const {WebExtensionPolicy} = Cu.getGlobalForObject(ExtensionStorageIDB);
+      const policy = WebExtensionPolicy.getByHostname(uuid);
+      const storagePrincipal = ExtensionStorageIDB.getStoragePrincipal(policy.extension);
+      const request = Services.qms.persisted(storagePrincipal);
+      request.callback = () => {
+        // request.result will be undeinfed if the request failed (request.resultCode !== Cr.NS_OK).
+        sendAsyncMessage("gotPersistedStatus", request.result);
+      };
+    });
+  });
+
+  const persistedPromise = chromeScript.promiseOneMessage("gotPersistedStatus");
+  chromeScript.sendAsyncMessage("getPersistedStatus", uuid);
+  is(await persistedPromise, true, "Got the expected persist status for the storagePrincipal");
+
+  await extension.awaitFinish("indexeddb-storagePersistent-unlimitedStorage-done");
+  await extension.unload();
+
+  checkSitePermissions(uuid, Services.perms.UNKNOWN_ACTION, "has been cleared");
+}
+
+add_task(async function test_unlimitedStorage() {
+  const EXTENSION_ID = "test-storagePersist@mozilla";
+  await SpecialPowers.pushPrefEnv({
+    "set": [
+      ["extensions.webextensions.ExtensionStorageIDB.enabled", true],
+    ],
+  });
+
+  // Verify persist mode enabled when the storage.local IDB database is opened from
+  // the main process (from parent/ext-storage.js).
+  info("Test unlimitedStorage on an extension migrating to the IndexedDB storage.local backend)");
+  await test_background_storagePersist(EXTENSION_ID);
+
+  await SpecialPowers.pushPrefEnv({
+    "set": [
+      [`extensions.webextensions.ExtensionStorageIDB.migrated.` + EXTENSION_ID, true],
+    ],
+  });
+
+  // Verify persist mode enabled when the storage.local IDB database is opened from
+  // the child process (from child/ext-storage.js).
+  info("Test unlimitedStorage on an extension migrated to the IndexedDB storage.local backend");
+  await test_background_storagePersist(EXTENSION_ID);
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_unlimitedStorage_legacy_persistent_indexedDB.html b/toolkit/components/extensions/test/mochitest/test_ext_unlimitedStorage_legacy_persistent_indexedDB.html
new file mode 100644
index 0000000000..fe06d22e8d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_unlimitedStorage_legacy_persistent_indexedDB.html
@@ -0,0 +1,81 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript" src="head_unlimitedStorage.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+
+"use strict";
+
+add_task(async function test_legacy_indexedDB_storagePersistent_unlimitedStorage() {
+  const EXTENSION_ID = "test-idbStoragePersistent@mozilla";
+
+  const extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+
+    manifest: {
+      permissions: ["unlimitedStorage"],
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+
+    background: async function() {
+      const PROMISE_RACE_TIMEOUT = 8000;
+
+      browser.test.sendMessage("extension-uuid", window.location.host);
+
+      try {
+        await Promise.race([
+          new Promise((resolve, reject) => {
+            const dbReq = indexedDB.open("test-persistent-idb", {version: 1.0, storage: "persistent"});
+
+            dbReq.onerror = evt => {
+              reject(evt.target.error);
+            };
+
+            dbReq.onsuccess = () => {
+              resolve();
+            };
+          }),
+          new Promise((resolve, reject) => {
+            setTimeout(() => {
+              reject(new Error("Timeout opening persistent db from background page"));
+            }, PROMISE_RACE_TIMEOUT);
+          }),
+        ]);
+
+        browser.test.notifyPass("indexeddb-storagePersistent-unlimitedStorage-done");
+      } catch (error) {
+        const loggedError = error instanceof DOMException ? error.message : error;
+        browser.test.fail(`error while testing persistent IndexedDB storage: ${loggedError}`);
+        browser.test.notifyFail("indexeddb-storagePersistent-unlimitedStorage-done");
+      }
+    },
+  });
+
+  await extension.startup();
+
+  const uuid = await extension.awaitMessage("extension-uuid");
+
+  await extension.awaitFinish("indexeddb-storagePersistent-unlimitedStorage-done");
+
+  await extension.unload();
+
+  checkSitePermissions(uuid, Services.perms.UNKNOWN_ACTION, "has been cleared");
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_web_accessible_incognito.html b/toolkit/components/extensions/test/mochitest/test_ext_web_accessible_incognito.html
new file mode 100644
index 0000000000..5c9de814e4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_web_accessible_incognito.html
@@ -0,0 +1,174 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test the web_accessible_resources incognito</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+let image = atob("iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAA" +
+                 "ACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=");
+const IMAGE_ARRAYBUFFER = Uint8Array.from(image, byte => byte.charCodeAt(0)).buffer;
+
+async function testImageLoading(src, expectedAction) {
+  let imageLoadingPromise = new Promise((resolve, reject) => {
+    let cleanupListeners;
+    let testImage = new window.Image();
+    // Set the src via wrappedJSObject so the load is triggered with the
+    // content page's principal rather than ours.
+    testImage.wrappedJSObject.setAttribute("src", src);
+
+    let loadListener = () => {
+      cleanupListeners();
+      resolve(expectedAction === "loaded");
+    };
+
+    let errorListener = (event) => {
+      cleanupListeners();
+      resolve(expectedAction === "blocked");
+      browser.test.log(`+++ image loading ${event.error}`);
+    };
+
+    cleanupListeners = () => {
+      testImage.removeEventListener("load", loadListener);
+      testImage.removeEventListener("error", errorListener);
+    };
+
+    testImage.addEventListener("load", loadListener);
+    testImage.addEventListener("error", errorListener);
+  });
+
+  let success = await imageLoadingPromise;
+  browser.runtime.sendMessage({name: "image-loading", expectedAction, success});
+}
+
+function testScript() {
+  window.postMessage("test-script-loaded", "*");
+}
+
+add_task(async function test_web_accessible_resources_incognito() {
+  await SpecialPowers.pushPrefEnv({set: [
+    ["extensions.allowPrivateBrowsingByDefault", false],
+  ]});
+
+  // This extension will not have access to private browsing so its
+  // accessible resources should not be able to load in them.
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      "web_accessible_resources": [
+        "image.png",
+        "test_script.js",
+        "accessible.html",
+      ],
+    },
+    background() {
+      browser.test.sendMessage("url", browser.extension.getURL(""));
+    },
+    files: {
+      "image.png": IMAGE_ARRAYBUFFER,
+      "test_script.js": testScript,
+      "accessible.html": `<html><head>
+        <meta charset="utf-8">
+      </head></html>`,
+    },
+  });
+
+  await extension.startup();
+  let baseUrl = await extension.awaitMessage("url");
+
+  async function content() {
+    let baseUrl = await browser.runtime.sendMessage({name: "get-url"});
+    testImageLoading(`${baseUrl}image.png`, "loaded");
+
+    let testScriptElement = document.createElement("script");
+    // Set the src via wrappedJSObject so the load is triggered with the
+    // content page's principal rather than ours.
+    testScriptElement.wrappedJSObject.setAttribute("src", `${baseUrl}test_script.js`);
+    document.head.appendChild(testScriptElement);
+
+    let iframe = document.createElement("iframe");
+    // Set the src via wrappedJSObject so the load is triggered with the
+    // content page's principal rather than ours.
+    iframe.wrappedJSObject.setAttribute("src", `${baseUrl}accessible.html`);
+    document.body.appendChild(iframe);
+
+    // eslint-disable-next-line mozilla/balanced-listeners
+    window.addEventListener("message", event => {
+      browser.runtime.sendMessage({"name": event.data});
+    });
+  }
+
+  let pb_extension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    manifest: {
+      permissions: ["tabs"],
+      content_scripts: [{
+        "matches": ["*://example.com/*/file_sample.html"],
+        "run_at": "document_end",
+        "js": ["content_script_helper.js", "content_script.js"],
+      }],
+    },
+    files: {
+      "content_script_helper.js": `${testImageLoading}`,
+      "content_script.js": content,
+    },
+    background() {
+      let url = "http://example.com/tests/toolkit/components/extensions/test/mochitest/file_sample.html";
+      let baseUrl;
+      let window;
+
+      browser.runtime.onMessage.addListener(async msg => {
+        switch (msg.name) {
+          case "image-loading":
+            browser.test.assertFalse(msg.success, `Image was ${msg.expectedAction}`);
+            browser.test.sendMessage(`image-${msg.expectedAction}`);
+            break;
+          case "get-url":
+            return baseUrl;
+          default:
+            browser.test.fail(`unexepected message ${msg.name}`);
+        }
+      });
+
+      browser.test.onMessage.addListener(async (msg, data) => {
+        if (msg == "start") {
+          baseUrl = data;
+          window = await browser.windows.create({url, incognito: true});
+        }
+        if (msg == "close") {
+          browser.windows.remove(window.id);
+        }
+      });
+    },
+  });
+  await pb_extension.startup();
+
+  consoleMonitor.start([
+    {message: /may not load or link to.*image.png/},
+    {message: /may not load or link to.*test_script.js/},
+    {message: /\<script\> source URI is not allowed in this document/},
+    {message: /may not load or link to.*accessible.html/},
+  ]);
+
+  pb_extension.sendMessage("start", baseUrl);
+
+  await pb_extension.awaitMessage("image-loaded");
+
+  pb_extension.sendMessage("close");
+
+  await extension.unload();
+  await pb_extension.unload();
+
+  await consoleMonitor.finished();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_web_accessible_resources.html b/toolkit/components/extensions/test/mochitest/test_ext_web_accessible_resources.html
new file mode 100644
index 0000000000..d6ae4358d4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_web_accessible_resources.html
@@ -0,0 +1,265 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test the web_accessible_resources manifest directive</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+/* eslint-disable mozilla/balanced-listeners */
+
+SimpleTest.registerCleanupFunction(() => {
+  SpecialPowers.clearUserPref("security.mixed_content.block_display_content");
+});
+
+let image = atob("iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAA" +
+                 "ACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=");
+const IMAGE_ARRAYBUFFER = Uint8Array.from(image, byte => byte.charCodeAt(0)).buffer;
+
+async function testImageLoading(src, expectedAction) {
+  let imageLoadingPromise = new Promise((resolve, reject) => {
+    let cleanupListeners;
+    let testImage = document.createElement("img");
+    // Set the src via wrappedJSObject so the load is triggered with the
+    // content page's principal rather than ours.
+    testImage.wrappedJSObject.setAttribute("src", src);
+
+    let loadListener = () => {
+      cleanupListeners();
+      resolve(expectedAction === "loaded");
+    };
+
+    let errorListener = () => {
+      cleanupListeners();
+      resolve(expectedAction === "blocked");
+    };
+
+    cleanupListeners = () => {
+      testImage.removeEventListener("load", loadListener);
+      testImage.removeEventListener("error", errorListener);
+    };
+
+    testImage.addEventListener("load", loadListener);
+    testImage.addEventListener("error", errorListener);
+
+    document.body.appendChild(testImage);
+  });
+
+  let success = await imageLoadingPromise;
+  browser.runtime.sendMessage({name: "image-loading", expectedAction, success});
+}
+
+add_task(async function test_web_accessible_resources() {
+  function background() {
+    let gotURL;
+    let tabId;
+
+    function loadFrame(url) {
+      return new Promise(resolve => {
+        browser.tabs.sendMessage(tabId, ["load-iframe", url], reply => {
+          resolve(reply);
+        });
+      });
+    }
+
+    let urls = [
+      [browser.extension.getURL("accessible.html"), true],
+      [browser.extension.getURL("accessible.html") + "?foo=bar", true],
+      [browser.extension.getURL("accessible.html") + "#!foo=bar", true],
+      [browser.extension.getURL("forbidden.html"), false],
+      [browser.extension.getURL("wild1.html"), true],
+      [browser.extension.getURL("wild2.htm"), false],
+    ];
+
+    async function runTests() {
+      for (let [url, shouldLoad] of urls) {
+        let success = await loadFrame(url);
+
+        browser.test.assertEq(shouldLoad, success, "Load was successful");
+        if (shouldLoad) {
+          browser.test.assertEq(url, gotURL, "Got expected url");
+        } else {
+          browser.test.assertEq(undefined, gotURL, "Got no url");
+        }
+        gotURL = undefined;
+      }
+
+      browser.test.notifyPass("web-accessible-resources");
+    }
+
+    browser.runtime.onMessage.addListener(([msg, url], sender) => {
+      if (msg == "content-script-ready") {
+        tabId = sender.tab.id;
+        runTests();
+      } else if (msg == "page-script") {
+        browser.test.assertEq(undefined, gotURL, "Should have gotten only one message");
+        browser.test.assertEq("string", typeof(url), "URL should be a string");
+        gotURL = url;
+      }
+    });
+
+    browser.test.sendMessage("ready");
+  }
+
+  function contentScript() {
+    browser.runtime.onMessage.addListener(([msg, url], sender, respond) => {
+      if (msg == "load-iframe") {
+        let iframe = document.createElement("iframe");
+        // Set the src via wrappedJSObject so the load is triggered with the
+        // content page's principal rather than ours.
+        iframe.wrappedJSObject.setAttribute("src", url);
+        iframe.addEventListener("load", () => { respond(true); });
+        iframe.addEventListener("error", () => { respond(false); });
+        document.body.appendChild(iframe);
+        return true;
+      }
+    });
+    browser.runtime.sendMessage(["content-script-ready"]);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          "matches": ["http://example.com/"],
+          "js": ["content_script.js"],
+          "run_at": "document_idle",
+        },
+      ],
+
+      "web_accessible_resources": [
+        "/accessible.html",
+        "wild*.html",
+      ],
+    },
+
+    background,
+
+    files: {
+      "content_script.js": contentScript,
+
+      "accessible.html": `<html><head>
+        <meta charset="utf-8">
+        <script src="accessible.js"><\/script>
+      </head></html>`,
+
+      "accessible.js": 'browser.runtime.sendMessage(["page-script", location.href]);',
+
+      "inaccessible.html": `<html><head>
+        <meta charset="utf-8">
+        <script src="inaccessible.js"><\/script>
+      </head></html>`,
+
+      "inaccessible.js": 'browser.runtime.sendMessage(["page-script", location.href]);',
+
+      "wild1.html": `<html><head>
+        <meta charset="utf-8">
+        <script src="wild.js"><\/script>
+      </head></html>`,
+
+      "wild2.htm": `<html><head>
+        <meta charset="utf-8">
+        <script src="wild.js"><\/script>
+      </head></html>`,
+
+      "wild.js": 'browser.runtime.sendMessage(["page-script", location.href]);',
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("ready");
+
+  let win = window.open("http://example.com/");
+
+  await extension.awaitFinish("web-accessible-resources");
+
+  win.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_web_accessible_resources_mixed_content() {
+  function background() {
+    browser.runtime.onMessage.addListener(msg => {
+      if (msg.name === "image-loading") {
+        browser.test.assertTrue(msg.success, `Image was ${msg.expectedAction}`);
+        browser.test.sendMessage(`image-${msg.expectedAction}`);
+      } else {
+        browser.test.sendMessage(msg);
+        if (msg === "accessible-script-loaded") {
+          browser.test.notifyPass("mixed-test");
+        }
+      }
+    });
+
+    browser.test.sendMessage("background-ready");
+  }
+
+  function content() {
+    testImageLoading("http://example.com/tests/toolkit/components/extensions/test/mochitest/file_image_bad.png", "blocked");
+    testImageLoading(browser.extension.getURL("image.png"), "loaded");
+
+    let testScriptElement = document.createElement("script");
+    // Set the src via wrappedJSObject so the load is triggered with the
+    // content page's principal rather than ours.
+    testScriptElement.wrappedJSObject.setAttribute("src", browser.extension.getURL("test_script.js"));
+    document.head.appendChild(testScriptElement);
+
+    window.addEventListener("message", event => {
+      browser.runtime.sendMessage(event.data);
+    });
+  }
+
+  function testScript() {
+    window.postMessage("accessible-script-loaded", "*");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      "content_scripts": [{
+        "matches": ["https://example.com/*/file_mixed.html"],
+        "run_at": "document_end",
+        "js": ["content_script_helper.js", "content_script.js"],
+      }],
+      "web_accessible_resources": [
+        "image.png",
+        "test_script.js",
+      ],
+    },
+    background,
+    files: {
+      "content_script_helper.js": `${testImageLoading}`,
+      "content_script.js": content,
+      "test_script.js": testScript,
+      "image.png": IMAGE_ARRAYBUFFER,
+    },
+  });
+
+  SpecialPowers.setBoolPref("security.mixed_content.block_display_content", true);
+
+  await Promise.all([extension.startup(), extension.awaitMessage("background-ready")]);
+
+  let win = window.open("https://example.com/tests/toolkit/components/extensions/test/mochitest/file_mixed.html");
+
+  await Promise.all([
+    extension.awaitMessage("image-blocked"),
+    extension.awaitMessage("image-loaded"),
+    extension.awaitMessage("accessible-script-loaded"),
+  ]);
+  await extension.awaitFinish("mixed-test");
+  win.close();
+
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webnavigation.html b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation.html
new file mode 100644
index 0000000000..f471ef6a2f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation.html
@@ -0,0 +1,611 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+if (AppConstants.platform === "android") {
+  SimpleTest.requestLongerTimeout(3);
+}
+
+/* globals sendMouseEvent */
+
+function backgroundScript() {
+  const BASE = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest";
+  const URL = BASE + "/file_WebNavigation_page1.html";
+
+  const EVENTS = [
+    "onTabReplaced",
+    "onBeforeNavigate",
+    "onCommitted",
+    "onDOMContentLoaded",
+    "onCompleted",
+    "onErrorOccurred",
+    "onReferenceFragmentUpdated",
+    "onHistoryStateUpdated",
+  ];
+
+  let expectedTabId = -1;
+
+  function gotEvent(event, details) {
+    if (!details.url.startsWith(BASE)) {
+      return;
+    }
+    browser.test.log(`Got ${event} ${details.url} ${details.frameId} ${details.parentFrameId}`);
+
+    if (expectedTabId == -1) {
+      browser.test.assertTrue(details.tabId !== undefined, "tab ID defined");
+      expectedTabId = details.tabId;
+    }
+
+    browser.test.assertEq(details.tabId, expectedTabId, "correct tab");
+
+    browser.test.sendMessage("received", {url: details.url, event});
+
+    if (details.url == URL) {
+      browser.test.assertEq(0, details.frameId, "root frame ID correct");
+      browser.test.assertEq(-1, details.parentFrameId, "root parent frame ID correct");
+    } else {
+      browser.test.assertEq(0, details.parentFrameId, "parent frame ID correct");
+      browser.test.assertTrue(details.frameId != 0, "frame ID probably okay");
+    }
+
+    browser.test.assertTrue(details.frameId !== undefined, "frameId != undefined");
+    browser.test.assertTrue(details.parentFrameId !== undefined, "parentFrameId != undefined");
+  }
+
+  let listeners = {};
+  for (let event of EVENTS) {
+    listeners[event] = gotEvent.bind(null, event);
+    browser.webNavigation[event].addListener(listeners[event]);
+  }
+
+  browser.test.sendMessage("ready");
+}
+
+const BASE = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest";
+const URL = BASE + "/file_WebNavigation_page1.html";
+const FORM_URL = URL + "?";
+const FRAME = BASE + "/file_WebNavigation_page2.html";
+const FRAME2 = BASE + "/file_WebNavigation_page3.html";
+const FRAME_PUSHSTATE = BASE + "/file_WebNavigation_page3_pushState.html";
+const REDIRECT = BASE + "/redirection.sjs";
+const REDIRECTED = BASE + "/dummy_page.html";
+const CLIENT_REDIRECT = BASE + "/file_webNavigation_clientRedirect.html";
+const CLIENT_REDIRECT_HTTPHEADER = BASE + "/file_webNavigation_clientRedirect_httpHeaders.html";
+const FRAME_CLIENT_REDIRECT = BASE + "/file_webNavigation_frameClientRedirect.html";
+const FRAME_REDIRECT = BASE + "/file_webNavigation_frameRedirect.html";
+const FRAME_MANUAL = BASE + "/file_webNavigation_manualSubframe.html";
+const FRAME_MANUAL_PAGE1 = BASE + "/file_webNavigation_manualSubframe_page1.html";
+const FRAME_MANUAL_PAGE2 = BASE + "/file_webNavigation_manualSubframe_page2.html";
+const INVALID_PAGE = "https://invalid.localhost/";
+
+const REQUIRED = [
+  "onBeforeNavigate",
+  "onCommitted",
+  "onDOMContentLoaded",
+  "onCompleted",
+];
+
+var received = [];
+var completedResolve;
+var waitingURL, waitingEvent;
+
+function loadAndWait(win, event, url, script) {
+  received = [];
+  waitingEvent = event;
+  waitingURL = url;
+  dump(`RUN ${script}\n`);
+  script();
+  return new Promise(resolve => { completedResolve = resolve; });
+}
+
+add_task(async function webnav_transitions_props() {
+  function backgroundScriptTransitions() {
+    const EVENTS = [
+      "onCommitted",
+      "onHistoryStateUpdated",
+      "onReferenceFragmentUpdated",
+      "onCompleted",
+    ];
+
+    function gotEvent(event, details) {
+      browser.test.log(`Got ${event} ${details.url} ${details.transitionType} ${details.transitionQualifiers && JSON.stringify(details.transitionQualifiers)}`);
+
+      browser.test.sendMessage("received", {url: details.url, details, event});
+    }
+
+    let listeners = {};
+    for (let event of EVENTS) {
+      listeners[event] = gotEvent.bind(null, event);
+      browser.webNavigation[event].addListener(listeners[event]);
+    }
+
+    browser.test.sendMessage("ready");
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: [
+        "webNavigation",
+      ],
+    },
+    background: backgroundScriptTransitions,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  extension.onMessage("received", ({url, event, details}) => {
+    received.push({url, event, details});
+
+    if (event == waitingEvent && url == waitingURL) {
+      completedResolve();
+    }
+  });
+
+  await Promise.all([extension.startup(), extension.awaitMessage("ready")]);
+  info("webnavigation extension loaded");
+
+  let win = window.open();
+
+  await loadAndWait(win, "onCompleted", URL, () => { win.location = URL; });
+
+  // transitionType: reload
+  received = [];
+  await loadAndWait(win, "onCompleted", URL, () => { win.location.reload(); });
+
+  let found = received.find((data) => (data.event == "onCommitted" && data.url == URL));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "reload",
+       "Got the expected 'reload' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers),
+       "transitionQualifiers found in the OnCommitted events");
+  }
+
+  // transitionType: auto_subframe
+  found = received.find((data) => (data.event == "onCommitted" && data.url == FRAME));
+
+  ok(found, "Got the sub-frame onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "auto_subframe",
+       "Got the expected 'auto_subframe' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers),
+       "transitionQualifiers found in the OnCommitted events");
+  }
+
+  // transitionType: form_submit
+  received = [];
+  await loadAndWait(win, "onCompleted", FORM_URL, () => {
+    win.document.querySelector("form").submit();
+  });
+
+  found = received.find((data) => (data.event == "onCommitted" && data.url == FORM_URL));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "form_submit",
+       "Got the expected 'form_submit' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers),
+       "transitionQualifiers found in the OnCommitted events");
+  }
+
+  // transitionQualifier: server_redirect
+  received = [];
+  await loadAndWait(win, "onCompleted", REDIRECTED, () => { win.location = REDIRECT; });
+
+  found = received.find((data) => (data.event == "onCommitted" && data.url == REDIRECTED));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "link",
+       "Got the expected 'link' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers) &&
+       found.details.transitionQualifiers.find((q) => q == "server_redirect"),
+       "Got the expected 'server_redirect' transitionQualifiers in the OnCommitted events");
+  }
+
+  // transitionQualifier: forward_back
+  received = [];
+  await loadAndWait(win, "onCompleted", FORM_URL, () => { win.history.back(); });
+
+  found = received.find((data) => (data.event == "onCommitted" && data.url == FORM_URL));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "link",
+       "Got the expected 'link' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers) &&
+       found.details.transitionQualifiers.find((q) => q == "forward_back"),
+       "Got the expected 'forward_back' transitionQualifiers in the OnCommitted events");
+  }
+
+  // transitionQualifier: client_redirect
+  // (from meta http-equiv tag)
+  received = [];
+  await loadAndWait(win, "onCompleted", REDIRECTED, () => {
+    win.location = CLIENT_REDIRECT;
+  });
+
+  found = received.find((data) => (data.event == "onCommitted" && data.url == REDIRECTED));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "link",
+       "Got the expected 'link' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers) &&
+       found.details.transitionQualifiers.find((q) => q == "client_redirect"),
+       "Got the expected 'client_redirect' transitionQualifiers in the OnCommitted events");
+  }
+
+  // transitionQualifier: client_redirect
+  // (from http headers)
+  received = [];
+  await loadAndWait(win, "onCompleted", REDIRECTED, () => {
+    win.location = CLIENT_REDIRECT_HTTPHEADER;
+  });
+
+  found = received.find((data) => (data.event == "onCommitted" &&
+                                   data.url == CLIENT_REDIRECT_HTTPHEADER));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "link",
+       "Got the expected 'link' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers) &&
+       found.details.transitionQualifiers.find((q) => q == "client_redirect"),
+       "Got the expected 'client_redirect' transitionQualifiers in the OnCommitted events");
+  }
+
+  // transitionQualifier: client_redirect (sub-frame)
+  // (from meta http-equiv tag)
+  received = [];
+  await loadAndWait(win, "onCompleted", REDIRECTED, () => {
+    win.location = FRAME_CLIENT_REDIRECT;
+  });
+
+  found = received.find((data) => (data.event == "onCommitted" && data.url == REDIRECTED));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "auto_subframe",
+       "Got the expected 'auto_subframe' transitionType in the OnCommitted event");
+    ok(Array.isArray(found.details.transitionQualifiers) &&
+       found.details.transitionQualifiers.find((q) => q == "client_redirect"),
+       "Got the expected 'client_redirect' transitionQualifiers in the OnCommitted events");
+  }
+
+  // transitionQualifier: server_redirect (sub-frame)
+  received = [];
+  await loadAndWait(win, "onCompleted", REDIRECTED, () => { win.location = FRAME_REDIRECT; });
+
+  found = received.find((data) => (data.event == "onCommitted" && data.url == REDIRECT));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "auto_subframe",
+       "Got the expected 'auto_subframe' transitionType in the OnCommitted event");
+    // TODO BUG 1264936: currently the server_redirect is not detected in sub-frames
+    // once we fix it we can test it here:
+    //
+    // ok(Array.isArray(found.details.transitionQualifiers) &&
+    //    found.details.transitionQualifiers.find((q) => q == "server_redirect"),
+    //    "Got the expected 'server_redirect' transitionQualifiers in the OnCommitted events");
+  }
+
+  // transitionType: manual_subframe
+  received = [];
+  await loadAndWait(win, "onCompleted", FRAME_MANUAL, () => { win.location = FRAME_MANUAL; });
+  found = received.find((data) => (data.event == "onCommitted" &&
+                                   data.url == FRAME_MANUAL_PAGE1));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    is(found.details.transitionType, "auto_subframe",
+       "Got the expected 'auto_subframe' transitionType in the OnCommitted event");
+  }
+
+  received = [];
+  await loadAndWait(win, "onCompleted", FRAME_MANUAL_PAGE2, () => {
+    let el = win.document.querySelector("iframe")
+                .contentDocument.querySelector("a");
+    sendMouseEvent({type: "click"}, el, win);
+  });
+
+  found = received.find((data) => (data.event == "onCommitted" &&
+                                   data.url == FRAME_MANUAL_PAGE2));
+
+  ok(found, "Got the onCommitted event");
+
+  if (found) {
+    if (AppConstants.MOZ_BUILD_APP === "browser") {
+      is(found.details.transitionType, "manual_subframe",
+         "Got the expected 'manual_subframe' transitionType in the OnCommitted event");
+    } else {
+      is(found.details.transitionType, "auto_subframe",
+         "Got the expected 'manual_subframe' transitionType in the OnCommitted event");
+    }
+  }
+
+  // Test transitions properties on onHistoryStateUpdated events.
+
+  received = [];
+  await loadAndWait(win, "onCompleted", FRAME2, () => { win.location = FRAME2; });
+
+  received = [];
+  await loadAndWait(win, "onHistoryStateUpdated", `${FRAME2}/pushState`, () => {
+    win.history.pushState({}, "History PushState", `${FRAME2}/pushState`);
+  });
+
+  found = received.find((data) => (data.event == "onHistoryStateUpdated" &&
+                                   data.url == `${FRAME2}/pushState`));
+
+  ok(found, "Got the onHistoryStateUpdated event");
+
+  if (found) {
+    is(typeof found.details.transitionType, "string",
+       "Got transitionType in the onHistoryStateUpdated event");
+    ok(Array.isArray(found.details.transitionQualifiers),
+       "Got transitionQualifiers in the onHistoryStateUpdated event");
+  }
+
+  // Test transitions properties on onReferenceFragmentUpdated events.
+
+  received = [];
+  await loadAndWait(win, "onReferenceFragmentUpdated", `${FRAME2}/pushState#ref2`, () => {
+    win.history.pushState({}, "ReferenceFragment Update", `${FRAME2}/pushState#ref2`);
+  });
+
+  found = received.find((data) => (data.event == "onReferenceFragmentUpdated" &&
+                                   data.url == `${FRAME2}/pushState#ref2`));
+
+  ok(found, "Got the onReferenceFragmentUpdated event");
+
+  if (found) {
+    is(typeof found.details.transitionType, "string",
+       "Got transitionType in the onReferenceFragmentUpdated event");
+    ok(Array.isArray(found.details.transitionQualifiers),
+       "Got transitionQualifiers in the onReferenceFragmentUpdated event");
+  }
+
+  // cleanup phase
+  win.close();
+
+  await extension.unload();
+  info("webnavigation extension unloaded");
+});
+
+add_task(async function webnav_ordering() {
+  let extensionData = {
+    manifest: {
+      permissions: [
+        "webNavigation",
+      ],
+    },
+    background: backgroundScript,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  extension.onMessage("received", ({url, event}) => {
+    received.push({url, event});
+
+    if (event == waitingEvent && url == waitingURL) {
+      completedResolve();
+    }
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  info("webnavigation extension loaded");
+
+  let win = window.open();
+
+  await loadAndWait(win, "onCompleted", URL, () => { win.location = URL; });
+
+  function checkRequired(url) {
+    for (let event of REQUIRED) {
+      let found = false;
+      for (let r of received) {
+        if (r.url == url && r.event == event) {
+          found = true;
+        }
+      }
+      ok(found, `Received event ${event} from ${url}`);
+    }
+  }
+
+  checkRequired(URL);
+  checkRequired(FRAME);
+
+  function checkBefore(action1, action2) {
+    function find(action) {
+      for (let i = 0; i < received.length; i++) {
+        if (received[i].url == action.url && received[i].event == action.event) {
+          return i;
+        }
+      }
+      return -1;
+    }
+
+    let index1 = find(action1);
+    let index2 = find(action2);
+    ok(index1 != -1, `Action ${JSON.stringify(action1)} happened`);
+    ok(index2 != -1, `Action ${JSON.stringify(action2)} happened`);
+    ok(index1 < index2, `Action ${JSON.stringify(action1)} happened before ${JSON.stringify(action2)}`);
+  }
+
+  // As required in the webNavigation API documentation:
+  // If a navigating frame contains subframes, its onCommitted is fired before any
+  // of its children's onBeforeNavigate; while onCompleted is fired after
+  // all of its children's onCompleted.
+  checkBefore({url: URL, event: "onCommitted"}, {url: FRAME, event: "onBeforeNavigate"});
+  checkBefore({url: FRAME, event: "onCompleted"}, {url: URL, event: "onCompleted"});
+
+  // As required in the webNAvigation API documentation, check the event sequence:
+  // onBeforeNavigate -> onCommitted -> onDOMContentLoaded -> onCompleted
+  let expectedEventSequence = [
+    "onBeforeNavigate", "onCommitted", "onDOMContentLoaded", "onCompleted",
+  ];
+
+  for (let i = 1; i < expectedEventSequence.length; i++) {
+    let after = expectedEventSequence[i];
+    let before = expectedEventSequence[i - 1];
+    checkBefore({url: URL, event: before}, {url: URL, event: after});
+    checkBefore({url: FRAME, event: before}, {url: FRAME, event: after});
+  }
+
+  await loadAndWait(win, "onCompleted", FRAME2, () => { win.frames[0].location = FRAME2; });
+
+  checkRequired(FRAME2);
+
+  let navigationSequence = [
+    {
+      action: () => { win.frames[0].document.getElementById("elt").click(); },
+      waitURL: `${FRAME2}#ref`,
+      expectedEvent: "onReferenceFragmentUpdated",
+      description: "clicked an anchor link",
+    },
+    {
+      action: () => { win.frames[0].history.pushState({}, "History PushState", `${FRAME2}#ref2`); },
+      waitURL: `${FRAME2}#ref2`,
+      expectedEvent: "onReferenceFragmentUpdated",
+      description: "history.pushState, same pathname, different hash",
+    },
+    {
+      action: () => { win.frames[0].history.pushState({}, "History PushState", `${FRAME2}#ref2`); },
+      waitURL: `${FRAME2}#ref2`,
+      expectedEvent: "onHistoryStateUpdated",
+      description: "history.pushState, same pathname, same hash",
+    },
+    {
+      action: () => {
+        win.frames[0].history.pushState({}, "History PushState", `${FRAME2}?query_param1=value#ref2`);
+      },
+      waitURL: `${FRAME2}?query_param1=value#ref2`,
+      expectedEvent: "onHistoryStateUpdated",
+      description: "history.pushState, same pathname, same hash, different query params",
+    },
+    {
+      action: () => {
+        win.frames[0].history.pushState({}, "History PushState", `${FRAME2}?query_param2=value#ref3`);
+      },
+      waitURL: `${FRAME2}?query_param2=value#ref3`,
+      expectedEvent: "onHistoryStateUpdated",
+      description: "history.pushState, same pathname, different hash, different query params",
+    },
+    {
+      action: () => { win.frames[0].history.pushState(null, "History PushState", FRAME_PUSHSTATE); },
+      waitURL: FRAME_PUSHSTATE,
+      expectedEvent: "onHistoryStateUpdated",
+      description: "history.pushState, different pathname",
+    },
+  ];
+
+  for (let navigation of navigationSequence) {
+    let {expectedEvent, waitURL, action, description} = navigation;
+    info(`Waiting ${expectedEvent} from ${waitURL} - ${description}`);
+    await loadAndWait(win, expectedEvent, waitURL, action);
+    info(`Received ${expectedEvent} from ${waitURL} - ${description}`);
+  }
+
+  for (let i = navigationSequence.length - 1; i > 0; i--) {
+    let {waitURL: fromURL, expectedEvent} = navigationSequence[i];
+    let {waitURL} = navigationSequence[i - 1];
+    info(`Waiting ${expectedEvent} from ${waitURL} - history.back() from ${fromURL} to ${waitURL}`);
+    await loadAndWait(win, expectedEvent, waitURL, () => { win.frames[0].history.back(); });
+    info(`Received ${expectedEvent} from ${waitURL} - history.back() from ${fromURL} to ${waitURL}`);
+  }
+
+  for (let i = 0; i < navigationSequence.length - 1; i++) {
+    let {waitURL: fromURL} = navigationSequence[i];
+    let {waitURL, expectedEvent} = navigationSequence[i + 1];
+    info(`Waiting ${expectedEvent} from ${waitURL} - history.forward() from ${fromURL} to ${waitURL}`);
+    await loadAndWait(win, expectedEvent, waitURL, () => { win.frames[0].history.forward(); });
+    info(`Received ${expectedEvent} from ${waitURL} - history.forward() from ${fromURL} to ${waitURL}`);
+  }
+
+  win.close();
+
+  await extension.unload();
+  info("webnavigation extension unloaded");
+});
+
+add_task(async function webnav_error_event() {
+  function backgroundScriptErrorEvent() {
+    browser.webNavigation.onErrorOccurred.addListener((details) => {
+      browser.test.log(`Got onErrorOccurred ${details.url} ${details.error}`);
+
+      browser.test.sendMessage("received", {url: details.url, details, event: "onErrorOccurred"});
+    });
+
+    browser.test.sendMessage("ready");
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: [
+        "webNavigation",
+      ],
+    },
+    background: backgroundScriptErrorEvent,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  extension.onMessage("received", ({url, event, details}) => {
+    received.push({url, event, details});
+
+    if (event == waitingEvent && url == waitingURL) {
+      completedResolve();
+    }
+  });
+
+  await Promise.all([extension.startup(), extension.awaitMessage("ready")]);
+  info("webnavigation extension loaded");
+
+  let win = window.open();
+
+  received = [];
+  await loadAndWait(win, "onErrorOccurred", INVALID_PAGE, () => { win.location = INVALID_PAGE; });
+
+  let found = received.find((data) => (data.event == "onErrorOccurred" &&
+                                   data.url == INVALID_PAGE));
+
+  ok(found, "Got the onErrorOccurred event");
+
+  if (found) {
+    ok(found.details.error.match(/Error code [0-9]+/),
+       "Got the expected error string in the onErrorOccurred event");
+  }
+
+  // cleanup phase
+  win.close();
+
+  await extension.unload();
+  info("webnavigation extension unloaded");
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webnavigation_filters.html b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation_filters.html
new file mode 100644
index 0000000000..60720e9663
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation_filters.html
@@ -0,0 +1,299 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_webnav_unresolved_uri_on_expected_URI_scheme() {
+  function background() {
+    let listeners = [];
+
+    function cleanupTestListeners() {
+      browser.test.log(`Cleanup previous test event listeners`);
+      for (let {event, listener} of listeners.splice(0)) {
+        browser.webNavigation[event].removeListener(listener);
+      }
+    }
+
+    function createTestListener(event, fail, urlFilter) {
+      return new Promise(resolve => {
+        function listener(details) {
+          let log = JSON.stringify({url: details.url, urlFilter});
+          if (fail) {
+            browser.test.fail(`Got an unexpected ${event} on the failure listener: ${log}`);
+          } else {
+            browser.test.succeed(`Got the expected ${event} on the success listener: ${log}`);
+          }
+
+          resolve();
+        }
+
+        browser.webNavigation[event].addListener(listener, {url: urlFilter});
+        listeners.push({event, listener});
+      });
+    }
+
+    browser.test.onMessage.addListener((msg, events, data) => {
+      if (msg !== "test-filters") {
+        return;
+      }
+
+      let promises = [];
+
+      for (let {okFilter, failFilter} of data.filters) {
+        for (let event of events) {
+          promises.push(
+            Promise.race([
+              createTestListener(event, false, okFilter),
+              createTestListener(event, true, failFilter),
+            ]));
+        }
+      }
+
+      Promise.all(promises).catch(e => {
+        browser.test.fail(`Error: ${e} :: ${e.stack}`);
+      }).then(() => {
+        cleanupTestListeners();
+        browser.test.sendMessage("test-filter-next");
+      });
+
+      browser.test.sendMessage("test-filter-ready");
+    });
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: [
+        "webNavigation",
+      ],
+    },
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  let win = window.open();
+
+  let testFilterScenarios = [
+    {
+      url: "http://example.net/browser",
+      filters: [
+        // schemes
+        {
+          okFilter: [{schemes: ["http"]}],
+          failFilter: [{schemes: ["https"]}],
+        },
+        // ports
+        {
+          okFilter: [{ports: [80, 22, 443]}],
+          failFilter: [{ports: [81, 82, 83]}],
+        },
+        {
+          okFilter: [{ports: [22, 443, [10, 80]]}],
+          failFilter: [{ports: [22, 23, [81, 100]]}],
+        },
+        // multiple criteria in a single filter:
+        // if one of the criteria is not verified, the event should not be received.
+        {
+          okFilter: [{schemes: ["http"], ports: [80, 22, 443]}],
+          failFilter: [{schemes: ["http"], ports: [81, 82, 83]}],
+        },
+        // multiple urlFilters on the same listener
+        // if at least one of the criteria is verified, the event should be received.
+        {
+          okFilter: [{schemes: ["https"]}, {ports: [80, 22, 443]}],
+          failFilter: [{schemes: ["https"]}, {ports: [81, 82, 83]}],
+        },
+      ],
+    },
+    {
+      url: "http://example.net/browser?param=1#ref",
+      filters: [
+        // host: Equals, Contains, Prefix, Suffix
+        {
+          okFilter: [{hostEquals: "example.net"}],
+          failFilter: [{hostEquals: "example.com"}],
+        },
+        {
+          okFilter: [{hostContains: ".example"}],
+          failFilter: [{hostContains: ".www"}],
+        },
+        {
+          okFilter: [{hostPrefix: "example"}],
+          failFilter: [{hostPrefix: "www"}],
+        },
+        {
+          okFilter: [{hostSuffix: "net"}],
+          failFilter: [{hostSuffix: "com"}],
+        },
+        // path: Equals, Contains, Prefix, Suffix
+        {
+          okFilter: [{pathEquals: "/browser"}],
+          failFilter: [{pathEquals: "/"}],
+        },
+        {
+          okFilter: [{pathContains: "brow"}],
+          failFilter: [{pathContains: "tool"}],
+        },
+        {
+          okFilter: [{pathPrefix: "/bro"}],
+          failFilter: [{pathPrefix: "/tool"}],
+        },
+        {
+          okFilter: [{pathSuffix: "wser"}],
+          failFilter: [{pathSuffix: "kit"}],
+        },
+        // query: Equals, Contains, Prefix, Suffix
+        {
+          okFilter: [{queryEquals: "param=1"}],
+          failFilter: [{queryEquals: "wrongparam=2"}],
+        },
+        {
+          okFilter: [{queryContains: "param"}],
+          failFilter: [{queryContains: "wrongparam"}],
+        },
+        {
+          okFilter: [{queryPrefix: "param="}],
+          failFilter: [{queryPrefix: "wrong"}],
+        },
+        {
+          okFilter: [{querySuffix: "=1"}],
+          failFilter: [{querySuffix: "=2"}],
+        },
+        // urlMatches, originAndPathMatches
+        {
+          okFilter: [{urlMatches: "example.net/.*\?param=1"}],
+          failFilter: [{urlMatches: "example.net/.*\?wrongparam=2"}],
+        },
+        {
+          okFilter: [{originAndPathMatches: "example.net\/browser"}],
+          failFilter: [{originAndPathMatches: "example.net/.*\?param=1"}],
+        },
+      ],
+    },
+  ];
+
+  info("WebNavigation event filters test scenarios starting...");
+
+  const EVENTS = [
+    "onBeforeNavigate",
+    "onCommitted",
+    "onDOMContentLoaded",
+    "onCompleted",
+  ];
+
+  for (let data of testFilterScenarios) {
+    info(`Prepare the new test scenario: ${JSON.stringify(data)}`);
+
+    // Bug 1589102: using plain "about:blank" crashes here in fission+debug.
+    win.location = "about:blank?2";
+
+    extension.sendMessage("test-filters", EVENTS, data);
+    await extension.awaitMessage("test-filter-ready");
+
+    info(`Loading the test url: ${data.url}`);
+    win.location = data.url;
+
+    await extension.awaitMessage("test-filter-next");
+
+    info("Test scenario completed. Moving to the next test scenario.");
+  }
+
+  info("WebNavigation event filters test onReferenceFragmentUpdated scenario starting...");
+
+  const BASE = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest";
+  let url = BASE + "/file_WebNavigation_page3.html";
+
+  let okFilter = [{urlContains: "_page3.html"}];
+  let failFilter = [{ports: [444]}];
+  let data = {filters: [{okFilter, failFilter}]};
+  let event = "onCompleted";
+
+  info(`Loading the initial test url: ${url}`);
+  extension.sendMessage("test-filters", [event], data);
+
+  await extension.awaitMessage("test-filter-ready");
+  win.location = url;
+  await extension.awaitMessage("test-filter-next");
+
+  event = "onReferenceFragmentUpdated";
+  extension.sendMessage("test-filters", [event], data);
+
+  await extension.awaitMessage("test-filter-ready");
+  win.location = url + "#ref1";
+  await extension.awaitMessage("test-filter-next");
+
+  info("WebNavigation event filters test onHistoryStateUpdated scenario starting...");
+
+  event = "onHistoryStateUpdated";
+  extension.sendMessage("test-filters", [event], data);
+  await extension.awaitMessage("test-filter-ready");
+
+  win.history.pushState({}, "", BASE + "/pushState_page3.html");
+  await extension.awaitMessage("test-filter-next");
+
+  // TODO: add additional specific tests for the other webNavigation events:
+  // onErrorOccurred (and onCreatedNavigationTarget on supported)
+
+  info("WebNavigation event filters test scenarios completed.");
+
+  await extension.unload();
+
+  win.close();
+});
+
+add_task(async function test_webnav_empty_filter_validation_error() {
+  function background() {
+    let catchedException;
+
+    try {
+      browser.webNavigation.onCompleted.addListener(
+        // Empty callback (not really used)
+        () => {},
+        // Empty filter (which should raise a validation error exception).
+        {url: []}
+      );
+    } catch (e) {
+      catchedException = e;
+      browser.test.log(`Got an exception`);
+    }
+
+    if (catchedException &&
+        catchedException.message.includes("Type error for parameter filters") &&
+        catchedException.message.includes("Array requires at least 1 items; you have 0")) {
+      browser.test.notifyPass("webNav.emptyFilterValidationError");
+    } else {
+      browser.test.notifyFail("webNav.emptyFilterValidationError");
+    }
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webNavigation",
+      ],
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await extension.awaitFinish("webNav.emptyFilterValidationError");
+
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webnavigation_incognito.html b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation_incognito.html
new file mode 100644
index 0000000000..6b161d8247
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation_incognito.html
@@ -0,0 +1,109 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function webnav_test_incognito() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["extensions.allowPrivateBrowsingByDefault", false]],
+  });
+
+  // Monitor will fail if it gets any event.
+  let monitor = ExtensionTestUtils.loadExtension({
+    manifest: {
+      "permissions": ["webNavigation", "*://mochi.test/*"],
+    },
+    background() {
+      const EVENTS = [
+        "onTabReplaced",
+        "onBeforeNavigate",
+        "onCommitted",
+        "onDOMContentLoaded",
+        "onCompleted",
+        "onErrorOccurred",
+        "onReferenceFragmentUpdated",
+        "onHistoryStateUpdated",
+      ];
+
+      function onEvent(event, details) {
+        browser.test.fail(`not_allowed - Got ${event} ${details.url} ${details.frameId} ${details.parentFrameId}`);
+      }
+
+      let listeners = {};
+      for (let event of EVENTS) {
+        listeners[event] = onEvent.bind(null, event);
+        browser.webNavigation[event].addListener(listeners[event]);
+      }
+
+      browser.test.onMessage.addListener(async (message, tabId) => {
+        // try to access the private window
+        await browser.test.assertRejects(browser.webNavigation.getAllFrames({tabId}),
+                                         /Invalid tab ID/,
+                                         "should not be able to get incognito frames");
+        await browser.test.assertRejects(browser.webNavigation.getFrame({tabId, frameId: 0}),
+                                         /Invalid tab ID/,
+                                         "should not be able to get incognito frames");
+        browser.test.notifyPass("completed");
+      });
+    },
+  });
+
+  // extension loads a private window and waits for the onCompleted event.
+  let extension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    manifest: {
+      permissions: ["tabs", "webNavigation", "*://mochi.test/*"],
+    },
+    async background() {
+      const BASE = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest";
+      const url = BASE + "/file_WebNavigation_page1.html";
+      let window;
+
+      browser.webNavigation.onCompleted.addListener(async (details) => {
+        if (details.url !== url) {
+          return;
+        }
+        browser.test.log(`spanning - Got onCompleted ${details.url} ${details.frameId} ${details.parentFrameId}`);
+        browser.test.sendMessage("completed");
+      });
+      browser.test.onMessage.addListener(async () => {
+        await browser.windows.remove(window.id);
+        browser.test.notifyPass("done");
+      });
+      window = await browser.windows.create({url, incognito: true});
+      let tabs = await browser.tabs.query({active: true, windowId: window.id});
+      browser.test.sendMessage("tabId", tabs[0].id);
+    },
+  });
+
+  await monitor.startup();
+  await extension.startup();
+
+  await extension.awaitMessage("completed");
+  let tabId = await extension.awaitMessage("tabId");
+
+  await monitor.sendMessage("tab", tabId);
+  await monitor.awaitFinish("completed");
+
+  await extension.sendMessage("close");
+  await extension.awaitFinish("done");
+
+  await extension.unload();
+  await monitor.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_and_proxy_filter.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_and_proxy_filter.html
new file mode 100644
index 0000000000..ea99ec244a
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_and_proxy_filter.html
@@ -0,0 +1,134 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css">
+<script>
+"use strict";
+
+// Check that the windowId and tabId filter work as expected in the webRequest
+// and proxy API:
+// - A non-matching windowId / tabId listener won't trigger events.
+// - A matching tabId from a tab triggers the event.
+// - A matching windowId from a tab triggers the event.
+//   (unlike test_ext_webrequest_filter.html, this also works on Android)
+// - Requests from background pages can be matched with windowId and tabId -1.
+add_task(async function test_filter_tabId_and_windowId() {
+  async function tabScript() {
+    let pendingExpectations = new Set();
+    // Helper to detect completion of expected requests.
+    function watchExpected(filter, desc) {
+      desc += ` - ${JSON.stringify(filter)}`;
+      const DESC_PROXY = `${desc} (proxy)`;
+      const DESC_WEBREQUEST = `${desc} (webRequest)`;
+      pendingExpectations.add(DESC_PROXY);
+      pendingExpectations.add(DESC_WEBREQUEST);
+      browser.proxy.onRequest.addListener(() => {
+        pendingExpectations.delete(DESC_PROXY);
+      }, filter);
+      browser.webRequest.onBeforeRequest.addListener(
+        () => {
+          pendingExpectations.delete(DESC_WEBREQUEST);
+        },
+        filter,
+        ["blocking"]
+      );
+    }
+
+    // Helper to detect unexpected requests.
+    function watchUnexpected(filter, desc) {
+      desc += ` - ${JSON.stringify(filter)}`;
+      browser.proxy.onRequest.addListener(() => {
+        browser.test.fail(`${desc} - unexpected proxy event`);
+      }, filter);
+      browser.webRequest.onBeforeRequest.addListener(() => {
+        browser.test.fail(`${desc} - unexpected webRequest event`);
+      }, filter);
+    }
+
+    function registerExpectations(url, windowId, tabId) {
+      const urls = [url];
+      watchUnexpected({ urls, windowId: 0 }, "non-matching windowId");
+      watchUnexpected({ urls, tabId: 0 }, "non-matching tabId");
+
+      watchExpected({ urls, windowId }, "windowId matches");
+      watchExpected({ urls, tabId }, "tabId matches");
+    }
+
+    try {
+      let { windowId, tabId } = await browser.runtime.sendMessage("getIds");
+      browser.test.log(`Dummy tab has: tabId=${tabId} windowId=${windowId}`);
+      registerExpectations("http://example.com/?tab", windowId, tabId);
+      registerExpectations("http://example.com/?bg", -1, -1);
+
+      // Call an API method implemented in the parent process to ensure that
+      // the listeners have been registered (workaround for bug 1300234).
+      // There is a .catch() at the end because the call is rejected on Android.
+      await browser.proxy.settings.get({}).catch(() => {});
+
+      browser.test.log("Triggering request from background page.");
+      await browser.runtime.sendMessage("triggerBackgroundRequest");
+
+      browser.test.log("Triggering request from tab.");
+      await fetch("http://example.com/?tab");
+
+      browser.test.assertEq(0, pendingExpectations.size, "got all events");
+      for (let description of pendingExpectations) {
+        browser.test.fail(`Event not observed: ${description}`);
+      }
+    } catch (e) {
+      browser.test.fail(`Unexpected test failure: ${e} :: ${e.stack}`);
+    }
+    browser.test.sendMessage("testCompleted");
+  }
+
+  function background() {
+    browser.runtime.onMessage.addListener(async (msg, sender) => {
+      if (msg === "getIds") {
+        return { windowId: sender.tab.windowId, tabId: sender.tab.id };
+      }
+      if (msg === "triggerBackgroundRequest") {
+        await fetch("http://example.com/?bg");
+      }
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "proxy",
+        "webRequest",
+        "webRequestBlocking",
+        "http://example.com/*",
+      ],
+      web_accessible_resources: ["tab.html"],
+    },
+    background,
+    files: {
+      "tab.html": `<!DOCTYPE html><script src="tab.js"><\/script>`,
+      "tab.js": tabScript,
+    },
+  });
+  await extension.startup();
+
+  // bug 1641735: tabs.create / tabs.remove does not work in GeckoView unless
+  // `useAddonManager: "permanent"` is used, so use window.open() instead.
+  //
+  // Note that somehow window.open() unexpectedly runs null when extensions
+  // run in-process, i.e. extensions.webextensions.remote=false. Fortunately,
+  // extension tabs are automatically closed as part of extension.unload()
+  // below (provided that extension APIs are used in the tab - bug 1399655).
+  window.open(`moz-extension://${extension.uuid}/tab.html`);
+
+  await extension.awaitMessage("testCompleted");
+  await extension.unload();
+});
+</script>
+</head>
+<body>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_auth.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_auth.html
new file mode 100644
index 0000000000..f191e58b56
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_auth.html
@@ -0,0 +1,182 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head_webrequest.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+<script>
+"use strict";
+
+// This file defines content scripts.
+/* eslint-env mozilla/frame-script */
+
+let baseUrl = "http://mochi.test:8888/tests/toolkit/components/passwordmgr/test/mochitest/authenticate.sjs";
+function testXHR(url) {
+  return new Promise((resolve, reject) => {
+    let xhr = new XMLHttpRequest();
+    xhr.open("GET", url);
+    xhr.onload = resolve;
+    xhr.onabort = reject;
+    xhr.onerror = reject;
+    xhr.send();
+  });
+}
+
+function getAuthHandler(result, blocking = true) {
+  function background(result) {
+    browser.webRequest.onAuthRequired.addListener((details) => {
+      browser.test.succeed(`authHandler.onAuthRequired called with ${details.requestId} ${details.url} result ${JSON.stringify(result)}`);
+      browser.test.sendMessage("onAuthRequired");
+      return result;
+    }, {urls: ["*://mochi.test/*"]}, ["blocking"]);
+    browser.webRequest.onCompleted.addListener((details) => {
+      browser.test.succeed(`authHandler.onCompleted called with ${details.requestId} ${details.url}`);
+      browser.test.sendMessage("onCompleted");
+    }, {urls: ["*://mochi.test/*"]});
+    browser.webRequest.onErrorOccurred.addListener((details) => {
+      browser.test.succeed(`authHandler.onErrorOccurred called with ${details.requestId} ${details.url}`);
+      browser.test.sendMessage("onErrorOccurred");
+    }, {urls: ["*://mochi.test/*"]});
+  }
+
+  let permissions = [
+    "webRequest",
+    "*://mochi.test/*",
+  ];
+  if (blocking) {
+    permissions.push("webRequestBlocking");
+  }
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions,
+    },
+    background: `(${background})(${JSON.stringify(result)})`,
+  });
+}
+
+add_task(async function test_webRequest_auth_nonblocking_forwardAuthProvider() {
+  // The chrome script sets up a default auth handler on the channel, the
+  // extension does not return anything in the authRequred call.  We should
+  // get the call in the extension first, then in the chrome code where we
+  // cancel the request to avoid dealing with the prompt dialog here.  The test
+  // is to ensure that WebRequest calls the previous notificationCallbacks
+  // if the authorization is not handled by the onAuthRequired handler.
+
+  let chromeScript = SpecialPowers.loadChromeScript(() => {
+    const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+    let observer = channel => {
+      if (!(channel instanceof Ci.nsIHttpChannel && channel.URI.host === "mochi.test")) {
+        return;
+      }
+      Services.obs.removeObserver(observer, "http-on-modify-request");
+      channel.notificationCallbacks = {
+        QueryInterface: ChromeUtils.generateQI(["nsIInterfaceRequestor",
+                                                "nsIAuthPromptProvider",
+                                                "nsIAuthPrompt2"]),
+        getInterface: ChromeUtils.generateQI(["nsIAuthPromptProvider",
+                                              "nsIAuthPrompt2"]),
+        promptAuth(channel, level, authInfo) {
+          throw Components.Exception("", Cr.NS_ERROR_NO_INTERFACE);
+        },
+        getAuthPrompt(reason, iid) {
+          return this;
+        },
+        asyncPromptAuth(channel, callback, context, level, authInfo) {
+          // We just cancel here, we're only ensuring that non-webrequest
+          // notificationcallbacks get called if webrequest doesn't handle it.
+          Promise.resolve().then(() => {
+            callback.onAuthCancelled(context, false);
+            channel.cancel(Cr.NS_BINDING_ABORTED);
+            sendAsyncMessage("callback-complete");
+          });
+        },
+      };
+    };
+    Services.obs.addObserver(observer, "http-on-modify-request");
+    sendAsyncMessage("chrome-ready");
+  });
+  await chromeScript.promiseOneMessage("chrome-ready");
+  let callbackComplete = chromeScript.promiseOneMessage("callback-complete");
+
+  let handlingExt = getAuthHandler();
+  await handlingExt.startup();
+
+  await Assert.rejects(testXHR(`${baseUrl}?realm=auth_nonblocking_forwardAuth&user=auth_nonblocking_forwardAuth&pass=auth_nonblocking_forwardAuth`),
+                       ProgressEvent,
+                       "caught rejected xhr");
+
+  await callbackComplete;
+  await handlingExt.awaitMessage("onAuthRequired");
+  // We expect onErrorOccurred because the "default" authprompt above cancelled
+  // the auth request to avoid a dialog.
+  await handlingExt.awaitMessage("onErrorOccurred");
+  await handlingExt.unload();
+  chromeScript.destroy();
+});
+
+add_task(async function test_webRequest_auth_nonblocking_forwardAuthPrompt2() {
+  // The chrome script sets up a default auth handler on the channel, the
+  // extension does not return anything in the authRequred call.  We should
+  // get the call in the extension first, then in the chrome code where we
+  // cancel the request to avoid dealing with the prompt dialog here.  The test
+  // is to ensure that WebRequest calls the previous notificationCallbacks
+  // if the authorization is not handled by the onAuthRequired handler.
+
+  let chromeScript = SpecialPowers.loadChromeScript(() => {
+    const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+    let observer = channel => {
+      if (!(channel instanceof Ci.nsIHttpChannel && channel.URI.host === "mochi.test")) {
+        return;
+      }
+      Services.obs.removeObserver(observer, "http-on-modify-request");
+      channel.notificationCallbacks = {
+        QueryInterface: ChromeUtils.generateQI(["nsIInterfaceRequestor",
+                                                "nsIAuthPrompt2"]),
+        getInterface: ChromeUtils.generateQI(["nsIAuthPrompt2"]),
+        promptAuth(request, level, authInfo) {
+          throw Components.Exception("", Cr.NS_ERROR_NO_INTERFACE);
+        },
+        asyncPromptAuth(request, callback, context, level, authInfo) {
+          // We just cancel here, we're only ensuring that non-webrequest
+          // notificationcallbacks get called if webrequest doesn't handle it.
+          Promise.resolve().then(() => {
+            request.cancel(Cr.NS_BINDING_ABORTED);
+            sendAsyncMessage("callback-complete");
+          });
+        },
+      };
+    };
+    Services.obs.addObserver(observer, "http-on-modify-request");
+    sendAsyncMessage("chrome-ready");
+  });
+  await chromeScript.promiseOneMessage("chrome-ready");
+  let callbackComplete = chromeScript.promiseOneMessage("callback-complete");
+
+  let handlingExt = getAuthHandler();
+  await handlingExt.startup();
+
+  await Assert.rejects(testXHR(`${baseUrl}?realm=auth_nonblocking_forwardAuthPromptProvider&user=auth_nonblocking_forwardAuth&pass=auth_nonblocking_forwardAuth`),
+                       ProgressEvent,
+                       "caught rejected xhr");
+
+  await callbackComplete;
+  await handlingExt.awaitMessage("onAuthRequired");
+  // We expect onErrorOccurred because the "default" authprompt above cancelled
+  // the auth request to avoid a dialog.
+  await handlingExt.awaitMessage("onErrorOccurred");
+  await handlingExt.unload();
+  chromeScript.destroy();
+});
+</script>
+</head>
+<body>
+<div id="test">Authorization Test</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_background_events.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_background_events.html
new file mode 100644
index 0000000000..86cec62fb4
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_background_events.html
@@ -0,0 +1,120 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_webRequest_serviceworker_events() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["dom.serviceWorkers.testing.enabled", true]],
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "<all_urls>",
+      ],
+    },
+    background() {
+      let eventNames = new Set([
+        "onBeforeRequest",
+        "onBeforeSendHeaders",
+        "onSendHeaders",
+        "onHeadersReceived",
+        "onResponseStarted",
+        "onCompleted",
+        "onErrorOccurred",
+      ]);
+
+      function listener(name, details) {
+        browser.test.assertTrue(eventNames.has(name), `received ${name}`);
+        eventNames.delete(name);
+        if (name == "onCompleted") {
+          eventNames.delete("onErrorOccurred");
+        } else if (name == "onErrorOccurred") {
+          eventNames.delete("onCompleted");
+        }
+        if (eventNames.size == 0) {
+          browser.test.sendMessage("done");
+        }
+      }
+
+      for (let name of eventNames) {
+        browser.webRequest[name].addListener(
+          listener.bind(null, name),
+          {urls: ["https://example.com/*"]}
+        );
+      }
+    },
+  });
+
+  await extension.startup();
+  let registration = await navigator.serviceWorker.register("webrequest_worker.js", {scope: "."});
+  await waitForState(registration.installing, "activated");
+  await extension.awaitMessage("done");
+  await registration.unregister();
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_background_events() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "<all_urls>",
+      ],
+    },
+    background() {
+      let eventNames = new Set([
+        "onBeforeRequest",
+        "onBeforeSendHeaders",
+        "onSendHeaders",
+        "onHeadersReceived",
+        "onResponseStarted",
+        "onCompleted",
+      ]);
+
+      function listener(name, details) {
+        browser.test.assertTrue(eventNames.has(name), `received ${name}`);
+        eventNames.delete(name);
+
+        if (eventNames.size === 0) {
+          browser.test.assertEq("xmlhttprequest", details.type, "correct type for fetch [see bug 1366710]");
+          browser.test.assertEq(0, eventNames.size, "messages received");
+          browser.test.sendMessage("done");
+        }
+      }
+
+      for (let name of eventNames) {
+        browser.webRequest[name].addListener(
+          listener.bind(null, name),
+          {urls: ["https://example.com/*"]}
+        );
+      }
+
+      fetch("https://example.com/example.txt").then(() => {
+        browser.test.succeed("Fetch succeeded.");
+      }, () => {
+        browser.test.fail("fetch received");
+        browser.test.sendMessage("done");
+      });
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_basic.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_basic.html
new file mode 100644
index 0000000000..742f048a8a
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_basic.html
@@ -0,0 +1,446 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head_webrequest.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+<script>
+"use strict";
+
+function promiseWindowEvent(name, accept) {
+  return new Promise(resolve => {
+    window.addEventListener(name, function listener(event) {
+      if (event.data !== accept) {
+        return;
+      }
+      window.removeEventListener(name, listener);
+      resolve(event);
+    });
+  });
+}
+
+if (AppConstants.platform === "android") {
+  SimpleTest.requestLongerTimeout(3);
+}
+
+let extension;
+add_task(async function setup() {
+  // Clear the image cache, since it gets in the way otherwise.
+  let imgTools = SpecialPowers.Cc["@mozilla.org/image/tools;1"].getService(SpecialPowers.Ci.imgITools);
+  let cache = imgTools.getImgCacheForDocument(document);
+  cache.clearCache(false);
+  function clearCache() {
+    ChromeUtils.import("resource://gre/modules/Services.jsm", {}).Services.cache2.clear();
+  }
+  SpecialPowers.loadChromeScript(clearCache);
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["network.http.rcwn.enabled", false]],
+  });
+
+  extension = makeExtension();
+  await extension.startup();
+});
+
+// expect is a set of test values used by the background script.
+//
+// type: type of request action
+// events: optional, If defined only the events listed are expected for the
+//                   request. If undefined, all events except onErrorOccurred
+//                   and onBeforeRedirect are expected.  Must be in order received.
+// redirect: url to redirect to during onBeforeSendHeaders
+// status: number    expected status during onHeadersReceived, 200 default
+// cancel: event in which we return cancel=true.  cancelled message is sent.
+// cached: expected fromCache value, default is false, checked in onCompletion
+// headers: request or response headers to modify
+// origin: The expected originUrl, a default origin can be passed for all files
+
+add_task(async function test_webRequest_links() {
+  let expect = {
+    "file_style_bad.css": {
+      type: "stylesheet",
+      events: ["onBeforeRequest", "onErrorOccurred"],
+      cancel: "onBeforeRequest",
+    },
+    "file_style_redirect.css": {
+      type: "stylesheet",
+      events: ["onBeforeRequest", "onBeforeSendHeaders", "onBeforeRedirect"],
+      optional_events: ["onHeadersReceived"],
+      redirect: "file_style_good.css",
+    },
+    "file_style_good.css": {
+      type: "stylesheet",
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  addStylesheet("file_style_bad.css");
+  await extension.awaitMessage("cancelled");
+  // we redirect to style_good which completes the test
+  addStylesheet("file_style_redirect.css");
+  await extension.awaitMessage("done");
+});
+
+add_task(async function test_webRequest_images() {
+  let expect = {
+    "file_image_bad.png": {
+      type: "image",
+      events: ["onBeforeRequest", "onErrorOccurred"],
+      cancel: "onBeforeRequest",
+    },
+    "file_image_redirect.png": {
+      type: "image",
+      events: ["onBeforeRequest", "onBeforeSendHeaders", "onBeforeRedirect"],
+      optional_events: ["onHeadersReceived"],
+      redirect: "file_image_good.png",
+    },
+    "file_image_good.png": {
+      type: "image",
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  addImage("file_image_bad.png");
+  await extension.awaitMessage("cancelled");
+  // we redirect to image_good which completes the test
+  addImage("file_image_redirect.png");
+  await extension.awaitMessage("done");
+});
+
+add_task(async function test_webRequest_scripts() {
+  let expect = {
+    "file_script_bad.js": {
+      type: "script",
+      events: ["onBeforeRequest", "onErrorOccurred"],
+      cancel: "onBeforeRequest",
+    },
+    "file_script_redirect.js": {
+      type: "script",
+      events: ["onBeforeRequest", "onBeforeSendHeaders", "onBeforeRedirect"],
+      optional_events: ["onHeadersReceived"],
+      redirect: "file_script_good.js",
+    },
+    "file_script_good.js": {
+      type: "script",
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  let message = promiseWindowEvent("message", "test1");
+  addScript("file_script_bad.js");
+  await extension.awaitMessage("cancelled");
+  // we redirect to script_good which completes the test
+  addScript("file_script_redirect.js?q=test1");
+  await extension.awaitMessage("done");
+
+  is((await message).data, "test1", "good script ran");
+});
+
+add_task(async function test_webRequest_xhr_get() {
+  let expect = {
+    "file_script_xhr.js": {
+      type: "script",
+    },
+    "xhr_resource": {
+      status: 404,
+      type: "xmlhttprequest",
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  addScript("file_script_xhr.js");
+  await extension.awaitMessage("done");
+});
+
+add_task(async function test_webRequest_nonexistent() {
+  let expect = {
+    "nonexistent_script_url.js": {
+      status: 404,
+      type: "script",
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  addScript("nonexistent_script_url.js");
+  await extension.awaitMessage("done");
+});
+
+add_task(async function test_webRequest_checkCached() {
+  let expect = {
+    "file_image_good.png": {
+      type: "image",
+      cached: true,
+    },
+    "file_script_good.js": {
+      type: "script",
+      cached: true,
+    },
+    "file_style_good.css": {
+      type: "stylesheet",
+      cached: true,
+    },
+    "nonexistent_script_url.js": {
+      status: 404,
+      type: "script",
+      cached: false,
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  let message = promiseWindowEvent("message", "test1");
+
+  addImage("file_image_good.png");
+  addScript("file_script_good.js?q=test1");
+
+  is((await message).data, "test1", "good script ran");
+
+  addStylesheet("file_style_good.css");
+  addScript("nonexistent_script_url.js");
+  await extension.awaitMessage("done");
+});
+
+add_task(async function test_webRequest_headers() {
+  let expect = {
+    "file_script_nonexistent.js": {
+      type: "script",
+      status: 404,
+      headers: {
+        request: {
+          add: {
+            "X-WebRequest-request": "text",
+            "X-WebRequest-request-binary": "binary",
+          },
+          modify: {
+            "user-agent": "WebRequest",
+          },
+          remove: [
+            "referer",
+          ],
+        },
+        response: {
+          add: {
+            "X-WebRequest-response": "text",
+            "X-WebRequest-response-binary": "binary",
+          },
+          modify: {
+            "server": "WebRequest",
+            "content-type": "text/html; charset=utf-8",
+          },
+          remove: [
+            "connection",
+          ],
+        },
+      },
+      completion: "onCompleted",
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  addScript("file_script_nonexistent.js");
+  await extension.awaitMessage("done");
+});
+
+add_task(async function test_webRequest_tabId() {
+  function background() {
+    let tab;
+    browser.tabs.onCreated.addListener(newTab => {
+      tab = newTab;
+    });
+
+    browser.test.onMessage.addListener(msg => {
+      if (msg === "close-tab") {
+        browser.tabs.remove(tab.id);
+        browser.test.sendMessage("tab-closed");
+      }
+    });
+  }
+
+  let tabExt = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "web_request_tab_id@tests.mozilla.org" } },
+      permissions: [
+        "tabs",
+      ],
+    },
+    background,
+  });
+  await tabExt.startup();
+
+  let linkUrl = `file_WebRequest_page3.html?trigger=a&nocache=${Math.random()}`;
+  let expect = {
+    "file_WebRequest_page3.html": {
+      type: "main_frame",
+    },
+  };
+
+  if (AppConstants.platform != "android") {
+    expect["favicon.ico"] = {
+      type: "image",
+      origin: SimpleTest.getTestFileURL(linkUrl),
+      cached: false,
+    };
+  }
+
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  let a = addLink(linkUrl);
+  a.click();
+  await extension.awaitMessage("done");
+
+  let closed = tabExt.awaitMessage("tab-closed");
+  tabExt.sendMessage("close-tab");
+  await closed;
+
+  await tabExt.unload();
+});
+
+add_task(async function test_webRequest_tabId_browser() {
+  async function background(url) {
+    let tabId;
+    browser.test.onMessage.addListener(async (msg, expected) => {
+      if (msg == "create") {
+        let tab = await browser.tabs.create({url});
+        tabId = tab.id;
+        return;
+      }
+      if (msg == "done") {
+        await browser.tabs.remove(tabId);
+        browser.test.sendMessage("done");
+      }
+    });
+    browser.test.sendMessage("origin", browser.runtime.getURL("/"));
+  }
+
+  let pageUrl = `${SimpleTest.getTestFileURL("file_sample.html")}?nocache=${Math.random()}`;
+  let tabExt = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "tab_id_browser@tests.mozilla.org" } },
+      permissions: [
+        "tabs",
+      ],
+    },
+    background: `(${background})('${pageUrl}')`,
+  });
+
+  let expect = {
+    "file_sample.html": {
+      type: "main_frame",
+    },
+  };
+
+  if (AppConstants.platform != "android") {
+    expect["favicon.ico"] = {
+      type: "image",
+      origin: pageUrl,
+      cached: true,
+    };
+  }
+
+  await tabExt.startup();
+  let origin = await tabExt.awaitMessage("origin");
+
+  // expecting origin == extension baseUrl
+  extension.sendMessage("set-expected", {expect, origin});
+  await extension.awaitMessage("continue");
+
+  // open a tab from an extension principal
+  tabExt.sendMessage("create");
+  await extension.awaitMessage("done");
+  tabExt.sendMessage("done");
+  await tabExt.awaitMessage("done");
+  await tabExt.unload();
+});
+
+add_task(async function test_webRequest_frames() {
+  let expect = {
+    "redirection.sjs": {
+      status: 302,
+      type: "sub_frame",
+      events: ["onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders", "onHeadersReceived", "onBeforeRedirect"],
+    },
+    "dummy_page.html": {
+      type: "sub_frame",
+      status: 404,
+    },
+    "badrobot": {
+      type: "sub_frame",
+      status: 404,
+      events: ["onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders", "onErrorOccurred"],
+      // When an url's hostname fails to be resolved, an NS_ERROR_NET_ON_RESOLVED/RESOLVING
+      // onError event may be fired right before the NS_ERROR_UNKNOWN_HOST
+      // (See Bug 1516862 for a rationale).
+      optional_events: ["onErrorOccurred"],
+      error: ["NS_ERROR_UNKNOWN_HOST", "NS_ERROR_NET_ON_RESOLVED", "NS_ERROR_NET_ON_RESOLVING"],
+    },
+  };
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+  addFrame("redirection.sjs");
+  addFrame("https://nonresolvablehostname.invalid/badrobot");
+  await extension.awaitMessage("done");
+});
+
+add_task(async function teardown() {
+  await extension.unload();
+});
+
+add_task(async function test_case_preserving() {
+  const manifest = {
+    permissions: [
+      "webRequest",
+      "webRequestBlocking",
+      "http://mochi.test/",
+    ],
+  };
+
+  async function background() {
+    // This is testing if header names preserve case,
+    // so the case-sensitive comparison is on purpose.
+    function ua({url, requestHeaders}) {
+      if (url.endsWith("?blind-add")) {
+        requestHeaders.push({name: "user-agent", value: "Blind/Add"});
+        return {requestHeaders};
+      }
+      for (const header of requestHeaders) {
+        if (header.name === "User-Agent") {
+          header.value = "Case/Sensitive";
+        }
+      }
+      return {requestHeaders};
+    }
+
+    await browser.webRequest.onBeforeSendHeaders.addListener(ua, {urls: ["<all_urls>"]}, ["blocking", "requestHeaders"]);
+    browser.test.sendMessage("ready");
+  }
+
+  const extension = ExtensionTestUtils.loadExtension({manifest, background});
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  const response1 = await fetch(SimpleTest.getTestFileURL("return_headers.sjs"));
+  const headers1 = JSON.parse(await response1.text());
+
+  is(headers1["user-agent"], "Case/Sensitive", "User-Agent header matched and changed.");
+
+  const response2 = await fetch(SimpleTest.getTestFileURL("return_headers.sjs?blind-add"));
+  const headers2 = JSON.parse(await response2.text());
+
+  is(headers2["user-agent"], "Blind/Add", "User-Agent header blindly added.");
+
+  await extension.unload();
+});
+
+</script>
+</head>
+<body>
+<div id="test">Sample text</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_errors.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_errors.html
new file mode 100644
index 0000000000..89ef9f4809
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_errors.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for WebRequest errors</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script type="text/javascript">
+"use strict";
+
+async function test_connection_refused(url, expectedError) {
+  async function background(url, expectedError) {
+    browser.test.log(`background url is ${url}`);
+    browser.webRequest.onErrorOccurred.addListener(details => {
+      if (details.url != url) {
+        return;
+      }
+      browser.test.assertTrue(details.error.startsWith(expectedError), "error correct");
+      browser.test.sendMessage("onErrorOccurred");
+    }, {urls: ["<all_urls>"]});
+
+    let tabId;
+    browser.test.onMessage.addListener(async (msg, expected) => {
+      await browser.tabs.remove(tabId);
+      browser.test.sendMessage("done");
+    });
+
+    let tab = await browser.tabs.create({url});
+    tabId = tab.id;
+  }
+
+  let extensionData = {
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: "connection_refused@tests.mozilla.org" } },
+      permissions: ["webRequest", "tabs", "*://badchain.include-subdomains.pinning.example.com/*"],
+    },
+    background: `(${background})("${url}", "${expectedError}")`,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await extension.awaitMessage("onErrorOccurred");
+  extension.sendMessage("close-tab");
+  await extension.awaitMessage("done");
+
+  await extension.unload();
+}
+
+add_task(function test_bad_cert() {
+  return test_connection_refused("https://badchain.include-subdomains.pinning.example.com/", "Unable to communicate securely with peer");
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_filter.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_filter.html
new file mode 100644
index 0000000000..62539b54bc
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_filter.html
@@ -0,0 +1,227 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript" src="head_webrequest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+<script>
+"use strict";
+
+if (AppConstants.platform === "android") {
+  SimpleTest.requestLongerTimeout(6);
+}
+
+let windowData, testWindow;
+
+add_task(async function setup() {
+  let chromeScript = SpecialPowers.loadChromeScript(function() {
+    ChromeUtils.import("resource://gre/modules/Services.jsm", {}).Services.cache2.clear();
+  });
+  chromeScript.destroy();
+
+  testWindow = window.open("about:blank", "_blank", "width=100,height=100");
+  await waitForLoad(testWindow);
+
+  // Fetch the windowId and tabId we need to filter with WebRequest.
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "tabs",
+      ],
+    },
+    background() {
+      browser.tabs.query({currentWindow: true}).then(tabs => {
+        let tab = tabs.find(tab => tab.active);
+        let {windowId} = tab;
+
+        browser.test.log(`current window ${windowId} tabs: ${JSON.stringify(tabs.map(tab => [tab.id, tab.url]))}`);
+        browser.test.sendMessage("windowData", {windowId, tabId: tab.id});
+      });
+    },
+  });
+  await extension.startup();
+  windowData = await extension.awaitMessage("windowData");
+  info(`window is ${JSON.stringify(windowData)}`);
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_filter_window() {
+  if (AppConstants.MOZ_BUILD_APP !== "browser") {
+    // Android does not support multiple windows.
+    return;
+  }
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["dom.serviceWorkers.testing.enabled", true],
+          ["network.http.rcwn.enabled", false]],
+  });
+
+  let events = {
+    "onBeforeRequest":     [{urls: ["<all_urls>"], windowId: windowData.windowId}],
+    "onBeforeSendHeaders": [{urls: ["<all_urls>"], windowId: windowData.windowId}, ["requestHeaders"]],
+    "onSendHeaders":       [{urls: ["<all_urls>"], windowId: windowData.windowId}, ["requestHeaders"]],
+    "onBeforeRedirect":    [{urls: ["<all_urls>"], windowId: windowData.windowId}],
+    "onHeadersReceived":   [{urls: ["<all_urls>"], windowId: windowData.windowId}, ["responseHeaders"]],
+    "onResponseStarted":   [{urls: ["<all_urls>"], windowId: windowData.windowId}],
+    "onCompleted":         [{urls: ["<all_urls>"], windowId: windowData.windowId}, ["responseHeaders"]],
+    "onErrorOccurred":     [{urls: ["<all_urls>"], windowId: windowData.windowId}],
+  };
+  let expect = {
+    "file_image_bad.png": {
+      optional_events: ["onBeforeRedirect", "onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders"],
+      type: "main_frame",
+    },
+  };
+
+  if (AppConstants.platform != "android") {
+    expect["favicon.ico"] = {
+      // These events only happen in non-e10s. See bug 1472156.
+      optional_events: ["onBeforeRedirect", "onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders"],
+      type: "image",
+      origin: SimpleTest.getTestFileURL("file_image_bad.png"),
+    };
+  }
+
+  let extension = makeExtension(events);
+  await extension.startup();
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+
+  // We should not get events for a new window load.
+  let newWindow = window.open("file_image_good.png", "_blank", "width=100,height=100");
+  await waitForLoad(newWindow);
+  newWindow.close();
+
+  // We should not get background events.
+  let registration = await navigator.serviceWorker.register("webrequest_worker.js?test0", {scope: "."});
+  await waitForState(registration.installing, "activated");
+
+  // We should get events for the reload.
+  testWindow.location = "file_image_bad.png";
+  await extension.awaitMessage("done");
+
+  testWindow.location = "about:blank";
+  await registration.unregister();
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_filter_tab() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["dom.serviceWorkers.testing.enabled", true]],
+  });
+
+  let img = `file_image_good.png?r=${Math.random()}`;
+
+  let events = {
+    "onBeforeRequest":     [{urls: ["<all_urls>"], tabId: windowData.tabId}],
+    "onBeforeSendHeaders": [{urls: ["<all_urls>"], tabId: windowData.tabId}, ["requestHeaders"]],
+    "onSendHeaders":       [{urls: ["<all_urls>"], tabId: windowData.tabId}, ["requestHeaders"]],
+    "onBeforeRedirect":    [{urls: ["<all_urls>"], tabId: windowData.tabId}],
+    "onHeadersReceived":   [{urls: ["<all_urls>"], tabId: windowData.tabId}, ["responseHeaders"]],
+    "onResponseStarted":   [{urls: ["<all_urls>"], tabId: windowData.tabId}],
+    "onCompleted":         [{urls: ["<all_urls>"], tabId: windowData.tabId}, ["responseHeaders"]],
+    "onErrorOccurred":     [{urls: ["<all_urls>"], tabId: windowData.tabId}],
+  };
+  let expect = {
+    "file_image_good.png": {
+      // These events only happen in non-e10s. See bug 1472156.
+      optional_events: ["onBeforeRedirect", "onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders"],
+      type: "main_frame",
+      // cached: AppConstants.MOZ_BUILD_APP === "browser",
+    },
+  };
+
+  if (AppConstants.platform != "android") {
+    // A favicon request may be initiated, and complete or be aborted.
+    expect["favicon.ico"] = {
+      optional_events: ["onBeforeRedirect", "onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders", "onHeadersReceived", "onResponseStarted", "onCompleted", "onErrorOccurred"],
+      type: "image",
+      origin: SimpleTest.getTestFileURL(img),
+    };
+  }
+
+  let extension = makeExtension(events);
+  await extension.startup();
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+
+  if (AppConstants.MOZ_BUILD_APP === "browser") {
+    // We should not get events for a new window load.
+    let newWindow = window.open(img, "_blank", "width=100,height=100");
+    await waitForLoad(newWindow);
+    newWindow.close();
+  }
+
+  // We should not get background events.
+  let registration = await navigator.serviceWorker.register("webrequest_worker.js?test1", {scope: "."});
+  await waitForState(registration.installing, "activated");
+
+  // We should get events for the reload.
+  testWindow.location = img;
+  await extension.awaitMessage("done");
+
+  testWindow.location = "about:blank";
+  await registration.unregister();
+  await extension.unload();
+});
+
+
+add_task(async function test_webRequest_filter_background() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["dom.serviceWorkers.testing.enabled", true]],
+  });
+
+  let events = {
+    "onBeforeRequest":     [{urls: ["<all_urls>"], tabId: -1}],
+    "onBeforeSendHeaders": [{urls: ["<all_urls>"], tabId: -1}, ["requestHeaders"]],
+    "onSendHeaders":       [{urls: ["<all_urls>"], tabId: -1}, ["requestHeaders"]],
+    "onBeforeRedirect":    [{urls: ["<all_urls>"], tabId: -1}],
+    "onHeadersReceived":   [{urls: ["<all_urls>"], tabId: -1}, ["responseHeaders"]],
+    "onResponseStarted":   [{urls: ["<all_urls>"], tabId: -1}],
+    "onCompleted":         [{urls: ["<all_urls>"], tabId: -1}, ["responseHeaders"]],
+    "onErrorOccurred":     [{urls: ["<all_urls>"], tabId: -1}],
+  };
+  let expect = {
+    "webrequest_worker.js": {
+      type: "script",
+    },
+    "example.txt": {
+      status: 404,
+      events: ["onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders", "onHeadersReceived", "onResponseStarted"],
+      optional_events: ["onCompleted", "onErrorOccurred"],
+      type: "xmlhttprequest",
+      origin: SimpleTest.getTestFileURL("webrequest_worker.js?test2"),
+    },
+  };
+
+  let extension = makeExtension(events);
+  await extension.startup();
+  extension.sendMessage("set-expected", {expect, origin: location.href});
+  await extension.awaitMessage("continue");
+
+  // We should not get events for a window.
+  testWindow.location = "file_image_bad.png";
+
+  // We should get events for the background page.
+  let registration = await navigator.serviceWorker.register(SimpleTest.getTestFileURL("webrequest_worker.js?test2"), {scope: "."});
+  await waitForState(registration.installing, "activated");
+  await extension.awaitMessage("done");
+  testWindow.location = "about:blank";
+  await registration.unregister();
+
+  await extension.unload();
+});
+
+add_task(async function teardown() {
+  testWindow.close();
+});
+</script>
+</head>
+<body>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_frameId.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_frameId.html
new file mode 100644
index 0000000000..1b26a77f2b
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_frameId.html
@@ -0,0 +1,214 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head_webrequest.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+<script>
+"use strict";
+
+let extensionData = {
+  manifest: {
+    permissions: ["webRequest", "webRequestBlocking", "<all_urls>", "tabs"],
+  },
+  background() {
+    browser.webRequest.onBeforeRequest.addListener(details => {
+      browser.test.sendMessage("onBeforeRequest", details);
+    }, {urls: ["<all_urls>"]}, ["blocking"]);
+
+    let tab;
+    browser.tabs.onCreated.addListener(newTab => {
+      browser.test.sendMessage("tab-created");
+      tab = newTab;
+    });
+
+    browser.test.onMessage.addListener(msg => {
+      if (msg === "close-tab") {
+        browser.tabs.remove(tab.id);
+        browser.test.sendMessage("tab-closed");
+      }
+    });
+  },
+};
+
+let expected = {
+  "file_simple_xhr.html": {
+    type: "main_frame",
+    toplevel: true,
+  },
+  "file_image_good.png": {
+    type: "image",
+    toplevel: true,
+    origin: "file_simple_xhr.html",
+  },
+  "example.txt": {
+    type: "xmlhttprequest",
+    toplevel: true,
+    origin: "file_simple_xhr.html",
+  },
+  // sub frames will have the origin and first ancestor is the
+  // parent document
+  "file_simple_xhr_frame.html": {
+    type: "sub_frame",
+    toplevelParent: true,
+    origin: "file_simple_xhr.html",
+    parent: "file_simple_xhr.html",
+  },
+  // a resource in a sub frame will have origin of the subframe,
+  // but the ancestor chain starts with the parent document
+  "xhr_resource": {
+    type: "xmlhttprequest",
+    origin: "file_simple_xhr_frame.html",
+    parent: "file_simple_xhr.html",
+  },
+  "file_image_bad.png": {
+    type: "image",
+    depth: 2,
+    origin: "file_simple_xhr_frame.html",
+    parent: "file_simple_xhr.html",
+  },
+  "file_simple_xhr_frame2.html": {
+    type: "sub_frame",
+    depth: 2,
+    origin: "file_simple_xhr_frame.html",
+    parent: "file_simple_xhr_frame.html",
+  },
+  "file_image_redirect.png": {
+    type: "image",
+    depth: 2,
+    origin: "file_simple_xhr_frame2.html",
+    parent: "file_simple_xhr_frame.html",
+  },
+  "xhr_resource_2": {
+    type: "xmlhttprequest",
+    depth: 2,
+    origin: "file_simple_xhr_frame2.html",
+    parent: "file_simple_xhr_frame.html",
+  },
+  // This is loaded in a sandbox iframe.  originUrl is not available for that,
+  // and requests within a sandboxed iframe will additionally have an empty
+  // url on their immediate parent/ancestor.
+  "file_simple_sandboxed_frame.html": {
+    type: "sub_frame",
+    depth: 3,
+    parent: "file_simple_xhr_frame2.html",
+  },
+  "xhr_sandboxed": {
+    type: "xmlhttprequest",
+    sandboxed: true,
+    depth: 3,
+    parent: "",
+  },
+  "file_image_great.png": {
+    type: "image",
+    sandboxed: true,
+    depth: 3,
+    parent: "",
+  },
+  "file_simple_sandboxed_subframe.html": {
+    type: "sub_frame",
+    depth: 4,
+    parent: "",
+  },
+};
+
+if (AppConstants.platform != "android") {
+  expected["favicon.ico"] = {
+    type: "image",
+    toplevel: true,
+    origin: "file_simple_xhr.html",
+    cached: false,
+  };
+}
+
+function checkDetails(details) {
+  // See bug 1471387
+  if (details.originUrl == "about:newtab") {
+    return;
+  }
+
+  let url = new URL(details.url);
+  let filename = url.pathname.split("/").pop();
+  ok(filename in expected, `Should be expecting a request for ${filename}`);
+  let expect = expected[filename];
+  is(expect.type, details.type, `${details.type} type matches`);
+  if (details.parentFrameId == -1) {
+    is(details.frameAncestors.length, 0, "no ancestors for main_frame requests");
+  } else if (details.parentFrameId == 0) {
+    is(details.frameAncestors.length, 1, "one ancestors for sub_frame requests");
+  } else {
+    ok(details.frameAncestors.length > 1, "have multiple ancestors for deep subframe requests");
+    is(details.frameAncestors.length, expect.depth, "have multiple ancestors for deep subframe requests");
+  }
+  if (details.parentFrameId > -1) {
+    ok(!expect.origin || details.originUrl.includes(expect.origin), "origin url is correct");
+    is(details.frameAncestors[0].frameId, details.parentFrameId, "first ancestor matches request.parentFrameId");
+    ok(details.frameAncestors[0].url.includes(expect.parent), "ancestor parent page correct");
+    is(details.frameAncestors[details.frameAncestors.length - 1].frameId, 0, "last ancestor is always zero");
+    // All our tests should be somewhere within the frame that we set topframe in the query string.  That
+    // frame will always be the last ancestor.
+    ok(details.frameAncestors[details.frameAncestors.length - 1].url.includes("topframe=true"), "last ancestor is always topframe");
+  }
+  if (expect.toplevel) {
+    is(details.frameId, 0, "expect load at top level");
+    is(details.parentFrameId, -1, "expect top level frame to have no parent");
+  } else if (details.type == "sub_frame") {
+    ok(details.frameId > 0, "expect sub_frame to load into a new frame");
+    if (expect.toplevelParent) {
+      is(details.parentFrameId, 0, "expect sub_frame to have top level parent");
+      is(details.frameAncestors.length, 1, "one ancestor for top sub_frame request");
+    } else {
+      ok(details.parentFrameId > 0, "expect sub_frame to have parent");
+      ok(details.frameAncestors.length > 1, "sub_frame has ancestors");
+    }
+    expect.subframeId = details.frameId;
+    expect.parentId = details.parentFrameId;
+  } else if (expect.sandboxed) {
+    is(details.documentUrl, undefined, "null principal documentUrl for sandboxed request");
+  } else {
+    // get the parent frame.
+    let purl = new URL(details.documentUrl);
+    let pfilename = purl.pathname.split("/").pop();
+    let parent = expected[pfilename];
+    is(details.frameId, parent.subframeId, "expect load in subframe");
+    is(details.parentFrameId, parent.parentId, "expect subframe parent");
+  }
+}
+
+add_task(async function test_webRequest_main_frame() {
+  // Clear the image cache, since it gets in the way otherwise.
+  let imgTools = SpecialPowers.Cc["@mozilla.org/image/tools;1"].getService(SpecialPowers.Ci.imgITools);
+  let cache = imgTools.getImgCacheForDocument(document);
+  cache.clearCache(false);
+  function clearCache() {
+    ChromeUtils.import("resource://gre/modules/Services.jsm", {}).Services.cache2.clear();
+  }
+  SpecialPowers.loadChromeScript(clearCache);
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let a = addLink(`file_simple_xhr.html?topframe=true&nocache=${Math.random()}`);
+  a.click();
+
+  for (let i = 0; i < Object.keys(expected).length; i++) {
+    checkDetails(await extension.awaitMessage("onBeforeRequest"));
+  }
+
+  await extension.awaitMessage("tab-created");
+  extension.sendMessage("close-tab");
+  await extension.awaitMessage("tab-closed");
+
+  await extension.unload();
+});
+</script>
+</head>
+<body>
+<div id="test">Sample text</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_hsts.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_hsts.html
new file mode 100644
index 0000000000..51ffc1e4f6
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_hsts.html
@@ -0,0 +1,223 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript" src="head_webrequest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+<script>
+"use strict";
+
+function getExtension() {
+  async function background() {
+    let expect;
+    let urls = ["*://*.example.org/tests/*"];
+    browser.webRequest.onBeforeRequest.addListener(details => {
+      browser.test.assertEq(expect.shift(), "onBeforeRequest");
+    }, {urls}, ["blocking"]);
+    browser.webRequest.onBeforeSendHeaders.addListener(details => {
+      browser.test.assertEq(expect.shift(), "onBeforeSendHeaders");
+    }, {urls}, ["blocking", "requestHeaders"]);
+    browser.webRequest.onSendHeaders.addListener(details => {
+      browser.test.assertEq(expect.shift(), "onSendHeaders");
+    }, {urls}, ["requestHeaders"]);
+
+    async function testSecurityInfo(details, options) {
+      let securityInfo = await browser.webRequest.getSecurityInfo(details.requestId, options);
+      browser.test.assertTrue(securityInfo && securityInfo.state == "secure",
+                              "security info reflects https");
+
+      if (options.certificateChain) {
+        // Some of the tests here only produce a single cert in the chain.
+        browser.test.assertTrue(securityInfo.certificates.length >= 1, "have certificate chain");
+      } else {
+        browser.test.assertTrue(securityInfo.certificates.length == 1, "no certificate chain");
+      }
+      let cert = securityInfo.certificates[0];
+      let now = Date.now();
+      browser.test.assertTrue(Number.isInteger(cert.validity.start), "cert start is integer");
+      browser.test.assertTrue(Number.isInteger(cert.validity.end), "cert end is integer");
+      browser.test.assertTrue(cert.validity.start < now, "cert start validity is correct");
+      browser.test.assertTrue(now < cert.validity.end, "cert end validity is correct");
+      if (options.rawDER) {
+        for (let cert of securityInfo.certificates) {
+          browser.test.assertTrue(!!cert.rawDER.length, "have rawDER");
+        }
+      }
+    }
+
+    browser.webRequest.onHeadersReceived.addListener(async (details) => {
+      browser.test.assertEq(expect.shift(), "onHeadersReceived");
+
+      // We exepect all requests to have been upgraded at this point.
+      browser.test.assertTrue(details.url.startsWith("https"), "connection is https");
+      await testSecurityInfo(details, {});
+      await testSecurityInfo(details, {certificateChain: true});
+      await testSecurityInfo(details, {rawDER: true});
+      await testSecurityInfo(details, {certificateChain: true, rawDER: true});
+
+      let headers = details.responseHeaders || [];
+      for (let header of headers) {
+        if (header.name.toLowerCase() === "strict-transport-security") {
+          return;
+        }
+      }
+
+      headers.push({
+        name: "Strict-Transport-Security",
+        value: "max-age=31536000000",
+      });
+      return {responseHeaders: headers};
+    }, {urls}, ["blocking", "responseHeaders"]);
+    browser.webRequest.onBeforeRedirect.addListener(details => {
+      browser.test.assertEq(expect.shift(), "onBeforeRedirect");
+    }, {urls});
+    browser.webRequest.onResponseStarted.addListener(details => {
+      browser.test.assertEq(expect.shift(), "onResponseStarted");
+    }, {urls});
+    browser.webRequest.onCompleted.addListener(details => {
+      browser.test.assertEq(expect.shift(), "onCompleted");
+      browser.test.sendMessage("onCompleted", details.url);
+    }, {urls});
+    browser.webRequest.onErrorOccurred.addListener(details => {
+      browser.test.notifyFail(`onErrorOccurred ${JSON.stringify(details)}`);
+    }, {urls});
+
+    async function onUpdated(tabId, tabInfo, tab) {
+      if (tabInfo.status !== "complete" || tab.url === "about:blank") {
+        return;
+      }
+      browser.tabs.remove(tabId);
+      browser.tabs.onUpdated.removeListener(onUpdated);
+      browser.test.sendMessage("tabs-done", tab.url);
+    }
+    browser.test.onMessage.addListener((url, expected) => {
+      expect = expected;
+      browser.tabs.onUpdated.addListener(onUpdated);
+      browser.tabs.create({url});
+    });
+  }
+
+  let manifest = {
+    "permissions": [
+      "tabs",
+      "webRequest",
+      "webRequestBlocking",
+      "<all_urls>",
+    ],
+  };
+  return ExtensionTestUtils.loadExtension({
+    manifest,
+    background,
+  });
+}
+
+// This test makes a request against a server that redirects with a 302.
+add_task(async function test_hsts_request() {
+  const testPath = "example.org/tests/toolkit/components/extensions/test/mochitest";
+
+  let extension = getExtension();
+  await extension.startup();
+
+  // simple redirect
+  let sample = "https://example.org/tests/toolkit/components/extensions/test/mochitest/file_sample.html";
+  extension.sendMessage(
+    `https://${testPath}/redirect_auto.sjs?redirect_uri=${sample}`,
+    ["onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders",
+     "onHeadersReceived", "onBeforeRedirect", "onBeforeRequest",
+     "onBeforeSendHeaders", "onSendHeaders", "onHeadersReceived",
+     "onResponseStarted", "onCompleted"]);
+  // redirect_auto adds a query string
+  ok((await extension.awaitMessage("tabs-done")).startsWith(sample), "redirection ok");
+  ok((await extension.awaitMessage("onCompleted")).startsWith(sample), "redirection ok");
+
+  // priming hsts
+  extension.sendMessage(
+    `https://${testPath}/hsts.sjs`,
+    ["onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders",
+     "onHeadersReceived", "onResponseStarted", "onCompleted"]);
+  is(await extension.awaitMessage("tabs-done"),
+     "https://example.org/tests/toolkit/components/extensions/test/mochitest/hsts.sjs",
+     "hsts primed");
+  is(await extension.awaitMessage("onCompleted"),
+     "https://example.org/tests/toolkit/components/extensions/test/mochitest/hsts.sjs");
+
+  // test upgrade
+  extension.sendMessage(
+    `http://${testPath}/hsts.sjs`,
+    ["onBeforeRequest", "onBeforeRedirect", "onBeforeRequest",
+     "onBeforeSendHeaders", "onSendHeaders", "onHeadersReceived",
+     "onResponseStarted", "onCompleted"]);
+  is(await extension.awaitMessage("tabs-done"),
+     "https://example.org/tests/toolkit/components/extensions/test/mochitest/hsts.sjs",
+     "hsts upgraded");
+  is(await extension.awaitMessage("onCompleted"),
+     "https://example.org/tests/toolkit/components/extensions/test/mochitest/hsts.sjs");
+
+  await extension.unload();
+});
+
+// This test makes a priming request and adds the STS header, then tests the upgrade.
+add_task(async function test_hsts_header() {
+  const testPath = "test1.example.org/tests/toolkit/components/extensions/test/mochitest";
+
+  let extension = getExtension();
+  await extension.startup();
+
+  // priming hsts, this time there is no STS header, onHeadersReceived adds it.
+  let completed = extension.awaitMessage("onCompleted");
+  let tabdone = extension.awaitMessage("tabs-done");
+  extension.sendMessage(
+    `https://${testPath}/file_sample.html`,
+    ["onBeforeRequest", "onBeforeSendHeaders", "onSendHeaders",
+     "onHeadersReceived", "onResponseStarted", "onCompleted"]);
+  is(await tabdone, `https://${testPath}/file_sample.html`, "priming request done");
+  is(await completed, `https://${testPath}/file_sample.html`, "priming request done");
+
+  // test upgrade from http to https due to onHeadersReceived adding STS header
+  completed = extension.awaitMessage("onCompleted");
+  tabdone = extension.awaitMessage("tabs-done");
+  extension.sendMessage(
+    `http://${testPath}/file_sample.html`,
+    ["onBeforeRequest", "onBeforeRedirect", "onBeforeRequest",
+     "onBeforeSendHeaders", "onSendHeaders", "onHeadersReceived",
+     "onResponseStarted", "onCompleted"]);
+  is(await tabdone, `https://${testPath}/file_sample.html`, "hsts upgraded");
+  is(await completed, `https://${testPath}/file_sample.html`, "request upgraded");
+
+  await extension.unload();
+});
+
+add_task(async function test_nonBlocking_securityInfo() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      "permissions": [
+        "webRequest",
+        "<all_urls>",
+      ],
+    },
+    async background() {
+      let tab;
+      browser.webRequest.onHeadersReceived.addListener(async (details) => {
+        let securityInfo = await browser.webRequest.getSecurityInfo(details.requestId, {});
+        browser.test.assertTrue(!securityInfo, "securityInfo undefined on http request");
+        browser.tabs.remove(tab.id);
+        browser.test.notifyPass("success");
+      }, {urls: ["<all_urls>"], types: ["main_frame"]});
+      tab = await browser.tabs.create({url: "https://example.org/tests/toolkit/components/extensions/test/mochitest/file_sample.html"});
+    },
+  });
+  await extension.startup();
+
+  await extension.awaitFinish("success");
+  await extension.unload();
+});
+</script>
+</head>
+<body>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_redirect_bypass_cors.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_redirect_bypass_cors.html
new file mode 100644
index 0000000000..457d0508b7
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_redirect_bypass_cors.html
@@ -0,0 +1,70 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1450965: Skip Cors Check for Early WebExtention Redirects </title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+/* Description of the test:
+ * We try to Check if a WebExtention can redirect a request and bypass CORS
+ * We're redirecting a fetch request in onBeforeRequest
+ * which should not be blocked, even though we do not have
+ * the CORS information yet.
+ */
+
+const WIN_URL =
+  "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_redirect_cors_bypass.html";
+
+
+add_task(async function test_webRequest_redirect_cors_bypass() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "<all_urls>",
+      ],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener((details) => {
+        if (details.url.includes("file_cors_blocked.txt")) {
+          // File_cors_blocked does not need to exist, because we're redirecting anyway.
+          const testPath = "example.org/tests/toolkit/components/extensions/test/mochitest";
+          let redirectUrl = `https://${testPath}/file_sample.txt`;
+
+          // If the WebExtion cant bypass CORS, the fetch will throw a CORS-Exception
+          // because we do not have the CORS header yet for 'file-cors-blocked.txt'
+          return {redirectUrl};
+        }
+      }, {urls: ["<all_urls>"]}, ["blocking"]);
+    },
+
+  });
+
+  await extension.startup();
+  let win = window.open(WIN_URL);
+  // Creating a message channel to the new tab.
+  const channel = new BroadcastChannel("test_bus");
+  await new Promise((resolve, reject) => {
+    channel.onmessage = async function(fetch_result) {
+      // Fetch result data will either be the text content of file_sample.txt -> 'Sample'
+      // or a network-Error.
+      // In case it's 'Sample' the redirect did happen correctly.
+      ok(fetch_result.data == "Sample", "Cors was Bypassed");
+      win.close();
+      await extension.unload();
+      resolve();
+    };
+  });
+});
+
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_redirect_data_uri.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_redirect_data_uri.html
new file mode 100644
index 0000000000..5d58549c46
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_redirect_data_uri.html
@@ -0,0 +1,83 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1434357: Allow Web Request API to redirect to data: URI</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+/* Description of the test:
+ * We load a *.js file which gets redirected to a data: URI.
+ * Since there is no good way to communicate loaded data: URI scripts
+ * we use updating a divContainer as a detour to verify the data: URI
+ * script has loaded.
+ */
+
+const WIN_URL =
+  "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_redirect_data_uri.html";
+
+add_task(async function test_webRequest_redirect_data_uri() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "*://mochi.test/tests/*",
+      ],
+      content_scripts: [{
+        matches: ["*://mochi.test/tests/*/file_redirect_data_uri.html"],
+        run_at: "document_end",
+        js: ["content_script.js"],
+        "all_frames": true,
+      }],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener((details) => {
+        if (details.url.includes("dummy_non_existend_file.js")) {
+          let redirectUrl =
+            "data:text/javascript,document.getElementById('testdiv').textContent='loaded'";
+          return {redirectUrl};
+        }
+      }, {urls: ["*://mochi.test/tests/*"]}, ["blocking"]);
+    },
+
+    files: {
+      "content_script.js": function() {
+        let scriptEl = document.createElement("script");
+        // please note that dummy_non_existend_file.js file does not really need
+        // to exist because we redirect the load within onBeforeRequest().
+        scriptEl.src = "dummy_non_existend_file.js";
+        document.body.appendChild(scriptEl);
+
+        scriptEl.onload = function() {
+          let divContent = document.getElementById("testdiv").textContent;
+          browser.test.assertEq(divContent, "loaded",
+                                "redirect to data: URI allowed");
+          browser.test.sendMessage("finished");
+        };
+        scriptEl.onerror = function() {
+          browser.test.fail("script load failure");
+          browser.test.sendMessage("finished");
+        };
+      },
+    },
+  });
+
+  await extension.startup();
+  let win = window.open(WIN_URL);
+  await extension.awaitMessage("finished");
+  win.close();
+  await extension.unload();
+});
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_upgrade.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_upgrade.html
new file mode 100644
index 0000000000..3d24f5a64d
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_upgrade.html
@@ -0,0 +1,89 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for simple WebExtension</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+add_task(async function test_webRequest_upgrade() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "*://mochi.test/tests/*",
+      ],
+    },
+    background() {
+      browser.webRequest.onSendHeaders.addListener((details) => {
+        // At this point, the request should have been upgraded.
+        browser.test.assertTrue(details.url.startsWith("https:"), "request is upgraded");
+        browser.test.assertTrue(details.url.includes("file_sample"), "redirect after upgrade worked");
+        browser.test.sendMessage("finished");
+      }, {urls: ["*://mochi.test/tests/*"]});
+
+      browser.webRequest.onBeforeRequest.addListener((details) => {
+        browser.test.log(`onBeforeRequest ${details.requestId} ${details.url}`);
+        let url = new URL(details.url);
+        if (url.protocol == "http:") {
+          return {upgradeToSecure: true};
+        }
+        // After the channel is initially upgraded, we get another onBeforeRequest
+        // call.  Here we can redirect again to a new url.
+        if (details.url.includes("file_mixed.html")) {
+          let redirectUrl = new URL("file_sample.html", details.url).href;
+          return {redirectUrl};
+        }
+      }, {urls: ["*://mochi.test/tests/*"]}, ["blocking"]);
+    },
+  });
+
+  await extension.startup();
+  let win = window.open("http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_mixed.html");
+  await extension.awaitMessage("finished");
+  win.close();
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_redirect_wins() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "*://mochi.test/tests/*",
+      ],
+    },
+    background() {
+      browser.webRequest.onSendHeaders.addListener((details) => {
+        // At this point, the request should have been redirected instead of upgraded.
+        browser.test.assertTrue(details.url.includes("file_sample"), "request was redirected");
+        browser.test.sendMessage("finished");
+      }, {urls: ["*://mochi.test/tests/*"]});
+
+      browser.webRequest.onBeforeRequest.addListener((details) => {
+        if (details.url.includes("file_mixed.html")) {
+          let redirectUrl = new URL("file_sample.html", details.url).href;
+          return {upgradeToSecure: true, redirectUrl};
+        }
+      }, {urls: ["*://mochi.test/tests/*"]}, ["blocking"]);
+    },
+  });
+
+  await extension.startup();
+  let win = window.open("http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_mixed.html");
+  await extension.awaitMessage("finished");
+  win.close();
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webrequest_upload.html b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_upload.html
new file mode 100644
index 0000000000..f4f2e66955
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webrequest_upload.html
@@ -0,0 +1,212 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<form method="post"
+  action="file_WebRequest_page3.html?trigger=form"
+  target="_blank"
+  enctype="multipart/form-data"
+  >
+<input type="text" name="&quot;special&quot; ch�rs" value="sp�cial">
+<input type="file" name="testFile">
+<input type="file" name="emptyFile">
+<input type="text" name="textInput1" value="value1">
+</form>
+
+<form method="post"
+  action="file_WebRequest_page3.html?trigger=form"
+  target="_blank"
+  enctype="multipart/form-data"
+  >
+<input type="text" name="textInput2" value="value2">
+<input type="file" name="testFile">
+<input type="file" name="emptyFile">
+</form>
+
+</form>
+<form method="post"
+  action="file_WebRequest_page3.html?trigger=form"
+  target="_blank"
+  >
+<input type="text" name="textInput" value="value1">
+<input type="text" name="textInput" value="value2">
+</form>
+<script>
+"use strict";
+
+let files, testFile, blob, file, uploads;
+add_task(async function test_setup() {
+  files = await new Promise(resolve => {
+    SpecialPowers.createFiles([{name: "testFile.pdf", data: "Not really a PDF file :)", "type": "application/x-pdf"}], (result) => {
+      resolve(result);
+    });
+  });
+  testFile = files[0];
+  blob = {
+    name: "blobAsFile",
+    content: new Blob(["A blob sent as a file"], {type: "text/csv"}),
+    fileName: "blobAsFile.csv",
+  };
+  file = {
+    name: "testFile",
+    fileName: testFile.name,
+  };
+  uploads = {
+    [blob.name]: blob,
+    [file.name]: file,
+  };
+});
+
+function background() {
+  const FILTERS = {urls: ["<all_urls>"]};
+
+  function onUpload(details) {
+    let url = new URL(details.url);
+    let upload = url.searchParams.get("upload");
+    if (!upload) {
+      return;
+    }
+
+    let requestBody = details.requestBody;
+    browser.test.log(`onBeforeRequest upload: ${details.url} ${JSON.stringify(details.requestBody)}`);
+    browser.test.assertTrue(!!requestBody, `Intercepted upload ${details.url} #${details.requestId} ${upload} have a requestBody`);
+    if (!requestBody) {
+      return;
+    }
+    let byteLength = parseInt(upload, 10);
+    if (byteLength) {
+      browser.test.assertTrue(!!requestBody.raw, `Binary upload ${details.url} #${details.requestId} ${upload} have a raw attribute`);
+      browser.test.assertEq(byteLength, requestBody.raw && requestBody.raw.map(r => r.bytes ? r.bytes.byteLength : 0).reduce((a, b) => a + b), `Binary upload size matches`);
+      return;
+    }
+    if ("raw" in requestBody) {
+      browser.test.assertEq(upload, JSON.stringify(requestBody.raw).replace(/(\bfile: ")[^"]+/, "$1<file>"), `Upload ${details.url} #${details.requestId} matches raw data`);
+    } else {
+      browser.test.assertEq(upload, JSON.stringify(requestBody.formData), `Upload ${details.url} #${details.requestId} matches form data.`);
+    }
+  }
+
+  browser.webRequest.onCompleted.addListener(
+    details => {
+      browser.test.log(`onCompleted ${details.requestId} ${details.url}`);
+      // See bug 1471387
+      if (details.url.endsWith("/favicon.ico") || details.originUrl == "about:newtab") {
+        return;
+      }
+
+      browser.test.sendMessage("done");
+    },
+    FILTERS);
+
+  let onBeforeRequest = details => {
+    browser.test.log(`${name} ${details.requestId} ${details.url}`);
+    // See bug 1471387
+    if (details.url.endsWith("/favicon.ico") || details.originUrl == "about:newtab") {
+      return;
+    }
+
+    onUpload(details);
+  };
+
+  browser.webRequest.onBeforeRequest.addListener(
+    onBeforeRequest, FILTERS, ["requestBody"]);
+
+  let tab;
+  browser.tabs.onCreated.addListener(newTab => {
+    tab = newTab;
+  });
+
+  browser.test.onMessage.addListener(msg => {
+    if (msg === "close-tab") {
+      browser.tabs.remove(tab.id);
+      browser.test.sendMessage("tab-closed");
+    }
+  });
+}
+
+add_task(async function test_xhr_forms() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "tabs",
+        "webRequest",
+        "webRequestBlocking",
+        "<all_urls>",
+      ],
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  async function doneAndTabClosed() {
+    await extension.awaitMessage("done");
+    let closed = extension.awaitMessage("tab-closed");
+    extension.sendMessage("close-tab");
+    await closed;
+  }
+
+  for (let form of document.forms) {
+    if (file.name in form.elements) {
+      SpecialPowers.wrap(form.elements[file.name]).mozSetFileArray(files);
+    }
+    let action = new URL(form.action);
+    let formData = new FormData(form);
+    let webRequestFD = {};
+
+    let updateActionURL = () => {
+      for (let name of formData.keys()) {
+        webRequestFD[name] = name in uploads ? [uploads[name].fileName] : formData.getAll(name);
+      }
+      action.searchParams.set("upload", JSON.stringify(webRequestFD));
+      action.searchParams.set("enctype", form.enctype);
+    };
+
+    updateActionURL();
+
+    form.action = action;
+    form.submit();
+    await doneAndTabClosed();
+
+    if (form.enctype !== "multipart/form-data") {
+      continue;
+    }
+
+    let post = (data) => {
+      let xhr = new XMLHttpRequest();
+      action.searchParams.set("xhr", "1");
+      xhr.open("POST", action.href);
+      xhr.send(data);
+      action.searchParams.delete("xhr");
+      return doneAndTabClosed();
+    };
+
+    formData.append(blob.name, blob.content, blob.fileName);
+    formData.append("formDataField", "some value");
+    updateActionURL();
+    await post(formData);
+
+    action.searchParams.set("upload", JSON.stringify([{file: "<file>"}]));
+    await post(testFile);
+
+    action.searchParams.set("upload", `${blob.content.size} bytes`);
+    await post(blob.content);
+
+    let byteLength = 16;
+    action.searchParams.set("upload", `${byteLength} bytes`);
+    await post(new ArrayBuffer(byteLength));
+  }
+
+  await extension.unload();
+});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_window_postMessage.html b/toolkit/components/extensions/test/mochitest/test_ext_window_postMessage.html
new file mode 100644
index 0000000000..53b19d0ead
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_window_postMessage.html
@@ -0,0 +1,104 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for content script</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+/* eslint-disable mozilla/balanced-listeners */
+
+add_task(async function test_postMessage() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          "matches": ["http://mochi.test/*/file_sample.html"],
+          "js": ["content_script.js"],
+          "run_at": "document_start",
+          "all_frames": true,
+        },
+      ],
+
+      web_accessible_resources: ["iframe.html"],
+    },
+
+    background() {
+      browser.test.sendMessage("iframe-url", browser.runtime.getURL("iframe.html"));
+    },
+
+    files: {
+      "content_script.js": function() {
+        window.addEventListener("message", event => {
+          if (event.data == "ping") {
+            event.source.postMessage({pong: location.href},
+                                     event.origin);
+          }
+        });
+      },
+
+      "iframe.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="content_script.js"><\/script>
+          </head>
+        </html>`,
+    },
+  };
+
+  let createIframe = url => {
+    let iframe = document.createElement("iframe");
+    return new Promise(resolve => {
+      iframe.src = url;
+      iframe.onload = resolve;
+      document.body.appendChild(iframe);
+    }).then(() => {
+      return iframe;
+    });
+  };
+
+  let awaitMessage = () => {
+    return new Promise(resolve => {
+      let listener = event => {
+        if (event.data.pong) {
+          window.removeEventListener("message", listener);
+          resolve(event.data);
+        }
+      };
+      window.addEventListener("message", listener);
+    });
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let iframeURL = await extension.awaitMessage("iframe-url");
+  let testURL = SimpleTest.getTestFileURL("file_sample.html");
+
+  for (let url of [iframeURL, testURL]) {
+    info(`Testing URL ${url}`);
+
+    let iframe = await createIframe(url);
+
+    iframe.contentWindow.postMessage(
+      "ping", url);
+
+    let pong = await awaitMessage();
+    is(pong.pong, url, "Got expected pong");
+
+    iframe.remove();
+  }
+
+  await extension.unload();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_verify_non_remote_mode.html b/toolkit/components/extensions/test/mochitest/test_verify_non_remote_mode.html
new file mode 100644
index 0000000000..6f46fa8eea
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_verify_non_remote_mode.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Verify non-remote mode</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+add_task(async function verify_extensions_in_parent_process() {
+  // This test ensures we are running with the proper settings.
+  const { WebExtensionPolicy } = SpecialPowers.Cu.getGlobalForObject(SpecialPowers.Services);
+  SimpleTest.ok(!WebExtensionPolicy.useRemoteWebExtensions, "extensions running in-process");
+
+  let chromeScript = SpecialPowers.loadChromeScript(() => {
+    const { WebExtensionPolicy } = Cu.getGlobalForObject(Services);
+    Assert.ok(WebExtensionPolicy.isExtensionProcess, "parent is extension process");
+    this.sendAsyncMessage("checks_done");
+  });
+  await chromeScript.promiseOneMessage("checks_done");
+  chromeScript.destroy();
+});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/test_verify_remote_mode.html b/toolkit/components/extensions/test/mochitest/test_verify_remote_mode.html
new file mode 100644
index 0000000000..2be0e19179
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_verify_remote_mode.html
@@ -0,0 +1,22 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Verify remote mode</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+  "use strict";
+  // This test ensures we are running with the proper settings.
+  const {WebExtensionPolicy} = SpecialPowers.Cu.getGlobalForObject(SpecialPowers.Services);
+  SimpleTest.ok(WebExtensionPolicy.useRemoteWebExtensions, "extensions running remote");
+  SimpleTest.ok(!WebExtensionPolicy.isExtensionProcess, "testing from remote process");
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/mochitest/webrequest_chromeworker.js b/toolkit/components/extensions/test/mochitest/webrequest_chromeworker.js
new file mode 100644
index 0000000000..6a44fcac2e
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/webrequest_chromeworker.js
@@ -0,0 +1,9 @@
+"use strict";
+
+/* eslint-env worker */
+
+onmessage = function(event) {
+  fetch("https://example.com/example.txt").then(() => {
+    postMessage("Done!");
+  });
+};
diff --git a/toolkit/components/extensions/test/mochitest/webrequest_test.jsm b/toolkit/components/extensions/test/mochitest/webrequest_test.jsm
new file mode 100644
index 0000000000..6fc2fe3d7f
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/webrequest_test.jsm
@@ -0,0 +1,22 @@
+"use strict";
+
+var EXPORTED_SYMBOLS = ["webrequest_test"];
+
+Cu.importGlobalProperties(["fetch"]);
+
+var webrequest_test = {
+  testFetch(url) {
+    return fetch(url);
+  },
+
+  testXHR(url) {
+    return new Promise(resolve => {
+      let xhr = new XMLHttpRequest();
+      xhr.open("HEAD", url);
+      xhr.onload = () => {
+        resolve();
+      };
+      xhr.send();
+    });
+  },
+};
diff --git a/toolkit/components/extensions/test/mochitest/webrequest_worker.js b/toolkit/components/extensions/test/mochitest/webrequest_worker.js
new file mode 100644
index 0000000000..dcffd08578
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/webrequest_worker.js
@@ -0,0 +1,3 @@
+"use strict";
+
+fetch("https://example.com/example.txt");
diff --git a/toolkit/components/extensions/test/xpcshell/.eslintrc.js b/toolkit/components/extensions/test/xpcshell/.eslintrc.js
new file mode 100644
index 0000000000..3622fff4f6
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/.eslintrc.js
@@ -0,0 +1,9 @@
+"use strict";
+
+module.exports = {
+  env: {
+    // The tests in this folder are testing based on WebExtensions, so lets
+    // just define the webextensions environment here.
+    webextensions: true,
+  },
+};
diff --git a/toolkit/components/extensions/test/xpcshell/data/dummy_page.html b/toolkit/components/extensions/test/xpcshell/data/dummy_page.html
new file mode 100644
index 0000000000..c1c9a4e043
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/dummy_page.html
@@ -0,0 +1,7 @@
+<!DOCTYPE html>
+
+<html>
+<body>
+<p>Page</p>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/empty_file_download.txt b/toolkit/components/extensions/test/xpcshell/data/empty_file_download.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/toolkit/components/extensions/test/xpcshell/data/file   download.txt b/toolkit/components/extensions/test/xpcshell/data/file   download.txt
new file mode 100644
index 0000000000..6293c7af79
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file   download.txt	
@@ -0,0 +1 @@
+This is a sample file used in download tests.
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_page2.html b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_page2.html
new file mode 100644
index 0000000000..b2cf48f9e1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_page2.html
@@ -0,0 +1,25 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+<link rel="stylesheet" href="file_style_good.css">
+<link rel="stylesheet" href="file_style_bad.css">
+<link rel="stylesheet" href="file_style_redirect.css">
+</head>
+<body>
+
+<div class="test">Sample text</div>
+
+<img id="img_good" src="file_image_good.png">
+<img id="img_bad" src="file_image_bad.png">
+<img id="img_redirect" src="file_image_redirect.png">
+
+<script src="file_script_good.js"></script>
+<script src="file_script_bad.js"></script>
+<script src="file_script_redirect.js"></script>
+
+<script src="nonexistent_script_url.js"></script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_original.html b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_original.html
new file mode 100644
index 0000000000..f6b5142c4d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_original.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script src="http://example.org/data/file_WebRequest_permission_original.js"></script>
+<script>
+"use strict";
+
+window.parent.postMessage({
+  page: "original",
+  script: window.testScript,
+}, "*");
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_original.js b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_original.js
new file mode 100644
index 0000000000..2981108b64
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_original.js
@@ -0,0 +1,2 @@
+"use strict";
+window.testScript = "original";
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_redirected.html b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_redirected.html
new file mode 100644
index 0000000000..0979593f7b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_redirected.html
@@ -0,0 +1,19 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script src="http://example.org/data/file_WebRequest_permission_original.js"></script>
+<script>
+"use strict";
+
+window.parent.postMessage({
+  page: "redirected",
+  script: window.testScript,
+}, "*");
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_redirected.js b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_redirected.js
new file mode 100644
index 0000000000..06fd42aa40
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_WebRequest_permission_redirected.js
@@ -0,0 +1,2 @@
+"use strict";
+window.testScript = "redirected";
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_csp.html b/toolkit/components/extensions/test/xpcshell/data/file_csp.html
new file mode 100644
index 0000000000..9f5cf92f5a
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_csp.html
@@ -0,0 +1,14 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<div id="test">Sample text</div>
+<img id="bad-image" src="http://example.org/data/file_image_bad.png">
+<script id="bad-script" src="http://example.org/data/file_script_bad.js"></script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_csp.html^headers^ b/toolkit/components/extensions/test/xpcshell/data/file_csp.html^headers^
new file mode 100644
index 0000000000..4c6fa3c26a
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_csp.html^headers^
@@ -0,0 +1 @@
+Content-Security-Policy: default-src 'self'
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_do_load_script_subresource.html b/toolkit/components/extensions/test/xpcshell/data/file_do_load_script_subresource.html
new file mode 100644
index 0000000000..c74dec5f5a
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_do_load_script_subresource.html
@@ -0,0 +1,9 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+<script src="http://example.net/intercept_by_webRequest.js"></script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_document_open.html b/toolkit/components/extensions/test/xpcshell/data/file_document_open.html
new file mode 100644
index 0000000000..dae5e90667
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_document_open.html
@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+  <iframe id="iframe"></iframe>
+
+  <script type="text/javascript">
+    "use strict";
+    addEventListener("load", () => {
+      let iframe = document.getElementById("iframe");
+      let doc = iframe.contentDocument;
+      doc.open("text/html");
+      doc.write("Hello.");
+      doc.close();
+    }, {once: true});
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_document_write.html b/toolkit/components/extensions/test/xpcshell/data/file_document_write.html
new file mode 100644
index 0000000000..fbae3d6d76
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_document_write.html
@@ -0,0 +1,35 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+  <iframe id="iframe"></iframe>
+
+  <script type="text/javascript">
+    "use strict";
+    addEventListener("load", () => {
+      // Send a heap-minimize observer notification so our script cache is
+      // cleared, and our content script isn't available for synchronous
+      // insertion.
+      window.dispatchEvent(new CustomEvent("MozHeapMinimize"));
+
+      let iframe = document.getElementById("iframe");
+      let doc = iframe.contentDocument;
+      doc.open("text/html");
+      // We need to do two writes here. The first creates the document element,
+      // which normally triggers parser blocking. The second triggers the
+      // creation of the element we're about to query for, which would normally
+      // happen asynchronously if the parser were blocked.
+      doc.write("<div id=meh>");
+      doc.write("<div id=beer></div>");
+
+      let elem = doc.getElementById("beer");
+      top.postMessage(elem instanceof HTMLDivElement ? "ok" : "fail",
+                      "*");
+
+      doc.close();
+    }, {once: true});
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_download.html b/toolkit/components/extensions/test/xpcshell/data/file_download.html
new file mode 100644
index 0000000000..d970c63259
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_download.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<div>Download HTML File</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_download.txt b/toolkit/components/extensions/test/xpcshell/data/file_download.txt
new file mode 100644
index 0000000000..6293c7af79
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_download.txt
@@ -0,0 +1 @@
+This is a sample file used in download tests.
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_iframe.html b/toolkit/components/extensions/test/xpcshell/data/file_iframe.html
new file mode 100644
index 0000000000..0cd68be586
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_iframe.html
@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title>Iframe document</title>
+</head>
+<body>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_image_bad.png b/toolkit/components/extensions/test/xpcshell/data/file_image_bad.png
new file mode 100644
index 0000000000..4c3be50847
Binary files /dev/null and b/toolkit/components/extensions/test/xpcshell/data/file_image_bad.png differ
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_image_good.png b/toolkit/components/extensions/test/xpcshell/data/file_image_good.png
new file mode 100644
index 0000000000..769c636340
Binary files /dev/null and b/toolkit/components/extensions/test/xpcshell/data/file_image_good.png differ
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_image_redirect.png b/toolkit/components/extensions/test/xpcshell/data/file_image_redirect.png
new file mode 100644
index 0000000000..4c3be50847
Binary files /dev/null and b/toolkit/components/extensions/test/xpcshell/data/file_image_redirect.png differ
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_page_xhr.html b/toolkit/components/extensions/test/xpcshell/data/file_page_xhr.html
new file mode 100644
index 0000000000..387b5285f5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_page_xhr.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script>
+"use strict";
+
+addEventListener("message", async function(event) {
+  const url = new URL("/return_headers.sjs", location).href;
+
+  const webpageFetchResult = await fetch(url).then(res => res.json());
+  const webpageXhrResult = await new Promise(resolve => {
+    const req = new XMLHttpRequest();
+    req.open("GET", url);
+    req.addEventListener("load", () => resolve(JSON.parse(req.responseText)),
+                         {once: true});
+    req.addEventListener("error", () => resolve({error: "webpage xhr failed to complete"}),
+                         {once: true});
+    req.send();
+  });
+
+  postMessage({
+    type: "testPageGlobals",
+    webpageFetchResult,
+    webpageXhrResult,
+  }, "*");
+}, {once: true});
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_permission_xhr.html b/toolkit/components/extensions/test/xpcshell/data/file_permission_xhr.html
new file mode 100644
index 0000000000..6f1bb4648b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_permission_xhr.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<script>
+"use strict";
+
+/* globals privilegedFetch, privilegedXHR */
+/* eslint-disable mozilla/balanced-listeners */
+
+addEventListener("message", function rcv(event) {
+  removeEventListener("message", rcv, false);
+
+  function assertTrue(condition, description) {
+    postMessage({msg: "assertTrue", condition, description}, "*");
+  }
+
+  function assertThrows(func, expectedError, msg) {
+    try {
+      func();
+    } catch (e) {
+      assertTrue(expectedError.test(e), msg + ": threw " + e);
+      return;
+    }
+
+    assertTrue(false, "Function did not throw, " +
+                      "expected error should have matched " + expectedError);
+  }
+
+  function passListener() {
+    assertTrue(true, "Content XHR has no elevated privileges");
+    postMessage({"msg": "finish"}, "*");
+  }
+
+  function failListener() {
+    assertTrue(false, "Content XHR has no elevated privileges");
+    postMessage({"msg": "finish"}, "*");
+  }
+
+  assertThrows(function() { new privilegedXHR(); },
+               /Permission denied to access object/,
+               "Content should not be allowed to construct a privileged XHR constructor");
+
+  assertThrows(function() { new privilegedFetch(); },
+               / is not a constructor/,
+               "Content should not be allowed to construct a privileged fetch() constructor");
+
+  let req = new XMLHttpRequest();
+  req.addEventListener("load", failListener);
+  req.addEventListener("error", passListener);
+  req.open("GET", "http://example.org/example.txt");
+  req.send();
+}, false);
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_privilege_escalation.html b/toolkit/components/extensions/test/xpcshell/data/file_privilege_escalation.html
new file mode 100644
index 0000000000..258f7058d9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_privilege_escalation.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+  <script type="text/javascript">
+    "use strict";
+    throw new Error(`WebExt Privilege Escalation: typeof(browser) = ${typeof(browser)}`);
+  </script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_sample.html b/toolkit/components/extensions/test/xpcshell/data/file_sample.html
new file mode 100644
index 0000000000..a20e49a1f0
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_sample.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<div id="test">Sample text</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_sample_registered_styles.html b/toolkit/components/extensions/test/xpcshell/data/file_sample_registered_styles.html
new file mode 100644
index 0000000000..9f5c5d5a6a
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_sample_registered_styles.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+
+<div id="registered-extension-url-style">Registered Extension URL style</div>
+<div id="registered-extension-text-style">Registered Extension Text style</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_script.html b/toolkit/components/extensions/test/xpcshell/data/file_script.html
new file mode 100644
index 0000000000..8d192b7d8e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_script.html
@@ -0,0 +1,14 @@
+<!DOCTYPE HTML>
+
+<html>
+<head>
+<meta charset="utf-8">
+<script type="application/javascript" src="file_script_good.js"></script>
+<script type="application/javascript" src="file_script_bad.js"></script>
+</head>
+<body>
+
+<div id="test">Sample text</div>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_script_bad.js b/toolkit/components/extensions/test/xpcshell/data/file_script_bad.js
new file mode 100644
index 0000000000..ff4572865b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_script_bad.js
@@ -0,0 +1,12 @@
+"use strict";
+
+window.failure = true;
+window.addEventListener(
+  "load",
+  () => {
+    let el = document.createElement("div");
+    el.setAttribute("id", "bad");
+    document.body.appendChild(el);
+  },
+  { once: true }
+);
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_script_good.js b/toolkit/components/extensions/test/xpcshell/data/file_script_good.js
new file mode 100644
index 0000000000..bf47fb36d2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_script_good.js
@@ -0,0 +1,12 @@
+"use strict";
+
+window.success = window.success ? window.success + 1 : 1;
+window.addEventListener(
+  "load",
+  () => {
+    let el = document.createElement("div");
+    el.setAttribute("id", "good");
+    document.body.appendChild(el);
+  },
+  { once: true }
+);
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_script_redirect.js b/toolkit/components/extensions/test/xpcshell/data/file_script_redirect.js
new file mode 100644
index 0000000000..c425122c71
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_script_redirect.js
@@ -0,0 +1,3 @@
+"use strict";
+
+window.failure = true;
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_script_xhr.js b/toolkit/components/extensions/test/xpcshell/data/file_script_xhr.js
new file mode 100644
index 0000000000..24a26cb8d1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_script_xhr.js
@@ -0,0 +1,9 @@
+"use strict";
+
+var request = new XMLHttpRequest();
+request.open(
+  "get",
+  "http://example.com/browser/toolkit/modules/tests/browser/xhr_resource",
+  false
+);
+request.send();
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_shadowdom.html b/toolkit/components/extensions/test/xpcshell/data/file_shadowdom.html
new file mode 100644
index 0000000000..c4e7db14e7
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_shadowdom.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+<div id="host">host</div>
+<script>
+  "use strict";
+  document.getElementById("host").attachShadow({mode: "closed"});
+</script>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_style_bad.css b/toolkit/components/extensions/test/xpcshell/data/file_style_bad.css
new file mode 100644
index 0000000000..8dbc8dc7a4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_style_bad.css
@@ -0,0 +1,3 @@
+#test {
+  color: green !important;
+}
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_style_good.css b/toolkit/components/extensions/test/xpcshell/data/file_style_good.css
new file mode 100644
index 0000000000..46f9774b5f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_style_good.css
@@ -0,0 +1,3 @@
+#test {
+  color: red;
+}
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_style_redirect.css b/toolkit/components/extensions/test/xpcshell/data/file_style_redirect.css
new file mode 100644
index 0000000000..8dbc8dc7a4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_style_redirect.css
@@ -0,0 +1,3 @@
+#test {
+  color: green !important;
+}
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache.css b/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache.css
new file mode 100644
index 0000000000..6a9140d97e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache.css
@@ -0,0 +1 @@
+:root { color: green; }
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache.html b/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache.html
new file mode 100644
index 0000000000..6d6d187a27
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache.html
@@ -0,0 +1,3 @@
+<!doctype html>
+<meta charset=utf-8>
+<link rel=stylesheet href=file_stylesheet_cache.css>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache_2.html b/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache_2.html
new file mode 100644
index 0000000000..07a4324c44
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_stylesheet_cache_2.html
@@ -0,0 +1,19 @@
+<!doctype html>
+<meta charset=utf-8>
+<!-- The first one should hit the cache, the second one should not. -->
+<link rel=stylesheet href=file_stylesheet_cache.css>
+<script>
+  "use strict";
+  // This script guarantees that the load of the above stylesheet has happened
+  // by now.
+  //
+  // Now we can go ahead and load the other one programmatically. It's
+  // important that we don't just throw a <link> in the markup below to
+  // guarantee
+  // that the load happens afterwards (that is, to cheat the parser's speculative
+  // load mechanism).
+  const link = document.createElement("link");
+  link.rel = "stylesheet";
+  link.href = "file_stylesheet_cache.css?2";
+  document.head.appendChild(link);
+</script>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_toplevel.html b/toolkit/components/extensions/test/xpcshell/data/file_toplevel.html
new file mode 100644
index 0000000000..d93813d0f5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_toplevel.html
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title>Top-level frame document</title>
+</head>
+<body>
+  <iframe src="file_iframe.html"></iframe>
+  <iframe src="about:blank"></iframe>
+  <iframe srcdoc="Iframe srcdoc"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/file_with_xorigin_frame.html b/toolkit/components/extensions/test/xpcshell/data/file_with_xorigin_frame.html
new file mode 100644
index 0000000000..199c2ce4d4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/data/file_with_xorigin_frame.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title>Document with example.org frame</title>
+</head>
+<body>
+  <iframe src="http://example.org/data/file_iframe.html"></iframe>
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/data/lorem.html.gz b/toolkit/components/extensions/test/xpcshell/data/lorem.html.gz
new file mode 100644
index 0000000000..9eb8d73d50
Binary files /dev/null and b/toolkit/components/extensions/test/xpcshell/data/lorem.html.gz differ
diff --git a/toolkit/components/extensions/test/xpcshell/data/pixel_green.gif b/toolkit/components/extensions/test/xpcshell/data/pixel_green.gif
new file mode 100644
index 0000000000..baf8166dae
Binary files /dev/null and b/toolkit/components/extensions/test/xpcshell/data/pixel_green.gif differ
diff --git a/toolkit/components/extensions/test/xpcshell/data/pixel_red.gif b/toolkit/components/extensions/test/xpcshell/data/pixel_red.gif
new file mode 100644
index 0000000000..48f97f74bd
Binary files /dev/null and b/toolkit/components/extensions/test/xpcshell/data/pixel_red.gif differ
diff --git a/toolkit/components/extensions/test/xpcshell/head.js b/toolkit/components/extensions/test/xpcshell/head.js
new file mode 100644
index 0000000000..4608f77bd6
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head.js
@@ -0,0 +1,277 @@
+"use strict";
+
+/* exported createHttpServer, cleanupDir, clearCache, promiseConsoleOutput,
+            promiseQuotaManagerServiceReset, promiseQuotaManagerServiceClear,
+            runWithPrefs, testEnv, withHandlingUserInput, resetHandlingUserInput */
+
+var { AppConstants } = ChromeUtils.import(
+  "resource://gre/modules/AppConstants.jsm"
+);
+var { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+var { XPCOMUtils } = ChromeUtils.import(
+  "resource://gre/modules/XPCOMUtils.jsm"
+);
+var {
+  clearInterval,
+  clearTimeout,
+  setInterval,
+  setIntervalWithTarget,
+  setTimeout,
+  setTimeoutWithTarget,
+} = ChromeUtils.import("resource://gre/modules/Timer.jsm");
+var { AddonTestUtils, MockAsyncShutdown } = ChromeUtils.import(
+  "resource://testing-common/AddonTestUtils.jsm"
+);
+
+// eslint-disable-next-line no-unused-vars
+XPCOMUtils.defineLazyModuleGetters(this, {
+  ContentTask: "resource://testing-common/ContentTask.jsm",
+  Extension: "resource://gre/modules/Extension.jsm",
+  ExtensionData: "resource://gre/modules/Extension.jsm",
+  ExtensionParent: "resource://gre/modules/ExtensionParent.jsm",
+  ExtensionTestUtils: "resource://testing-common/ExtensionXPCShellUtils.jsm",
+  FileUtils: "resource://gre/modules/FileUtils.jsm",
+  MessageChannel: "resource://gre/modules/MessageChannel.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+  PromiseTestUtils: "resource://testing-common/PromiseTestUtils.jsm",
+  Schemas: "resource://gre/modules/Schemas.jsm",
+});
+
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /Message manager disconnected/
+);
+
+// These values may be changed in later head files and tested in check_remote
+// below.
+Services.prefs.setBoolPref("browser.tabs.remote.autostart", false);
+Services.prefs.setBoolPref("extensions.webextensions.remote", false);
+const testEnv = {
+  expectRemote: false,
+};
+
+add_task(function check_remote() {
+  Assert.equal(
+    WebExtensionPolicy.useRemoteWebExtensions,
+    testEnv.expectRemote,
+    "useRemoteWebExtensions matches"
+  );
+  Assert.equal(
+    WebExtensionPolicy.isExtensionProcess,
+    !testEnv.expectRemote,
+    "testing from extension process"
+  );
+});
+
+ExtensionTestUtils.init(this);
+
+var createHttpServer = (...args) => {
+  AddonTestUtils.maybeInit(this);
+  return AddonTestUtils.createHttpServer(...args);
+};
+
+if (AppConstants.platform === "android") {
+  Services.io.offline = true;
+}
+
+/**
+ * Clears the HTTP and content image caches.
+ */
+function clearCache() {
+  Services.cache2.clear();
+
+  let imageCache = Cc["@mozilla.org/image/tools;1"]
+    .getService(Ci.imgITools)
+    .getImgCacheForDocument(null);
+  imageCache.clearCache(false);
+}
+
+var promiseConsoleOutput = async function(task) {
+  const DONE = `=== console listener ${Math.random()} done ===`;
+
+  let listener;
+  let messages = [];
+  let awaitListener = new Promise(resolve => {
+    listener = msg => {
+      if (msg == DONE) {
+        resolve();
+      } else {
+        void (msg instanceof Ci.nsIConsoleMessage);
+        void (msg instanceof Ci.nsIScriptError);
+        messages.push(msg);
+      }
+    };
+  });
+
+  Services.console.registerListener(listener);
+  try {
+    let result = await task();
+
+    Services.console.logStringMessage(DONE);
+    await awaitListener;
+
+    return { messages, result };
+  } finally {
+    Services.console.unregisterListener(listener);
+  }
+};
+
+// Attempt to remove a directory.  If the Windows OS is still using the
+// file sometimes remove() will fail.  So try repeatedly until we can
+// remove it or we give up.
+function cleanupDir(dir) {
+  let count = 0;
+  return new Promise((resolve, reject) => {
+    function tryToRemoveDir() {
+      count += 1;
+      try {
+        dir.remove(true);
+      } catch (e) {
+        // ignore
+      }
+      if (!dir.exists()) {
+        return resolve();
+      }
+      if (count >= 25) {
+        return reject(`Failed to cleanup directory: ${dir}`);
+      }
+      setTimeout(tryToRemoveDir, 100);
+    }
+    tryToRemoveDir();
+  });
+}
+
+// Run a test with the specified preferences and then restores their initial values
+// right after the test function run (whether it passes or fails).
+async function runWithPrefs(prefsToSet, testFn) {
+  const setPrefs = prefs => {
+    for (let [pref, value] of prefs) {
+      if (value === undefined) {
+        // Clear any pref that didn't have a user value.
+        info(`Clearing pref "${pref}"`);
+        Services.prefs.clearUserPref(pref);
+        continue;
+      }
+
+      info(`Setting pref "${pref}": ${value}`);
+      switch (typeof value) {
+        case "boolean":
+          Services.prefs.setBoolPref(pref, value);
+          break;
+        case "number":
+          Services.prefs.setIntPref(pref, value);
+          break;
+        case "string":
+          Services.prefs.setStringPref(pref, value);
+          break;
+        default:
+          throw new Error("runWithPrefs doesn't support this pref type yet");
+      }
+    }
+  };
+
+  const getPrefs = prefs => {
+    return prefs.map(([pref, value]) => {
+      info(`Getting initial pref value for "${pref}"`);
+      if (!Services.prefs.prefHasUserValue(pref)) {
+        // Check if the pref doesn't have a user value.
+        return [pref, undefined];
+      }
+      switch (typeof value) {
+        case "boolean":
+          return [pref, Services.prefs.getBoolPref(pref)];
+        case "number":
+          return [pref, Services.prefs.getIntPref(pref)];
+        case "string":
+          return [pref, Services.prefs.getStringPref(pref)];
+        default:
+          throw new Error("runWithPrefs doesn't support this pref type yet");
+      }
+    });
+  };
+
+  let initialPrefsValues = [];
+
+  try {
+    initialPrefsValues = getPrefs(prefsToSet);
+
+    setPrefs(prefsToSet);
+
+    await testFn();
+  } finally {
+    info("Restoring initial preferences values on exit");
+    setPrefs(initialPrefsValues);
+  }
+}
+
+// "Handling User Input" test helpers.
+
+let extensionHandlers = new WeakSet();
+
+function handlingUserInputFrameScript() {
+  /* globals content */
+  // eslint-disable-next-line no-shadow
+  const { MessageChannel } = ChromeUtils.import(
+    "resource://gre/modules/MessageChannel.jsm"
+  );
+
+  let handle;
+  MessageChannel.addListener(this, "ExtensionTest:HandleUserInput", {
+    receiveMessage({ name, data }) {
+      if (data) {
+        handle = content.windowUtils.setHandlingUserInput(true);
+      } else if (handle) {
+        handle.destruct();
+        handle = null;
+      }
+    },
+  });
+}
+
+// If you use withHandlingUserInput then restart the addon manager,
+// you need to reset this before using withHandlingUserInput again.
+function resetHandlingUserInput() {
+  extensionHandlers = new WeakSet();
+}
+
+async function withHandlingUserInput(extension, fn) {
+  let { messageManager } = extension.extension.groupFrameLoader;
+
+  if (!extensionHandlers.has(extension)) {
+    messageManager.loadFrameScript(
+      `data:,(${encodeURI(handlingUserInputFrameScript)}).call(this)`,
+      false,
+      true
+    );
+    extensionHandlers.add(extension);
+  }
+
+  await MessageChannel.sendMessage(
+    messageManager,
+    "ExtensionTest:HandleUserInput",
+    true
+  );
+  await fn();
+  await MessageChannel.sendMessage(
+    messageManager,
+    "ExtensionTest:HandleUserInput",
+    false
+  );
+}
+
+// QuotaManagerService test helpers.
+
+function promiseQuotaManagerServiceReset() {
+  info("Calling QuotaManagerService.reset to enforce new test storage limits");
+  return new Promise(resolve => {
+    Services.qms.reset().callback = resolve;
+  });
+}
+
+function promiseQuotaManagerServiceClear() {
+  info(
+    "Calling QuotaManagerService.clear to empty the test data and refresh test storage limits"
+  );
+  return new Promise(resolve => {
+    Services.qms.clear().callback = resolve;
+  });
+}
diff --git a/toolkit/components/extensions/test/xpcshell/head_e10s.js b/toolkit/components/extensions/test/xpcshell/head_e10s.js
new file mode 100644
index 0000000000..196afae7c9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head_e10s.js
@@ -0,0 +1,8 @@
+"use strict";
+
+/* globals ExtensionTestUtils */
+
+// xpcshell disables e10s by default. Turn it on.
+Services.prefs.setBoolPref("browser.tabs.remote.autostart", true);
+
+ExtensionTestUtils.remoteContentScripts = true;
diff --git a/toolkit/components/extensions/test/xpcshell/head_legacy_ep.js b/toolkit/components/extensions/test/xpcshell/head_legacy_ep.js
new file mode 100644
index 0000000000..01f16ec54c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head_legacy_ep.js
@@ -0,0 +1,13 @@
+"use strict";
+
+// Bug 1646182: Test the legacy ExtensionPermission backend until we fully
+// migrate to rkv
+
+{
+  const { ExtensionPermissions } = ChromeUtils.import(
+    "resource://gre/modules/ExtensionPermissions.jsm"
+  );
+
+  ExtensionPermissions._useLegacyStorageBackend = true;
+  ExtensionPermissions._uninit();
+}
diff --git a/toolkit/components/extensions/test/xpcshell/head_native_messaging.js b/toolkit/components/extensions/test/xpcshell/head_native_messaging.js
new file mode 100644
index 0000000000..e0b977c22c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head_native_messaging.js
@@ -0,0 +1,153 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* globals AppConstants, FileUtils */
+/* exported getSubprocessCount, setupHosts, waitForSubprocessExit */
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "MockRegistry",
+  "resource://testing-common/MockRegistry.jsm"
+);
+ChromeUtils.defineModuleGetter(this, "OS", "resource://gre/modules/osfile.jsm");
+
+let { Subprocess, SubprocessImpl } = ChromeUtils.import(
+  "resource://gre/modules/Subprocess.jsm",
+  null
+);
+
+// It's important that we use a space in this directory name to make sure we
+// correctly handle executing batch files with spaces in their path.
+let tmpDir = FileUtils.getDir("TmpD", ["Native Messaging"]);
+tmpDir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+const TYPE_SLUG =
+  AppConstants.platform === "linux"
+    ? "native-messaging-hosts"
+    : "NativeMessagingHosts";
+OS.File.makeDir(OS.Path.join(tmpDir.path, TYPE_SLUG));
+
+registerCleanupFunction(() => {
+  tmpDir.remove(true);
+});
+
+function getPath(filename) {
+  return OS.Path.join(tmpDir.path, TYPE_SLUG, filename);
+}
+
+const ID = "native@tests.mozilla.org";
+
+async function setupHosts(scripts) {
+  const PERMS = { unixMode: 0o755 };
+
+  const env = Cc["@mozilla.org/process/environment;1"].getService(
+    Ci.nsIEnvironment
+  );
+  const pythonPath = await Subprocess.pathSearch(env.get("PYTHON"));
+
+  async function writeManifest(script, scriptPath, path) {
+    let body = `#!${pythonPath} -u\n${script.script}`;
+
+    await OS.File.writeAtomic(scriptPath, body);
+    await OS.File.setPermissions(scriptPath, PERMS);
+
+    let manifest = {
+      name: script.name,
+      description: script.description,
+      path,
+      type: "stdio",
+      allowed_extensions: [ID],
+    };
+
+    let manifestPath = getPath(`${script.name}.json`);
+    await OS.File.writeAtomic(manifestPath, JSON.stringify(manifest));
+
+    return manifestPath;
+  }
+
+  switch (AppConstants.platform) {
+    case "macosx":
+    case "linux":
+      let dirProvider = {
+        getFile(property) {
+          if (property == "XREUserNativeManifests") {
+            return tmpDir.clone();
+          } else if (property == "XRESysNativeManifests") {
+            return tmpDir.clone();
+          }
+          return null;
+        },
+      };
+
+      Services.dirsvc.registerProvider(dirProvider);
+      registerCleanupFunction(() => {
+        Services.dirsvc.unregisterProvider(dirProvider);
+      });
+
+      for (let script of scripts) {
+        let path = getPath(`${script.name}.py`);
+
+        await writeManifest(script, path, path);
+      }
+      break;
+
+    case "win":
+      const REGKEY = String.raw`Software\Mozilla\NativeMessagingHosts`;
+
+      let registry = new MockRegistry();
+      registerCleanupFunction(() => {
+        registry.shutdown();
+      });
+
+      for (let script of scripts) {
+        let { scriptExtension = "bat" } = script;
+
+        // It's important that we use a space in this filename. See directory
+        // name comment above.
+        let batPath = getPath(`batch ${script.name}.${scriptExtension}`);
+        let scriptPath = getPath(`${script.name}.py`);
+
+        let batBody = `@ECHO OFF\n${pythonPath} -u "${scriptPath}" %*\n`;
+        await OS.File.writeAtomic(batPath, batBody);
+
+        // Create absolute and relative path versions of the entry.
+        for (let [name, path] of [
+          [script.name, batPath],
+          [`relative.${script.name}`, OS.Path.basename(batPath)],
+        ]) {
+          script.name = name;
+          let manifestPath = await writeManifest(script, scriptPath, path);
+
+          registry.setValue(
+            Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+            `${REGKEY}\\${script.name}`,
+            "",
+            manifestPath
+          );
+        }
+      }
+      break;
+
+    default:
+      ok(
+        false,
+        `Native messaging is not supported on ${AppConstants.platform}`
+      );
+  }
+}
+
+function getSubprocessCount() {
+  return SubprocessImpl.Process.getWorker()
+    .call("getProcesses", [])
+    .then(result => result.size);
+}
+function waitForSubprocessExit() {
+  return SubprocessImpl.Process.getWorker()
+    .call("waitForNoProcesses", [])
+    .then(() => {
+      // Return to the main event loop to give IO handlers enough time to consume
+      // their remaining buffered input.
+      return new Promise(resolve => setTimeout(resolve, 0));
+    });
+}
diff --git a/toolkit/components/extensions/test/xpcshell/head_remote.js b/toolkit/components/extensions/test/xpcshell/head_remote.js
new file mode 100644
index 0000000000..f9c31144c9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head_remote.js
@@ -0,0 +1,7 @@
+"use strict";
+
+Services.prefs.setBoolPref("extensions.webextensions.remote", true);
+Services.prefs.setIntPref("dom.ipc.keepProcessesAlive.extension", 1);
+
+/* globals testEnv */
+testEnv.expectRemote = true; // tested in head_test.js
diff --git a/toolkit/components/extensions/test/xpcshell/head_storage.js b/toolkit/components/extensions/test/xpcshell/head_storage.js
new file mode 100644
index 0000000000..09a5b45b0e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head_storage.js
@@ -0,0 +1,1227 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* import-globals-from head.js */
+
+const STORAGE_SYNC_PREF = "webextensions.storage.sync.enabled";
+
+// Test implementations and utility functions that are used against multiple
+// storage areas (eg, a test which is run against browser.storage.local and
+// browser.storage.sync, or a test against browser.storage.sync but needs to
+// be run against both the kinto and rust implementations.)
+
+/**
+ * Utility function to ensure that all supported APIs for getting are
+ * tested.
+ *
+ * @param {string} areaName
+ *        either "local" or "sync" according to what we want to test
+ * @param {string} prop
+ *        "key" to look up using the storage API
+ * @param {Object} value
+ *        "value" to compare against
+ */
+async function checkGetImpl(areaName, prop, value) {
+  let storage = browser.storage[areaName];
+
+  let data = await storage.get();
+  browser.test.assertEq(
+    value,
+    data[prop],
+    `unspecified getter worked for ${prop} in ${areaName}`
+  );
+
+  data = await storage.get(null);
+  browser.test.assertEq(
+    value,
+    data[prop],
+    `null getter worked for ${prop} in ${areaName}`
+  );
+
+  data = await storage.get(prop);
+  browser.test.assertEq(
+    value,
+    data[prop],
+    `string getter worked for ${prop} in ${areaName}`
+  );
+  browser.test.assertEq(
+    Object.keys(data).length,
+    1,
+    `string getter should return an object with a single property`
+  );
+
+  data = await storage.get([prop]);
+  browser.test.assertEq(
+    value,
+    data[prop],
+    `array getter worked for ${prop} in ${areaName}`
+  );
+  browser.test.assertEq(
+    Object.keys(data).length,
+    1,
+    `array getter with a single key should return an object with a single property`
+  );
+
+  data = await storage.get({ [prop]: undefined });
+  browser.test.assertEq(
+    value,
+    data[prop],
+    `object getter worked for ${prop} in ${areaName}`
+  );
+  browser.test.assertEq(
+    Object.keys(data).length,
+    1,
+    `object getter with a single key should return an object with a single property`
+  );
+}
+
+function test_config_flag_needed() {
+  async function testFn() {
+    function background() {
+      let promises = [];
+      let apiTests = [
+        { method: "get", args: ["foo"] },
+        { method: "set", args: [{ foo: "bar" }] },
+        { method: "remove", args: ["foo"] },
+        { method: "clear", args: [] },
+      ];
+      apiTests.forEach(testDef => {
+        promises.push(
+          browser.test.assertRejects(
+            browser.storage.sync[testDef.method](...testDef.args),
+            "Please set webextensions.storage.sync.enabled to true in about:config",
+            `storage.sync.${testDef.method} is behind a flag`
+          )
+        );
+      });
+
+      Promise.all(promises).then(() => browser.test.notifyPass("flag needed"));
+    }
+
+    ok(
+      !Services.prefs.getBoolPref(STORAGE_SYNC_PREF, false),
+      "The `${STORAGE_SYNC_PREF}` should be set to false"
+    );
+
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        permissions: ["storage"],
+      },
+      background,
+    });
+
+    await extension.startup();
+    await extension.awaitFinish("flag needed");
+    await extension.unload();
+  }
+
+  return runWithPrefs([[STORAGE_SYNC_PREF, false]], testFn);
+}
+
+function test_sync_reloading_extensions_works() {
+  async function testFn() {
+    // Just some random extension ID that we can re-use
+    const extensionId = "my-extension-id@1";
+
+    function loadExtension() {
+      function background() {
+        browser.storage.sync.set({ a: "b" }).then(() => {
+          browser.test.notifyPass("set-works");
+        });
+      }
+
+      return ExtensionTestUtils.loadExtension(
+        {
+          manifest: {
+            permissions: ["storage"],
+          },
+          background: `(${background})()`,
+        },
+        extensionId
+      );
+    }
+
+    ok(
+      Services.prefs.getBoolPref(STORAGE_SYNC_PREF, false),
+      "The `${STORAGE_SYNC_PREF}` should be set to true"
+    );
+
+    let extension1 = loadExtension();
+
+    await extension1.startup();
+    await extension1.awaitFinish("set-works");
+    await extension1.unload();
+
+    let extension2 = loadExtension();
+
+    await extension2.startup();
+    await extension2.awaitFinish("set-works");
+    await extension2.unload();
+  }
+
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], testFn);
+}
+
+async function test_background_page_storage(testAreaName) {
+  async function backgroundScript(checkGet) {
+    let globalChanges, gResolve;
+    function clearGlobalChanges() {
+      globalChanges = new Promise(resolve => {
+        gResolve = resolve;
+      });
+    }
+    clearGlobalChanges();
+    let expectedAreaName;
+
+    browser.storage.onChanged.addListener((changes, areaName) => {
+      browser.test.assertEq(
+        expectedAreaName,
+        areaName,
+        "Expected area name received by listener"
+      );
+      gResolve(changes);
+    });
+
+    async function checkChanges(areaName, changes, message) {
+      function checkSub(obj1, obj2) {
+        for (let prop in obj1) {
+          browser.test.assertTrue(
+            obj1[prop] !== undefined,
+            `checkChanges ${areaName} ${prop} is missing (${message})`
+          );
+          browser.test.assertTrue(
+            obj2[prop] !== undefined,
+            `checkChanges ${areaName} ${prop} is missing (${message})`
+          );
+          browser.test.assertEq(
+            obj1[prop].oldValue,
+            obj2[prop].oldValue,
+            `checkChanges ${areaName} ${prop} old (${message})`
+          );
+          browser.test.assertEq(
+            obj1[prop].newValue,
+            obj2[prop].newValue,
+            `checkChanges ${areaName} ${prop} new (${message})`
+          );
+        }
+      }
+
+      const recentChanges = await globalChanges;
+      checkSub(changes, recentChanges);
+      checkSub(recentChanges, changes);
+      clearGlobalChanges();
+    }
+
+    // Regression test for https://bugzilla.mozilla.org/show_bug.cgi?id=1645598
+    async function testNonExistingKeys(storage, storageAreaDesc) {
+      let data = await storage.get({ test6: 6 });
+      browser.test.assertEq(
+        `{"test6":6}`,
+        JSON.stringify(data),
+        `Use default value when not stored for ${storageAreaDesc}`
+      );
+
+      data = await storage.get({ test6: null });
+      browser.test.assertEq(
+        `{"test6":null}`,
+        JSON.stringify(data),
+        `Use default value, even if null for ${storageAreaDesc}`
+      );
+
+      data = await storage.get("test6");
+      browser.test.assertEq(
+        `{}`,
+        JSON.stringify(data),
+        `Empty result if key is not found for ${storageAreaDesc}`
+      );
+
+      data = await storage.get(["test6", "test7"]);
+      browser.test.assertEq(
+        `{}`,
+        JSON.stringify(data),
+        `Empty result if list of keys is not found for ${storageAreaDesc}`
+      );
+    }
+
+    async function testFalseyValues(areaName) {
+      let storage = browser.storage[areaName];
+      const dataInitial = {
+        "test-falsey-value-bool": false,
+        "test-falsey-value-string": "",
+        "test-falsey-value-number": 0,
+      };
+      const dataUpdate = {
+        "test-falsey-value-bool": true,
+        "test-falsey-value-string": "non-empty-string",
+        "test-falsey-value-number": 10,
+      };
+
+      // Compute the expected changes.
+      const onSetInitial = {
+        "test-falsey-value-bool": { newValue: false },
+        "test-falsey-value-string": { newValue: "" },
+        "test-falsey-value-number": { newValue: 0 },
+      };
+      const onRemovedFalsey = {
+        "test-falsey-value-bool": { oldValue: false },
+        "test-falsey-value-string": { oldValue: "" },
+        "test-falsey-value-number": { oldValue: 0 },
+      };
+      const onUpdatedFalsey = {
+        "test-falsey-value-bool": { newValue: true, oldValue: false },
+        "test-falsey-value-string": {
+          newValue: "non-empty-string",
+          oldValue: "",
+        },
+        "test-falsey-value-number": { newValue: 10, oldValue: 0 },
+      };
+      const keys = Object.keys(dataInitial);
+
+      // Test on removing falsey values.
+      await storage.set(dataInitial);
+      await checkChanges(areaName, onSetInitial, "set falsey values");
+      await storage.remove(keys);
+      await checkChanges(areaName, onRemovedFalsey, "remove falsey value");
+
+      // Test on updating falsey values.
+      await storage.set(dataInitial);
+      await checkChanges(areaName, onSetInitial, "set falsey values");
+      await storage.set(dataUpdate);
+      await checkChanges(areaName, onUpdatedFalsey, "set non-falsey values");
+
+      // Clear the storage state.
+      await testNonExistingKeys(storage, `${areaName} before clearing`);
+      await storage.clear();
+      await testNonExistingKeys(storage, `${areaName} after clearing`);
+      await globalChanges;
+      clearGlobalChanges();
+    }
+
+    function CustomObj() {
+      this.testKey1 = "testValue1";
+    }
+
+    CustomObj.prototype.toString = function() {
+      return '{"testKey2":"testValue2"}';
+    };
+
+    CustomObj.prototype.toJSON = function customObjToJSON() {
+      return { testKey1: "testValue3" };
+    };
+
+    /* eslint-disable dot-notation */
+    async function runTests(areaName) {
+      expectedAreaName = areaName;
+      let storage = browser.storage[areaName];
+      // Set some data and then test getters.
+      try {
+        await storage.set({ "test-prop1": "value1", "test-prop2": "value2" });
+        await checkChanges(
+          areaName,
+          {
+            "test-prop1": { newValue: "value1" },
+            "test-prop2": { newValue: "value2" },
+          },
+          "set (a)"
+        );
+
+        await checkGet(areaName, "test-prop1", "value1");
+        await checkGet(areaName, "test-prop2", "value2");
+
+        let data = await storage.get({
+          "test-prop1": undefined,
+          "test-prop2": undefined,
+          other: "default",
+        });
+        browser.test.assertEq(
+          "value1",
+          data["test-prop1"],
+          "prop1 correct (a)"
+        );
+        browser.test.assertEq(
+          "value2",
+          data["test-prop2"],
+          "prop2 correct (a)"
+        );
+        browser.test.assertEq("default", data["other"], "other correct");
+
+        data = await storage.get(["test-prop1", "test-prop2", "other"]);
+        browser.test.assertEq(
+          "value1",
+          data["test-prop1"],
+          "prop1 correct (b)"
+        );
+        browser.test.assertEq(
+          "value2",
+          data["test-prop2"],
+          "prop2 correct (b)"
+        );
+        browser.test.assertFalse("other" in data, "other correct");
+
+        // Remove data in various ways.
+        await storage.remove("test-prop1");
+        await checkChanges(
+          areaName,
+          { "test-prop1": { oldValue: "value1" } },
+          "remove string"
+        );
+
+        data = await storage.get(["test-prop1", "test-prop2"]);
+        browser.test.assertFalse(
+          "test-prop1" in data,
+          "prop1 absent (remove string)"
+        );
+        browser.test.assertTrue(
+          "test-prop2" in data,
+          "prop2 present (remove string)"
+        );
+
+        await storage.set({ "test-prop1": "value1" });
+        await checkChanges(
+          areaName,
+          { "test-prop1": { newValue: "value1" } },
+          "set (c)"
+        );
+
+        data = await storage.get(["test-prop1", "test-prop2"]);
+        browser.test.assertEq(
+          data["test-prop1"],
+          "value1",
+          "prop1 correct (c)"
+        );
+        browser.test.assertEq(
+          data["test-prop2"],
+          "value2",
+          "prop2 correct (c)"
+        );
+
+        await storage.remove(["test-prop1", "test-prop2"]);
+        await checkChanges(
+          areaName,
+          {
+            "test-prop1": { oldValue: "value1" },
+            "test-prop2": { oldValue: "value2" },
+          },
+          "remove array"
+        );
+
+        data = await storage.get(["test-prop1", "test-prop2"]);
+        browser.test.assertFalse(
+          "test-prop1" in data,
+          "prop1 absent (remove array)"
+        );
+        browser.test.assertFalse(
+          "test-prop2" in data,
+          "prop2 absent (remove array)"
+        );
+
+        await testFalseyValues(areaName);
+
+        // test storage.clear
+        await storage.set({ "test-prop1": "value1", "test-prop2": "value2" });
+        // Make sure that set() handler happened before we clear the
+        // promise again.
+        await globalChanges;
+
+        clearGlobalChanges();
+        await storage.clear();
+
+        await checkChanges(
+          areaName,
+          {
+            "test-prop1": { oldValue: "value1" },
+            "test-prop2": { oldValue: "value2" },
+          },
+          "clear"
+        );
+        data = await storage.get(["test-prop1", "test-prop2"]);
+        browser.test.assertFalse("test-prop1" in data, "prop1 absent (clear)");
+        browser.test.assertFalse("test-prop2" in data, "prop2 absent (clear)");
+
+        // Make sure we can store complex JSON data.
+        // known previous values
+        await storage.set({ "test-prop1": "value1", "test-prop2": "value2" });
+
+        // Make sure the set() handler landed.
+        await globalChanges;
+
+        let date = new Date(0);
+
+        clearGlobalChanges();
+        await storage.set({
+          "test-prop1": {
+            str: "hello",
+            bool: true,
+            null: null,
+            undef: undefined,
+            obj: {},
+            nestedObj: {
+              testKey: {},
+            },
+            intKeyObj: {
+              4: "testValue1",
+              3: "testValue2",
+              99: "testValue3",
+            },
+            floatKeyObj: {
+              1.4: "testValue1",
+              5.5: "testValue2",
+            },
+            customObj: new CustomObj(),
+            arr: [1, 2],
+            nestedArr: [1, [2, 3]],
+            date,
+            regexp: /regexp/,
+          },
+        });
+
+        await browser.test.assertRejects(
+          storage.set({
+            window,
+          }),
+          /DataCloneError|cyclic object value/
+        );
+
+        await browser.test.assertRejects(
+          storage.set({ "test-prop2": function func() {} }),
+          /DataCloneError/
+        );
+
+        const recentChanges = await globalChanges;
+
+        browser.test.assertEq(
+          "value1",
+          recentChanges["test-prop1"].oldValue,
+          "oldValue correct"
+        );
+        browser.test.assertEq(
+          "object",
+          typeof recentChanges["test-prop1"].newValue,
+          "newValue is obj"
+        );
+        clearGlobalChanges();
+
+        data = await storage.get({
+          "test-prop1": undefined,
+          "test-prop2": undefined,
+        });
+        let obj = data["test-prop1"];
+
+        browser.test.assertEq(
+          "object",
+          typeof obj.customObj,
+          "custom object part correct"
+        );
+        browser.test.assertEq(
+          1,
+          Object.keys(obj.customObj).length,
+          "customObj keys correct"
+        );
+
+        if (areaName === "local") {
+          browser.test.assertEq(
+            String(date),
+            String(obj.date),
+            "date part correct"
+          );
+          browser.test.assertEq(
+            "/regexp/",
+            obj.regexp.toString(),
+            "regexp part correct"
+          );
+          // storage.local doesn't call toJSON
+          browser.test.assertEq(
+            "testValue1",
+            obj.customObj.testKey1,
+            "customObj keys correct"
+          );
+        } else {
+          browser.test.assertEq(
+            "1970-01-01T00:00:00.000Z",
+            String(obj.date),
+            "date part correct"
+          );
+
+          browser.test.assertEq(
+            "object",
+            typeof obj.regexp,
+            "regexp part is an object"
+          );
+          browser.test.assertEq(
+            0,
+            Object.keys(obj.regexp).length,
+            "regexp part is an empty object"
+          );
+          // storage.sync does call toJSON
+          browser.test.assertEq(
+            "testValue3",
+            obj.customObj.testKey1,
+            "customObj keys correct"
+          );
+        }
+
+        browser.test.assertEq("hello", obj.str, "string part correct");
+        browser.test.assertEq(true, obj.bool, "bool part correct");
+        browser.test.assertEq(null, obj.null, "null part correct");
+        browser.test.assertEq(undefined, obj.undef, "undefined part correct");
+        browser.test.assertEq(undefined, obj.window, "window part correct");
+        browser.test.assertEq("object", typeof obj.obj, "object part correct");
+        browser.test.assertEq(
+          "object",
+          typeof obj.nestedObj,
+          "nested object part correct"
+        );
+        browser.test.assertEq(
+          "object",
+          typeof obj.nestedObj.testKey,
+          "nestedObj.testKey part correct"
+        );
+        browser.test.assertEq(
+          "object",
+          typeof obj.intKeyObj,
+          "int key object part correct"
+        );
+        browser.test.assertEq(
+          "testValue1",
+          obj.intKeyObj[4],
+          "intKeyObj[4] part correct"
+        );
+        browser.test.assertEq(
+          "testValue2",
+          obj.intKeyObj[3],
+          "intKeyObj[3] part correct"
+        );
+        browser.test.assertEq(
+          "testValue3",
+          obj.intKeyObj[99],
+          "intKeyObj[99] part correct"
+        );
+        browser.test.assertEq(
+          "object",
+          typeof obj.floatKeyObj,
+          "float key object part correct"
+        );
+        browser.test.assertEq(
+          "testValue1",
+          obj.floatKeyObj[1.4],
+          "floatKeyObj[1.4] part correct"
+        );
+        browser.test.assertEq(
+          "testValue2",
+          obj.floatKeyObj[5.5],
+          "floatKeyObj[5.5] part correct"
+        );
+
+        browser.test.assertTrue(Array.isArray(obj.arr), "array part present");
+        browser.test.assertEq(1, obj.arr[0], "arr[0] part correct");
+        browser.test.assertEq(2, obj.arr[1], "arr[1] part correct");
+        browser.test.assertEq(2, obj.arr.length, "arr.length part correct");
+        browser.test.assertTrue(
+          Array.isArray(obj.nestedArr),
+          "nested array part present"
+        );
+        browser.test.assertEq(
+          2,
+          obj.nestedArr.length,
+          "nestedArr.length part correct"
+        );
+        browser.test.assertEq(1, obj.nestedArr[0], "nestedArr[0] part correct");
+        browser.test.assertTrue(
+          Array.isArray(obj.nestedArr[1]),
+          "nestedArr[1] part present"
+        );
+        browser.test.assertEq(
+          2,
+          obj.nestedArr[1].length,
+          "nestedArr[1].length part correct"
+        );
+        browser.test.assertEq(
+          2,
+          obj.nestedArr[1][0],
+          "nestedArr[1][0] part correct"
+        );
+        browser.test.assertEq(
+          3,
+          obj.nestedArr[1][1],
+          "nestedArr[1][1] part correct"
+        );
+      } catch (e) {
+        browser.test.fail(`Error: ${e} :: ${e.stack}`);
+        browser.test.notifyFail("storage");
+      }
+    }
+
+    browser.test.onMessage.addListener(msg => {
+      let promise;
+      if (msg === "test-local") {
+        promise = runTests("local");
+      } else if (msg === "test-sync") {
+        promise = runTests("sync");
+      }
+      promise.then(() => browser.test.sendMessage("test-finished"));
+    });
+
+    browser.test.sendMessage("ready");
+  }
+
+  let extensionData = {
+    background: `(${backgroundScript})(${checkGetImpl})`,
+    manifest: {
+      permissions: ["storage"],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  extension.sendMessage(`test-${testAreaName}`);
+  await extension.awaitMessage("test-finished");
+
+  await extension.unload();
+}
+
+function test_storage_sync_requires_real_id() {
+  async function testFn() {
+    async function background() {
+      const EXCEPTION_MESSAGE =
+        "The storage API is not available with a temporary addon ID. " +
+        "Please add an explicit addon ID to your manifest. " +
+        "For more information see https://mzl.la/3lPk1aE.";
+
+      await browser.test.assertRejects(
+        browser.storage.sync.set({ foo: "bar" }),
+        EXCEPTION_MESSAGE
+      );
+
+      browser.test.notifyPass("exception correct");
+    }
+
+    let extensionData = {
+      background,
+      manifest: {
+        permissions: ["storage"],
+      },
+      useAddonManager: "temporary",
+    };
+
+    let extension = ExtensionTestUtils.loadExtension(extensionData);
+    await extension.startup();
+    await extension.awaitFinish("exception correct");
+
+    await extension.unload();
+  }
+
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], testFn);
+}
+
+// Test for storage areas which don't support getBytesInUse() nor QUOTA
+// constants.
+async function check_storage_area_no_bytes_in_use(area) {
+  let impl = browser.storage[area];
+
+  browser.test.assertEq(
+    typeof impl.getBytesInUse,
+    "undefined",
+    "getBytesInUse API method should not be available"
+  );
+  browser.test.sendMessage("test-complete");
+}
+
+async function test_background_storage_area_no_bytes_in_use(area) {
+  const EXT_ID = "test-gbiu@mozilla.org";
+
+  const extensionDef = {
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: EXT_ID } },
+    },
+    background: `(${check_storage_area_no_bytes_in_use})("${area}")`,
+  };
+
+  const extension = ExtensionTestUtils.loadExtension(extensionDef);
+
+  await extension.startup();
+  await extension.awaitMessage("test-complete");
+  await extension.unload();
+}
+
+async function test_contentscript_storage_area_no_bytes_in_use(area) {
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  function contentScript(checkImpl) {
+    browser.test.onMessage.addListener(msg => {
+      if (msg === "test-local") {
+        checkImpl("local");
+      } else if (msg === "test-sync") {
+        checkImpl("sync");
+      } else {
+        browser.test.fail(`Unexpected test message received: ${msg}`);
+        browser.test.sendMessage("test-complete");
+      }
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+
+      permissions: ["storage"],
+    },
+
+    files: {
+      "content_script.js": `(${contentScript})(${check_storage_area_no_bytes_in_use})`,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  extension.sendMessage(`test-${area}`);
+  await extension.awaitMessage("test-complete");
+
+  await extension.unload();
+  await contentPage.close();
+}
+
+// Test for storage areas which do support getBytesInUse() (but which may or may
+// not support enforcement of the quota)
+async function check_storage_area_with_bytes_in_use(area, expectQuota) {
+  let impl = browser.storage[area];
+
+  // QUOTA_* constants aren't currently exposed - see bug 1396810.
+  // However, the quotas are still enforced, so test them here.
+  // (Note that an implication of this is that we can't test area other than
+  // 'sync', because its limits are different - so for completeness...)
+  browser.test.assertEq(
+    area,
+    "sync",
+    "Running test on storage.sync API as expected"
+  );
+  const QUOTA_BYTES_PER_ITEM = 8192;
+  const MAX_ITEMS = 512;
+
+  // bytes is counted as "length of key as a string, length of value as
+  // JSON" - ie, quotes not counted in the key, but are in the value.
+  let value = "x".repeat(QUOTA_BYTES_PER_ITEM - 3);
+
+  await impl.set({ x: value }); // Shouldn't reject on either kinto or rust-based storage.sync.
+  browser.test.assertEq(await impl.getBytesInUse(null), QUOTA_BYTES_PER_ITEM);
+  // kinto does implement getBytesInUse() but doesn't enforce a quota.
+  if (expectQuota) {
+    await browser.test.assertRejects(
+      impl.set({ x: value + "x" }),
+      /QuotaExceededError/,
+      "Got a rejection with the expected error message"
+    );
+    // MAX_ITEMS
+    await impl.clear();
+    let ob = {};
+    for (let i = 0; i < MAX_ITEMS; i++) {
+      ob[`key-${i}`] = "x";
+    }
+    await impl.set(ob); // should work.
+    await browser.test.assertRejects(
+      impl.set({ straw: "camel's back" }), // exceeds MAX_ITEMS
+      /QuotaExceededError/,
+      "Got a rejection with the expected error message"
+    );
+    // QUOTA_BYTES is being already tested for the underlying StorageSyncService
+    // so we don't duplicate those tests here.
+  } else {
+    // Exceeding quota should work on the previous kinto-based storage.sync implementation
+    await impl.set({ x: value + "x" }); // exceeds quota but should work.
+    browser.test.assertEq(
+      await impl.getBytesInUse(null),
+      QUOTA_BYTES_PER_ITEM + 1,
+      "Got the expected result from getBytesInUse"
+    );
+  }
+  browser.test.sendMessage("test-complete");
+}
+
+async function test_background_storage_area_with_bytes_in_use(
+  area,
+  expectQuota
+) {
+  const EXT_ID = "test-gbiu@mozilla.org";
+
+  const extensionDef = {
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: EXT_ID } },
+    },
+    background: `(${check_storage_area_with_bytes_in_use})("${area}", ${expectQuota})`,
+  };
+
+  const extension = ExtensionTestUtils.loadExtension(extensionDef);
+
+  await extension.startup();
+  await extension.awaitMessage("test-complete");
+  await extension.unload();
+}
+
+async function test_contentscript_storage_area_with_bytes_in_use(
+  area,
+  expectQuota
+) {
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  function contentScript(checkImpl) {
+    browser.test.onMessage.addListener(([area, expectQuota]) => {
+      if (
+        !["local", "sync"].includes(area) ||
+        typeof expectQuota !== "boolean"
+      ) {
+        browser.test.fail(`Unexpected test message: [${area}, ${expectQuota}]`);
+        // Let the test to fail immediately instead of wait for a timeout failure.
+        browser.test.sendMessage("test-complete");
+        return;
+      }
+      checkImpl(area, expectQuota);
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+
+      permissions: ["storage"],
+    },
+
+    files: {
+      "content_script.js": `(${contentScript})(${check_storage_area_with_bytes_in_use})`,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  extension.sendMessage([area, expectQuota]);
+  await extension.awaitMessage("test-complete");
+
+  await extension.unload();
+  await contentPage.close();
+}
+
+// A couple of common tests for checking content scripts.
+async function testStorageContentScript(checkGet) {
+  let globalChanges, gResolve;
+  function clearGlobalChanges() {
+    globalChanges = new Promise(resolve => {
+      gResolve = resolve;
+    });
+  }
+  clearGlobalChanges();
+  let expectedAreaName;
+
+  browser.storage.onChanged.addListener((changes, areaName) => {
+    browser.test.assertEq(
+      expectedAreaName,
+      areaName,
+      "Expected area name received by listener"
+    );
+    gResolve(changes);
+  });
+
+  async function checkChanges(areaName, changes, message) {
+    function checkSub(obj1, obj2) {
+      for (let prop in obj1) {
+        browser.test.assertTrue(
+          obj1[prop] !== undefined,
+          `checkChanges ${areaName} ${prop} is missing (${message})`
+        );
+        browser.test.assertTrue(
+          obj2[prop] !== undefined,
+          `checkChanges ${areaName} ${prop} is missing (${message})`
+        );
+        browser.test.assertEq(
+          obj1[prop].oldValue,
+          obj2[prop].oldValue,
+          `checkChanges ${areaName} ${prop} old (${message})`
+        );
+        browser.test.assertEq(
+          obj1[prop].newValue,
+          obj2[prop].newValue,
+          `checkChanges ${areaName} ${prop} new (${message})`
+        );
+      }
+    }
+
+    const recentChanges = await globalChanges;
+    checkSub(changes, recentChanges);
+    checkSub(recentChanges, changes);
+    clearGlobalChanges();
+  }
+
+  /* eslint-disable dot-notation */
+  async function runTests(areaName) {
+    expectedAreaName = areaName;
+    let storage = browser.storage[areaName];
+    // Set some data and then test getters.
+    try {
+      await storage.set({ "test-prop1": "value1", "test-prop2": "value2" });
+      await checkChanges(
+        areaName,
+        {
+          "test-prop1": { newValue: "value1" },
+          "test-prop2": { newValue: "value2" },
+        },
+        "set (a)"
+      );
+
+      await checkGet(areaName, "test-prop1", "value1");
+      await checkGet(areaName, "test-prop2", "value2");
+
+      let data = await storage.get({
+        "test-prop1": undefined,
+        "test-prop2": undefined,
+        other: "default",
+      });
+      browser.test.assertEq("value1", data["test-prop1"], "prop1 correct (a)");
+      browser.test.assertEq("value2", data["test-prop2"], "prop2 correct (a)");
+      browser.test.assertEq("default", data["other"], "other correct");
+
+      data = await storage.get(["test-prop1", "test-prop2", "other"]);
+      browser.test.assertEq("value1", data["test-prop1"], "prop1 correct (b)");
+      browser.test.assertEq("value2", data["test-prop2"], "prop2 correct (b)");
+      browser.test.assertFalse("other" in data, "other correct");
+
+      // Remove data in various ways.
+      await storage.remove("test-prop1");
+      await checkChanges(
+        areaName,
+        { "test-prop1": { oldValue: "value1" } },
+        "remove string"
+      );
+
+      data = await storage.get(["test-prop1", "test-prop2"]);
+      browser.test.assertFalse(
+        "test-prop1" in data,
+        "prop1 absent (remove string)"
+      );
+      browser.test.assertTrue(
+        "test-prop2" in data,
+        "prop2 present (remove string)"
+      );
+
+      await storage.set({ "test-prop1": "value1" });
+      await checkChanges(
+        areaName,
+        { "test-prop1": { newValue: "value1" } },
+        "set (c)"
+      );
+
+      data = await storage.get(["test-prop1", "test-prop2"]);
+      browser.test.assertEq(data["test-prop1"], "value1", "prop1 correct (c)");
+      browser.test.assertEq(data["test-prop2"], "value2", "prop2 correct (c)");
+
+      await storage.remove(["test-prop1", "test-prop2"]);
+      await checkChanges(
+        areaName,
+        {
+          "test-prop1": { oldValue: "value1" },
+          "test-prop2": { oldValue: "value2" },
+        },
+        "remove array"
+      );
+
+      data = await storage.get(["test-prop1", "test-prop2"]);
+      browser.test.assertFalse(
+        "test-prop1" in data,
+        "prop1 absent (remove array)"
+      );
+      browser.test.assertFalse(
+        "test-prop2" in data,
+        "prop2 absent (remove array)"
+      );
+
+      // test storage.clear
+      await storage.set({ "test-prop1": "value1", "test-prop2": "value2" });
+      // Make sure that set() handler happened before we clear the
+      // promise again.
+      await globalChanges;
+
+      clearGlobalChanges();
+      await storage.clear();
+
+      await checkChanges(
+        areaName,
+        {
+          "test-prop1": { oldValue: "value1" },
+          "test-prop2": { oldValue: "value2" },
+        },
+        "clear"
+      );
+      data = await storage.get(["test-prop1", "test-prop2"]);
+      browser.test.assertFalse("test-prop1" in data, "prop1 absent (clear)");
+      browser.test.assertFalse("test-prop2" in data, "prop2 absent (clear)");
+
+      // Make sure we can store complex JSON data.
+      // known previous values
+      await storage.set({ "test-prop1": "value1", "test-prop2": "value2" });
+
+      // Make sure the set() handler landed.
+      await globalChanges;
+
+      let date = new Date(0);
+
+      clearGlobalChanges();
+      await storage.set({
+        "test-prop1": {
+          str: "hello",
+          bool: true,
+          null: null,
+          undef: undefined,
+          obj: {},
+          arr: [1, 2],
+          date: new Date(0),
+          regexp: /regexp/,
+        },
+      });
+
+      await browser.test.assertRejects(
+        storage.set({
+          window,
+        }),
+        /DataCloneError|cyclic object value/
+      );
+
+      await browser.test.assertRejects(
+        storage.set({ "test-prop2": function func() {} }),
+        /DataCloneError/
+      );
+
+      const recentChanges = await globalChanges;
+
+      browser.test.assertEq(
+        "value1",
+        recentChanges["test-prop1"].oldValue,
+        "oldValue correct"
+      );
+      browser.test.assertEq(
+        "object",
+        typeof recentChanges["test-prop1"].newValue,
+        "newValue is obj"
+      );
+      clearGlobalChanges();
+
+      data = await storage.get({
+        "test-prop1": undefined,
+        "test-prop2": undefined,
+      });
+      let obj = data["test-prop1"];
+
+      if (areaName === "local") {
+        browser.test.assertEq(
+          String(date),
+          String(obj.date),
+          "date part correct"
+        );
+        browser.test.assertEq(
+          "/regexp/",
+          obj.regexp.toString(),
+          "regexp part correct"
+        );
+      } else {
+        browser.test.assertEq(
+          "1970-01-01T00:00:00.000Z",
+          String(obj.date),
+          "date part correct"
+        );
+
+        browser.test.assertEq(
+          "object",
+          typeof obj.regexp,
+          "regexp part is an object"
+        );
+        browser.test.assertEq(
+          0,
+          Object.keys(obj.regexp).length,
+          "regexp part is an empty object"
+        );
+      }
+
+      browser.test.assertEq("hello", obj.str, "string part correct");
+      browser.test.assertEq(true, obj.bool, "bool part correct");
+      browser.test.assertEq(null, obj.null, "null part correct");
+      browser.test.assertEq(undefined, obj.undef, "undefined part correct");
+      browser.test.assertEq(undefined, obj.window, "window part correct");
+      browser.test.assertEq("object", typeof obj.obj, "object part correct");
+      browser.test.assertTrue(Array.isArray(obj.arr), "array part present");
+      browser.test.assertEq(1, obj.arr[0], "arr[0] part correct");
+      browser.test.assertEq(2, obj.arr[1], "arr[1] part correct");
+      browser.test.assertEq(2, obj.arr.length, "arr.length part correct");
+    } catch (e) {
+      browser.test.fail(`Error: ${e} :: ${e.stack}`);
+      browser.test.notifyFail("storage");
+    }
+  }
+
+  browser.test.onMessage.addListener(msg => {
+    let promise;
+    if (msg === "test-local") {
+      promise = runTests("local");
+    } else if (msg === "test-sync") {
+      promise = runTests("sync");
+    }
+    promise.then(() => browser.test.sendMessage("test-finished"));
+  });
+
+  browser.test.sendMessage("ready");
+}
+
+async function test_contentscript_storage(storageType) {
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+
+      permissions: ["storage"],
+    },
+
+    files: {
+      "content_script.js": `(${testStorageContentScript})(${checkGetImpl})`,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  extension.sendMessage(`test-${storageType}`);
+  await extension.awaitMessage("test-finished");
+
+  await extension.unload();
+  await contentPage.close();
+}
diff --git a/toolkit/components/extensions/test/xpcshell/head_sync.js b/toolkit/components/extensions/test/xpcshell/head_sync.js
new file mode 100644
index 0000000000..691743c696
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head_sync.js
@@ -0,0 +1,65 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/* exported withSyncContext */
+
+ChromeUtils.import("resource://gre/modules/Services.jsm", this);
+ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm", this);
+
+class KintoExtContext extends ExtensionCommon.BaseContext {
+  constructor(principal) {
+    super();
+    Object.defineProperty(this, "principal", {
+      value: principal,
+      configurable: true,
+    });
+    this.sandbox = Cu.Sandbox(principal, { wantXrays: false });
+    this.extension = { id: "test@web.extension" };
+  }
+
+  get cloneScope() {
+    return this.sandbox;
+  }
+}
+
+/**
+ * Call the given function with a newly-constructed context.
+ * Unload the context on the way out.
+ *
+ * @param {function} f    the function to call
+ */
+async function withContext(f) {
+  const ssm = Services.scriptSecurityManager;
+  const PRINCIPAL1 = ssm.createContentPrincipalFromOrigin(
+    "http://www.example.org"
+  );
+  const context = new KintoExtContext(PRINCIPAL1);
+  try {
+    await f(context);
+  } finally {
+    await context.unload();
+  }
+}
+
+/**
+ * Like withContext(), but also turn on the "storage.sync" pref for
+ * the duration of the function.
+ * Calls to this function can be replaced with calls to withContext
+ * once the pref becomes on by default.
+ *
+ * @param {function} f    the function to call
+ */
+async function withSyncContext(f) {
+  const STORAGE_SYNC_PREF = "webextensions.storage.sync.enabled";
+  let prefs = Services.prefs;
+
+  try {
+    prefs.setBoolPref(STORAGE_SYNC_PREF, true);
+    await withContext(f);
+  } finally {
+    prefs.clearUserPref(STORAGE_SYNC_PREF);
+  }
+}
diff --git a/toolkit/components/extensions/test/xpcshell/head_telemetry.js b/toolkit/components/extensions/test/xpcshell/head_telemetry.js
new file mode 100644
index 0000000000..6492d8f995
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/head_telemetry.js
@@ -0,0 +1,110 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* exported IS_OOP, valueSum, clearHistograms, getSnapshots, promiseTelemetryRecorded */
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ContentTaskUtils",
+  "resource://testing-common/ContentTaskUtils.jsm"
+);
+
+const IS_OOP = Services.prefs.getBoolPref("extensions.webextensions.remote");
+
+function valueSum(arr) {
+  return Object.values(arr).reduce((a, b) => a + b, 0);
+}
+
+function clearHistograms() {
+  Services.telemetry.getSnapshotForHistograms("main", true /* clear */);
+  Services.telemetry.getSnapshotForKeyedHistograms("main", true /* clear */);
+}
+
+function getSnapshots(process) {
+  return Services.telemetry.getSnapshotForHistograms("main", false /* clear */)[
+    process
+  ];
+}
+
+function getKeyedSnapshots(process) {
+  return Services.telemetry.getSnapshotForKeyedHistograms(
+    "main",
+    false /* clear */
+  )[process];
+}
+
+// TODO Bug 1357509: There is no good way to make sure that the parent received
+// the histogram entries from the extension and content processes.  Let's stick
+// to the ugly, spinning the event loop until we have a good approach.
+function promiseTelemetryRecorded(id, process, expectedCount) {
+  let condition = () => {
+    let snapshot = Services.telemetry.getSnapshotForHistograms(
+      "main",
+      false /* clear */
+    )[process][id];
+    return snapshot && valueSum(snapshot.values) >= expectedCount;
+  };
+  return ContentTaskUtils.waitForCondition(condition);
+}
+
+function promiseKeyedTelemetryRecorded(
+  id,
+  process,
+  expectedKey,
+  expectedCount
+) {
+  let condition = () => {
+    let snapshot = Services.telemetry.getSnapshotForKeyedHistograms(
+      "main",
+      false /* clear */
+    )[process][id];
+    return (
+      snapshot &&
+      snapshot[expectedKey] &&
+      valueSum(snapshot[expectedKey].values) >= expectedCount
+    );
+  };
+  return ContentTaskUtils.waitForCondition(condition);
+}
+
+function assertHistogramSnapshot(
+  histogramId,
+  { keyed, processSnapshot, expectedValue },
+  msg
+) {
+  let histogram;
+
+  if (keyed) {
+    histogram = Services.telemetry.getKeyedHistogramById(histogramId);
+  } else {
+    histogram = Services.telemetry.getHistogramById(histogramId);
+  }
+
+  let res = processSnapshot(histogram.snapshot());
+  Assert.deepEqual(res, expectedValue, msg);
+  return res;
+}
+
+function assertHistogramEmpty(histogramId) {
+  assertHistogramSnapshot(
+    histogramId,
+    {
+      processSnapshot: snapshot => snapshot.sum,
+      expectedValue: 0,
+    },
+    `No data recorded for histogram: ${histogramId}.`
+  );
+}
+
+function assertKeyedHistogramEmpty(histogramId) {
+  assertHistogramSnapshot(
+    histogramId,
+    {
+      keyed: true,
+      processSnapshot: snapshot => Object.keys(snapshot).length,
+      expectedValue: 0,
+    },
+    `No data recorded for histogram: ${histogramId}.`
+  );
+}
diff --git a/toolkit/components/extensions/test/xpcshell/native_messaging.ini b/toolkit/components/extensions/test/xpcshell/native_messaging.ini
new file mode 100644
index 0000000000..b64cda83c8
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/native_messaging.ini
@@ -0,0 +1,15 @@
+[DEFAULT]
+head = head.js head_e10s.js head_native_messaging.js
+tail =
+firefox-appdir = browser
+skip-if = appname == "thunderbird" || os == "android"
+subprocess = true
+support-files =
+  data/**
+tags = webextensions
+
+[test_ext_native_messaging.js]
+skip-if = (os == "win" && processor == "aarch64") # bug 1530841
+[test_ext_native_messaging_perf.js]
+skip-if = tsan # Unreasonably slow, bug 1612707
+[test_ext_native_messaging_unresponsive.js]
diff --git a/toolkit/components/extensions/test/xpcshell/test_ExtensionStorageSync_migration_kinto.js b/toolkit/components/extensions/test/xpcshell/test_ExtensionStorageSync_migration_kinto.js
new file mode 100644
index 0000000000..ad763cb321
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ExtensionStorageSync_migration_kinto.js
@@ -0,0 +1,86 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+// Import the rust-based and kinto-based implementations
+const { extensionStorageSync: rustImpl } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageSync.jsm"
+);
+const { extensionStorageSync: kintoImpl } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageSyncKinto.jsm"
+);
+
+Services.prefs.setBoolPref("webextensions.storage.sync.kinto", false);
+
+add_task(async function test_sync_migration() {
+  // There's no good reason to perform this test via test extensions - we just
+  // call the underlying APIs directly.
+
+  // Set some stuff using the kinto-based impl.
+  let e1 = { id: "test@mozilla.com" };
+  let c1 = { extension: e1, callOnClose() {} };
+  await kintoImpl.set(e1, { foo: "bar" }, c1);
+
+  let e2 = { id: "test-2@mozilla.com" };
+  let c2 = { extension: e2, callOnClose() {} };
+  await kintoImpl.set(e2, { second: "2nd" }, c2);
+
+  let e3 = { id: "test-3@mozilla.com" };
+  let c3 = { extension: e3, callOnClose() {} };
+
+  // And all the data should be magically migrated.
+  Assert.deepEqual(await rustImpl.get(e1, "foo", c1), { foo: "bar" });
+  Assert.deepEqual(await rustImpl.get(e2, null, c2), { second: "2nd" });
+
+  // Sanity check we really are doing what we think we are - set a value in our
+  // new one, it should not be reflected by kinto.
+  await rustImpl.set(e3, { third: "3rd" }, c3);
+  Assert.deepEqual(await rustImpl.get(e3, null, c3), { third: "3rd" });
+  Assert.deepEqual(await kintoImpl.get(e3, null, c3), {});
+  // cleanup.
+  await kintoImpl.clear(e1, c1);
+  await kintoImpl.clear(e2, c2);
+  await kintoImpl.clear(e3, c3);
+  await rustImpl.clear(e1, c1);
+  await rustImpl.clear(e2, c2);
+  await rustImpl.clear(e3, c3);
+});
+
+// It would be great to have failure tests, but that seems impossible to have
+// in automated tests given the conditions under which we migrate - it would
+// basically require us to arrange for zero free disk space or to somehow
+// arrange for sqlite to see an io error. Specially crafted "corrupt"
+// sqlite files doesn't help because that file must not exist for us to even
+// attempt migration.
+//
+// But - what we can test is that if .migratedOk on the new impl ever goes to
+// false we delegate correctly.
+add_task(async function test_sync_migration_delgates() {
+  let e1 = { id: "test@mozilla.com" };
+  let c1 = { extension: e1, callOnClose() {} };
+  await kintoImpl.set(e1, { foo: "bar" }, c1);
+
+  // We think migration went OK - `get` shouldn't see kinto.
+  Assert.deepEqual(rustImpl.get(e1, null, c1), {});
+
+  info(
+    "Setting migration failure flag to ensure we delegate to kinto implementation"
+  );
+  rustImpl.migrationOk = false;
+  // get should now be seeing kinto.
+  Assert.deepEqual(await rustImpl.get(e1, null, c1), { foo: "bar" });
+  // check everything else delegates.
+
+  await rustImpl.set(e1, { foo: "foo" }, c1);
+  Assert.deepEqual(await kintoImpl.get(e1, null, c1), { foo: "foo" });
+
+  Assert.equal(await rustImpl.getBytesInUse(e1, null, c1), 8);
+
+  await rustImpl.remove(e1, "foo", c1);
+  Assert.deepEqual(await kintoImpl.get(e1, null, c1), {});
+
+  await rustImpl.set(e1, { foo: "foo" }, c1);
+  Assert.deepEqual(await kintoImpl.get(e1, null, c1), { foo: "foo" });
+  await rustImpl.clear(e1, c1);
+  Assert.deepEqual(await kintoImpl.get(e1, null, c1), {});
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_MatchPattern.js b/toolkit/components/extensions/test/xpcshell/test_MatchPattern.js
new file mode 100644
index 0000000000..c0aa4254ad
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_MatchPattern.js
@@ -0,0 +1,552 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_MatchPattern_matches() {
+  function test(url, pattern, normalized = pattern, options = {}, explicit) {
+    let uri = Services.io.newURI(url);
+
+    pattern = Array.prototype.concat.call(pattern);
+    normalized = Array.prototype.concat.call(normalized);
+
+    let patterns = pattern.map(pat => new MatchPattern(pat, options));
+
+    let set = new MatchPatternSet(pattern, options);
+    let set2 = new MatchPatternSet(patterns, options);
+
+    deepEqual(
+      set2.patterns,
+      patterns,
+      "Patterns in set should equal the input patterns"
+    );
+
+    equal(
+      set.matches(uri, explicit),
+      set2.matches(uri, explicit),
+      "Single pattern and pattern set should return the same match"
+    );
+
+    for (let [i, pat] of patterns.entries()) {
+      equal(
+        pat.pattern,
+        normalized[i],
+        "Pattern property should contain correct normalized pattern value"
+      );
+    }
+
+    if (patterns.length == 1) {
+      equal(
+        patterns[0].matches(uri, explicit),
+        set.matches(uri, explicit),
+        "Single pattern and string set should return the same match"
+      );
+    }
+
+    return set.matches(uri, explicit);
+  }
+
+  function pass({ url, pattern, normalized, options, explicit }) {
+    ok(
+      test(url, pattern, normalized, options, explicit),
+      `Expected match: ${JSON.stringify(pattern)}, ${url}`
+    );
+  }
+
+  function fail({ url, pattern, normalized, options, explicit }) {
+    ok(
+      !test(url, pattern, normalized, options, explicit),
+      `Expected no match: ${JSON.stringify(pattern)}, ${url}`
+    );
+  }
+
+  function invalid({ pattern }) {
+    Assert.throws(
+      () => new MatchPattern(pattern),
+      /.*/,
+      `Invalid pattern '${pattern}' should throw`
+    );
+    Assert.throws(
+      () => new MatchPatternSet([pattern]),
+      /.*/,
+      `Invalid pattern '${pattern}' should throw`
+    );
+  }
+
+  // Invalid pattern.
+  invalid({ pattern: "" });
+
+  // Pattern must include trailing slash.
+  invalid({ pattern: "http://mozilla.org" });
+
+  // Protocol not allowed.
+  invalid({ pattern: "gopher://wuarchive.wustl.edu/" });
+
+  pass({ url: "http://mozilla.org", pattern: "http://mozilla.org/" });
+  pass({ url: "http://mozilla.org/", pattern: "http://mozilla.org/" });
+
+  pass({ url: "http://mozilla.org/", pattern: "*://mozilla.org/" });
+  pass({ url: "https://mozilla.org/", pattern: "*://mozilla.org/" });
+  fail({ url: "file://mozilla.org/", pattern: "*://mozilla.org/" });
+  fail({ url: "ftp://mozilla.org/", pattern: "*://mozilla.org/" });
+
+  fail({ url: "http://mozilla.com", pattern: "http://*mozilla.com*/" });
+  fail({ url: "http://mozilla.com", pattern: "http://mozilla.*/" });
+  invalid({ pattern: "http:/mozilla.com/" });
+
+  pass({ url: "http://google.com", pattern: "http://*.google.com/" });
+  pass({ url: "http://docs.google.com", pattern: "http://*.google.com/" });
+
+  pass({ url: "http://mozilla.org:8080", pattern: "http://mozilla.org/" });
+  pass({ url: "http://mozilla.org:8080", pattern: "*://mozilla.org/" });
+  fail({ url: "http://mozilla.org:8080", pattern: "http://mozilla.org:8080/" });
+
+  // Now try with * in the path.
+  pass({ url: "http://mozilla.org", pattern: "http://mozilla.org/*" });
+  pass({ url: "http://mozilla.org/", pattern: "http://mozilla.org/*" });
+
+  pass({ url: "http://mozilla.org/", pattern: "*://mozilla.org/*" });
+  pass({ url: "https://mozilla.org/", pattern: "*://mozilla.org/*" });
+  fail({ url: "file://mozilla.org/", pattern: "*://mozilla.org/*" });
+  fail({ url: "http://mozilla.com", pattern: "http://mozilla.*/*" });
+
+  pass({ url: "http://google.com", pattern: "http://*.google.com/*" });
+  pass({ url: "http://docs.google.com", pattern: "http://*.google.com/*" });
+
+  // Check path stuff.
+  fail({ url: "http://mozilla.com/abc/def", pattern: "http://mozilla.com/" });
+  pass({ url: "http://mozilla.com/abc/def", pattern: "http://mozilla.com/*" });
+  pass({
+    url: "http://mozilla.com/abc/def",
+    pattern: "http://mozilla.com/a*f",
+  });
+  pass({ url: "http://mozilla.com/abc/def", pattern: "http://mozilla.com/a*" });
+  pass({ url: "http://mozilla.com/abc/def", pattern: "http://mozilla.com/*f" });
+  fail({ url: "http://mozilla.com/abc/def", pattern: "http://mozilla.com/*e" });
+  fail({ url: "http://mozilla.com/abc/def", pattern: "http://mozilla.com/*c" });
+
+  invalid({ pattern: "http:///a.html" });
+  pass({ url: "file:///foo", pattern: "file:///foo*" });
+  pass({ url: "file:///foo/bar.html", pattern: "file:///foo*" });
+
+  pass({ url: "http://mozilla.org/a", pattern: "<all_urls>" });
+  pass({ url: "https://mozilla.org/a", pattern: "<all_urls>" });
+  pass({ url: "ftp://mozilla.org/a", pattern: "<all_urls>" });
+  pass({ url: "file:///a", pattern: "<all_urls>" });
+  fail({ url: "gopher://wuarchive.wustl.edu/a", pattern: "<all_urls>" });
+
+  // Multiple patterns.
+  pass({ url: "http://mozilla.org", pattern: ["http://mozilla.org/"] });
+  pass({
+    url: "http://mozilla.org",
+    pattern: ["http://mozilla.org/", "http://mozilla.com/"],
+  });
+  pass({
+    url: "http://mozilla.com",
+    pattern: ["http://mozilla.org/", "http://mozilla.com/"],
+  });
+  fail({
+    url: "http://mozilla.biz",
+    pattern: ["http://mozilla.org/", "http://mozilla.com/"],
+  });
+
+  // Match url with fragments.
+  pass({
+    url: "http://mozilla.org/base#some-fragment",
+    pattern: "http://mozilla.org/base",
+  });
+
+  // Match data:-URLs.
+  pass({ url: "data:text/plain,foo", pattern: ["data:text/plain,foo"] });
+  pass({ url: "data:text/plain,foo", pattern: ["data:text/plain,*"] });
+  pass({
+    url: "data:text/plain;charset=utf-8,foo",
+    pattern: ["data:text/plain;charset=utf-8,foo"],
+  });
+  fail({
+    url: "data:text/plain,foo",
+    pattern: ["data:text/plain;charset=utf-8,foo"],
+  });
+  fail({
+    url: "data:text/plain;charset=utf-8,foo",
+    pattern: ["data:text/plain,foo"],
+  });
+
+  // Privileged matchers:
+  invalid({ pattern: "about:foo" });
+  invalid({ pattern: "resource://foo/*" });
+
+  pass({
+    url: "about:foo",
+    pattern: ["about:foo", "about:foo*"],
+    options: { restrictSchemes: false },
+  });
+  pass({
+    url: "about:foo",
+    pattern: ["about:foo*"],
+    options: { restrictSchemes: false },
+  });
+  pass({
+    url: "about:foobar",
+    pattern: ["about:foo*"],
+    options: { restrictSchemes: false },
+  });
+
+  pass({
+    url: "resource://foo/bar",
+    pattern: ["resource://foo/bar"],
+    options: { restrictSchemes: false },
+  });
+  fail({
+    url: "resource://fog/bar",
+    pattern: ["resource://foo/bar"],
+    options: { restrictSchemes: false },
+  });
+  fail({
+    url: "about:foo",
+    pattern: ["about:meh"],
+    options: { restrictSchemes: false },
+  });
+
+  // Matchers for schemes without host should ignore ignorePath.
+  pass({
+    url: "about:reader?http://e.com/",
+    pattern: ["about:reader*"],
+    options: { ignorePath: true, restrictSchemes: false },
+  });
+  pass({ url: "data:,", pattern: ["data:,*"], options: { ignorePath: true } });
+
+  // Matchers for schems without host should still match even if the explicit (host) flag is set.
+  pass({
+    url: "about:reader?explicit",
+    pattern: ["about:reader*"],
+    options: { restrictSchemes: false },
+    explicit: true,
+  });
+  pass({
+    url: "about:reader?explicit",
+    pattern: ["about:reader?explicit"],
+    options: { restrictSchemes: false },
+    explicit: true,
+  });
+  pass({ url: "data:,explicit", pattern: ["data:,explicit"], explicit: true });
+  pass({ url: "data:,explicit", pattern: ["data:,*"], explicit: true });
+
+  // Matchers without "//" separator in the pattern.
+  pass({ url: "data:text/plain;charset=utf-8,foo", pattern: ["data:*"] });
+  pass({
+    url: "about:blank",
+    pattern: ["about:*"],
+    options: { restrictSchemes: false },
+  });
+  pass({
+    url: "view-source:https://example.com",
+    pattern: ["view-source:*"],
+    options: { restrictSchemes: false },
+  });
+  invalid({ pattern: ["chrome:*"], options: { restrictSchemes: false } });
+  invalid({ pattern: "http:*" });
+
+  // Matchers for unrecognized schemes.
+  invalid({ pattern: "unknown-scheme:*" });
+  pass({
+    url: "unknown-scheme:foo",
+    pattern: ["unknown-scheme:foo"],
+    options: { restrictSchemes: false },
+  });
+  pass({
+    url: "unknown-scheme:foo",
+    pattern: ["unknown-scheme:*"],
+    options: { restrictSchemes: false },
+  });
+  pass({
+    url: "unknown-scheme://foo",
+    pattern: ["unknown-scheme://foo"],
+    options: { restrictSchemes: false },
+  });
+  pass({
+    url: "unknown-scheme://foo",
+    pattern: ["unknown-scheme://*"],
+    options: { restrictSchemes: false },
+  });
+  pass({
+    url: "unknown-scheme://foo",
+    pattern: ["unknown-scheme:*"],
+    options: { restrictSchemes: false },
+  });
+  fail({
+    url: "unknown-scheme://foo",
+    pattern: ["unknown-scheme:foo"],
+    options: { restrictSchemes: false },
+  });
+  fail({
+    url: "unknown-scheme:foo",
+    pattern: ["unknown-scheme://foo"],
+    options: { restrictSchemes: false },
+  });
+  fail({
+    url: "unknown-scheme:foo",
+    pattern: ["unknown-scheme://*"],
+    options: { restrictSchemes: false },
+  });
+
+  // Matchers for IPv6
+  pass({ url: "http://[::1]/", pattern: ["http://[::1]/"] });
+  pass({
+    url: "http://[2a03:4000:6:310e:216:3eff:fe53:99b]/",
+    pattern: ["http://[2a03:4000:6:310e:216:3eff:fe53:99b]/"],
+  });
+  fail({
+    url: "http://[2:4:6:3:2:3:f:b]/",
+    pattern: ["http://[2a03:4000:6:310e:216:3eff:fe53:99b]/"],
+  });
+
+  // Before fixing Bug 1529230, the only way to match a specific IPv6 url is by droping the brackets in pattern,
+  // thus we keep this pattern valid for the sake of backward compatibility
+  pass({ url: "http://[::1]/", pattern: ["http://::1/"] });
+  pass({
+    url: "http://[2a03:4000:6:310e:216:3eff:fe53:99b]/",
+    pattern: ["http://2a03:4000:6:310e:216:3eff:fe53:99b/"],
+  });
+});
+
+add_task(async function test_MatchPattern_overlaps() {
+  function test(filter, hosts, optional) {
+    filter = Array.prototype.concat.call(filter);
+    hosts = Array.prototype.concat.call(hosts);
+    optional = Array.prototype.concat.call(optional);
+
+    const set = new MatchPatternSet([...hosts, ...optional]);
+    const pat = new MatchPatternSet(filter);
+    return set.overlapsAll(pat);
+  }
+
+  function pass({ filter = [], hosts = [], optional = [] }) {
+    ok(
+      test(filter, hosts, optional),
+      `Expected overlap: ${filter}, ${hosts} (${optional})`
+    );
+  }
+
+  function fail({ filter = [], hosts = [], optional = [] }) {
+    ok(
+      !test(filter, hosts, optional),
+      `Expected no overlap: ${filter}, ${hosts} (${optional})`
+    );
+  }
+
+  // Direct comparison.
+  pass({ hosts: "http://ab.cd/", filter: "http://ab.cd/" });
+  fail({ hosts: "http://ab.cd/", filter: "ftp://ab.cd/" });
+
+  // Wildcard protocol.
+  pass({ hosts: "*://ab.cd/", filter: "https://ab.cd/" });
+  fail({ hosts: "*://ab.cd/", filter: "ftp://ab.cd/" });
+
+  // Wildcard subdomain.
+  pass({ hosts: "http://*.ab.cd/", filter: "http://ab.cd/" });
+  pass({ hosts: "http://*.ab.cd/", filter: "http://www.ab.cd/" });
+  fail({ hosts: "http://*.ab.cd/", filter: "http://ab.cd.ef/" });
+  fail({ hosts: "http://*.ab.cd/", filter: "http://www.cd/" });
+
+  // Wildcard subsumed.
+  pass({ hosts: "http://*.ab.cd/", filter: "http://*.cd/" });
+  fail({ hosts: "http://*.cd/", filter: "http://*.xy/" });
+
+  // Subdomain vs substring.
+  fail({ hosts: "http://*.ab.cd/", filter: "http://fake-ab.cd/" });
+  fail({ hosts: "http://*.ab.cd/", filter: "http://*.fake-ab.cd/" });
+
+  // Wildcard domain.
+  pass({ hosts: "http://*/", filter: "http://ab.cd/" });
+  fail({ hosts: "http://*/", filter: "https://ab.cd/" });
+
+  // Wildcard wildcards.
+  pass({ hosts: "<all_urls>", filter: "ftp://ab.cd/" });
+  fail({ hosts: "<all_urls>" });
+
+  // Multiple hosts.
+  pass({ hosts: ["http://ab.cd/"], filter: ["http://ab.cd/"] });
+  pass({ hosts: ["http://ab.cd/", "http://ab.xy/"], filter: "http://ab.cd/" });
+  pass({ hosts: ["http://ab.cd/", "http://ab.xy/"], filter: "http://ab.xy/" });
+  fail({ hosts: ["http://ab.cd/", "http://ab.xy/"], filter: "http://ab.zz/" });
+
+  // Multiple Multiples.
+  pass({
+    hosts: ["http://*.ab.cd/"],
+    filter: ["http://ab.cd/", "http://www.ab.cd/"],
+  });
+  pass({
+    hosts: ["http://ab.cd/", "http://ab.xy/"],
+    filter: ["http://ab.cd/", "http://ab.xy/"],
+  });
+  fail({
+    hosts: ["http://ab.cd/", "http://ab.xy/"],
+    filter: ["http://ab.cd/", "http://ab.zz/"],
+  });
+
+  // Optional.
+  pass({ hosts: [], optional: "http://ab.cd/", filter: "http://ab.cd/" });
+  pass({
+    hosts: "http://ab.cd/",
+    optional: "http://ab.xy/",
+    filter: ["http://ab.cd/", "http://ab.xy/"],
+  });
+  fail({
+    hosts: "http://ab.cd/",
+    optional: "https://ab.xy/",
+    filter: "http://ab.xy/",
+  });
+});
+
+add_task(async function test_MatchGlob() {
+  function test(url, pattern) {
+    let m = new MatchGlob(pattern[0]);
+    return m.matches(Services.io.newURI(url).spec);
+  }
+
+  function pass({ url, pattern }) {
+    ok(
+      test(url, pattern),
+      `Expected match: ${JSON.stringify(pattern)}, ${url}`
+    );
+  }
+
+  function fail({ url, pattern }) {
+    ok(
+      !test(url, pattern),
+      `Expected no match: ${JSON.stringify(pattern)}, ${url}`
+    );
+  }
+
+  let moz = "http://mozilla.org";
+
+  pass({ url: moz, pattern: ["*"] });
+  pass({ url: moz, pattern: ["http://*"] });
+  pass({ url: moz, pattern: ["*mozilla*"] });
+  // pass({url: moz, pattern: ["*example*", "*mozilla*"]});
+
+  pass({ url: moz, pattern: ["*://*"] });
+  pass({ url: "https://mozilla.org", pattern: ["*://*"] });
+
+  // Documentation example
+  pass({
+    url: "http://www.example.com/foo/bar",
+    pattern: ["http://???.example.com/foo/*"],
+  });
+  pass({
+    url: "http://the.example.com/foo/",
+    pattern: ["http://???.example.com/foo/*"],
+  });
+  fail({
+    url: "http://my.example.com/foo/bar",
+    pattern: ["http://???.example.com/foo/*"],
+  });
+  fail({
+    url: "http://example.com/foo/",
+    pattern: ["http://???.example.com/foo/*"],
+  });
+  fail({
+    url: "http://www.example.com/foo",
+    pattern: ["http://???.example.com/foo/*"],
+  });
+
+  // Matches path
+  let path = moz + "/abc/def";
+  pass({ url: path, pattern: ["*def"] });
+  pass({ url: path, pattern: ["*c/d*"] });
+  pass({ url: path, pattern: ["*org/abc*"] });
+  fail({ url: path + "/", pattern: ["*def"] });
+
+  // Trailing slash
+  pass({ url: moz, pattern: ["*.org/"] });
+  fail({ url: moz, pattern: ["*.org"] });
+
+  // Wrong TLD
+  fail({ url: moz, pattern: ["*oz*.com/"] });
+  // Case sensitive
+  fail({ url: moz, pattern: ["*.ORG/"] });
+});
+
+add_task(async function test_MatchPattern_subsumes() {
+  function test(oldPat, newPat) {
+    let m = new MatchPatternSet(oldPat);
+    return m.subsumes(new MatchPattern(newPat));
+  }
+
+  function pass({ oldPat, newPat }) {
+    ok(test(oldPat, newPat), `${JSON.stringify(oldPat)} subsumes "${newPat}"`);
+  }
+
+  function fail({ oldPat, newPat }) {
+    ok(
+      !test(oldPat, newPat),
+      `${JSON.stringify(oldPat)} doesn't subsume "${newPat}"`
+    );
+  }
+
+  pass({ oldPat: ["<all_urls>"], newPat: "*://*/*" });
+  pass({ oldPat: ["<all_urls>"], newPat: "http://*/*" });
+  pass({ oldPat: ["<all_urls>"], newPat: "http://*.example.com/*" });
+
+  pass({ oldPat: ["*://*/*"], newPat: "http://*/*" });
+  pass({ oldPat: ["*://*/*"], newPat: "wss://*/*" });
+  pass({ oldPat: ["*://*/*"], newPat: "http://*.example.com/*" });
+
+  pass({ oldPat: ["*://*.example.com/*"], newPat: "http://*.example.com/*" });
+  pass({ oldPat: ["*://*.example.com/*"], newPat: "*://sub.example.com/*" });
+
+  pass({ oldPat: ["https://*/*"], newPat: "https://*.example.com/*" });
+  pass({
+    oldPat: ["http://*.example.com/*"],
+    newPat: "http://subdomain.example.com/*",
+  });
+  pass({
+    oldPat: ["http://*.sub.example.com/*"],
+    newPat: "http://sub.example.com/*",
+  });
+  pass({
+    oldPat: ["http://*.sub.example.com/*"],
+    newPat: "http://sec.sub.example.com/*",
+  });
+  pass({
+    oldPat: ["http://www.example.com/*"],
+    newPat: "http://www.example.com/path/*",
+  });
+  pass({
+    oldPat: ["http://www.example.com/path/*"],
+    newPat: "http://www.example.com/*",
+  });
+
+  fail({ oldPat: ["*://*/*"], newPat: "<all_urls>" });
+  fail({ oldPat: ["*://*/*"], newPat: "ftp://*/*" });
+  fail({ oldPat: ["*://*/*"], newPat: "file://*/*" });
+
+  fail({ oldPat: ["http://example.com/*"], newPat: "*://example.com/*" });
+  fail({ oldPat: ["http://example.com/*"], newPat: "https://example.com/*" });
+  fail({
+    oldPat: ["http://example.com/*"],
+    newPat: "http://otherexample.com/*",
+  });
+  fail({ oldPat: ["http://example.com/*"], newPat: "http://*.example.com/*" });
+  fail({
+    oldPat: ["http://example.com/*"],
+    newPat: "http://subdomain.example.com/*",
+  });
+
+  fail({
+    oldPat: ["http://subdomain.example.com/*"],
+    newPat: "http://example.com/*",
+  });
+  fail({
+    oldPat: ["http://subdomain.example.com/*"],
+    newPat: "http://*.example.com/*",
+  });
+  fail({
+    oldPat: ["http://sub.example.com/*"],
+    newPat: "http://*.sub.example.com/*",
+  });
+
+  fail({ oldPat: ["ws://example.com/*"], newPat: "wss://example.com/*" });
+  fail({ oldPat: ["http://example.com/*"], newPat: "ws://example.com/*" });
+  fail({ oldPat: ["https://example.com/*"], newPat: "wss://example.com/*" });
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_StorageSyncService.js b/toolkit/components/extensions/test/xpcshell/test_StorageSyncService.js
new file mode 100644
index 0000000000..8b627a0ee9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_StorageSyncService.js
@@ -0,0 +1,286 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const NS_ERROR_DOM_QUOTA_EXCEEDED_ERR = 0x80530016;
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "StorageSyncService",
+  "@mozilla.org/extensions/storage/sync;1",
+  "nsIInterfaceRequestor"
+);
+
+function promisify(func, ...params) {
+  return new Promise((resolve, reject) => {
+    let changes = [];
+    func(...params, {
+      QueryInterface: ChromeUtils.generateQI([
+        "mozIExtensionStorageListener",
+        "mozIExtensionStorageCallback",
+        "mozIBridgedSyncEngineCallback",
+        "mozIBridgedSyncEngineApplyCallback",
+      ]),
+      onChanged(extId, json) {
+        changes.push({ extId, changes: JSON.parse(json) });
+      },
+      handleSuccess(value) {
+        resolve({
+          changes,
+          value: typeof value == "string" ? JSON.parse(value) : value,
+        });
+      },
+      handleError(code, message) {
+        reject(Components.Exception(message, code));
+      },
+    });
+  });
+}
+
+add_task(async function setup_storage_sync() {
+  // So that we can write to the profile directory.
+  do_get_profile();
+});
+
+add_task(async function test_storage_sync_service() {
+  const service = StorageSyncService.getInterface(Ci.mozIExtensionStorageArea);
+  {
+    let { changes, value } = await promisify(
+      service.set,
+      "ext-1",
+      JSON.stringify({
+        hi: "hello! 💖",
+        bye: "adiós",
+      })
+    );
+    deepEqual(
+      changes,
+      [
+        {
+          extId: "ext-1",
+          changes: {
+            hi: {
+              newValue: "hello! 💖",
+            },
+            bye: {
+              newValue: "adiós",
+            },
+          },
+        },
+      ],
+      "`set` should notify listeners about changes"
+    );
+    ok(!value, "`set` should not return a value");
+  }
+
+  {
+    let { changes, value } = await promisify(
+      service.get,
+      "ext-1",
+      JSON.stringify(["hi"])
+    );
+    deepEqual(changes, [], "`get` should not notify listeners");
+    deepEqual(
+      value,
+      {
+        hi: "hello! 💖",
+      },
+      "`get` with key should return value"
+    );
+
+    let { value: allValues } = await promisify(service.get, "ext-1", "null");
+    deepEqual(
+      allValues,
+      {
+        hi: "hello! 💖",
+        bye: "adiós",
+      },
+      "`get` without a key should return all values"
+    );
+  }
+
+  {
+    await promisify(
+      service.set,
+      "ext-2",
+      JSON.stringify({
+        hi: "hola! 👋",
+      })
+    );
+    await promisify(service.clear, "ext-1");
+    let { value: allValues } = await promisify(service.get, "ext-1", "null");
+    deepEqual(allValues, {}, "clear removed ext-1");
+
+    let { value: allValues2 } = await promisify(service.get, "ext-2", "null");
+    deepEqual(allValues2, { hi: "hola! 👋" }, "clear didn't remove ext-2");
+    // We need to clear data for ext-2 too, so later tests don't fail due to
+    // this data.
+    await promisify(service.clear, "ext-2");
+  }
+});
+
+add_task(async function test_storage_sync_bridged_engine() {
+  const area = StorageSyncService.getInterface(Ci.mozIExtensionStorageArea);
+  const engine = StorageSyncService.getInterface(Ci.mozIBridgedSyncEngine);
+
+  info("Add some local items");
+  await promisify(area.set, "ext-1", JSON.stringify({ a: "abc" }));
+  await promisify(area.set, "ext-2", JSON.stringify({ b: "xyz" }));
+
+  info("Start a sync");
+  await promisify(engine.syncStarted);
+
+  info("Store some incoming synced items");
+  let incomingEnvelopesAsJSON = [
+    {
+      id: "guidAAA",
+      modified: 0.1,
+      cleartext: JSON.stringify({
+        id: "guidAAA",
+        extId: "ext-2",
+        data: JSON.stringify({
+          c: 1234,
+        }),
+      }),
+    },
+    {
+      id: "guidBBB",
+      modified: 0.1,
+      cleartext: JSON.stringify({
+        id: "guidBBB",
+        extId: "ext-3",
+        data: JSON.stringify({
+          d: "new! ✨",
+        }),
+      }),
+    },
+  ].map(e => JSON.stringify(e));
+  await promisify(area.storeIncoming, incomingEnvelopesAsJSON);
+
+  info("Merge");
+  // Three levels of JSON wrapping: each outgoing envelope, the cleartext in
+  // each envelope, and the extension storage data in each cleartext.
+  let { value: outgoingEnvelopesAsJSON } = await promisify(area.apply);
+  let outgoingEnvelopes = outgoingEnvelopesAsJSON.map(json => JSON.parse(json));
+  let parsedCleartexts = outgoingEnvelopes.map(e => JSON.parse(e.cleartext));
+  let parsedData = parsedCleartexts.map(c => JSON.parse(c.data));
+
+  let { changes } = await promisify(
+    area.QueryInterface(Ci.mozISyncedExtensionStorageArea)
+      .fetchPendingSyncChanges
+  );
+  deepEqual(
+    changes,
+    [
+      {
+        extId: "ext-2",
+        changes: {
+          c: { newValue: 1234 },
+        },
+      },
+      {
+        extId: "ext-3",
+        changes: {
+          d: { newValue: "new! ✨" },
+        },
+      },
+    ],
+    "Should return pending synced changes for observers"
+  );
+
+  // ext-1 doesn't exist remotely yet, so the Rust sync layer will generate
+  // a GUID for it. We don't know what it is, so we find it by the extension
+  // ID.
+  let ext1Index = parsedCleartexts.findIndex(c => c.extId == "ext-1");
+  greater(ext1Index, -1, "Should find envelope for ext-1");
+  let ext1Guid = outgoingEnvelopes[ext1Index].id;
+
+  // ext-2 has a remote GUID that we set in the test above.
+  let ext2Index = outgoingEnvelopes.findIndex(c => c.id == "guidAAA");
+  greater(ext2Index, -1, "Should find envelope for ext-2");
+
+  equal(outgoingEnvelopes.length, 2, "Should upload ext-1 and ext-2");
+  equal(
+    ext1Guid,
+    parsedCleartexts[ext1Index].id,
+    "ext-1 ID in envelope should match cleartext"
+  );
+  deepEqual(
+    parsedData[ext1Index],
+    {
+      a: "abc",
+    },
+    "Should upload new data for ext-1"
+  );
+  equal(
+    outgoingEnvelopes[ext2Index].id,
+    parsedCleartexts[ext2Index].id,
+    "ext-2 ID in envelope should match cleartext"
+  );
+  deepEqual(
+    parsedData[ext2Index],
+    {
+      b: "xyz",
+      c: 1234,
+    },
+    "Should merge local and remote data for ext-2"
+  );
+
+  info("Mark all extensions as uploaded");
+  await promisify(engine.setUploaded, 0, [ext1Guid, "guidAAA"]);
+
+  info("Finish sync");
+  await promisify(engine.syncFinished);
+
+  // Try fetching values for the remote-only extension we just synced.
+  let { value: ext3Value } = await promisify(area.get, "ext-3", "null");
+  deepEqual(
+    ext3Value,
+    {
+      d: "new! ✨",
+    },
+    "Should return new keys for ext-3"
+  );
+
+  info("Try applying a second time");
+  let secondApply = await promisify(area.apply);
+  deepEqual(secondApply.value, {}, "Shouldn't merge anything on second apply");
+
+  info("Wipe all items");
+  await promisify(engine.wipe);
+
+  for (let extId of ["ext-1", "ext-2", "ext-3"]) {
+    // `get` always returns an object, even if there are no keys for the
+    // extension ID.
+    let { value } = await promisify(area.get, extId, "null");
+    deepEqual(value, {}, `Wipe should remove all values for ${extId}`);
+  }
+});
+
+add_task(async function test_storage_sync_quota() {
+  const service = StorageSyncService.getInterface(Ci.mozIExtensionStorageArea);
+  const engine = StorageSyncService.getInterface(Ci.mozIBridgedSyncEngine);
+  await promisify(engine.wipe);
+  await promisify(service.set, "ext-1", JSON.stringify({ x: "hi" }));
+  await promisify(service.set, "ext-1", JSON.stringify({ longer: "value" }));
+
+  let { value: v1 } = await promisify(service.getBytesInUse, "ext-1", '"x"');
+  Assert.equal(v1, 5); // key len without quotes, value len with quotes.
+  let { value: v2 } = await promisify(service.getBytesInUse, "ext-1", "null");
+  // 5 from 'x', plus 'longer' (6 for key, 7 for value = 13) = 18.
+  Assert.equal(v2, 18);
+
+  // Now set something greater than our quota.
+  await Assert.rejects(
+    promisify(
+      service.set,
+      "ext-1",
+      JSON.stringify({
+        big: "x".repeat(Ci.mozIExtensionStorageArea.SYNC_QUOTA_BYTES),
+      })
+    ),
+    ex => ex.result == NS_ERROR_DOM_QUOTA_EXCEEDED_ERR,
+    "should reject with NS_ERROR_DOM_QUOTA_EXCEEDED_ERR"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_WebExtensionContentScript.js b/toolkit/components/extensions/test/xpcshell/test_WebExtensionContentScript.js
new file mode 100644
index 0000000000..78d61d4b29
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_WebExtensionContentScript.js
@@ -0,0 +1,209 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { newURI } = Services.io;
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+let policy = new WebExtensionPolicy({
+  id: "foo@bar.baz",
+  mozExtensionHostname: "88fb51cd-159f-4859-83db-7065485bc9b2",
+  baseURL: "file:///foo",
+
+  allowedOrigins: new MatchPatternSet([]),
+  localizeCallback() {},
+});
+
+add_task(async function test_WebExtensinonContentScript_url_matching() {
+  let contentScript = new WebExtensionContentScript(policy, {
+    matches: new MatchPatternSet(["http://foo.com/bar", "*://bar.com/baz/*"]),
+
+    excludeMatches: new MatchPatternSet(["*://bar.com/baz/quux"]),
+
+    includeGlobs: ["*flerg*", "*.com/bar", "*/quux"].map(
+      glob => new MatchGlob(glob)
+    ),
+
+    excludeGlobs: ["*glorg*"].map(glob => new MatchGlob(glob)),
+  });
+
+  ok(
+    contentScript.matchesURI(newURI("http://foo.com/bar")),
+    "Simple matches include should match"
+  );
+
+  ok(
+    contentScript.matchesURI(newURI("https://bar.com/baz/xflergx")),
+    "Simple matches include should match"
+  );
+
+  ok(
+    !contentScript.matchesURI(newURI("https://bar.com/baz/xx")),
+    "Failed includeGlobs match pattern should not match"
+  );
+
+  ok(
+    !contentScript.matchesURI(newURI("https://bar.com/baz/quux")),
+    "Excluded match pattern should not match"
+  );
+
+  ok(
+    !contentScript.matchesURI(newURI("https://bar.com/baz/xflergxglorgx")),
+    "Excluded match glob should not match"
+  );
+});
+
+async function loadURL(url) {
+  let requests = new Map();
+
+  function requestObserver(request) {
+    request.QueryInterface(Ci.nsIChannel);
+    if (request.isDocument) {
+      requests.set(request.name, request);
+    }
+  }
+
+  Services.obs.addObserver(requestObserver, "http-on-examine-response");
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+
+  Services.obs.removeObserver(requestObserver, "http-on-examine-response");
+
+  return { contentPage, requests };
+}
+
+add_task(async function test_WebExtensinonContentScript_frame_matching() {
+  if (AppConstants.platform == "linux") {
+    // The windowless browser currently does not load correctly on Linux on
+    // infra.
+    return;
+  }
+
+  let baseURL = `http://example.com/data`;
+  let urls = {
+    topLevel: `${baseURL}/file_toplevel.html`,
+    iframe: `${baseURL}/file_iframe.html`,
+    srcdoc: "about:srcdoc",
+    aboutBlank: "about:blank",
+  };
+
+  let { contentPage, requests } = await loadURL(urls.topLevel);
+
+  let tests = [
+    {
+      matches: ["http://example.com/data/*"],
+      contentScript: {},
+      topLevel: true,
+      iframe: false,
+      aboutBlank: false,
+      srcdoc: false,
+    },
+
+    {
+      matches: ["http://example.com/data/*"],
+      contentScript: {
+        frameID: 0,
+      },
+      topLevel: true,
+      iframe: false,
+      aboutBlank: false,
+      srcdoc: false,
+    },
+
+    {
+      matches: ["http://example.com/data/*"],
+      contentScript: {
+        allFrames: true,
+      },
+      topLevel: true,
+      iframe: true,
+      aboutBlank: false,
+      srcdoc: false,
+    },
+
+    {
+      matches: ["http://example.com/data/*"],
+      contentScript: {
+        allFrames: true,
+        matchAboutBlank: true,
+      },
+      topLevel: true,
+      iframe: true,
+      aboutBlank: true,
+      srcdoc: true,
+    },
+
+    {
+      matches: ["http://foo.com/data/*"],
+      contentScript: {
+        allFrames: true,
+        matchAboutBlank: true,
+      },
+      topLevel: false,
+      iframe: false,
+      aboutBlank: false,
+      srcdoc: false,
+    },
+  ];
+
+  // matchesWindowGlobal tests against content frames
+  await contentPage.spawn({ tests, urls }, args => {
+    this.windows = new Map();
+    this.windows.set(this.content.location.href, this.content);
+    for (let c of Array.from(this.content.frames)) {
+      this.windows.set(c.location.href, c);
+    }
+    this.policy = new WebExtensionPolicy({
+      id: "foo@bar.baz",
+      mozExtensionHostname: "88fb51cd-159f-4859-83db-7065485bc9b2",
+      baseURL: "file:///foo",
+
+      allowedOrigins: new MatchPatternSet([]),
+      localizeCallback() {},
+    });
+
+    let tests = args.tests.map(t => {
+      t.contentScript.matches = new MatchPatternSet(t.matches);
+      t.script = new WebExtensionContentScript(this.policy, t.contentScript);
+      return t;
+    });
+    for (let [i, test] of tests.entries()) {
+      for (let [frame, url] of Object.entries(args.urls)) {
+        let should = test[frame] ? "should" : "should not";
+        let wgc = this.windows.get(url).windowGlobalChild;
+        Assert.equal(
+          test.script.matchesWindowGlobal(wgc),
+          test[frame],
+          `Script ${i} ${should} match the ${frame} frame`
+        );
+      }
+    }
+  });
+
+  // Parent tests against loadInfo
+  tests = tests.map(t => {
+    t.contentScript.matches = new MatchPatternSet(t.matches);
+    t.script = new WebExtensionContentScript(policy, t.contentScript);
+    return t;
+  });
+
+  for (let [i, test] of tests.entries()) {
+    for (let [frame, url] of Object.entries(urls)) {
+      let should = test[frame] ? "should" : "should not";
+
+      if (url.startsWith("http")) {
+        let request = requests.get(url);
+
+        equal(
+          test.script.matchesLoadInfo(request.URI, request.loadInfo),
+          test[frame],
+          `Script ${i} ${should} match the request LoadInfo for ${frame} frame`
+        );
+      }
+    }
+  }
+
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_WebExtensionPolicy.js b/toolkit/components/extensions/test/xpcshell/test_WebExtensionPolicy.js
new file mode 100644
index 0000000000..75c6edd9c4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_WebExtensionPolicy.js
@@ -0,0 +1,376 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { newURI } = Services.io;
+
+add_task(async function test_WebExtensionPolicy() {
+  const id = "foo@bar.baz";
+  const uuid = "ca9d3f23-125c-4b24-abfc-1ca2692b0610";
+
+  const baseURL = "file:///foo/";
+  const mozExtURL = `moz-extension://${uuid}/`;
+  const mozExtURI = newURI(mozExtURL);
+
+  let policy = new WebExtensionPolicy({
+    id,
+    mozExtensionHostname: uuid,
+    baseURL,
+
+    localizeCallback(str) {
+      return `<${str}>`;
+    },
+
+    allowedOrigins: new MatchPatternSet(["http://foo.bar/", "*://*.baz/"], {
+      ignorePath: true,
+    }),
+    permissions: ["<all_urls>"],
+    webAccessibleResources: ["/foo/*", "/bar.baz"].map(
+      glob => new MatchGlob(glob)
+    ),
+  });
+
+  equal(policy.active, false, "Active attribute should initially be false");
+
+  // GetURL
+
+  equal(
+    policy.getURL(),
+    mozExtURL,
+    "getURL() should return the correct root URL"
+  );
+  equal(
+    policy.getURL("path/foo.html"),
+    `${mozExtURL}path/foo.html`,
+    "getURL(path) should return the correct URL"
+  );
+
+  // Permissions
+
+  deepEqual(
+    policy.permissions,
+    ["<all_urls>"],
+    "Initial permissions should be correct"
+  );
+
+  ok(
+    policy.hasPermission("<all_urls>"),
+    "hasPermission should match existing permission"
+  );
+  ok(
+    !policy.hasPermission("history"),
+    "hasPermission should not match nonexistent permission"
+  );
+
+  Assert.throws(
+    () => {
+      policy.permissions[0] = "foo";
+    },
+    TypeError,
+    "Permissions array should be frozen"
+  );
+
+  policy.permissions = ["history"];
+  deepEqual(
+    policy.permissions,
+    ["history"],
+    "Permissions should be updateable as a set"
+  );
+
+  ok(
+    policy.hasPermission("history"),
+    "hasPermission should match existing permission"
+  );
+  ok(
+    !policy.hasPermission("<all_urls>"),
+    "hasPermission should not match nonexistent permission"
+  );
+
+  // Origins
+
+  ok(
+    policy.canAccessURI(newURI("http://foo.bar/quux")),
+    "Should be able to access permitted URI"
+  );
+  ok(
+    policy.canAccessURI(newURI("https://x.baz/foo")),
+    "Should be able to access permitted URI"
+  );
+
+  ok(
+    !policy.canAccessURI(newURI("https://foo.bar/quux")),
+    "Should not be able to access non-permitted URI"
+  );
+
+  policy.allowedOrigins = new MatchPatternSet(["https://foo.bar/"], {
+    ignorePath: true,
+  });
+
+  ok(
+    policy.canAccessURI(newURI("https://foo.bar/quux")),
+    "Should be able to access updated permitted URI"
+  );
+  ok(
+    !policy.canAccessURI(newURI("https://x.baz/foo")),
+    "Should not be able to access removed permitted URI"
+  );
+
+  // Web-accessible resources
+
+  ok(
+    policy.isPathWebAccessible("/foo/bar"),
+    "Web-accessible glob should be web-accessible"
+  );
+  ok(
+    policy.isPathWebAccessible("/bar.baz"),
+    "Web-accessible path should be web-accessible"
+  );
+  ok(
+    !policy.isPathWebAccessible("/bar.baz/quux"),
+    "Non-web-accessible path should not be web-accessible"
+  );
+
+  // Localization
+
+  equal(
+    policy.localize("foo"),
+    "<foo>",
+    "Localization callback should work as expected"
+  );
+
+  // Protocol and lookups.
+
+  let proto = Services.io
+    .getProtocolHandler("moz-extension", uuid)
+    .QueryInterface(Ci.nsISubstitutingProtocolHandler);
+
+  deepEqual(
+    WebExtensionPolicy.getActiveExtensions(),
+    [],
+    "Should have no active extensions"
+  );
+  equal(
+    WebExtensionPolicy.getByID(id),
+    null,
+    "ID lookup should not return extension when not active"
+  );
+  equal(
+    WebExtensionPolicy.getByHostname(uuid),
+    null,
+    "Hostname lookup should not return extension when not active"
+  );
+  Assert.throws(
+    () => proto.resolveURI(mozExtURI),
+    /NS_ERROR_NOT_AVAILABLE/,
+    "URL should not resolve when not active"
+  );
+
+  policy.active = true;
+  equal(policy.active, true, "Active attribute should be updated");
+
+  let exts = WebExtensionPolicy.getActiveExtensions();
+  equal(exts.length, 1, "Should have one active extension");
+  equal(exts[0], policy, "Should have the correct active extension");
+
+  equal(
+    WebExtensionPolicy.getByID(id),
+    policy,
+    "ID lookup should return extension when active"
+  );
+  equal(
+    WebExtensionPolicy.getByHostname(uuid),
+    policy,
+    "Hostname lookup should return extension when active"
+  );
+
+  equal(
+    proto.resolveURI(mozExtURI),
+    baseURL,
+    "URL should resolve correctly while active"
+  );
+
+  policy.active = false;
+  equal(policy.active, false, "Active attribute should be updated");
+
+  deepEqual(
+    WebExtensionPolicy.getActiveExtensions(),
+    [],
+    "Should have no active extensions"
+  );
+  equal(
+    WebExtensionPolicy.getByID(id),
+    null,
+    "ID lookup should not return extension when not active"
+  );
+  equal(
+    WebExtensionPolicy.getByHostname(uuid),
+    null,
+    "Hostname lookup should not return extension when not active"
+  );
+  Assert.throws(
+    () => proto.resolveURI(mozExtURI),
+    /NS_ERROR_NOT_AVAILABLE/,
+    "URL should not resolve when not active"
+  );
+
+  // Conflicting policies.
+
+  // This asserts in debug builds, so only test in non-debug builds.
+  if (!AppConstants.DEBUG) {
+    policy.active = true;
+
+    let attrs = [
+      { id, uuid },
+      { id, uuid: "d916886c-cfdf-482e-b7b1-d7f5b0facfa5" },
+      { id: "foo@quux", uuid },
+    ];
+
+    // eslint-disable-next-line no-shadow
+    for (let { id, uuid } of attrs) {
+      let policy2 = new WebExtensionPolicy({
+        id,
+        mozExtensionHostname: uuid,
+        baseURL: "file://bar/",
+
+        localizeCallback() {},
+
+        allowedOrigins: new MatchPatternSet([]),
+      });
+
+      Assert.throws(
+        () => {
+          policy2.active = true;
+        },
+        /NS_ERROR_UNEXPECTED/,
+        `Should not be able to activate conflicting policy: ${id} ${uuid}`
+      );
+    }
+
+    policy.active = false;
+  }
+});
+
+add_task(async function test_WebExtensionPolicy_registerContentScripts() {
+  const id = "foo@bar.baz";
+  const uuid = "77a7b9d3-e73c-4cf3-97fb-1824868fe00f";
+
+  const id2 = "foo-2@bar.baz";
+  const uuid2 = "89383c45-7db4-4999-83f7-f4cc246372cd";
+
+  const baseURL = "file:///foo/";
+
+  const mozExtURL = `moz-extension://${uuid}/`;
+  const mozExtURL2 = `moz-extension://${uuid2}/`;
+
+  let policy = new WebExtensionPolicy({
+    id,
+    mozExtensionHostname: uuid,
+    baseURL,
+    localizeCallback() {},
+    allowedOrigins: new MatchPatternSet([]),
+    permissions: ["<all_urls>"],
+  });
+
+  let policy2 = new WebExtensionPolicy({
+    id: id2,
+    mozExtensionHostname: uuid2,
+    baseURL,
+    localizeCallback() {},
+    allowedOrigins: new MatchPatternSet([]),
+    permissions: ["<all_urls>"],
+  });
+
+  let script1 = new WebExtensionContentScript(policy, {
+    run_at: "document_end",
+    js: [`${mozExtURL}/registered-content-script.js`],
+    matches: new MatchPatternSet(["http://localhost/data/*"]),
+  });
+
+  let script2 = new WebExtensionContentScript(policy, {
+    run_at: "document_end",
+    css: [`${mozExtURL}/registered-content-style.css`],
+    matches: new MatchPatternSet(["http://localhost/data/*"]),
+  });
+
+  let script3 = new WebExtensionContentScript(policy2, {
+    run_at: "document_end",
+    css: [`${mozExtURL2}/registered-content-style.css`],
+    matches: new MatchPatternSet(["http://localhost/data/*"]),
+  });
+
+  deepEqual(
+    policy.contentScripts,
+    [],
+    "The policy contentScripts is initially empty"
+  );
+
+  policy.registerContentScript(script1);
+
+  deepEqual(
+    policy.contentScripts,
+    [script1],
+    "script1 has been added to the policy contentScripts"
+  );
+
+  Assert.throws(
+    () => policy.registerContentScript(script1),
+    e => e.result == Cr.NS_ERROR_ILLEGAL_VALUE,
+    "Got the expected NS_ERROR_ILLEGAL_VALUE when trying to register a script more than once"
+  );
+
+  Assert.throws(
+    () => policy.registerContentScript(script3),
+    e => e.result == Cr.NS_ERROR_ILLEGAL_VALUE,
+    "Got the expected NS_ERROR_ILLEGAL_VALUE when trying to register a script related to " +
+      "a different extension"
+  );
+
+  Assert.throws(
+    () => policy.unregisterContentScript(script3),
+    e => e.result == Cr.NS_ERROR_ILLEGAL_VALUE,
+    "Got the expected NS_ERROR_ILLEGAL_VALUE when trying to unregister a script related to " +
+      "a different extension"
+  );
+
+  deepEqual(
+    policy.contentScripts,
+    [script1],
+    "script1 has not been added twice"
+  );
+
+  policy.registerContentScript(script2);
+
+  deepEqual(
+    policy.contentScripts,
+    [script1, script2],
+    "script2 has the last item of the policy contentScripts array"
+  );
+
+  policy.unregisterContentScript(script1);
+
+  deepEqual(
+    policy.contentScripts,
+    [script2],
+    "script1 has been removed from the policy contentscripts"
+  );
+
+  Assert.throws(
+    () => policy.unregisterContentScript(script1),
+    e => e.result == Cr.NS_ERROR_ILLEGAL_VALUE,
+    "Got the expected NS_ERROR_ILLEGAL_VALUE when trying to unregister a script more than once"
+  );
+
+  deepEqual(
+    policy.contentScripts,
+    [script2],
+    "the policy contentscripts is unmodified when unregistering an unknown contentScript"
+  );
+
+  policy.unregisterContentScript(script2);
+
+  deepEqual(
+    policy.contentScripts,
+    [],
+    "script2 has been removed from the policy contentScripts"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_change_remote_mode.js b/toolkit/components/extensions/test/xpcshell/test_change_remote_mode.js
new file mode 100644
index 0000000000..a6d22e8703
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_change_remote_mode.js
@@ -0,0 +1,20 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function change_remote() {
+  let remote = Services.prefs.getBoolPref("extensions.webextensions.remote");
+  Assert.equal(
+    WebExtensionPolicy.useRemoteWebExtensions,
+    remote,
+    "value of useRemoteWebExtensions matches the pref"
+  );
+
+  Services.prefs.setBoolPref("extensions.webextensions.remote", !remote);
+
+  Assert.equal(
+    WebExtensionPolicy.useRemoteWebExtensions,
+    remote,
+    "value of useRemoteWebExtensions is still the same after changing the pref"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_csp_custom_policies.js b/toolkit/components/extensions/test/xpcshell/test_csp_custom_policies.js
new file mode 100644
index 0000000000..0b24cc4c50
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_csp_custom_policies.js
@@ -0,0 +1,278 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { Preferences } = ChromeUtils.import(
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const ADDON_ID = "test@web.extension";
+
+const aps = Cc["@mozilla.org/addons/policy-service;1"].getService(
+  Ci.nsIAddonPolicyService
+);
+
+const v2_csp = Preferences.get(
+  "extensions.webextensions.base-content-security-policy"
+);
+const v3_csp = Preferences.get(
+  "extensions.webextensions.base-content-security-policy.v3"
+);
+
+add_task(async function test_invalid_addon_csp() {
+  await Assert.throws(
+    () => aps.getBaseCSP("invalid@missing"),
+    /NS_ERROR_ILLEGAL_VALUE/,
+    "no base csp for non-existent addon"
+  );
+  await Assert.throws(
+    () => aps.getExtensionPageCSP("invalid@missing"),
+    /NS_ERROR_ILLEGAL_VALUE/,
+    "no extension page csp for non-existent addon"
+  );
+});
+
+add_task(async function test_policy_csp() {
+  equal(
+    aps.defaultCSP,
+    Preferences.get("extensions.webextensions.default-content-security-policy"),
+    "Expected default CSP value"
+  );
+
+  const CUSTOM_POLICY =
+    "script-src: 'self' https://xpcshell.test.custom.csp; object-src: 'none'";
+
+  let tests = [
+    {
+      name: "manifest version 2, no custom policy",
+      policyData: {},
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest version 2, no custom policy",
+      policyData: {
+        manifestVersion: 2,
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "version 2 custom extension policy",
+      policyData: {
+        extensionPageCSP: CUSTOM_POLICY,
+      },
+      expectedPolicy: CUSTOM_POLICY,
+    },
+    {
+      name: "manifest version 2 set, custom extension policy",
+      policyData: {
+        manifestVersion: 2,
+        extensionPageCSP: CUSTOM_POLICY,
+      },
+      expectedPolicy: CUSTOM_POLICY,
+    },
+    {
+      name: "manifest version 3, no custom policy",
+      policyData: {
+        manifestVersion: 3,
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest 3 version set, custom extensionPage policy",
+      policyData: {
+        manifestVersion: 3,
+        extensionPageCSP: CUSTOM_POLICY,
+      },
+      expectedPolicy: CUSTOM_POLICY,
+    },
+  ];
+
+  let policy = null;
+
+  function setExtensionCSP({ manifestVersion, extensionPageCSP }) {
+    if (policy) {
+      policy.active = false;
+    }
+
+    policy = new WebExtensionPolicy({
+      id: ADDON_ID,
+      mozExtensionHostname: ADDON_ID,
+      baseURL: "file:///",
+
+      allowedOrigins: new MatchPatternSet([]),
+      localizeCallback() {},
+
+      manifestVersion,
+      extensionPageCSP,
+    });
+
+    policy.active = true;
+  }
+
+  for (let test of tests) {
+    info(test.name);
+    setExtensionCSP(test.policyData);
+    equal(
+      aps.getBaseCSP(ADDON_ID),
+      test.policyData.manifestVersion == 3 ? v3_csp : v2_csp,
+      "baseCSP is correct"
+    );
+    equal(
+      aps.getExtensionPageCSP(ADDON_ID),
+      test.expectedPolicy,
+      "extensionPageCSP is correct"
+    );
+  }
+});
+
+add_task(async function test_extension_csp() {
+  Services.prefs.setBoolPref("extensions.manifestV3.enabled", true);
+
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+
+  let extension_pages = "script-src 'self'; object-src 'none'; img-src 'none'";
+
+  let tests = [
+    {
+      name: "manifest_v2 invalid csp results in default csp used",
+      manifest: {
+        content_security_policy: `script-src 'none'`,
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v2 allows https protocol",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages: `script-src 'self' https://*; object-src 'self'`,
+        },
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v2 allows unsafe-eval",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages: `script-src 'self' 'unsafe-eval'; object-src 'self'`,
+        },
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v3 invalid csp results in default csp used",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages: `script-src 'none'`,
+        },
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v3 forbidden protocol results in default csp used",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages: `script-src 'self' https://*; object-src 'self'`,
+        },
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v3 forbidden eval results in default csp used",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages: `script-src 'self' 'unsafe-eval'; object-src 'self'`,
+        },
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v3 allows localhost",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages: `script-src 'self' https://localhost; object-src 'self'`,
+        },
+      },
+      expectedPolicy: `script-src 'self' https://localhost; object-src 'self'`,
+    },
+    {
+      name: "manifest_v3 allows 127.0.0.1",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages: `script-src 'self' https://127.0.0.1; object-src 'self'`,
+        },
+      },
+      expectedPolicy: `script-src 'self' https://127.0.0.1; object-src 'self'`,
+    },
+    {
+      name: "manifest_v2 csp",
+      manifest: {
+        manifest_version: 2,
+        content_security_policy: extension_pages,
+      },
+      expectedPolicy: extension_pages,
+    },
+    {
+      name: "manifest_v2 with no csp, expect default",
+      manifest: {
+        manifest_version: 2,
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v3 used with no csp, expect default",
+      manifest: {
+        manifest_version: 3,
+      },
+      expectedPolicy: aps.defaultCSP,
+    },
+    {
+      name: "manifest_v3 used with v2 syntax",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: extension_pages,
+      },
+      expectedPolicy: extension_pages,
+    },
+    {
+      name: "manifest_v3 syntax used",
+      manifest: {
+        manifest_version: 3,
+        content_security_policy: {
+          extension_pages,
+        },
+      },
+      expectedPolicy: extension_pages,
+    },
+  ];
+
+  for (let test of tests) {
+    info(test.name);
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: test.manifest,
+    });
+    await extension.startup();
+    let policy = WebExtensionPolicy.getByID(extension.id);
+    equal(
+      policy.baseCSP,
+      test.manifest.manifest_version == 3 ? v3_csp : v2_csp,
+      "baseCSP is correct"
+    );
+    equal(
+      policy.extensionPageCSP,
+      test.expectedPolicy,
+      "extensionPageCSP is correct."
+    );
+    await extension.unload();
+  }
+
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+
+  Services.prefs.clearUserPref("extensions.manifestV3.enabled");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_csp_validator.js b/toolkit/components/extensions/test/xpcshell/test_csp_validator.js
new file mode 100644
index 0000000000..fb494f3da2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_csp_validator.js
@@ -0,0 +1,298 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const cps = Cc["@mozilla.org/addons/content-policy;1"].getService(
+  Ci.nsIAddonContentPolicy
+);
+
+add_task(async function test_csp_validator_flags() {
+  let checkPolicy = (policy, flags, expectedResult, message = null) => {
+    info(`Checking policy: ${policy}`);
+
+    let result = cps.validateAddonCSP(policy, flags);
+    equal(result, expectedResult);
+  };
+
+  let flags = Ci.nsIAddonContentPolicy;
+
+  checkPolicy(
+    "default-src 'self'; script-src 'self' http://localhost",
+    0,
+    "\u2018script-src\u2019 directive contains a forbidden http: protocol source",
+    "localhost disallowed"
+  );
+  checkPolicy(
+    "default-src 'self'; script-src 'self' http://localhost",
+    flags.CSP_ALLOW_LOCALHOST,
+    null,
+    "localhost allowed"
+  );
+
+  checkPolicy(
+    "default-src 'self'; script-src 'self' 'unsafe-eval'",
+    0,
+    "\u2018script-src\u2019 directive contains a forbidden 'unsafe-eval' keyword",
+    "eval disallowed"
+  );
+  checkPolicy(
+    "default-src 'self'; script-src 'self' 'unsafe-eval'",
+    flags.CSP_ALLOW_EVAL,
+    null,
+    "eval allowed"
+  );
+
+  checkPolicy(
+    "default-src 'self'; script-src 'self' https://example.com",
+    0,
+    "\u2018script-src\u2019 directive contains a forbidden https: protocol source",
+    "remote disallowed"
+  );
+  checkPolicy(
+    "default-src 'self'; script-src 'self' https://example.com",
+    flags.CSP_ALLOW_REMOTE,
+    null,
+    "remote allowed"
+  );
+});
+
+add_task(async function test_csp_validator() {
+  let checkPolicy = (policy, expectedResult, message = null) => {
+    info(`Checking policy: ${policy}`);
+
+    let result = cps.validateAddonCSP(
+      policy,
+      Ci.nsIAddonContentPolicy.CSP_ALLOW_ANY
+    );
+    equal(result, expectedResult);
+  };
+
+  checkPolicy("script-src 'self'; object-src 'self';", null);
+
+  let hash =
+    "'sha256-NjZhMDQ1YjQ1MjEwMmM1OWQ4NDBlYzA5N2Q1OWQ5NDY3ZTEzYTNmMzRmNjQ5NGU1MzlmZmQzMmMxYmIzNWYxOCAgLQo='";
+
+  checkPolicy(
+    `script-src 'self' https://com https://*.example.com moz-extension://09abcdef blob: filesystem: ${hash} 'unsafe-eval'; ` +
+      `object-src 'self' https://com https://*.example.com moz-extension://09abcdef blob: filesystem: ${hash}`,
+    null
+  );
+
+  checkPolicy(
+    "",
+    "Policy is missing a required \u2018script-src\u2019 directive"
+  );
+
+  checkPolicy(
+    "object-src 'none';",
+    "Policy is missing a required \u2018script-src\u2019 directive"
+  );
+
+  checkPolicy(
+    "default-src 'self'",
+    null,
+    "A valid default-src should count as a valid script-src or object-src"
+  );
+
+  checkPolicy(
+    "default-src 'self'; script-src 'self'",
+    null,
+    "A valid default-src should count as a valid script-src or object-src"
+  );
+
+  checkPolicy(
+    "default-src 'self'; object-src 'self'",
+    null,
+    "A valid default-src should count as a valid script-src or object-src"
+  );
+
+  checkPolicy(
+    "default-src 'self'; script-src http://example.com",
+    "\u2018script-src\u2019 directive contains a forbidden http: protocol source",
+    "A valid default-src should not allow an invalid script-src directive"
+  );
+
+  checkPolicy(
+    "default-src 'self'; object-src http://example.com",
+    "\u2018object-src\u2019 directive contains a forbidden http: protocol source",
+    "A valid default-src should not allow an invalid object-src directive"
+  );
+
+  checkPolicy(
+    "script-src 'self';",
+    "Policy is missing a required \u2018object-src\u2019 directive"
+  );
+
+  checkPolicy(
+    "script-src 'none'; object-src 'none'",
+    "\u2018script-src\u2019 must include the source 'self'"
+  );
+
+  checkPolicy("script-src 'self'; object-src 'none';", null);
+
+  checkPolicy(
+    "script-src 'self' 'unsafe-inline'; object-src 'self';",
+    "\u2018script-src\u2019 directive contains a forbidden 'unsafe-inline' keyword"
+  );
+
+  // Localhost is always valid
+  for (let src of [
+    "http://localhost",
+    "https://localhost",
+    "http://127.0.0.1",
+    "https://127.0.0.1",
+  ]) {
+    checkPolicy(`script-src 'self' ${src}; object-src 'none';`, null);
+  }
+
+  let directives = ["script-src", "object-src"];
+
+  for (let [directive, other] of [directives, directives.slice().reverse()]) {
+    for (let src of ["https://*", "https://*.blogspot.com", "https://*"]) {
+      checkPolicy(
+        `${directive} 'self' ${src}; ${other} 'self';`,
+        `https: wildcard sources in \u2018${directive}\u2019 directives must include at least one non-generic sub-domain (e.g., *.example.com rather than *.com)`
+      );
+    }
+
+    for (let protocol of ["http", "https"]) {
+      checkPolicy(
+        `${directive} 'self' ${protocol}:; ${other} 'self';`,
+        `${protocol}: protocol requires a host in \u2018${directive}\u2019 directives`
+      );
+    }
+
+    checkPolicy(
+      `${directive} 'self' http://example.com; ${other} 'self';`,
+      `\u2018${directive}\u2019 directive contains a forbidden http: protocol source`
+    );
+
+    for (let protocol of ["ftp", "meh"]) {
+      checkPolicy(
+        `${directive} 'self' ${protocol}:; ${other} 'self';`,
+        `\u2018${directive}\u2019 directive contains a forbidden ${protocol}: protocol source`
+      );
+    }
+
+    checkPolicy(
+      `${directive} 'self' 'nonce-01234'; ${other} 'self';`,
+      `\u2018${directive}\u2019 directive contains a forbidden 'nonce-*' keyword`
+    );
+  }
+});
+
+add_task(async function test_csp_validator_extension_pages() {
+  let checkPolicy = (policy, expectedResult, message = null) => {
+    info(`Checking policy: ${policy}`);
+
+    let result = cps.validateAddonCSP(
+      policy,
+      Ci.nsIAddonContentPolicy.CSP_ALLOW_LOCALHOST
+    );
+    equal(result, expectedResult);
+  };
+
+  checkPolicy("script-src 'self'; object-src 'self';", null);
+  checkPolicy("script-src 'self'; object-src 'self'; worker-src 'none'", null);
+  checkPolicy("script-src 'self'; object-src 'none'; worker-src 'self'", null);
+
+  let hash =
+    "'sha256-NjZhMDQ1YjQ1MjEwMmM1OWQ4NDBlYzA5N2Q1OWQ5NDY3ZTEzYTNmMzRmNjQ5NGU1MzlmZmQzMmMxYmIzNWYxOCAgLQo='";
+
+  checkPolicy(
+    `script-src 'self' moz-extension://09abcdef blob: filesystem: ${hash}; ` +
+      `object-src 'self' moz-extension://09abcdef blob: filesystem: ${hash}`,
+    null
+  );
+
+  for (let policy of ["", "object-src 'none';", "worker-src 'none';"]) {
+    checkPolicy(
+      policy,
+      "Policy is missing a required \u2018script-src\u2019 directive"
+    );
+  }
+
+  checkPolicy(
+    "default-src 'self'",
+    null,
+    "A valid default-src should count as a valid script-src or object-src"
+  );
+
+  for (let directive of ["script-src", "object-src", "worker-src"]) {
+    checkPolicy(
+      `default-src 'self'; ${directive} 'self'`,
+      null,
+      `A valid default-src should count as a valid ${directive}`
+    );
+    checkPolicy(
+      `default-src 'self'; ${directive} http://example.com`,
+      `\u2018${directive}\u2019 directive contains a forbidden http: protocol source`,
+      `A valid default-src should not allow an invalid ${directive} directive`
+    );
+  }
+
+  checkPolicy(
+    "script-src 'self';",
+    "Policy is missing a required \u2018object-src\u2019 directive"
+  );
+
+  checkPolicy(
+    "script-src 'none'; object-src 'none'",
+    "\u2018script-src\u2019 must include the source 'self'"
+  );
+
+  checkPolicy("script-src 'self'; object-src 'none';", null);
+
+  checkPolicy(
+    "script-src 'self' 'unsafe-inline'; object-src 'self';",
+    "\u2018script-src\u2019 directive contains a forbidden 'unsafe-inline' keyword"
+  );
+
+  checkPolicy(
+    "script-src 'self' 'unsafe-eval'; object-src 'self';",
+    "\u2018script-src\u2019 directive contains a forbidden 'unsafe-eval' keyword"
+  );
+
+  // Localhost is always valid
+  for (let src of [
+    "http://localhost",
+    "https://localhost",
+    "http://127.0.0.1",
+    "https://127.0.0.1",
+  ]) {
+    checkPolicy(`script-src 'self' ${src}; object-src 'none';`, null);
+  }
+
+  let directives = ["script-src", "object-src"];
+
+  for (let [directive, other] of [directives, directives.slice().reverse()]) {
+    for (let protocol of ["http", "https"]) {
+      checkPolicy(
+        `${directive} 'self' ${protocol}:; ${other} 'self';`,
+        `${protocol}: protocol requires a host in \u2018${directive}\u2019 directives`
+      );
+    }
+
+    checkPolicy(
+      `${directive} 'self' https://example.com; ${other} 'self';`,
+      `\u2018${directive}\u2019 directive contains a forbidden https: protocol source`
+    );
+
+    checkPolicy(
+      `${directive} 'self' http://example.com; ${other} 'self';`,
+      `\u2018${directive}\u2019 directive contains a forbidden http: protocol source`
+    );
+
+    for (let protocol of ["ftp", "meh"]) {
+      checkPolicy(
+        `${directive} 'self' ${protocol}:; ${other} 'self';`,
+        `\u2018${directive}\u2019 directive contains a forbidden ${protocol}: protocol source`
+      );
+    }
+
+    checkPolicy(
+      `${directive} 'self' 'nonce-01234'; ${other} 'self';`,
+      `\u2018${directive}\u2019 directive contains a forbidden 'nonce-*' keyword`
+    );
+  }
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_MessageManagerProxy.js b/toolkit/components/extensions/test/xpcshell/test_ext_MessageManagerProxy.js
new file mode 100644
index 0000000000..20ffb71d18
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_MessageManagerProxy.js
@@ -0,0 +1,80 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { MessageManagerProxy } = ChromeUtils.import(
+  "resource://gre/modules/MessageManagerProxy.jsm"
+);
+const { PromiseUtils } = ChromeUtils.import(
+  "resource://gre/modules/PromiseUtils.jsm"
+);
+
+class TestMessageManagerProxy extends MessageManagerProxy {
+  constructor(contentPage, identifier) {
+    super(contentPage.browser);
+    this.identifier = identifier;
+    this.contentPage = contentPage;
+    this.deferred = null;
+  }
+
+  // Registers message listeners. Call dispose() once you've finished.
+  async setupPingPongListeners() {
+    await this.contentPage.loadFrameScript(`() => {
+      this.addMessageListener("test:MessageManagerProxy:Ping", ({data}) => {
+        this.sendAsyncMessage("test:MessageManagerProxy:Pong", "${this.identifier}:" + data);
+      });
+    }`);
+
+    // Register the listener here instead of during testPingPong, to make sure
+    // that the listener is correctly registered during the whole test.
+    this.addMessageListener("test:MessageManagerProxy:Pong", event => {
+      ok(
+        this.deferred,
+        `[${this.identifier}] expected to be waiting for ping-pong`
+      );
+      this.deferred.resolve(event.data);
+      this.deferred = null;
+    });
+  }
+
+  async testPingPong(description) {
+    equal(this.deferred, null, "should not be waiting for a message");
+    this.deferred = PromiseUtils.defer();
+    this.sendAsyncMessage("test:MessageManagerProxy:Ping", description);
+    let result = await this.deferred.promise;
+    equal(result, `${this.identifier}:${description}`, "Expected ping-pong");
+  }
+}
+
+// Tests that MessageManagerProxy continues to proxy messages after docshells
+// have been swapped.
+add_task(async function test_message_after_swapdocshells() {
+  let page1 = await ExtensionTestUtils.loadContentPage("about:blank");
+  let page2 = await ExtensionTestUtils.loadContentPage("about:blank");
+
+  let testProxyOne = new TestMessageManagerProxy(page1, "page1");
+  let testProxyTwo = new TestMessageManagerProxy(page2, "page2");
+
+  await testProxyOne.setupPingPongListeners();
+  await testProxyTwo.setupPingPongListeners();
+
+  await testProxyOne.testPingPong("after setup (to 1)");
+  await testProxyTwo.testPingPong("after setup (to 2)");
+
+  page1.browser.swapDocShells(page2.browser);
+
+  await testProxyOne.testPingPong("after docshell swap (to 1)");
+  await testProxyTwo.testPingPong("after docshell swap (to 2)");
+
+  // Swap again to verify that listeners are repeatedly moved when needed.
+  page1.browser.swapDocShells(page2.browser);
+
+  await testProxyOne.testPingPong("after another docshell swap (to 1)");
+  await testProxyTwo.testPingPong("after another docshell swap (to 2)");
+
+  // Verify that dispose() works regardless of the browser's validity.
+  await testProxyOne.dispose();
+  await page1.close();
+  await page2.close();
+  await testProxyTwo.dispose();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_activityLog.js b/toolkit/components/extensions/test/xpcshell/test_ext_activityLog.js
new file mode 100644
index 0000000000..4a23b65264
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_activityLog.js
@@ -0,0 +1,21 @@
+"use strict";
+
+add_task(async function test_api_restricted() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: { id: "activityLog-permission@tests.mozilla.org" },
+      },
+      permissions: ["activityLog"],
+    },
+    async background() {
+      browser.test.assertEq(
+        undefined,
+        browser.activityLog,
+        "activityLog is privileged"
+      );
+    },
+  });
+  await extension.startup();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_adoption_with_private_field_xrays.js b/toolkit/components/extensions/test/xpcshell/test_ext_adoption_with_private_field_xrays.js
new file mode 100644
index 0000000000..bc4e0409cb
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_adoption_with_private_field_xrays.js
@@ -0,0 +1,160 @@
+"use strict";
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function test_contentscript_private_field_xrays() {
+  async function contentScript() {
+    let node = window.document.createElement("div");
+
+    class Base {
+      constructor(o) {
+        return o;
+      }
+    }
+
+    class A extends Base {
+      #x = 5;
+      static gx(o) {
+        return o.#x;
+      }
+      static sx(o, v) {
+        o.#x = v;
+      }
+    }
+
+    browser.test.log(A.toString());
+
+    // Stamp node with A's private field.
+    new A(node);
+
+    browser.test.log("stamped");
+
+    browser.test.assertEq(
+      A.gx(node),
+      5,
+      "We should be able to see our expando private field"
+    );
+    browser.test.log("Read");
+    browser.test.assertThrows(
+      () => A.gx(node.wrappedJSObject),
+      /Trying to read undeclared field/,
+      "Underlying object should not have our private field"
+    );
+
+    browser.test.log("threw");
+    window.frames[0].document.adoptNode(node);
+    browser.test.log("adopted");
+    browser.test.assertEq(
+      A.gx(node),
+      5,
+      "Adoption should not change expando private field"
+    );
+    browser.test.log("read");
+    browser.test.assertThrows(
+      () => A.gx(node.wrappedJSObject),
+      /Trying to read undeclared field/,
+      "Adoption should really not change expandos private fields"
+    );
+    browser.test.log("threw2");
+
+    // Repeat but now with an object that has a reference from the
+    // window it's being cloned into.
+    node = window.document.createElement("div");
+    // Stamp node with A's private field.
+    new A(node);
+    A.sx(node, 6);
+
+    browser.test.assertEq(
+      A.gx(node),
+      6,
+      "We should be able to see our expando (2)"
+    );
+    browser.test.assertThrows(
+      () => A.gx(node.wrappedJSObject),
+      /Trying to read undeclared field/,
+      "Underlying object should not have exxpando. (2)"
+    );
+
+    window.frames[0].wrappedJSObject.incoming = node.wrappedJSObject;
+    window.frames[0].document.adoptNode(node);
+
+    browser.test.assertEq(
+      A.gx(node),
+      6,
+      "We should be able to see our expando (3)"
+    );
+    browser.test.assertThrows(
+      () => A.gx(node.wrappedJSObject),
+      /Trying to read undeclared field/,
+      "Underlying object should not have exxpando. (3)"
+    );
+
+    // Repeat once more, now with an expando that refers to the object itself
+    node = window.document.createElement("div");
+    new A(node);
+    A.sx(node, node);
+
+    browser.test.assertEq(
+      A.gx(node),
+      node,
+      "We should be able to see our self-referential expando (4)"
+    );
+    browser.test.assertThrows(
+      () => A.gx(node.wrappedJSObject),
+      /Trying to read undeclared field/,
+      "Underlying object should not have exxpando. (4)"
+    );
+
+    window.frames[0].document.adoptNode(node);
+
+    browser.test.assertEq(
+      A.gx(node),
+      node,
+      "Adoption should not change our self-referential expando (4)"
+    );
+    browser.test.assertThrows(
+      () => A.gx(node.wrappedJSObject),
+      /Trying to read undeclared field/,
+      "Adoption should not change underlying object. (4)"
+    );
+
+    // And test what happens if we now set document.domain and cause
+    // wrapper remapping.
+    let doc = window.frames[0].document;
+    // eslint-disable-next-line no-self-assign
+    doc.domain = doc.domain;
+
+    browser.test.notifyPass("privateFieldXRayAdoption");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_toplevel.html"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_toplevel.html`
+  );
+
+  await extension.awaitFinish("privateFieldXRayAdoption");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_adoption_with_xrays.js b/toolkit/components/extensions/test/xpcshell/test_ext_adoption_with_xrays.js
new file mode 100644
index 0000000000..9655c157d1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_adoption_with_xrays.js
@@ -0,0 +1,129 @@
+"use strict";
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function test_contentscript_xrays() {
+  async function contentScript() {
+    let node = window.document.createElement("div");
+    node.expando = 5;
+
+    browser.test.assertEq(
+      node.expando,
+      5,
+      "We should be able to see our expando"
+    );
+    browser.test.assertEq(
+      node.wrappedJSObject.expando,
+      undefined,
+      "Underlying object should not have our expando"
+    );
+
+    window.frames[0].document.adoptNode(node);
+    browser.test.assertEq(
+      node.expando,
+      5,
+      "Adoption should not change expandos"
+    );
+    browser.test.assertEq(
+      node.wrappedJSObject.expando,
+      undefined,
+      "Adoption should really not change expandos"
+    );
+
+    // Repeat but now with an object that has a reference from the
+    // window it's being cloned into.
+    node = window.document.createElement("div");
+    node.expando = 6;
+
+    browser.test.assertEq(
+      node.expando,
+      6,
+      "We should be able to see our expando (2)"
+    );
+    browser.test.assertEq(
+      node.wrappedJSObject.expando,
+      undefined,
+      "Underlying object should not have our expando (2)"
+    );
+
+    window.frames[0].wrappedJSObject.incoming = node.wrappedJSObject;
+
+    window.frames[0].document.adoptNode(node);
+    browser.test.assertEq(
+      node.expando,
+      6,
+      "Adoption should not change expandos (2)"
+    );
+    browser.test.assertEq(
+      node.wrappedJSObject.expando,
+      undefined,
+      "Adoption should really not change expandos (2)"
+    );
+
+    // Repeat once more, now with an expando that refers to the object itself.
+    node = window.document.createElement("div");
+    node.expando = node;
+
+    browser.test.assertEq(
+      node.expando,
+      node,
+      "We should be able to see our self-referential expando (3)"
+    );
+    browser.test.assertEq(
+      node.wrappedJSObject.expando,
+      undefined,
+      "Underlying object should not have our self-referential expando (3)"
+    );
+
+    window.frames[0].document.adoptNode(node);
+    browser.test.assertEq(
+      node.expando,
+      node,
+      "Adoption should not change self-referential expando (3)"
+    );
+    browser.test.assertEq(
+      node.wrappedJSObject.expando,
+      undefined,
+      "Adoption should really not change self-referential expando (3)"
+    );
+
+    // And test what happens if we now set document.domain and cause
+    // wrapper remapping.
+    let doc = window.frames[0].document;
+    // eslint-disable-next-line no-self-assign
+    doc.domain = doc.domain;
+
+    browser.test.notifyPass("contentScriptAdoptionWithXrays");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_toplevel.html"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_toplevel.html`
+  );
+
+  await extension.awaitFinish("contentScriptAdoptionWithXrays");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_alarms.js b/toolkit/components/extensions/test/xpcshell/test_ext_alarms.js
new file mode 100644
index 0000000000..0751f7d573
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_alarms.js
@@ -0,0 +1,219 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+"use strict";
+
+add_task(async function test_alarm_without_permissions() {
+  function backgroundScript() {
+    browser.test.assertTrue(
+      !browser.alarms,
+      "alarm API is not available when the alarm permission is not required"
+    );
+    browser.test.notifyPass("alarms_permission");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: [],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarms_permission");
+  await extension.unload();
+});
+
+add_task(async function test_alarm_clear_non_matching_name() {
+  async function backgroundScript() {
+    let ALARM_NAME = "test_ext_alarms";
+
+    browser.alarms.create(ALARM_NAME, { when: Date.now() + 2000000 });
+
+    let wasCleared = await browser.alarms.clear(ALARM_NAME + "1");
+    browser.test.assertFalse(wasCleared, "alarm was not cleared");
+
+    let alarms = await browser.alarms.getAll();
+    browser.test.assertEq(1, alarms.length, "alarm was not removed");
+    browser.test.notifyPass("alarm-clear");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarm-clear");
+  await extension.unload();
+});
+
+add_task(async function test_alarm_get_and_clear_single_argument() {
+  async function backgroundScript() {
+    browser.alarms.create({ when: Date.now() + 2000000 });
+
+    let alarm = await browser.alarms.get();
+    browser.test.assertEq("", alarm.name, "expected alarm returned");
+
+    let wasCleared = await browser.alarms.clear();
+    browser.test.assertTrue(wasCleared, "alarm was cleared");
+
+    let alarms = await browser.alarms.getAll();
+    browser.test.assertEq(0, alarms.length, "alarm was removed");
+
+    browser.test.notifyPass("alarm-single-arg");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarm-single-arg");
+  await extension.unload();
+});
+
+add_task(async function test_get_get_all_clear_all_alarms() {
+  async function backgroundScript() {
+    const ALARM_NAME = "test_alarm";
+
+    let suffixes = [0, 1, 2];
+
+    for (let suffix of suffixes) {
+      browser.alarms.create(ALARM_NAME + suffix, {
+        when: Date.now() + (suffix + 1) * 10000,
+      });
+    }
+
+    let alarms = await browser.alarms.getAll();
+    browser.test.assertEq(
+      suffixes.length,
+      alarms.length,
+      "expected number of alarms were found"
+    );
+    alarms.forEach((alarm, index) => {
+      browser.test.assertEq(
+        ALARM_NAME + index,
+        alarm.name,
+        "alarm has the expected name"
+      );
+    });
+
+    for (let suffix of suffixes) {
+      let alarm = await browser.alarms.get(ALARM_NAME + suffix);
+      browser.test.assertEq(
+        ALARM_NAME + suffix,
+        alarm.name,
+        "alarm has the expected name"
+      );
+      browser.test.sendMessage(`get-${suffix}`);
+    }
+
+    let wasCleared = await browser.alarms.clear(ALARM_NAME + suffixes[0]);
+    browser.test.assertTrue(wasCleared, "alarm was cleared");
+
+    alarms = await browser.alarms.getAll();
+    browser.test.assertEq(2, alarms.length, "alarm was removed");
+
+    let alarm = await browser.alarms.get(ALARM_NAME + suffixes[0]);
+    browser.test.assertEq(undefined, alarm, "non-existent alarm is undefined");
+    browser.test.sendMessage(`get-invalid`);
+
+    wasCleared = await browser.alarms.clearAll();
+    browser.test.assertTrue(wasCleared, "alarms were cleared");
+
+    alarms = await browser.alarms.getAll();
+    browser.test.assertEq(0, alarms.length, "no alarms exist");
+    browser.test.sendMessage("clearAll");
+    browser.test.sendMessage("clear");
+    browser.test.sendMessage("getAll");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await Promise.all([
+    extension.startup(),
+    extension.awaitMessage("getAll"),
+    extension.awaitMessage("get-0"),
+    extension.awaitMessage("get-1"),
+    extension.awaitMessage("get-2"),
+    extension.awaitMessage("clear"),
+    extension.awaitMessage("get-invalid"),
+    extension.awaitMessage("clearAll"),
+  ]);
+  await extension.unload();
+});
+
+async function test_alarm_fires_with_options(alarmCreateOptions) {
+  info(
+    `Test alarms.create fires with options: ${JSON.stringify(
+      alarmCreateOptions
+    )}`
+  );
+
+  function backgroundScript(createOptions) {
+    let ALARM_NAME = "test_ext_alarms";
+    let timer;
+
+    browser.alarms.onAlarm.addListener(alarm => {
+      browser.test.assertEq(
+        ALARM_NAME,
+        alarm.name,
+        "alarm has the expected name"
+      );
+      clearTimeout(timer);
+      browser.test.notifyPass("alarms-create-with-options");
+    });
+
+    browser.alarms.create(ALARM_NAME, createOptions);
+
+    timer = setTimeout(async () => {
+      browser.test.fail("alarm fired within expected time");
+      let wasCleared = await browser.alarms.clear(ALARM_NAME);
+      browser.test.assertTrue(wasCleared, "alarm was cleared");
+      browser.test.notifyFail("alarms-create-with-options");
+    }, 10000);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    // Pass the alarms.create options to the background page.
+    background: `(${backgroundScript})(${JSON.stringify(alarmCreateOptions)})`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarms-create-with-options");
+
+  // Defer unloading the extension so the asynchronous event listener
+  // reply finishes.
+  await new Promise(resolve => setTimeout(resolve, 0));
+  await extension.unload();
+}
+
+add_task(async function test_alarm_fires() {
+  Services.prefs.setBoolPref(
+    "privacy.resistFingerprinting.reduceTimerPrecision.jitter",
+    false
+  );
+
+  await test_alarm_fires_with_options({ delayInMinutes: 0.01 });
+  await test_alarm_fires_with_options({ when: Date.now() + 1000 });
+  await test_alarm_fires_with_options({ delayInMinutes: -10 });
+  await test_alarm_fires_with_options({ when: Date.now() - 1000 });
+
+  Services.prefs.clearUserPref(
+    "privacy.resistFingerprinting.reduceTimerPrecision.jitter"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_alarms_does_not_fire.js b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_does_not_fire.js
new file mode 100644
index 0000000000..fe385004ba
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_does_not_fire.js
@@ -0,0 +1,34 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+"use strict";
+
+add_task(async function test_cleared_alarm_does_not_fire() {
+  async function backgroundScript() {
+    let ALARM_NAME = "test_ext_alarms";
+
+    browser.alarms.onAlarm.addListener(alarm => {
+      browser.test.fail("cleared alarm does not fire");
+      browser.test.notifyFail("alarm-cleared");
+    });
+    browser.alarms.create(ALARM_NAME, { when: Date.now() + 1000 });
+
+    let wasCleared = await browser.alarms.clear(ALARM_NAME);
+    browser.test.assertTrue(wasCleared, "alarm was cleared");
+
+    await new Promise(resolve => setTimeout(resolve, 2000));
+
+    browser.test.notifyPass("alarm-cleared");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarm-cleared");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_alarms_periodic.js b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_periodic.js
new file mode 100644
index 0000000000..b78d6da649
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_periodic.js
@@ -0,0 +1,50 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+"use strict";
+
+add_task(async function test_periodic_alarm_fires() {
+  function backgroundScript() {
+    const ALARM_NAME = "test_ext_alarms";
+    let count = 0;
+    let timer;
+
+    browser.alarms.onAlarm.addListener(alarm => {
+      browser.test.assertEq(
+        alarm.name,
+        ALARM_NAME,
+        "alarm has the expected name"
+      );
+      if (count++ === 3) {
+        clearTimeout(timer);
+        browser.alarms.clear(ALARM_NAME).then(wasCleared => {
+          browser.test.assertTrue(wasCleared, "alarm was cleared");
+
+          browser.test.notifyPass("alarm-periodic");
+        });
+      }
+    });
+
+    browser.alarms.create(ALARM_NAME, { periodInMinutes: 0.02 });
+
+    timer = setTimeout(async () => {
+      browser.test.fail("alarm fired expected number of times");
+
+      let wasCleared = await browser.alarms.clear(ALARM_NAME);
+      browser.test.assertTrue(wasCleared, "alarm was cleared");
+
+      browser.test.notifyFail("alarm-periodic");
+    }, 30000);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarm-periodic");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_alarms_replaces.js b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_replaces.js
new file mode 100644
index 0000000000..0d7597fa5a
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_replaces.js
@@ -0,0 +1,56 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_duplicate_alarm_name_replaces_alarm() {
+  function backgroundScript() {
+    let count = 0;
+
+    browser.alarms.onAlarm.addListener(async alarm => {
+      browser.test.assertEq(
+        "replaced alarm",
+        alarm.name,
+        "Expected last alarm"
+      );
+      browser.test.assertEq(
+        0,
+        count++,
+        "duplicate named alarm replaced existing alarm"
+      );
+      let results = await browser.alarms.getAll();
+
+      // "replaced alarm" is expected to be replaced with a non-repeating
+      // alarm, so it should not appear in the list of alarms.
+      browser.test.assertEq(1, results.length, "exactly one alarms exists");
+      browser.test.assertEq(
+        "unrelated alarm",
+        results[0].name,
+        "remaining alarm has the expected name"
+      );
+
+      browser.test.notifyPass("alarm-duplicate");
+    });
+
+    // Alarm that is so far in the future that it is never triggered.
+    browser.alarms.create("unrelated alarm", { delayInMinutes: 60 });
+    // Alarm that repeats.
+    browser.alarms.create("replaced alarm", {
+      delayInMinutes: 1 / 60,
+      periodInMinutes: 1 / 60,
+    });
+    // Before the repeating alarm is triggered, it is immediately replaced with
+    // a non-repeating alarm.
+    browser.alarms.create("replaced alarm", { delayInMinutes: 3 / 60 });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarm-duplicate");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_api_permissions.js b/toolkit/components/extensions/test/xpcshell/test_ext_api_permissions.js
new file mode 100644
index 0000000000..4be29dc848
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_api_permissions.js
@@ -0,0 +1,76 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+let { Management } = ChromeUtils.import(
+  "resource://gre/modules/Extension.jsm",
+  null
+);
+function getNextContext() {
+  return new Promise(resolve => {
+    Management.on("proxy-context-load", function listener(type, context) {
+      Management.off("proxy-context-load", listener);
+      resolve(context);
+    });
+  });
+}
+
+add_task(async function test_storage_api_without_permissions() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      // Force API initialization.
+      try {
+        browser.storage.onChanged.addListener(() => {});
+      } catch (e) {
+        // Ignore.
+      }
+    },
+
+    manifest: {
+      permissions: [],
+    },
+  });
+
+  let contextPromise = getNextContext();
+  await extension.startup();
+
+  let context = await contextPromise;
+
+  // Force API initialization.
+  void context.apiObj;
+
+  ok(
+    !("storage" in context.apiObj),
+    "The storage API should not be initialized"
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_storage_api_with_permissions() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.storage.onChanged.addListener(() => {});
+    },
+
+    manifest: {
+      permissions: ["storage"],
+    },
+  });
+
+  let contextPromise = getNextContext();
+  await extension.startup();
+
+  let context = await contextPromise;
+
+  // Force API initialization.
+  void context.apiObj;
+
+  equal(
+    typeof context.apiObj.storage,
+    "object",
+    "The storage API should be initialized"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_api_injection.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_api_injection.js
new file mode 100644
index 0000000000..a603b03a29
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_api_injection.js
@@ -0,0 +1,35 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function testBackgroundWindow() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.log("background script executed");
+      window.location =
+        "http://example.com/data/file_privilege_escalation.html";
+    },
+  });
+
+  let awaitConsole = new Promise(resolve => {
+    Services.console.registerListener(function listener(message) {
+      if (/WebExt Privilege Escalation/.test(message.message)) {
+        Services.console.unregisterListener(listener);
+        resolve(message);
+      }
+    });
+  });
+
+  await extension.startup();
+
+  let message = await awaitConsole;
+  ok(
+    message.message.includes(
+      "WebExt Privilege Escalation: typeof(browser) = undefined"
+    ),
+    "Document does not have `browser` APIs."
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_early_shutdown.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_early_shutdown.js
new file mode 100644
index 0000000000..ec9d9a6c43
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_early_shutdown.js
@@ -0,0 +1,195 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { BrowserTestUtils } = ChromeUtils.import(
+  "resource://testing-common/BrowserTestUtils.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "43"
+);
+
+let {
+  promiseRestartManager,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  true
+);
+
+let { Management } = ChromeUtils.import(
+  "resource://gre/modules/Extension.jsm",
+  null
+);
+
+// Crashes a <browser>'s remote process.
+// Based on BrowserTestUtils.crashFrame.
+function crashFrame(browser) {
+  if (!browser.isRemoteBrowser) {
+    // The browser should be remote, or the test runner would be killed.
+    throw new Error("<browser> must be remote");
+  }
+
+  // Trigger crash by sending a message to BrowserTestUtils actor.
+  BrowserTestUtils.sendAsyncMessage(
+    browser.browsingContext,
+    "BrowserTestUtils:CrashFrame",
+    {}
+  );
+}
+
+// Verifies that a delayed background page is not loaded when an extension is
+// shut down during startup.
+add_task(async function test_unload_extension_before_background_page_startup() {
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background() {
+      browser.test.sendMessage("background_startup_observed");
+    },
+  });
+
+  // Delayed startup are only enabled for browser (re)starts, so we need to
+  // install the extension first, and then unload it.
+
+  await extension.startup();
+  await extension.awaitMessage("background_startup_observed");
+
+  // Now the actual test: Unloading an extension before the startup has
+  // finished should interrupt the start-up and abort pending delayed loads.
+  info("Starting extension whose startup will be interrupted");
+  ExtensionParent._resetStartupPromises();
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  let extensionBrowserInsertions = 0;
+  let onExtensionBrowserInserted = () => ++extensionBrowserInsertions;
+  Management.on("extension-browser-inserted", onExtensionBrowserInserted);
+
+  info("Unloading extension before the delayed background page starts loading");
+  await extension.addon.disable();
+
+  // Re-enable the add-on to let enough time pass to load a whole background
+  // page. If at the end of this the original background page hasn't loaded,
+  // we can consider the test successful.
+  await extension.addon.enable();
+
+  // Trigger the notification that would load a background page.
+  info("Forcing pending delayed background page to load");
+  Services.obs.notifyObservers(null, "sessionstore-windows-restored");
+
+  // This is the expected message from the re-enabled add-on.
+  await extension.awaitMessage("background_startup_observed");
+  await extension.unload();
+
+  await promiseShutdownManager();
+  ExtensionParent._resetStartupPromises();
+
+  Management.off("extension-browser-inserted", onExtensionBrowserInserted);
+  Assert.equal(
+    extensionBrowserInsertions,
+    1,
+    "Extension browser should have been inserted only once"
+  );
+});
+
+// Verifies that the "build" method of BackgroundPage in ext-backgroundPage.js
+// does not deadlock when startup is interrupted by extension shutdown.
+add_task(async function test_unload_extension_during_background_page_startup() {
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background() {
+      browser.test.sendMessage("background_starting");
+    },
+  });
+
+  // Delayed startup are only enabled for browser (re)starts, so we need to
+  // install the extension first, and then reload it.
+  await extension.startup();
+  await extension.awaitMessage("background_starting");
+
+  ExtensionParent._resetStartupPromises();
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  let bgStartupPromise = new Promise(resolve => {
+    function onBackgroundPageDone(eventName) {
+      extension.extension.off("background-page-started", onBackgroundPageDone);
+      extension.extension.off("background-page-aborted", onBackgroundPageDone);
+
+      if (eventName === "background-page-aborted") {
+        info("Background page startup was interrupted");
+        resolve("bg_aborted");
+      } else {
+        info("Background page startup finished normally");
+        resolve("bg_fully_loaded");
+      }
+    }
+    extension.extension.on("background-page-started", onBackgroundPageDone);
+    extension.extension.on("background-page-aborted", onBackgroundPageDone);
+  });
+
+  let bgStartingPromise = new Promise(resolve => {
+    let backgroundLoadCount = 0;
+    let backgroundPageUrl = extension.extension.baseURI.resolve(
+      "_generated_background_page.html"
+    );
+
+    // Prevent the background page from actually loading.
+    Management.once("extension-browser-inserted", (eventName, browser) => {
+      // Intercept background page load.
+      let browserLoadURI = browser.loadURI;
+      browser.loadURI = function() {
+        Assert.equal(++backgroundLoadCount, 1, "loadURI should be called once");
+        Assert.equal(
+          arguments[0],
+          backgroundPageUrl,
+          "Expected background page"
+        );
+        // Reset to "about:blank" to not load the actual background page.
+        arguments[0] = "about:blank";
+        browserLoadURI.apply(this, arguments);
+
+        // And force the extension process to crash.
+        if (browser.isRemote) {
+          crashFrame(browser);
+        } else {
+          // If extensions are not running in out-of-process mode, then the
+          // non-remote process should not be killed (or the test runner dies).
+          // Remove <browser> instead, to simulate the immediate disconnection
+          // of the message manager (that would happen if the process crashed).
+          browser.remove();
+        }
+        resolve();
+      };
+    });
+  });
+
+  // Force background page to initialize.
+  Services.obs.notifyObservers(null, "sessionstore-windows-restored");
+  await bgStartingPromise;
+
+  await extension.unload();
+  await promiseShutdownManager();
+
+  // This part is the regression test for bug 1501375. It verifies that the
+  // background building completes eventually.
+  // If it does not, then the next line will cause a timeout.
+  info("Waiting for background builder to finish");
+  let bgLoadState = await bgStartupPromise;
+  Assert.equal(bgLoadState, "bg_aborted", "Startup should be interrupted");
+
+  ExtensionParent._resetStartupPromises();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_generated_load_events.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_generated_load_events.js
new file mode 100644
index 0000000000..cac574b8ca
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_generated_load_events.js
@@ -0,0 +1,23 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* eslint-disable mozilla/balanced-listeners */
+
+add_task(async function test_DOMContentLoaded_in_generated_background_page() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      function reportListener(event) {
+        browser.test.sendMessage("eventname", event.type);
+      }
+      document.addEventListener("DOMContentLoaded", reportListener);
+      window.addEventListener("load", reportListener);
+    },
+  });
+
+  await extension.startup();
+  equal("DOMContentLoaded", await extension.awaitMessage("eventname"));
+  equal("load", await extension.awaitMessage("eventname"));
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_generated_reload.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_generated_reload.js
new file mode 100644
index 0000000000..a22db9d582
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_generated_reload.js
@@ -0,0 +1,24 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_reload_generated_background_page() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      if (location.hash !== "#firstrun") {
+        browser.test.sendMessage("first run");
+        location.hash = "#firstrun";
+        browser.test.assertEq("#firstrun", location.hash);
+        location.reload();
+      } else {
+        browser.test.notifyPass("second run");
+      }
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("first run");
+  await extension.awaitFinish("second run");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_global_history.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_global_history.js
new file mode 100644
index 0000000000..eaf20827e5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_global_history.js
@@ -0,0 +1,24 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { PlacesTestUtils } = ChromeUtils.import(
+  "resource://testing-common/PlacesTestUtils.jsm"
+);
+
+add_task(async function test_global_history() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.sendMessage("background-loaded", location.href);
+    },
+  });
+
+  await extension.startup();
+
+  let backgroundURL = await extension.awaitMessage("background-loaded");
+
+  await extension.unload();
+
+  let exists = await PlacesTestUtils.isPageInDB(backgroundURL);
+  ok(!exists, "Background URL should not be in history database");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_private_browsing.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_private_browsing.js
new file mode 100644
index 0000000000..5075e643be
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_private_browsing.js
@@ -0,0 +1,46 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_background_incognito() {
+  info(
+    "Test background page incognito value with permanent private browsing enabled"
+  );
+
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+  Services.prefs.setBoolPref("browser.privatebrowsing.autostart", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("browser.privatebrowsing.autostart");
+    Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    async background() {
+      browser.test.assertEq(
+        window,
+        browser.extension.getBackgroundPage(),
+        "Caller should be able to access itself as a background page"
+      );
+      browser.test.assertEq(
+        window,
+        await browser.runtime.getBackgroundPage(),
+        "Caller should be able to access itself as a background page"
+      );
+
+      browser.test.assertEq(
+        browser.extension.inIncognitoContext,
+        true,
+        "inIncognitoContext is true for permanent private browsing"
+      );
+
+      browser.test.notifyPass("incognito");
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitFinish("incognito");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_runtime_connect_params.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_runtime_connect_params.js
new file mode 100644
index 0000000000..aa0976434b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_runtime_connect_params.js
@@ -0,0 +1,88 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+function backgroundScript() {
+  let received_ports_number = 0;
+
+  const expected_received_ports_number = 1;
+
+  function countReceivedPorts(port) {
+    received_ports_number++;
+
+    if (port.name == "check-results") {
+      browser.runtime.onConnect.removeListener(countReceivedPorts);
+
+      browser.test.assertEq(
+        expected_received_ports_number,
+        received_ports_number,
+        "invalid connect should not create a port"
+      );
+
+      browser.test.notifyPass("runtime.connect invalid params");
+    }
+  }
+
+  browser.runtime.onConnect.addListener(countReceivedPorts);
+
+  let childFrame = document.createElement("iframe");
+  childFrame.src = "extensionpage.html";
+  document.body.appendChild(childFrame);
+}
+
+function senderScript() {
+  let detected_invalid_connect_params = 0;
+
+  const invalid_connect_params = [
+    // too many params
+    [
+      "fake-extensions-id",
+      { name: "fake-conn-name" },
+      "unexpected third params",
+    ],
+    // invalid params format
+    [{}, {}],
+    ["fake-extensions-id", "invalid-connect-info-format"],
+  ];
+  const expected_detected_invalid_connect_params =
+    invalid_connect_params.length;
+
+  function assertInvalidConnectParamsException(params) {
+    try {
+      browser.runtime.connect(...params);
+    } catch (e) {
+      detected_invalid_connect_params++;
+      browser.test.assertTrue(
+        e.toString().includes("Incorrect argument types for runtime.connect."),
+        "exception message is correct"
+      );
+    }
+  }
+  for (let params of invalid_connect_params) {
+    assertInvalidConnectParamsException(params);
+  }
+  browser.test.assertEq(
+    expected_detected_invalid_connect_params,
+    detected_invalid_connect_params,
+    "all invalid runtime.connect params detected"
+  );
+
+  browser.runtime.connect(browser.runtime.id, { name: "check-results" });
+}
+
+let extensionData = {
+  background: backgroundScript,
+  files: {
+    "senderScript.js": senderScript,
+    "extensionpage.html": `<!DOCTYPE html><meta charset="utf-8"><script src="senderScript.js"></script>`,
+  },
+};
+
+add_task(async function test_backgroundRuntimeConnectParams() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await extension.awaitFinish("runtime.connect invalid params");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_sub_windows.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_sub_windows.js
new file mode 100644
index 0000000000..1c3180b1b6
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_sub_windows.js
@@ -0,0 +1,46 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function testBackgroundWindow() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.log("background script executed");
+
+      browser.test.sendMessage("background-script-load");
+
+      let img = document.createElement("img");
+      img.src =
+        "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7";
+      document.body.appendChild(img);
+
+      img.onload = () => {
+        browser.test.log("image loaded");
+
+        let iframe = document.createElement("iframe");
+        iframe.src = "about:blank?1";
+
+        iframe.onload = () => {
+          browser.test.log("iframe loaded");
+          setTimeout(() => {
+            browser.test.notifyPass("background sub-window test done");
+          }, 0);
+        };
+        document.body.appendChild(iframe);
+      };
+    },
+  });
+
+  let loadCount = 0;
+  extension.onMessage("background-script-load", () => {
+    loadCount++;
+  });
+
+  await extension.startup();
+
+  await extension.awaitFinish("background sub-window test done");
+
+  equal(loadCount, 1, "background script loaded only once");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_teardown.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_teardown.js
new file mode 100644
index 0000000000..013a68726c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_teardown.js
@@ -0,0 +1,99 @@
+"use strict";
+
+add_task(async function test_background_reload_and_unload() {
+  let events = [];
+  {
+    let { Management } = ChromeUtils.import(
+      "resource://gre/modules/Extension.jsm",
+      null
+    );
+    let record = (type, extensionContext) => {
+      let eventType = type == "proxy-context-load" ? "load" : "unload";
+      let url = extensionContext.uri.spec;
+      let extensionId = extensionContext.extension.id;
+      events.push({ eventType, url, extensionId });
+    };
+
+    Management.on("proxy-context-load", record);
+    Management.on("proxy-context-unload", record);
+    registerCleanupFunction(() => {
+      Management.off("proxy-context-load", record);
+      Management.off("proxy-context-unload", record);
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.onMessage.addListener(msg => {
+        browser.test.assertEq("reload-background", msg);
+        location.reload();
+      });
+      browser.test.sendMessage("background-url", location.href);
+    },
+  });
+
+  await extension.startup();
+  let backgroundUrl = await extension.awaitMessage("background-url");
+
+  let contextEvents = events.splice(0);
+  equal(
+    contextEvents.length,
+    1,
+    "ExtensionContext state change after loading an extension"
+  );
+  equal(contextEvents[0].eventType, "load");
+  equal(
+    contextEvents[0].url,
+    backgroundUrl,
+    "The ExtensionContext should be the background page"
+  );
+
+  extension.sendMessage("reload-background");
+  await extension.awaitMessage("background-url");
+
+  contextEvents = events.splice(0);
+  equal(
+    contextEvents.length,
+    2,
+    "ExtensionContext state changes after reloading the background page"
+  );
+  equal(
+    contextEvents[0].eventType,
+    "unload",
+    "Unload ExtensionContext of background page"
+  );
+  equal(
+    contextEvents[0].url,
+    backgroundUrl,
+    "ExtensionContext URL = background"
+  );
+  equal(
+    contextEvents[1].eventType,
+    "load",
+    "Create new ExtensionContext for background page"
+  );
+  equal(
+    contextEvents[1].url,
+    backgroundUrl,
+    "ExtensionContext URL = background"
+  );
+
+  await extension.unload();
+
+  contextEvents = events.splice(0);
+  equal(
+    contextEvents.length,
+    1,
+    "ExtensionContext state change after unloading the extension"
+  );
+  equal(
+    contextEvents[0].eventType,
+    "unload",
+    "Unload ExtensionContext for background page after extension unloads"
+  );
+  equal(
+    contextEvents[0].url,
+    backgroundUrl,
+    "ExtensionContext URL = background"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_telemetry.js
new file mode 100644
index 0000000000..8ca76ea3c2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_telemetry.js
@@ -0,0 +1,104 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const HISTOGRAM = "WEBEXT_BACKGROUND_PAGE_LOAD_MS";
+const HISTOGRAM_KEYED = "WEBEXT_BACKGROUND_PAGE_LOAD_MS_BY_ADDONID";
+
+add_task(async function test_telemetry() {
+  Services.prefs.setBoolPref(
+    "toolkit.telemetry.testing.overrideProductsCheck",
+    true
+  );
+
+  let extension1 = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.sendMessage("loaded");
+    },
+  });
+
+  let extension2 = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.sendMessage("loaded");
+    },
+  });
+
+  clearHistograms();
+
+  assertHistogramEmpty(HISTOGRAM);
+  assertKeyedHistogramEmpty(HISTOGRAM_KEYED);
+
+  await extension1.startup();
+  await extension1.awaitMessage("loaded");
+
+  const processSnapshot = snapshot => {
+    return snapshot.sum > 0;
+  };
+
+  const processKeyedSnapshot = snapshot => {
+    let res = {};
+    for (let key of Object.keys(snapshot)) {
+      res[key] = snapshot[key].sum > 0;
+    }
+    return res;
+  };
+
+  assertHistogramSnapshot(
+    HISTOGRAM,
+    { processSnapshot, expectedValue: true },
+    `Data recorded for first extension for histogram: ${HISTOGRAM}.`
+  );
+
+  assertHistogramSnapshot(
+    HISTOGRAM_KEYED,
+    {
+      keyed: true,
+      processSnapshot: processKeyedSnapshot,
+      expectedValue: {
+        [extension1.extension.id]: true,
+      },
+    },
+    `Data recorded for first extension for histogram ${HISTOGRAM_KEYED}`
+  );
+
+  let histogram = Services.telemetry.getHistogramById(HISTOGRAM);
+  let histogramKeyed = Services.telemetry.getKeyedHistogramById(
+    HISTOGRAM_KEYED
+  );
+  let histogramSum = histogram.snapshot().sum;
+  let histogramSumExt1 = histogramKeyed.snapshot()[extension1.extension.id].sum;
+
+  await extension2.startup();
+  await extension2.awaitMessage("loaded");
+
+  assertHistogramSnapshot(
+    HISTOGRAM,
+    {
+      processSnapshot: snapshot => snapshot.sum > histogramSum,
+      expectedValue: true,
+    },
+    `Data recorded for second extension for histogram: ${HISTOGRAM}.`
+  );
+
+  assertHistogramSnapshot(
+    HISTOGRAM_KEYED,
+    {
+      keyed: true,
+      processSnapshot: processKeyedSnapshot,
+      expectedValue: {
+        [extension1.extension.id]: true,
+        [extension2.extension.id]: true,
+      },
+    },
+    `Data recorded for second extension for histogram ${HISTOGRAM_KEYED}`
+  );
+
+  equal(
+    histogramKeyed.snapshot()[extension1.extension.id].sum,
+    histogramSumExt1,
+    `Data recorder for first extension is unchanged on the keyed histogram ${HISTOGRAM_KEYED}`
+  );
+
+  await extension1.unload();
+  await extension2.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_background_window_properties.js b/toolkit/components/extensions/test/xpcshell/test_ext_background_window_properties.js
new file mode 100644
index 0000000000..fb2ca27482
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_background_window_properties.js
@@ -0,0 +1,41 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function testBackgroundWindowProperties() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      let expectedValues = {
+        screenX: 0,
+        screenY: 0,
+        outerWidth: 0,
+        outerHeight: 0,
+      };
+
+      for (let k in window) {
+        try {
+          if (k in expectedValues) {
+            browser.test.assertEq(
+              expectedValues[k],
+              window[k],
+              `should return the expected value for window property: ${k}`
+            );
+          } else {
+            void window[k];
+          }
+        } catch (e) {
+          browser.test.assertEq(
+            null,
+            e,
+            `unexpected exception accessing window property: ${k}`
+          );
+        }
+      }
+
+      browser.test.notifyPass("background.testWindowProperties.done");
+    },
+  });
+  await extension.startup();
+  await extension.awaitFinish("background.testWindowProperties.done");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_brokenlinks.js b/toolkit/components/extensions/test/xpcshell/test_ext_brokenlinks.js
new file mode 100644
index 0000000000..c066147268
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_brokenlinks.js
@@ -0,0 +1,54 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/*
+ * This test extension has a background script 'missing.js' that is missing
+ * from the XPI. Such an extension should install/uninstall cleanly without
+ * causing timeouts.
+ */
+add_task(async function testXPIMissingBackGroundScript() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      background: {
+        scripts: ["missing.js"],
+      },
+    },
+  });
+
+  await extension.startup();
+  await extension.unload();
+  ok(true, "load/unload completed without timing out");
+});
+
+/*
+ * This test extension includes a page with a missing script. The
+ * extension should install/uninstall cleanly without causing hangs.
+ */
+add_task(async function testXPIMissingPageScript() {
+  async function pageScript() {
+    browser.test.sendMessage("pageReady");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.sendMessage("ready", browser.runtime.getURL("page.html"));
+    },
+    files: {
+      "page.html": `<html><head>
+                    <script src="missing.js"></script>
+                    <script src="page.js"></script>
+                    </head></html>`,
+      "page.js": pageScript,
+    },
+  });
+
+  await extension.startup();
+  let url = await extension.awaitMessage("ready");
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+  await extension.awaitMessage("pageReady");
+  await extension.unload();
+  await contentPage.close();
+
+  ok(true, "load/unload completed without timing out");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings.js b/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings.js
new file mode 100644
index 0000000000..ed4eb8a664
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings.js
@@ -0,0 +1,454 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "Preferences",
+  "resource://gre/modules/Preferences.jsm"
+);
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "AddonManager",
+  "resource://gre/modules/AddonManager.jsm"
+);
+
+// The test extension uses an insecure update url.
+Services.prefs.setBoolPref("extensions.checkUpdateSecurity", false);
+
+const SETTINGS_ID = "test_settings_staged_restart_webext@tests.mozilla.org";
+
+const {
+  createAppInfo,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "42", "42");
+
+add_task(async function test_browser_settings() {
+  const PERM_DENY_ACTION = Services.perms.DENY_ACTION;
+  const PERM_UNKNOWN_ACTION = Services.perms.UNKNOWN_ACTION;
+
+  // Create an object to hold the values to which we will initialize the prefs.
+  const PREFS = {
+    "browser.cache.disk.enable": true,
+    "browser.cache.memory.enable": true,
+    "dom.popup_allowed_events": Preferences.get("dom.popup_allowed_events"),
+    "image.animation_mode": "none",
+    "permissions.default.desktop-notification": PERM_UNKNOWN_ACTION,
+    "ui.context_menus.after_mouseup": false,
+    "browser.tabs.closeTabByDblclick": false,
+    "browser.tabs.loadBookmarksInTabs": false,
+    "browser.search.openintab": false,
+    "browser.tabs.insertRelatedAfterCurrent": true,
+    "browser.tabs.insertAfterCurrent": false,
+    "browser.display.document_color_use": 1,
+    "browser.display.use_document_fonts": 1,
+    "browser.zoom.full": true,
+    "browser.zoom.siteSpecific": true,
+  };
+
+  async function background() {
+    let listeners = new Set([]);
+    browser.test.onMessage.addListener(async (msg, apiName, value) => {
+      let apiObj = browser.browserSettings[apiName];
+      // Don't add more than one listner per apiName.  We leave the
+      // listener to ensure we do not get more calls than we expect.
+      if (!listeners.has(apiName)) {
+        apiObj.onChange.addListener(details => {
+          browser.test.sendMessage("onChange", {
+            details,
+            setting: apiName,
+          });
+        });
+        listeners.add(apiName);
+      }
+      let result = await apiObj.set({ value });
+      if (msg === "set") {
+        browser.test.assertTrue(result, "set returns true.");
+        browser.test.sendMessage("settingData", await apiObj.get({}));
+      } else {
+        browser.test.assertFalse(result, "set returns false for a no-op.");
+        browser.test.sendMessage("no-op set");
+      }
+    });
+  }
+
+  // Set prefs to our initial values.
+  for (let pref in PREFS) {
+    Preferences.set(pref, PREFS[pref]);
+  }
+
+  registerCleanupFunction(() => {
+    // Reset the prefs.
+    for (let pref in PREFS) {
+      Preferences.reset(pref);
+    }
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browserSettings"],
+    },
+    useAddonManager: "temporary",
+  });
+
+  await promiseStartupManager();
+  await extension.startup();
+
+  async function testSetting(setting, value, expected, expectedValue = value) {
+    extension.sendMessage("set", setting, value);
+    let data = await extension.awaitMessage("settingData");
+    let dataChange = await extension.awaitMessage("onChange");
+    equal(setting, dataChange.setting, "onChange fired");
+    equal(
+      data.value,
+      dataChange.details.value,
+      "onChange fired with correct value"
+    );
+    deepEqual(
+      data.value,
+      expectedValue,
+      `The ${setting} setting has the expected value.`
+    );
+    equal(
+      data.levelOfControl,
+      "controlled_by_this_extension",
+      `The ${setting} setting has the expected levelOfControl.`
+    );
+    for (let pref in expected) {
+      equal(
+        Preferences.get(pref),
+        expected[pref],
+        `${pref} set correctly for ${value}`
+      );
+    }
+  }
+
+  async function testNoOpSetting(setting, value, expected) {
+    extension.sendMessage("setNoOp", setting, value);
+    await extension.awaitMessage("no-op set");
+    for (let pref in expected) {
+      equal(
+        Preferences.get(pref),
+        expected[pref],
+        `${pref} set correctly for ${value}`
+      );
+    }
+  }
+
+  await testSetting("cacheEnabled", false, {
+    "browser.cache.disk.enable": false,
+    "browser.cache.memory.enable": false,
+  });
+  await testSetting("cacheEnabled", true, {
+    "browser.cache.disk.enable": true,
+    "browser.cache.memory.enable": true,
+  });
+
+  await testSetting("allowPopupsForUserEvents", false, {
+    "dom.popup_allowed_events": "",
+  });
+  await testSetting("allowPopupsForUserEvents", true, {
+    "dom.popup_allowed_events": PREFS["dom.popup_allowed_events"],
+  });
+
+  for (let value of ["normal", "none", "once"]) {
+    await testSetting("imageAnimationBehavior", value, {
+      "image.animation_mode": value,
+    });
+  }
+
+  await testSetting("webNotificationsDisabled", true, {
+    "permissions.default.desktop-notification": PERM_DENY_ACTION,
+  });
+  await testSetting("webNotificationsDisabled", false, {
+    // This pref is not defaulted on Android.
+    "permissions.default.desktop-notification":
+      AppConstants.MOZ_BUILD_APP !== "browser"
+        ? undefined
+        : PERM_UNKNOWN_ACTION,
+  });
+
+  // This setting is a no-op on Android.
+  if (AppConstants.platform === "android") {
+    await testNoOpSetting("contextMenuShowEvent", "mouseup", {
+      "ui.context_menus.after_mouseup": false,
+    });
+  } else {
+    await testSetting("contextMenuShowEvent", "mouseup", {
+      "ui.context_menus.after_mouseup": true,
+    });
+  }
+
+  // "mousedown" is also a no-op on Windows.
+  if (["android", "win"].includes(AppConstants.platform)) {
+    await testNoOpSetting("contextMenuShowEvent", "mousedown", {
+      "ui.context_menus.after_mouseup": AppConstants.platform === "win",
+    });
+  } else {
+    await testSetting("contextMenuShowEvent", "mousedown", {
+      "ui.context_menus.after_mouseup": false,
+    });
+  }
+
+  if (AppConstants.platform !== "android") {
+    await testSetting("closeTabsByDoubleClick", true, {
+      "browser.tabs.closeTabByDblclick": true,
+    });
+    await testSetting("closeTabsByDoubleClick", false, {
+      "browser.tabs.closeTabByDblclick": false,
+    });
+  }
+
+  await testSetting("ftpProtocolEnabled", false, {
+    "network.ftp.enabled": false,
+  });
+  await testSetting("ftpProtocolEnabled", true, {
+    "network.ftp.enabled": true,
+  });
+
+  await testSetting("newTabPosition", "afterCurrent", {
+    "browser.tabs.insertRelatedAfterCurrent": false,
+    "browser.tabs.insertAfterCurrent": true,
+  });
+  await testSetting("newTabPosition", "atEnd", {
+    "browser.tabs.insertRelatedAfterCurrent": false,
+    "browser.tabs.insertAfterCurrent": false,
+  });
+  await testSetting("newTabPosition", "relatedAfterCurrent", {
+    "browser.tabs.insertRelatedAfterCurrent": true,
+    "browser.tabs.insertAfterCurrent": false,
+  });
+
+  await testSetting("openBookmarksInNewTabs", true, {
+    "browser.tabs.loadBookmarksInTabs": true,
+  });
+  await testSetting("openBookmarksInNewTabs", false, {
+    "browser.tabs.loadBookmarksInTabs": false,
+  });
+
+  await testSetting("openSearchResultsInNewTabs", true, {
+    "browser.search.openintab": true,
+  });
+  await testSetting("openSearchResultsInNewTabs", false, {
+    "browser.search.openintab": false,
+  });
+
+  await testSetting("openUrlbarResultsInNewTabs", true, {
+    "browser.urlbar.openintab": true,
+  });
+  await testSetting("openUrlbarResultsInNewTabs", false, {
+    "browser.urlbar.openintab": false,
+  });
+
+  await testSetting("overrideDocumentColors", "high-contrast-only", {
+    "browser.display.document_color_use": 0,
+  });
+  await testSetting("overrideDocumentColors", "never", {
+    "browser.display.document_color_use": 1,
+  });
+  await testSetting("overrideDocumentColors", "always", {
+    "browser.display.document_color_use": 2,
+  });
+
+  await testSetting("useDocumentFonts", false, {
+    "browser.display.use_document_fonts": 0,
+  });
+  await testSetting("useDocumentFonts", true, {
+    "browser.display.use_document_fonts": 1,
+  });
+
+  await testSetting("zoomFullPage", true, {
+    "browser.zoom.full": true,
+  });
+  await testSetting("zoomFullPage", false, {
+    "browser.zoom.full": false,
+  });
+
+  await testSetting("zoomSiteSpecific", true, {
+    "browser.zoom.siteSpecific": true,
+  });
+  await testSetting("zoomSiteSpecific", false, {
+    "browser.zoom.siteSpecific": false,
+  });
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
+
+add_task(async function test_bad_value() {
+  async function background() {
+    await browser.test.assertRejects(
+      browser.browserSettings.contextMenuShowEvent.set({ value: "bad" }),
+      /bad is not a valid value for contextMenuShowEvent/,
+      "contextMenuShowEvent.set rejects with an invalid value."
+    );
+
+    await browser.test.assertRejects(
+      browser.browserSettings.overrideDocumentColors.set({ value: 2 }),
+      /2 is not a valid value for overrideDocumentColors/,
+      "overrideDocumentColors.set rejects with an invalid value."
+    );
+
+    await browser.test.assertRejects(
+      browser.browserSettings.overrideDocumentColors.set({ value: "bad" }),
+      /bad is not a valid value for overrideDocumentColors/,
+      "overrideDocumentColors.set rejects with an invalid value."
+    );
+
+    browser.test.sendMessage("done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browserSettings"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_bad_value_android() {
+  if (AppConstants.platform !== "android") {
+    return;
+  }
+
+  async function background() {
+    await browser.test.assertRejects(
+      browser.browserSettings.closeTabsByDoubleClick.set({ value: true }),
+      /android is not a supported platform for the closeTabsByDoubleClick setting/,
+      "closeTabsByDoubleClick.set rejects on Android."
+    );
+
+    await browser.test.assertRejects(
+      browser.browserSettings.closeTabsByDoubleClick.get({}),
+      /android is not a supported platform for the closeTabsByDoubleClick setting/,
+      "closeTabsByDoubleClick.get rejects on Android."
+    );
+
+    await browser.test.assertRejects(
+      browser.browserSettings.closeTabsByDoubleClick.clear({}),
+      /android is not a supported platform for the closeTabsByDoubleClick setting/,
+      "closeTabsByDoubleClick.clear rejects on Android."
+    );
+
+    browser.test.sendMessage("done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browserSettings"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+// Verifies settings remain after a staged update on restart.
+add_task(async function delay_updates_settings_after_restart() {
+  let server = AddonTestUtils.createHttpServer({ hosts: ["example.com"] });
+  AddonTestUtils.registerJSON(server, "/test_update.json", {
+    addons: {
+      "test_settings_staged_restart_webext@tests.mozilla.org": {
+        updates: [
+          {
+            version: "2.0",
+            update_link:
+              "http://example.com/addons/test_settings_staged_restart_v2.xpi",
+          },
+        ],
+      },
+    },
+  });
+  const update_xpi = AddonTestUtils.createTempXPIFile({
+    "manifest.json": {
+      manifest_version: 2,
+      name: "Delay Upgrade",
+      version: "2.0",
+      applications: {
+        gecko: { id: SETTINGS_ID },
+      },
+      permissions: ["browserSettings"],
+    },
+  });
+  server.registerFile(
+    `/addons/test_settings_staged_restart_v2.xpi`,
+    update_xpi
+  );
+
+  await AddonTestUtils.promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: {
+          id: SETTINGS_ID,
+          update_url: `http://example.com/test_update.json`,
+        },
+      },
+      permissions: ["browserSettings"],
+    },
+    background() {
+      browser.runtime.onUpdateAvailable.addListener(async details => {
+        if (details) {
+          await browser.browserSettings.webNotificationsDisabled.set({
+            value: true,
+          });
+          if (details.version) {
+            // This should be the version of the pending update.
+            browser.test.assertEq("2.0", details.version, "correct version");
+            browser.test.notifyPass("delay");
+          }
+        } else {
+          browser.test.fail("no details object passed");
+        }
+      });
+      browser.test.sendMessage("ready");
+    },
+  });
+
+  await Promise.all([extension.startup(), extension.awaitMessage("ready")]);
+
+  let prefname = "permissions.default.desktop-notification";
+  let val = Services.prefs.getIntPref(prefname);
+  Assert.notEqual(val, 2, "webNotificationsDisabled pref not set");
+
+  let update = await AddonTestUtils.promiseFindAddonUpdates(extension.addon);
+  let install = update.updateAvailable;
+  Assert.ok(install, `install is available ${update.error}`);
+
+  await AddonTestUtils.promiseCompleteAllInstalls([install]);
+
+  Assert.equal(install.state, AddonManager.STATE_POSTPONED);
+  await extension.awaitFinish("delay");
+
+  // restarting allows upgrade to proceed
+  await AddonTestUtils.promiseRestartManager();
+
+  await extension.awaitStartup();
+
+  // If an update is not handled correctly we would fail here.  Bug 1639705.
+  val = Services.prefs.getIntPref(prefname);
+  Assert.equal(val, 2, "webNotificationsDisabled pref set");
+
+  await extension.unload();
+  await AddonTestUtils.promiseShutdownManager();
+
+  val = Services.prefs.getIntPref(prefname);
+  Assert.notEqual(val, 2, "webNotificationsDisabled pref not set");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings_homepage.js b/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings_homepage.js
new file mode 100644
index 0000000000..8d1d16c743
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings_homepage.js
@@ -0,0 +1,36 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_homepage_get_without_set() {
+  async function background() {
+    let homepage = await browser.browserSettings.homepageOverride.get({});
+    browser.test.sendMessage("homepage", homepage);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browserSettings"],
+    },
+  });
+
+  let defaultHomepage = Services.prefs.getStringPref(
+    "browser.startup.homepage"
+  );
+
+  await extension.startup();
+  let homepage = await extension.awaitMessage("homepage");
+  equal(
+    homepage.value,
+    defaultHomepage,
+    "The homepageOverride setting has the expected value."
+  );
+  equal(
+    homepage.levelOfControl,
+    "not_controllable",
+    "The homepageOverride setting has the expected levelOfControl."
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_browsingData.js b/toolkit/components/extensions/test/xpcshell/test_ext_browsingData.js
new file mode 100644
index 0000000000..1df5e60478
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_browsingData.js
@@ -0,0 +1,48 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function testInvalidArguments() {
+  async function background() {
+    const UNSUPPORTED_DATA_TYPES = ["appcache", "fileSystems", "webSQL"];
+
+    await browser.test.assertRejects(
+      browser.browsingData.remove(
+        { originTypes: { protectedWeb: true } },
+        { cookies: true }
+      ),
+      "Firefox does not support protectedWeb or extension as originTypes.",
+      "Expected error received when using protectedWeb originType."
+    );
+
+    await browser.test.assertRejects(
+      browser.browsingData.removeCookies({ originTypes: { extension: true } }),
+      "Firefox does not support protectedWeb or extension as originTypes.",
+      "Expected error received when using extension originType."
+    );
+
+    for (let dataType of UNSUPPORTED_DATA_TYPES) {
+      let dataTypes = {};
+      dataTypes[dataType] = true;
+      browser.test.assertThrows(
+        () => browser.browsingData.remove({}, dataTypes),
+        /Type error for parameter dataToRemove/,
+        `Expected error received when using ${dataType} dataType.`
+      );
+    }
+
+    browser.test.notifyPass("invalidArguments");
+  }
+
+  let extensionData = {
+    background: background,
+    manifest: {
+      permissions: ["browsingData"],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitFinish("invalidArguments");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_browsingData_cookies_cache.js b/toolkit/components/extensions/test/xpcshell/test_ext_browsingData_cookies_cache.js
new file mode 100644
index 0000000000..612f2dd0f3
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_browsingData_cookies_cache.js
@@ -0,0 +1,456 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+"use strict";
+
+const { SiteDataTestUtils } = ChromeUtils.import(
+  "resource://testing-common/SiteDataTestUtils.jsm"
+);
+
+const COOKIE = {
+  host: "example.com",
+  name: "test_cookie",
+  path: "/",
+};
+const COOKIE_NET = {
+  host: "example.net",
+  name: "test_cookie",
+  path: "/",
+};
+const COOKIE_ORG = {
+  host: "example.org",
+  name: "test_cookie",
+  path: "/",
+};
+let since, oldCookie;
+
+function addCookie(cookie) {
+  Services.cookies.add(
+    cookie.host,
+    cookie.path,
+    cookie.name,
+    "test",
+    false,
+    false,
+    false,
+    Date.now() / 1000 + 10000,
+    {},
+    Ci.nsICookie.SAMESITE_NONE,
+    Ci.nsICookie.SCHEME_HTTPS
+  );
+  ok(
+    Services.cookies.cookieExists(cookie.host, cookie.path, cookie.name, {}),
+    `Cookie ${cookie.name} was created.`
+  );
+}
+
+async function setUpCookies() {
+  Services.cookies.removeAll();
+
+  // Add a cookie which will end up with an older creationTime.
+  oldCookie = Object.assign({}, COOKIE, { name: Date.now() });
+  addCookie(oldCookie);
+  await new Promise(resolve => setTimeout(resolve, 10));
+  since = Date.now();
+  await new Promise(resolve => setTimeout(resolve, 10));
+
+  // Add a cookie which will end up with a more recent creationTime.
+  addCookie(COOKIE);
+
+  // Add cookies for different domains.
+  addCookie(COOKIE_NET);
+  addCookie(COOKIE_ORG);
+}
+
+async function setUpCache() {
+  Services.cache2.clear();
+
+  // Add cache entries for different domains.
+  for (const domain of ["example.net", "example.org", "example.com"]) {
+    await SiteDataTestUtils.addCacheEntry(`http://${domain}/`, "disk");
+    await SiteDataTestUtils.addCacheEntry(`http://${domain}/`, "memory");
+  }
+}
+
+function hasCacheEntry(domain) {
+  const disk = SiteDataTestUtils.hasCacheEntry(`http://${domain}/`, "disk");
+  const memory = SiteDataTestUtils.hasCacheEntry(`http://${domain}/`, "memory");
+
+  equal(
+    disk,
+    memory,
+    `For ${domain} either either both or neither caches need to exists.`
+  );
+  return disk;
+}
+
+add_task(async function testCache() {
+  function background() {
+    browser.test.onMessage.addListener(async msg => {
+      if (msg == "removeCache") {
+        await browser.browsingData.removeCache({});
+      } else {
+        await browser.browsingData.remove({}, { cache: true });
+      }
+      browser.test.sendMessage("cacheRemoved");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browsingData"],
+    },
+  });
+
+  async function testRemovalMethod(method) {
+    await setUpCache();
+
+    extension.sendMessage(method);
+    await extension.awaitMessage("cacheRemoved");
+
+    ok(!hasCacheEntry("example.net"), "example.net cache was removed");
+    ok(!hasCacheEntry("example.org"), "example.org cache was removed");
+    ok(!hasCacheEntry("example.com"), "example.com cache was removed");
+  }
+
+  await extension.startup();
+
+  await testRemovalMethod("removeCache");
+  await testRemovalMethod("remove");
+
+  await extension.unload();
+});
+
+add_task(async function testCookies() {
+  // Above in setUpCookies we create an 'old' cookies, wait 10ms, then log a timestamp.
+  // Here we ask the browser to delete all cookies after the timestamp, with the intention
+  // that the 'old' cookie is not removed. The issue arises when the timer precision is
+  // low enough such that the timestamp that gets logged is the same as the 'old' cookie.
+  // We hardcode a precision value to ensure that there is time between the 'old' cookie
+  // and the timestamp generation.
+  Services.prefs.setBoolPref("privacy.reduceTimerPrecision", true);
+  Services.prefs.setIntPref(
+    "privacy.resistFingerprinting.reduceTimerPrecision.microseconds",
+    2000
+  );
+
+  registerCleanupFunction(function() {
+    Services.prefs.clearUserPref("privacy.reduceTimerPrecision");
+    Services.prefs.clearUserPref(
+      "privacy.resistFingerprinting.reduceTimerPrecision.microseconds"
+    );
+  });
+
+  function background() {
+    browser.test.onMessage.addListener(async (msg, options) => {
+      if (msg == "removeCookies") {
+        await browser.browsingData.removeCookies(options);
+      } else {
+        await browser.browsingData.remove(options, { cookies: true });
+      }
+      browser.test.sendMessage("cookiesRemoved");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browsingData"],
+    },
+  });
+
+  async function testRemovalMethod(method) {
+    // Clear cookies with a recent since value.
+    await setUpCookies();
+    extension.sendMessage(method, { since });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(
+      Services.cookies.cookieExists(
+        oldCookie.host,
+        oldCookie.path,
+        oldCookie.name,
+        {}
+      ),
+      "Old cookie was not removed."
+    );
+    ok(
+      !Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+      "Recent cookie was removed."
+    );
+
+    // Clear cookies with an old since value.
+    await setUpCookies();
+    addCookie(COOKIE);
+    extension.sendMessage(method, { since: since - 100000 });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(
+      !Services.cookies.cookieExists(
+        oldCookie.host,
+        oldCookie.path,
+        oldCookie.name,
+        {}
+      ),
+      "Old cookie was removed."
+    );
+    ok(
+      !Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+      "Recent cookie was removed."
+    );
+
+    // Clear cookies with no since value and valid originTypes.
+    await setUpCookies();
+    extension.sendMessage(method, {
+      originTypes: { unprotectedWeb: true, protectedWeb: false },
+    });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(
+      !Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+      `Cookie ${COOKIE.name}  was removed.`
+    );
+    ok(
+      !Services.cookies.cookieExists(
+        oldCookie.host,
+        oldCookie.path,
+        oldCookie.name,
+        {}
+      ),
+      `Cookie ${oldCookie.name}  was removed.`
+    );
+  }
+
+  await extension.startup();
+
+  await testRemovalMethod("removeCookies");
+  await testRemovalMethod("remove");
+
+  await extension.unload();
+});
+
+add_task(async function testCacheAndCookies() {
+  function background() {
+    browser.test.onMessage.addListener(async options => {
+      await browser.browsingData.remove(options, {
+        cache: true,
+        cookies: true,
+      });
+      browser.test.sendMessage("cacheAndCookiesRemoved");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browsingData"],
+    },
+  });
+
+  await extension.startup();
+
+  // Clear cache and cookies with a recent since value.
+  await setUpCookies();
+  await setUpCache();
+  extension.sendMessage({ since });
+  await extension.awaitMessage("cacheAndCookiesRemoved");
+
+  ok(
+    Services.cookies.cookieExists(
+      oldCookie.host,
+      oldCookie.path,
+      oldCookie.name,
+      {}
+    ),
+    "Old cookie was not removed."
+  );
+  ok(
+    !Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+    "Recent cookie was removed."
+  );
+
+  // Cache does not support |since| and deletes everything!
+  ok(!hasCacheEntry("example.net"), "example.net cache was removed");
+  ok(!hasCacheEntry("example.org"), "example.org cache was removed");
+  ok(!hasCacheEntry("example.com"), "example.com cache was removed");
+
+  // Clear cache and cookies with an old since value.
+  await setUpCookies();
+  await setUpCache();
+  extension.sendMessage({ since: since - 100000 });
+  await extension.awaitMessage("cacheAndCookiesRemoved");
+
+  // Cache does not support |since| and deletes everything!
+  ok(!hasCacheEntry("example.net"), "example.net cache was removed");
+  ok(!hasCacheEntry("example.org"), "example.org cache was removed");
+  ok(!hasCacheEntry("example.com"), "example.com cache was removed");
+
+  ok(
+    !Services.cookies.cookieExists(
+      oldCookie.host,
+      oldCookie.path,
+      oldCookie.name,
+      {}
+    ),
+    "Old cookie was removed."
+  );
+  ok(
+    !Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+    "Recent cookie was removed."
+  );
+
+  // Clear cache and cookies with hostnames value.
+  await setUpCookies();
+  await setUpCache();
+  extension.sendMessage({
+    hostnames: ["example.net", "example.org", "unknown.com"],
+  });
+  await extension.awaitMessage("cacheAndCookiesRemoved");
+
+  ok(
+    Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+    `Cookie ${COOKIE.name}  was not removed.`
+  );
+  ok(
+    !Services.cookies.cookieExists(
+      COOKIE_NET.host,
+      COOKIE_NET.path,
+      COOKIE_NET.name,
+      {}
+    ),
+    `Cookie ${COOKIE_NET.name}  was removed.`
+  );
+  ok(
+    !Services.cookies.cookieExists(
+      COOKIE_ORG.host,
+      COOKIE_ORG.path,
+      COOKIE_ORG.name,
+      {}
+    ),
+    `Cookie ${COOKIE_ORG.name}  was removed.`
+  );
+
+  ok(!hasCacheEntry("example.net"), "example.net cache was removed");
+  ok(!hasCacheEntry("example.org"), "example.org cache was removed");
+  ok(hasCacheEntry("example.com"), "example.com cache was not removed");
+
+  // Clear cache and cookies with (empty) hostnames value.
+  await setUpCookies();
+  await setUpCache();
+  extension.sendMessage({ hostnames: [] });
+  await extension.awaitMessage("cacheAndCookiesRemoved");
+
+  ok(
+    Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+    `Cookie ${COOKIE.name}  was not removed.`
+  );
+  ok(
+    Services.cookies.cookieExists(
+      COOKIE_NET.host,
+      COOKIE_NET.path,
+      COOKIE_NET.name,
+      {}
+    ),
+    `Cookie ${COOKIE_NET.name}  was not removed.`
+  );
+  ok(
+    Services.cookies.cookieExists(
+      COOKIE_ORG.host,
+      COOKIE_ORG.path,
+      COOKIE_ORG.name,
+      {}
+    ),
+    `Cookie ${COOKIE_ORG.name}  was not removed.`
+  );
+
+  ok(hasCacheEntry("example.net"), "example.net cache was not removed");
+  ok(hasCacheEntry("example.org"), "example.org cache was not removed");
+  ok(hasCacheEntry("example.com"), "example.com cache was not removed");
+
+  // Clear cache and cookies with both hostnames and since values.
+  await setUpCache();
+  await setUpCookies();
+  extension.sendMessage({ hostnames: ["example.com"], since });
+  await extension.awaitMessage("cacheAndCookiesRemoved");
+
+  ok(
+    Services.cookies.cookieExists(
+      oldCookie.host,
+      oldCookie.path,
+      oldCookie.name,
+      {}
+    ),
+    "Old cookie was not removed."
+  );
+  ok(
+    !Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+    "Recent cookie was removed."
+  );
+  ok(
+    Services.cookies.cookieExists(
+      COOKIE_NET.host,
+      COOKIE_NET.path,
+      COOKIE_NET.name,
+      {}
+    ),
+    "Cookie with different hostname was not removed"
+  );
+  ok(
+    Services.cookies.cookieExists(
+      COOKIE_ORG.host,
+      COOKIE_ORG.path,
+      COOKIE_ORG.name,
+      {}
+    ),
+    "Cookie with different hostname was not removed"
+  );
+
+  ok(hasCacheEntry("example.net"), "example.net cache was not removed");
+  ok(hasCacheEntry("example.org"), "example.org cache was not removed");
+  ok(!hasCacheEntry("example.com"), "example.com cache was removed");
+
+  // Clear cache and cookies with no since or hostnames value.
+  await setUpCache();
+  await setUpCookies();
+  extension.sendMessage({});
+  await extension.awaitMessage("cacheAndCookiesRemoved");
+
+  ok(
+    !Services.cookies.cookieExists(COOKIE.host, COOKIE.path, COOKIE.name, {}),
+    `Cookie ${COOKIE.name}  was removed.`
+  );
+  ok(
+    !Services.cookies.cookieExists(
+      oldCookie.host,
+      oldCookie.path,
+      oldCookie.name,
+      {}
+    ),
+    `Cookie ${oldCookie.name}  was removed.`
+  );
+  ok(
+    !Services.cookies.cookieExists(
+      COOKIE_NET.host,
+      COOKIE_NET.path,
+      COOKIE_NET.name,
+      {}
+    ),
+    `Cookie ${COOKIE_NET.name}  was removed.`
+  );
+  ok(
+    !Services.cookies.cookieExists(
+      COOKIE_ORG.host,
+      COOKIE_ORG.path,
+      COOKIE_ORG.name,
+      {}
+    ),
+    `Cookie ${COOKIE_ORG.name}  was removed.`
+  );
+
+  ok(!hasCacheEntry("example.net"), "example.net cache was removed");
+  ok(!hasCacheEntry("example.org"), "example.org cache was removed");
+  ok(!hasCacheEntry("example.com"), "example.com cache was removed");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_browsingData_cookies_cookieStoreId.js b/toolkit/components/extensions/test/xpcshell/test_ext_browsingData_cookies_cookieStoreId.js
new file mode 100644
index 0000000000..d3d066efd2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_browsingData_cookies_cookieStoreId.js
@@ -0,0 +1,192 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+"use strict";
+
+// "Normal" cookie
+const COOKIE_NORMAL = {
+  host: "example.com",
+  name: "test_cookie",
+  path: "/",
+  originAttributes: {},
+};
+// Private browsing cookie
+const COOKIE_PRIVATE = {
+  host: "example.net",
+  name: "test_cookie",
+  path: "/",
+  originAttributes: {
+    privateBrowsingId: 1,
+  },
+};
+// "firefox-container-1" cookie
+const COOKIE_CONTAINER = {
+  host: "example.org",
+  name: "test_cookie",
+  path: "/",
+  originAttributes: {
+    userContextId: 1,
+  },
+};
+
+function cookieExists(cookie) {
+  return Services.cookies.cookieExists(
+    cookie.host,
+    cookie.path,
+    cookie.name,
+    cookie.originAttributes
+  );
+}
+
+function addCookie(cookie) {
+  const THE_FUTURE = Date.now() + 5 * 60;
+
+  Services.cookies.add(
+    cookie.host,
+    cookie.path,
+    cookie.name,
+    "test",
+    false,
+    false,
+    false,
+    THE_FUTURE,
+    cookie.originAttributes,
+    Ci.nsICookie.SAMESITE_NONE,
+    Ci.nsICookie.SCHEME_HTTPS
+  );
+
+  ok(cookieExists(cookie), `Cookie ${cookie.name} was created.`);
+}
+
+async function setUpCookies() {
+  Services.cookies.removeAll();
+
+  addCookie(COOKIE_NORMAL);
+  addCookie(COOKIE_PRIVATE);
+  addCookie(COOKIE_CONTAINER);
+}
+
+add_task(async function testCookies() {
+  Services.prefs.setBoolPref("privacy.userContext.enabled", true);
+
+  function background() {
+    browser.test.onMessage.addListener(async (msg, options) => {
+      if (msg == "removeCookies") {
+        await browser.browsingData.removeCookies(options);
+      } else {
+        await browser.browsingData.remove(options, { cookies: true });
+      }
+      browser.test.sendMessage("cookiesRemoved");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["browsingData"],
+    },
+  });
+
+  async function testRemovalMethod(method) {
+    // Clear only "normal"/default cookies.
+    await setUpCookies();
+
+    extension.sendMessage(method, { cookieStoreId: "firefox-default" });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(!cookieExists(COOKIE_NORMAL), "Normal cookie was removed");
+    ok(cookieExists(COOKIE_PRIVATE), "Private cookie was not removed");
+    ok(cookieExists(COOKIE_CONTAINER), "Container cookie was not removed");
+
+    // Clear container cookie
+    await setUpCookies();
+
+    extension.sendMessage(method, { cookieStoreId: "firefox-container-1" });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(cookieExists(COOKIE_NORMAL), "Normal cookie was not removed");
+    ok(cookieExists(COOKIE_PRIVATE), "Private cookie was not removed");
+    ok(!cookieExists(COOKIE_CONTAINER), "Container cookie was removed");
+
+    // Clear private cookie
+    await setUpCookies();
+
+    extension.sendMessage(method, { cookieStoreId: "firefox-private" });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(cookieExists(COOKIE_NORMAL), "Normal cookie was not removed");
+    ok(!cookieExists(COOKIE_PRIVATE), "Private cookie was removed");
+    ok(cookieExists(COOKIE_CONTAINER), "Container cookie was not removed");
+
+    // Clear container cookie with correct hostname
+    await setUpCookies();
+
+    extension.sendMessage(method, {
+      cookieStoreId: "firefox-container-1",
+      hostnames: ["example.org"],
+    });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(cookieExists(COOKIE_NORMAL), "Normal cookie was not removed");
+    ok(cookieExists(COOKIE_PRIVATE), "Private cookie was not removed");
+    ok(!cookieExists(COOKIE_CONTAINER), "Container cookie was removed");
+
+    // Clear container cookie with incorrect hostname; nothing is removed
+    await setUpCookies();
+
+    extension.sendMessage(method, {
+      cookieStoreId: "firefox-container-1",
+      hostnames: ["example.com"],
+    });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(cookieExists(COOKIE_NORMAL), "Normal cookie was not removed");
+    ok(cookieExists(COOKIE_PRIVATE), "Private cookie was not removed");
+    ok(cookieExists(COOKIE_CONTAINER), "Container cookie was not removed");
+
+    // Clear private cookie with correct hostname
+    await setUpCookies();
+
+    extension.sendMessage(method, {
+      cookieStoreId: "firefox-private",
+      hostnames: ["example.net"],
+    });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(cookieExists(COOKIE_NORMAL), "Normal cookie was not removed");
+    ok(!cookieExists(COOKIE_PRIVATE), "Private cookie was removed");
+    ok(cookieExists(COOKIE_CONTAINER), "Container cookie was not removed");
+
+    // Clear private cookie with incorrect hostname; nothing is removed
+    await setUpCookies();
+
+    extension.sendMessage(method, {
+      cookieStoreId: "firefox-private",
+      hostnames: ["example.com"],
+    });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(cookieExists(COOKIE_NORMAL), "Normal cookie was not removed");
+    ok(cookieExists(COOKIE_PRIVATE), "Private cookie was not removed");
+    ok(cookieExists(COOKIE_CONTAINER), "Container cookie was not removed");
+
+    // Clear private cookie by hostname
+    await setUpCookies();
+
+    extension.sendMessage(method, {
+      hostnames: ["example.net"],
+    });
+    await extension.awaitMessage("cookiesRemoved");
+
+    ok(cookieExists(COOKIE_NORMAL), "Normal cookie was not removed");
+    ok(!cookieExists(COOKIE_PRIVATE), "Private cookie was removed");
+    ok(cookieExists(COOKIE_CONTAINER), "Container cookie was not removed");
+  }
+
+  await extension.startup();
+
+  await testRemovalMethod("removeCookies");
+  await testRemovalMethod("remove");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_captivePortal.js b/toolkit/components/extensions/test/xpcshell/test_ext_captivePortal.js
new file mode 100644
index 0000000000..45c6a122fd
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_captivePortal.js
@@ -0,0 +1,109 @@
+"use strict";
+
+/**
+ * This duplicates the test from netwerk/test/unit/test_captive_portal_service.js
+ * however using an extension to gather the captive portal information.
+ */
+
+const PREF_CAPTIVE_ENABLED = "network.captive-portal-service.enabled";
+const PREF_CAPTIVE_TESTMODE = "network.captive-portal-service.testMode";
+const PREF_CAPTIVE_MINTIME = "network.captive-portal-service.minInterval";
+const PREF_CAPTIVE_ENDPOINT = "captivedetect.canonicalURL";
+const PREF_DNS_NATIVE_IS_LOCALHOST = "network.dns.native-is-localhost";
+
+const SUCCESS_STRING = "success\n";
+let cpResponse = SUCCESS_STRING;
+
+const httpserver = createHttpServer();
+httpserver.registerPathHandler("/captive.txt", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/plain");
+  response.write(cpResponse);
+});
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref(PREF_CAPTIVE_ENABLED);
+  Services.prefs.clearUserPref(PREF_CAPTIVE_TESTMODE);
+  Services.prefs.clearUserPref(PREF_CAPTIVE_ENDPOINT);
+  Services.prefs.clearUserPref(PREF_CAPTIVE_MINTIME);
+  Services.prefs.clearUserPref(PREF_DNS_NATIVE_IS_LOCALHOST);
+});
+
+add_task(function setup() {
+  Services.prefs.setCharPref(
+    PREF_CAPTIVE_ENDPOINT,
+    `http://localhost:${httpserver.identity.primaryPort}/captive.txt`
+  );
+  Services.prefs.setBoolPref(PREF_CAPTIVE_TESTMODE, true);
+  Services.prefs.setIntPref(PREF_CAPTIVE_MINTIME, 0);
+  Services.prefs.setBoolPref(PREF_DNS_NATIVE_IS_LOCALHOST, true);
+});
+
+add_task(async function test_captivePortal_basic() {
+  let cps = Cc["@mozilla.org/network/captive-portal-service;1"].getService(
+    Ci.nsICaptivePortalService
+  );
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["captivePortal"],
+    },
+    isPrivileged: true,
+    async background() {
+      browser.captivePortal.onConnectivityAvailable.addListener(details => {
+        browser.test.log(
+          `onConnectivityAvailable received ${JSON.stringify(details)}`
+        );
+        browser.test.sendMessage("connectivity", details);
+      });
+
+      browser.captivePortal.onStateChanged.addListener(details => {
+        browser.test.log(`onStateChanged received ${JSON.stringify(details)}`);
+        browser.test.sendMessage("state", details);
+      });
+
+      browser.test.onMessage.addListener(async msg => {
+        if (msg == "getstate") {
+          browser.test.sendMessage(
+            "getstate",
+            await browser.captivePortal.getState()
+          );
+        }
+      });
+      browser.test.assertEq(
+        "unknown",
+        await browser.captivePortal.getState(),
+        "initial state unknown"
+      );
+    },
+  });
+  await extension.startup();
+
+  // The captive portal service is started by nsIOService when the pref becomes true, so we
+  // toggle the pref.  We cannot set to false before the extension loads above.
+  Services.prefs.setBoolPref(PREF_CAPTIVE_ENABLED, false);
+  Services.prefs.setBoolPref(PREF_CAPTIVE_ENABLED, true);
+
+  let details = await extension.awaitMessage("connectivity");
+  equal(details.status, "clear", "initial connectivity");
+  extension.sendMessage("getstate");
+  details = await extension.awaitMessage("getstate");
+  equal(details, "not_captive", "initial state");
+
+  info("REFRESH to other");
+  cpResponse = "other";
+  cps.recheckCaptivePortal();
+  details = await extension.awaitMessage("state");
+  equal(details.state, "locked_portal", "state in portal");
+
+  info("REFRESH to success");
+  cpResponse = SUCCESS_STRING;
+  cps.recheckCaptivePortal();
+  details = await extension.awaitMessage("connectivity");
+  equal(details.status, "captive", "final connectivity");
+
+  details = await extension.awaitMessage("state");
+  equal(details.state, "unlocked_portal", "state after unlocking portal");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_captivePortal_url.js b/toolkit/components/extensions/test/xpcshell/test_ext_captivePortal_url.js
new file mode 100644
index 0000000000..7bd83b0572
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_captivePortal_url.js
@@ -0,0 +1,53 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_url_get_without_set() {
+  async function background() {
+    browser.captivePortal.canonicalURL.onChange.addListener(details => {
+      browser.test.sendMessage("url", details);
+    });
+    let url = await browser.captivePortal.canonicalURL.get({});
+    browser.test.sendMessage("url", url);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["captivePortal"],
+    },
+  });
+
+  let defaultURL = Services.prefs.getStringPref("captivedetect.canonicalURL");
+
+  await extension.startup();
+  let url = await extension.awaitMessage("url");
+  equal(
+    url.value,
+    defaultURL,
+    "The canonicalURL setting has the expected value."
+  );
+  equal(
+    url.levelOfControl,
+    "not_controllable",
+    "The canonicalURL setting has the expected levelOfControl."
+  );
+
+  Services.prefs.setStringPref(
+    "captivedetect.canonicalURL",
+    "http://example.com"
+  );
+  url = await extension.awaitMessage("url");
+  equal(
+    url.value,
+    "http://example.com",
+    "The canonicalURL setting has the expected value."
+  );
+  equal(
+    url.levelOfControl,
+    "not_controllable",
+    "The canonicalURL setting has the expected levelOfControl."
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentScripts_register.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentScripts_register.js
new file mode 100644
index 0000000000..71174716fd
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentScripts_register.js
@@ -0,0 +1,591 @@
+"use strict";
+
+const { createAppInfo } = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "49");
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+function check_applied_styles() {
+  const urlElStyle = getComputedStyle(
+    document.querySelector("#registered-extension-url-style")
+  );
+  const blobElStyle = getComputedStyle(
+    document.querySelector("#registered-extension-text-style")
+  );
+
+  browser.test.sendMessage("registered-styles-results", {
+    registeredExtensionUrlStyleBG: urlElStyle["background-color"],
+    registeredExtensionBlobStyleBG: blobElStyle["background-color"],
+  });
+}
+
+add_task(async function test_contentscripts_register_css() {
+  async function background() {
+    let cssCode = `
+      #registered-extension-text-style {
+        background-color: blue;
+      }
+    `;
+
+    const matches = ["http://localhost/*/file_sample_registered_styles.html"];
+
+    browser.test.assertThrows(
+      () => {
+        browser.contentScripts.register({
+          matches,
+          unknownParam: "unexpected property",
+        });
+      },
+      /Unexpected property "unknownParam"/,
+      "contentScripts.register throws on unexpected properties"
+    );
+
+    let fileScript = await browser.contentScripts.register({
+      css: [{ file: "registered_ext_style.css" }],
+      matches,
+      runAt: "document_start",
+    });
+
+    let textScript = await browser.contentScripts.register({
+      css: [{ code: cssCode }],
+      matches,
+      runAt: "document_start",
+    });
+
+    browser.test.onMessage.addListener(async msg => {
+      switch (msg) {
+        case "unregister-text":
+          await textScript.unregister().catch(err => {
+            browser.test.fail(
+              `Unexpected exception while unregistering text style: ${err}`
+            );
+          });
+
+          await browser.test.assertRejects(
+            textScript.unregister(),
+            /Content script already unregistered/,
+            "Got the expected rejection on calling script.unregister() multiple times"
+          );
+
+          browser.test.sendMessage("unregister-text:done");
+          break;
+        case "unregister-file":
+          await fileScript.unregister().catch(err => {
+            browser.test.fail(
+              `Unexpected exception while unregistering url style: ${err}`
+            );
+          });
+
+          await browser.test.assertRejects(
+            fileScript.unregister(),
+            /Content script already unregistered/,
+            "Got the expected rejection on calling script.unregister() multiple times"
+          );
+
+          browser.test.sendMessage("unregister-file:done");
+          break;
+        default:
+          browser.test.fail(`Unexpected test message received: ${msg}`);
+      }
+    });
+
+    browser.test.sendMessage("background_ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "http://localhost/*/file_sample_registered_styles.html",
+        "<all_urls>",
+      ],
+      content_scripts: [
+        {
+          matches: ["http://localhost/*/file_sample_registered_styles.html"],
+          run_at: "document_idle",
+          js: ["check_applied_styles.js"],
+        },
+      ],
+    },
+    background,
+
+    files: {
+      "check_applied_styles.js": check_applied_styles,
+      "registered_ext_style.css": `
+        #registered-extension-url-style {
+          background-color: red;
+        }
+      `,
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("background_ready");
+
+  // Ensure that a content page running in a content process and which has been
+  // started after the content scripts has been registered, it still receives
+  // and registers the expected content scripts.
+  let contentPage = await ExtensionTestUtils.loadContentPage(`about:blank`);
+
+  await contentPage.loadURL(`${BASE_URL}/file_sample_registered_styles.html`);
+
+  const registeredStylesResults = await extension.awaitMessage(
+    "registered-styles-results"
+  );
+
+  equal(
+    registeredStylesResults.registeredExtensionUrlStyleBG,
+    "rgb(255, 0, 0)",
+    "The expected style has been applied from the registered extension url style"
+  );
+  equal(
+    registeredStylesResults.registeredExtensionBlobStyleBG,
+    "rgb(0, 0, 255)",
+    "The expected style has been applied from the registered extension blob style"
+  );
+
+  extension.sendMessage("unregister-file");
+  await extension.awaitMessage("unregister-file:done");
+
+  await contentPage.loadURL(`${BASE_URL}/file_sample_registered_styles.html`);
+
+  const unregisteredURLStylesResults = await extension.awaitMessage(
+    "registered-styles-results"
+  );
+
+  equal(
+    unregisteredURLStylesResults.registeredExtensionUrlStyleBG,
+    "rgba(0, 0, 0, 0)",
+    "The expected style has been applied once extension url style has been unregistered"
+  );
+  equal(
+    unregisteredURLStylesResults.registeredExtensionBlobStyleBG,
+    "rgb(0, 0, 255)",
+    "The expected style has been applied from the registered extension blob style"
+  );
+
+  extension.sendMessage("unregister-text");
+  await extension.awaitMessage("unregister-text:done");
+
+  await contentPage.loadURL(`${BASE_URL}/file_sample_registered_styles.html`);
+
+  const unregisteredBlobStylesResults = await extension.awaitMessage(
+    "registered-styles-results"
+  );
+
+  equal(
+    unregisteredBlobStylesResults.registeredExtensionUrlStyleBG,
+    "rgba(0, 0, 0, 0)",
+    "The expected style has been applied once extension url style has been unregistered"
+  );
+  equal(
+    unregisteredBlobStylesResults.registeredExtensionBlobStyleBG,
+    "rgba(0, 0, 0, 0)",
+    "The expected style has been applied once extension blob style has been unregistered"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_contentscripts_unregister_on_context_unload() {
+  async function background() {
+    const frame = document.createElement("iframe");
+    frame.setAttribute("src", "/background-frame.html");
+
+    document.body.appendChild(frame);
+
+    browser.test.onMessage.addListener(msg => {
+      switch (msg) {
+        case "unload-frame":
+          frame.remove();
+          browser.test.sendMessage("unload-frame:done");
+          break;
+        default:
+          browser.test.fail(`Unexpected test message received: ${msg}`);
+      }
+    });
+
+    browser.test.sendMessage("background_ready");
+  }
+
+  async function background_frame() {
+    await browser.contentScripts.register({
+      css: [{ file: "registered_ext_style.css" }],
+      matches: ["http://localhost/*/file_sample_registered_styles.html"],
+      runAt: "document_start",
+    });
+
+    browser.test.sendMessage("background_frame_ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://localhost/*/file_sample_registered_styles.html"],
+      content_scripts: [
+        {
+          matches: ["http://localhost/*/file_sample_registered_styles.html"],
+          run_at: "document_idle",
+          js: ["check_applied_styles.js"],
+        },
+      ],
+    },
+    background,
+
+    files: {
+      "background-frame.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <script src="background-frame.js"></script>
+          </head>
+          <body>
+          </body>
+        </html>
+      `,
+      "background-frame.js": background_frame,
+      "check_applied_styles.js": check_applied_styles,
+      "registered_ext_style.css": `
+        #registered-extension-url-style {
+          background-color: red;
+        }
+      `,
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("background_ready");
+
+  // Wait the background frame to have been loaded and its script
+  // executed.
+  await extension.awaitMessage("background_frame_ready");
+
+  // Ensure that a content page running in a content process and which has been
+  // started after the content scripts has been registered, it still receives
+  // and registers the expected content scripts.
+  let contentPage = await ExtensionTestUtils.loadContentPage(`about:blank`);
+
+  await contentPage.loadURL(`${BASE_URL}/file_sample_registered_styles.html`);
+
+  const registeredStylesResults = await extension.awaitMessage(
+    "registered-styles-results"
+  );
+
+  equal(
+    registeredStylesResults.registeredExtensionUrlStyleBG,
+    "rgb(255, 0, 0)",
+    "The expected style has been applied from the registered extension url style"
+  );
+
+  extension.sendMessage("unload-frame");
+  await extension.awaitMessage("unload-frame:done");
+
+  await contentPage.loadURL(`${BASE_URL}/file_sample_registered_styles.html`);
+
+  const unregisteredURLStylesResults = await extension.awaitMessage(
+    "registered-styles-results"
+  );
+
+  equal(
+    unregisteredURLStylesResults.registeredExtensionUrlStyleBG,
+    "rgba(0, 0, 0, 0)",
+    "The expected style has been applied once extension url style has been unregistered"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_contentscripts_register_js() {
+  async function background() {
+    browser.runtime.onMessage.addListener(
+      ([msg, expectedStates, readyState], sender) => {
+        if (msg == "chrome-namespace-ok") {
+          browser.test.sendMessage(msg);
+          return;
+        }
+
+        browser.test.assertEq("script-run", msg, "message type is correct");
+        browser.test.assertTrue(
+          expectedStates.includes(readyState),
+          `readyState "${readyState}" is one of [${expectedStates}]`
+        );
+        browser.test.sendMessage("script-run-" + expectedStates[0]);
+      }
+    );
+
+    // Raise an exception when the content script cannot be registered
+    // because the extension has no permission to access the specified origin.
+
+    await browser.test.assertRejects(
+      browser.contentScripts.register({
+        matches: ["http://*/*"],
+        js: [
+          {
+            code:
+              'browser.test.fail("content script with wrong matches should not run")',
+          },
+        ],
+      }),
+      /Permission denied to register a content script for/,
+      "The reject contains the expected error message"
+    );
+
+    // Register a content script from a JS code string.
+
+    function textScriptCodeStart() {
+      browser.runtime.sendMessage([
+        "script-run",
+        ["loading"],
+        document.readyState,
+      ]);
+    }
+    function textScriptCodeEnd() {
+      browser.runtime.sendMessage([
+        "script-run",
+        ["interactive", "complete"],
+        document.readyState,
+      ]);
+    }
+    function textScriptCodeIdle() {
+      browser.runtime.sendMessage([
+        "script-run",
+        ["complete"],
+        document.readyState,
+      ]);
+    }
+
+    // Register content scripts from both extension URLs and plain JS code strings.
+
+    const content_scripts = [
+      // Plain JS code strings.
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: [{ code: `(${textScriptCodeStart})()` }],
+        runAt: "document_start",
+      },
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: [{ code: `(${textScriptCodeEnd})()` }],
+        runAt: "document_end",
+      },
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: [{ code: `(${textScriptCodeIdle})()` }],
+        runAt: "document_idle",
+      },
+      // Extension URLs.
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: [{ file: "content_script_start.js" }],
+        runAt: "document_start",
+      },
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: [{ file: "content_script_end.js" }],
+        runAt: "document_end",
+      },
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: [{ file: "content_script_idle.js" }],
+        runAt: "document_idle",
+      },
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: [{ file: "content_script.js" }],
+        // "runAt" is not specified here to ensure that it defaults to document_idle when missing.
+      },
+    ];
+
+    const expectedAPIs = ["unregister"];
+
+    for (const scriptOptions of content_scripts) {
+      const script = await browser.contentScripts.register(scriptOptions);
+      const actualAPIs = Object.keys(script);
+
+      browser.test.assertEq(
+        JSON.stringify(expectedAPIs),
+        JSON.stringify(actualAPIs),
+        `Got a script API object for ${scriptOptions.js[0]}`
+      );
+    }
+
+    browser.test.sendMessage("background-ready");
+  }
+
+  function contentScriptStart() {
+    browser.runtime.sendMessage([
+      "script-run",
+      ["loading"],
+      document.readyState,
+    ]);
+  }
+  function contentScriptEnd() {
+    browser.runtime.sendMessage([
+      "script-run",
+      ["interactive", "complete"],
+      document.readyState,
+    ]);
+  }
+  function contentScriptIdle() {
+    browser.runtime.sendMessage([
+      "script-run",
+      ["complete"],
+      document.readyState,
+    ]);
+  }
+
+  function contentScript() {
+    let manifest = browser.runtime.getManifest();
+    void manifest.permissions;
+    browser.runtime.sendMessage(["chrome-namespace-ok"]);
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: ["http://localhost/*/file_sample.html"],
+    },
+    background,
+
+    files: {
+      "content_script_start.js": contentScriptStart,
+      "content_script_end.js": contentScriptEnd,
+      "content_script_idle.js": contentScriptIdle,
+      "content_script.js": contentScript,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  let loadingCount = 0;
+  let interactiveCount = 0;
+  let completeCount = 0;
+  extension.onMessage("script-run-loading", () => {
+    loadingCount++;
+  });
+  extension.onMessage("script-run-interactive", () => {
+    interactiveCount++;
+  });
+
+  let completePromise = new Promise(resolve => {
+    extension.onMessage("script-run-complete", () => {
+      completeCount++;
+      resolve();
+    });
+  });
+
+  let chromeNamespacePromise = extension.awaitMessage("chrome-namespace-ok");
+
+  // Ensure that a content page running in a content process and which has been
+  // already loaded when the content scripts has been registered, it has received
+  // and registered the expected content scripts.
+  let contentPage = await ExtensionTestUtils.loadContentPage(`about:blank`);
+
+  await extension.startup();
+  await extension.awaitMessage("background-ready");
+
+  await contentPage.loadURL(`${BASE_URL}/file_sample.html`);
+
+  await Promise.all([completePromise, chromeNamespacePromise]);
+
+  await contentPage.close();
+
+  // Expect two content scripts to run (one registered using an extension URL
+  // and one registered from plain JS code).
+  equal(loadingCount, 2, "document_start script ran exactly twice");
+  equal(interactiveCount, 2, "document_end script ran exactly twice");
+  equal(completeCount, 2, "document_idle script ran exactly twice");
+
+  await extension.unload();
+});
+
+// Test that the contentScript.register options are correctly translated
+// into the expected WebExtensionContentScript properties.
+add_task(async function test_contentscripts_register_all_options() {
+  async function background() {
+    await browser.contentScripts.register({
+      js: [{ file: "content_script.js" }],
+      css: [{ file: "content_style.css" }],
+      matches: ["http://localhost/*"],
+      excludeMatches: ["http://localhost/exclude/*"],
+      excludeGlobs: ["*_exclude.html"],
+      includeGlobs: ["*_include.html"],
+      allFrames: true,
+      matchAboutBlank: true,
+      runAt: "document_start",
+    });
+
+    browser.test.sendMessage("background-ready", window.location.origin);
+  }
+
+  const extensionData = {
+    manifest: {
+      permissions: ["http://localhost/*"],
+    },
+    background,
+
+    files: {
+      "content_script.js": "",
+      "content_style.css": "",
+    },
+  };
+
+  const extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  const baseExtURL = await extension.awaitMessage("background-ready");
+
+  const policy = WebExtensionPolicy.getByID(extension.id);
+
+  ok(policy, "Got the WebExtensionPolicy for the test extension");
+  equal(
+    policy.contentScripts.length,
+    1,
+    "Got the expected number of registered content scripts"
+  );
+
+  const script = policy.contentScripts[0];
+  let { allFrames, cssPaths, jsPaths, matchAboutBlank, runAt } = script;
+
+  deepEqual(
+    {
+      allFrames,
+      cssPaths,
+      jsPaths,
+      matchAboutBlank,
+      runAt,
+    },
+    {
+      allFrames: true,
+      cssPaths: [`${baseExtURL}/content_style.css`],
+      jsPaths: [`${baseExtURL}/content_script.js`],
+      matchAboutBlank: true,
+      runAt: "document_start",
+    },
+    "Got the expected content script properties"
+  );
+
+  ok(
+    script.matchesURI(Services.io.newURI("http://localhost/ok_include.html")),
+    "matched and include globs should match"
+  );
+  ok(
+    !script.matchesURI(
+      Services.io.newURI("http://localhost/exclude/ok_include.html")
+    ),
+    "exclude matches should not match"
+  );
+  ok(
+    !script.matchesURI(Services.io.newURI("http://localhost/ok_exclude.html")),
+    "exclude globs should not match"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_content_security_policy.js b/toolkit/components/extensions/test/xpcshell/test_ext_content_security_policy.js
new file mode 100644
index 0000000000..47de723f0f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_content_security_policy.js
@@ -0,0 +1,251 @@
+"use strict";
+
+Services.prefs.setBoolPref("extensions.manifestV3.enabled", true);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+server.registerPathHandler("/worker.js", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "application/javascript", false);
+  response.write("let x = true;");
+});
+
+const baseCSP = [];
+baseCSP[2] = {
+  "object-src": ["blob:", "filesystem:", "moz-extension:", "'self'"],
+  "script-src": [
+    "'unsafe-eval'",
+    "'unsafe-inline'",
+    "blob:",
+    "filesystem:",
+    "http://localhost:*",
+    "http://127.0.0.1:*",
+    "https://*",
+    "moz-extension:",
+    "'self'",
+  ],
+};
+baseCSP[3] = {
+  "object-src": ["'self'"],
+  "script-src": ["http://localhost:*", "http://127.0.0.1:*", "'self'"],
+  "worker-src": ["http://localhost:*", "http://127.0.0.1:*", "'self'"],
+};
+
+/**
+ * Tests that content security policies for an add-on are actually applied to *
+ * documents that belong to it. This tests both the base policies and add-on
+ * specific policies, and ensures that the parsed policies applied to the
+ * document's principal match what was specified in the policy string.
+ *
+ * @param {number} [manifest_version]
+ * @param {object} [customCSP]
+ */
+async function testPolicy(manifest_version = 2, customCSP = null) {
+  let baseURL;
+
+  let addonCSP = {
+    "object-src": ["'self'"],
+    "script-src": ["'self'"],
+  };
+
+  let content_security_policy = null;
+
+  if (customCSP) {
+    for (let key of Object.keys(customCSP)) {
+      addonCSP[key] = customCSP[key].split(/\s+/);
+    }
+
+    content_security_policy = Object.keys(customCSP)
+      .map(key => `${key} ${customCSP[key]}`)
+      .join("; ");
+  }
+
+  function checkSource(name, policy, expected) {
+    // fallback to script-src when comparing worker-src if policy does not include worker-src
+    let policySrc =
+      name != "worker-src" || policy[name]
+        ? policy[name]
+        : policy["script-src"];
+    equal(
+      JSON.stringify(policySrc.sort()),
+      JSON.stringify(expected[name].sort()),
+      `Expected value for ${name}`
+    );
+  }
+
+  function checkCSP(csp, location) {
+    let policies = csp["csp-policies"];
+
+    info(`Base policy for ${location}`);
+    let base = baseCSP[manifest_version];
+
+    equal(policies[0]["report-only"], false, "Policy is not report-only");
+    for (let key in base) {
+      checkSource(key, policies[0], base);
+    }
+
+    info(`Add-on policy for ${location}`);
+
+    equal(policies[1]["report-only"], false, "Policy is not report-only");
+    for (let key in addonCSP) {
+      checkSource(key, policies[1], addonCSP);
+    }
+  }
+
+  function background() {
+    browser.test.sendMessage(
+      "base-url",
+      browser.extension.getURL("").replace(/\/$/, "")
+    );
+
+    browser.test.sendMessage("background-csp", window.getCSP());
+  }
+
+  function tabScript() {
+    browser.test.sendMessage("tab-csp", window.getCSP());
+
+    const worker = new Worker("worker.js");
+    worker.onmessage = event => {
+      browser.test.sendMessage("worker-csp", event.data);
+    };
+
+    worker.postMessage({});
+  }
+
+  function testWorker(port) {
+    this.onmessage = () => {
+      try {
+        // eslint-disable-next-line no-undef
+        importScripts(`http://127.0.0.1:${port}/worker.js`);
+        postMessage({ loaded: true });
+      } catch (e) {
+        postMessage({ loaded: false });
+      }
+    };
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+
+    files: {
+      "tab.html": `<html><head><meta charset="utf-8">
+                   <script src="tab.js"></${"script"}></head></html>`,
+
+      "tab.js": tabScript,
+
+      "content.html": `<html><head><meta charset="utf-8"></head></html>`,
+      "worker.js": `(${testWorker})(${server.identity.primaryPort})`,
+    },
+
+    manifest: {
+      manifest_version,
+      content_security_policy,
+
+      web_accessible_resources: ["content.html", "tab.html"],
+    },
+  });
+
+  function frameScript() {
+    // eslint-disable-next-line mozilla/balanced-listeners
+    addEventListener(
+      "DOMWindowCreated",
+      event => {
+        let win = event.target.ownerGlobal;
+        function getCSP() {
+          let { cspJSON } = win.document;
+          return win.wrappedJSObject.JSON.parse(cspJSON);
+        }
+        Cu.exportFunction(getCSP, win, { defineAs: "getCSP" });
+      },
+      true
+    );
+  }
+  let frameScriptURL = `data:,(${encodeURI(frameScript)}).call(this)`;
+  Services.mm.loadFrameScript(frameScriptURL, true, true);
+
+  info(`Testing CSP for policy: ${content_security_policy}`);
+
+  await extension.startup();
+
+  baseURL = await extension.awaitMessage("base-url");
+
+  let tabPage = await ExtensionTestUtils.loadContentPage(
+    `${baseURL}/tab.html`,
+    { extension }
+  );
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+
+  let contentCSP = await contentPage.spawn(
+    `${baseURL}/content.html`,
+    async src => {
+      let doc = this.content.document;
+
+      let frame = doc.createElement("iframe");
+      frame.src = src;
+      doc.body.appendChild(frame);
+
+      await new Promise(resolve => {
+        frame.onload = resolve;
+      });
+
+      return frame.contentWindow.wrappedJSObject.getCSP();
+    }
+  );
+
+  let backgroundCSP = await extension.awaitMessage("background-csp");
+  checkCSP(backgroundCSP, "background page");
+
+  let tabCSP = await extension.awaitMessage("tab-csp");
+  checkCSP(tabCSP, "tab page");
+
+  checkCSP(contentCSP, "content frame");
+
+  let workerCSP = await extension.awaitMessage("worker-csp");
+  // TODO BUG 1685627: This test should fail if localhost is not in the csp.
+  ok(workerCSP.loaded, "worker loaded");
+
+  await contentPage.close();
+  await tabPage.close();
+
+  await extension.unload();
+
+  Services.mm.removeDelayedFrameScript(frameScriptURL);
+}
+
+add_task(async function testCSP() {
+  await testPolicy(2, null);
+
+  let hash =
+    "'sha256-NjZhMDQ1YjQ1MjEwMmM1OWQ4NDBlYzA5N2Q1OWQ5NDY3ZTEzYTNmMzRmNjQ5NGU1MzlmZmQzMmMxYmIzNWYxOCAgLQo='";
+
+  await testPolicy(2, {
+    "object-src": "'self' https://*.example.com",
+    "script-src": `'self' https://*.example.com 'unsafe-eval' ${hash}`,
+  });
+
+  await testPolicy(2, {
+    "object-src": "'none'",
+    "script-src": `'self'`,
+  });
+
+  await testPolicy(3, {
+    "object-src": "'self' http://localhost",
+    "script-src": `'self' http://localhost:123 ${hash}`,
+    "worker-src": `'self' http://127.0.0.1:*`,
+  });
+
+  await testPolicy(3, {
+    "object-src": "'none'",
+    "script-src": `'self'`,
+    "worker-src": `'self'`,
+  });
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript.js
new file mode 100644
index 0000000000..1d130798f6
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript.js
@@ -0,0 +1,266 @@
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+add_task(async function test_contentscript_runAt() {
+  function background() {
+    browser.runtime.onMessage.addListener(
+      ([msg, expectedStates, readyState], sender) => {
+        if (msg == "chrome-namespace-ok") {
+          browser.test.sendMessage(msg);
+          return;
+        }
+
+        browser.test.assertEq("script-run", msg, "message type is correct");
+        browser.test.assertTrue(
+          expectedStates.includes(readyState),
+          `readyState "${readyState}" is one of [${expectedStates}]`
+        );
+        browser.test.sendMessage("script-run-" + expectedStates[0]);
+      }
+    );
+  }
+
+  function contentScriptStart() {
+    browser.runtime.sendMessage([
+      "script-run",
+      ["loading"],
+      document.readyState,
+    ]);
+  }
+  function contentScriptEnd() {
+    browser.runtime.sendMessage([
+      "script-run",
+      ["interactive", "complete"],
+      document.readyState,
+    ]);
+  }
+  function contentScriptIdle() {
+    browser.runtime.sendMessage([
+      "script-run",
+      ["complete"],
+      document.readyState,
+    ]);
+  }
+
+  function contentScript() {
+    let manifest = browser.runtime.getManifest();
+    void manifest.applications.gecko.id;
+    browser.runtime.sendMessage(["chrome-namespace-ok"]);
+  }
+
+  let extensionData = {
+    manifest: {
+      applications: { gecko: { id: "contentscript@tests.mozilla.org" } },
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script_start.js"],
+          run_at: "document_start",
+        },
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script_end.js"],
+          run_at: "document_end",
+        },
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script_idle.js"],
+          run_at: "document_idle",
+        },
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script_idle.js"],
+          // Test default `run_at`.
+        },
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+    },
+    background,
+
+    files: {
+      "content_script_start.js": contentScriptStart,
+      "content_script_end.js": contentScriptEnd,
+      "content_script_idle.js": contentScriptIdle,
+      "content_script.js": contentScript,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  let loadingCount = 0;
+  let interactiveCount = 0;
+  let completeCount = 0;
+  extension.onMessage("script-run-loading", () => {
+    loadingCount++;
+  });
+  extension.onMessage("script-run-interactive", () => {
+    interactiveCount++;
+  });
+
+  let completePromise = new Promise(resolve => {
+    extension.onMessage("script-run-complete", () => {
+      completeCount++;
+      if (completeCount > 1) {
+        resolve();
+      }
+    });
+  });
+
+  let chromeNamespacePromise = extension.awaitMessage("chrome-namespace-ok");
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  await Promise.all([completePromise, chromeNamespacePromise]);
+
+  await contentPage.close();
+
+  equal(loadingCount, 1, "document_start script ran exactly once");
+  equal(interactiveCount, 1, "document_end script ran exactly once");
+  equal(completeCount, 2, "document_idle script ran exactly twice");
+
+  await extension.unload();
+});
+
+add_task(async function test_contentscript_window_open() {
+  if (AppConstants.DEBUG && ExtensionTestUtils.remoteContentScripts) {
+    return;
+  }
+
+  let script = async () => {
+    /* globals x */
+    browser.test.assertEq(1, x, "Should only run once");
+
+    if (top !== window) {
+      // Wait for our parent page to load, then set a timeout to wait for the
+      // document.open call, so we make sure to not tear down the extension
+      // until after we've done the document.open.
+      await new Promise(resolve => {
+        top.addEventListener("load", () => setTimeout(resolve, 0), {
+          once: true,
+        });
+      });
+    }
+
+    browser.test.sendMessage("content-script", [location.href, top === window]);
+  };
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "contentscript@tests.mozilla.org" } },
+      content_scripts: [
+        {
+          matches: ["<all_urls>"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+          match_about_blank: true,
+          all_frames: true,
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": `
+        var x = (x || 0) + 1;
+        (${script})();
+      `,
+    },
+  });
+
+  await extension.startup();
+
+  let url = `${BASE_URL}/file_document_open.html`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+
+  let [pageURL, pageIsTop] = await extension.awaitMessage("content-script");
+
+  // Sometimes we get a content script load for the initial about:blank
+  // top level frame here, sometimes we don't. Either way is fine, as long as we
+  // don't get two loads into the same document.open() document.
+  if (pageURL === "about:blank") {
+    equal(pageIsTop, true);
+    [pageURL, pageIsTop] = await extension.awaitMessage("content-script");
+  }
+
+  Assert.deepEqual([pageURL, pageIsTop], [url, true]);
+
+  let [frameURL, isTop] = await extension.awaitMessage("content-script");
+  Assert.deepEqual([frameURL, isTop], [url, false]);
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test verify that a cached script is still able to catch the document
+// while it is still loading (when we do not block the document parsing as
+// we do for a non cached script).
+add_task(async function test_cached_contentscript_on_document_start() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://localhost/*/file_document_open.html"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": `
+        browser.test.sendMessage("content-script-loaded", {
+          url: window.location.href,
+          documentReadyState: document.readyState,
+        });
+      `,
+    },
+  });
+
+  await extension.startup();
+
+  let url = `${BASE_URL}/file_document_open.html`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+
+  let msg = await extension.awaitMessage("content-script-loaded");
+  Assert.deepEqual(
+    msg,
+    {
+      url,
+      documentReadyState: "loading",
+    },
+    "Got the expected url and document.readyState from a non cached script"
+  );
+
+  // Reload the page and check that the cached content script is still able to
+  // run on document_start.
+  await contentPage.loadURL(url);
+
+  let msgFromCached = await extension.awaitMessage("content-script-loaded");
+  Assert.deepEqual(
+    msgFromCached,
+    {
+      url,
+      documentReadyState: "loading",
+    },
+    "Got the expected url and document.readyState from a cached script"
+  );
+
+  await extension.unload();
+
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_about_blank_start.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_about_blank_start.js
new file mode 100644
index 0000000000..023cc3d2a4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_about_blank_start.js
@@ -0,0 +1,78 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/blank-iframe.html", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+  response.write("<iframe></iframe>");
+});
+
+add_task(async function content_script_at_document_start() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["<all_urls>"],
+          js: ["start.js"],
+          run_at: "document_start",
+          match_about_blank: true,
+        },
+      ],
+    },
+
+    files: {
+      "start.js": function() {
+        browser.test.sendMessage("content-script-done");
+      },
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(`about:blank`);
+  await extension.awaitMessage("content-script-done");
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function content_style_at_document_start() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["<all_urls>"],
+          css: ["start.css"],
+          run_at: "document_start",
+          match_about_blank: true,
+        },
+        {
+          matches: ["<all_urls>"],
+          js: ["end.js"],
+          run_at: "document_end",
+          match_about_blank: true,
+        },
+      ],
+    },
+
+    files: {
+      "start.css": "body { background: red; }",
+      "end.js": function() {
+        let style = window.getComputedStyle(document.body);
+        browser.test.assertEq(
+          "rgb(255, 0, 0)",
+          style.backgroundColor,
+          "document_start style should have been applied"
+        );
+        browser.test.sendMessage("content-script-done");
+      },
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(`about:blank`);
+  await extension.awaitMessage("content-script-done");
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_api_injection.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_api_injection.js
new file mode 100644
index 0000000000..4e42181e71
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_api_injection.js
@@ -0,0 +1,65 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_contentscript_api_injection() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+        },
+      ],
+      web_accessible_resources: ["content_script_iframe.html"],
+    },
+
+    files: {
+      "content_script.js"() {
+        let iframe = document.createElement("iframe");
+        iframe.src = browser.runtime.getURL("content_script_iframe.html");
+        document.body.appendChild(iframe);
+      },
+      "content_script_iframe.js"() {
+        window.location = `http://example.com/data/file_privilege_escalation.html`;
+      },
+      "content_script_iframe.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script type="text/javascript" src="content_script_iframe.js"></script>
+          </head>
+        </html>`,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  let awaitConsole = new Promise(resolve => {
+    Services.console.registerListener(function listener(message) {
+      if (/WebExt Privilege Escalation/.test(message.message)) {
+        Services.console.unregisterListener(listener);
+        resolve(message);
+      }
+    });
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  let message = await awaitConsole;
+  ok(
+    message.message.includes(
+      "WebExt Privilege Escalation: typeof(browser) = undefined"
+    ),
+    "Document does not have `browser` APIs."
+  );
+
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_async_loading.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_async_loading.js
new file mode 100644
index 0000000000..cb9a07142d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_async_loading.js
@@ -0,0 +1,79 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_async_loading() {
+  const adder = `(function add(a = 1) { this.count += a; })();\n`;
+
+  const extension = {
+    manifest: {
+      content_scripts: [
+        {
+          run_at: "document_start",
+          matches: ["http://example.com/dummy"],
+          js: ["first.js", "second.js"],
+        },
+        {
+          run_at: "document_end",
+          matches: ["http://example.com/dummy"],
+          js: ["third.js"],
+        },
+      ],
+    },
+    files: {
+      "first.js": `
+        this.count = 0;
+        ${adder.repeat(50000)};  // 2Mb
+        browser.test.assertEq(this.count, 50000, "A 50k line script");
+
+        this.order = (this.order || 0) + 1;
+        browser.test.sendMessage("first", this.order);
+      `,
+      "second.js": `
+        this.order = (this.order || 0) + 1;
+        browser.test.sendMessage("second", this.order);
+      `,
+      "third.js": `
+        this.order = (this.order || 0) + 1;
+        browser.test.sendMessage("third", this.order);
+      `,
+    },
+  };
+
+  async function checkOrder(ext) {
+    const [first, second, third] = await Promise.all([
+      ext.awaitMessage("first"),
+      ext.awaitMessage("second"),
+      ext.awaitMessage("third"),
+    ]);
+
+    equal(first, 1, "first.js finished execution first.");
+    equal(second, 2, "second.js finished execution second.");
+    equal(third, 3, "third.js finished execution third.");
+  }
+
+  info("Test pages observed while extension is running");
+  const observed = ExtensionTestUtils.loadExtension(extension);
+  await observed.startup();
+
+  const contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+  await checkOrder(observed);
+  await observed.unload();
+
+  info("Test pages already existing on extension startup");
+  const existing = ExtensionTestUtils.loadExtension(extension);
+
+  await existing.startup();
+  await checkOrder(existing);
+  await existing.unload();
+
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_canvas_tainting.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_canvas_tainting.js
new file mode 100644
index 0000000000..4ac22dc700
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_canvas_tainting.js
@@ -0,0 +1,128 @@
+"use strict";
+
+const server = createHttpServer({
+  hosts: ["green.example.com", "red.example.com"],
+});
+
+server.registerDirectory("/data/", do_get_file("data"));
+
+server.registerPathHandler("/pixel.html", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write(`<!DOCTYPE html>
+    <script>
+      function readByWeb() {
+        let ctx = document.querySelector("canvas").getContext("2d");
+        let {data} = ctx.getImageData(0, 0, 1, 1);
+        return data.slice(0, 3).join();
+      }
+    </script>
+  `);
+});
+
+add_task(async function test_contentscript_canvas_tainting() {
+  async function contentScript() {
+    let canvas = document.createElement("canvas");
+    let ctx = canvas.getContext("2d");
+    document.body.appendChild(canvas);
+
+    function draw(url) {
+      return new Promise(resolve => {
+        let img = document.createElement("img");
+        img.onload = () => {
+          ctx.drawImage(img, 0, 0, 1, 1);
+          resolve();
+        };
+        img.src = url;
+      });
+    }
+
+    function readByExt() {
+      let { data } = ctx.getImageData(0, 0, 1, 1);
+      return data.slice(0, 3).join();
+    }
+
+    let readByWeb = window.wrappedJSObject.readByWeb;
+
+    // Test reading after drawing an image from the same origin as the web page.
+    await draw("http://green.example.com/data/pixel_green.gif");
+    browser.test.assertEq(
+      readByWeb(),
+      "0,255,0",
+      "Content can read same-origin image"
+    );
+    browser.test.assertEq(
+      readByExt(),
+      "0,255,0",
+      "Extension can read same-origin image"
+    );
+
+    // Test reading after drawing a blue pixel data URI from extension content script.
+    await draw(
+      "data:image/gif;base64,R0lGODlhAQABAIABAAAA/wAAACwAAAAAAQABAAACAkQBADs="
+    );
+    browser.test.assertThrows(
+      readByWeb,
+      /operation is insecure/,
+      "Content can't read extension's image"
+    );
+    browser.test.assertEq(
+      readByExt(),
+      "0,0,255",
+      "Extension can read its own image"
+    );
+
+    // Test after tainting the canvas with an image from a third party domain.
+    await draw("http://red.example.com/data/pixel_red.gif");
+    browser.test.assertThrows(
+      readByWeb,
+      /operation is insecure/,
+      "Content can't read third party image"
+    );
+    browser.test.assertThrows(
+      readByExt,
+      /operation is insecure/,
+      "Extension can't read fully tainted"
+    );
+
+    // Test canvas is still fully tainted after drawing extension's data: image again.
+    await draw(
+      "data:image/gif;base64,R0lGODlhAQABAIABAAAA/wAAACwAAAAAAQABAAACAkQBADs="
+    );
+    browser.test.assertThrows(
+      readByWeb,
+      /operation is insecure/,
+      "Canvas still fully tainted for content"
+    );
+    browser.test.assertThrows(
+      readByExt,
+      /operation is insecure/,
+      "Canvas still fully tainted for extension"
+    );
+
+    browser.test.sendMessage("done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://green.example.com/pixel.html"],
+          js: ["cs.js"],
+        },
+      ],
+    },
+    files: {
+      "cs.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://green.example.com/pixel.html"
+  );
+  await extension.awaitMessage("done");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_context.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_context.js
new file mode 100644
index 0000000000..2bb30f3c90
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_context.js
@@ -0,0 +1,348 @@
+"use strict";
+
+/* eslint-disable mozilla/balanced-listeners */
+
+const server = createHttpServer({ hosts: ["example.com", "example.org"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+function loadExtension() {
+  function contentScript() {
+    browser.test.sendMessage("content-script-ready");
+
+    window.addEventListener(
+      "pagehide",
+      () => {
+        browser.test.sendMessage("content-script-hide");
+      },
+      true
+    );
+    window.addEventListener("pageshow", () => {
+      browser.test.sendMessage("content-script-show");
+    });
+  }
+
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/dummy*"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+}
+
+add_task(async function test_contentscript_context() {
+  let extension = loadExtension();
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+  await extension.awaitMessage("content-script-ready");
+  await extension.awaitMessage("content-script-show");
+
+  // Get the content script context and check that it points to the correct window.
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { DocumentManager } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionContent.jsm",
+      null
+    );
+    this.context = DocumentManager.getContext(extensionId, this.content);
+
+    Assert.ok(this.context, "Got content script context");
+
+    Assert.equal(
+      this.context.contentWindow,
+      this.content,
+      "Context's contentWindow property is correct"
+    );
+
+    // Navigate so that the content page is hidden in the bfcache.
+
+    this.content.location = "http://example.org/dummy";
+  });
+
+  await extension.awaitMessage("content-script-hide");
+
+  await contentPage.spawn(null, async () => {
+    Assert.equal(
+      this.context.contentWindow,
+      null,
+      "Context's contentWindow property is null"
+    );
+
+    // Navigate back so the content page is resurrected from the bfcache.
+    this.content.history.back();
+  });
+
+  await extension.awaitMessage("content-script-show");
+
+  await contentPage.spawn(null, async () => {
+    Assert.equal(
+      this.context.contentWindow,
+      this.content,
+      "Context's contentWindow property is correct"
+    );
+  });
+
+  await contentPage.close();
+  await extension.awaitMessage("content-script-hide");
+  await extension.unload();
+});
+
+async function contentscript_context_incognito_not_allowed_test() {
+  async function background() {
+    await browser.contentScripts.register({
+      js: [{ file: "registered_script.js" }],
+      matches: ["http://example.com/dummy"],
+      runAt: "document_start",
+    });
+
+    browser.test.sendMessage("background-ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/dummy"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+        },
+      ],
+      permissions: ["http://example.com/*"],
+    },
+    background,
+    files: {
+      "content_script.js": () => {
+        browser.test.notifyFail("content_script_loaded");
+      },
+      "registered_script.js": () => {
+        browser.test.notifyFail("registered_script_loaded");
+      },
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("background-ready");
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy",
+    { privateBrowsing: true }
+  );
+
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { DocumentManager } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionContent.jsm",
+      null
+    );
+    let context = DocumentManager.getContext(extensionId, this.content);
+    Assert.equal(
+      context,
+      null,
+      "Extension unable to use content_script in private browsing window"
+    );
+  });
+
+  await contentPage.close();
+  await extension.unload();
+}
+
+add_task(async function test_contentscript_context_incognito_not_allowed() {
+  return runWithPrefs(
+    [["extensions.allowPrivateBrowsingByDefault", false]],
+    contentscript_context_incognito_not_allowed_test
+  );
+});
+
+add_task(async function test_contentscript_context_unload_while_in_bfcache() {
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy?first"
+  );
+  let extension = loadExtension();
+  await extension.startup();
+  await extension.awaitMessage("content-script-ready");
+
+  // Get the content script context and check that it points to the correct window.
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { DocumentManager } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionContent.jsm",
+      null
+    );
+    // Save context so we can verify that contentWindow is nulled after unload.
+    this.context = DocumentManager.getContext(extensionId, this.content);
+
+    Assert.equal(
+      this.context.contentWindow,
+      this.content,
+      "Context's contentWindow property is correct"
+    );
+
+    this.contextUnloadedPromise = new Promise(resolve => {
+      this.context.callOnClose({ close: resolve });
+    });
+    this.pageshownPromise = new Promise(resolve => {
+      this.content.addEventListener(
+        "pageshow",
+        () => {
+          // Yield to the event loop once more to ensure that all pageshow event
+          // handlers have been dispatched before fulfilling the promise.
+          let { setTimeout } = ChromeUtils.import(
+            "resource://gre/modules/Timer.jsm"
+          );
+          setTimeout(resolve, 0);
+        },
+        { once: true, mozSystemGroup: true }
+      );
+    });
+
+    // Navigate so that the content page is hidden in the bfcache.
+    this.content.location = "http://example.org/dummy?second";
+  });
+
+  await extension.awaitMessage("content-script-hide");
+
+  await extension.unload();
+  await contentPage.spawn(null, async () => {
+    await this.contextUnloadedPromise;
+    Assert.equal(this.context.unloaded, true, "Context has been unloaded");
+
+    // Normally, when a page is not in the bfcache, context.contentWindow is
+    // not null when the callOnClose handler is invoked (this is checked by the
+    // previous subtest).
+    // Now wait a little bit and check again to ensure that the contentWindow
+    // property is not somehow restored.
+    await new Promise(resolve => this.content.setTimeout(resolve, 0));
+    Assert.equal(
+      this.context.contentWindow,
+      null,
+      "Context's contentWindow property is null"
+    );
+
+    // Navigate back so the content page is resurrected from the bfcache.
+    this.content.history.back();
+
+    await this.pageshownPromise;
+
+    Assert.equal(
+      this.context.contentWindow,
+      null,
+      "Context's contentWindow property is null after restore from bfcache"
+    );
+  });
+
+  await contentPage.close();
+});
+
+add_task(async function test_contentscript_context_valid_during_execution() {
+  // This test does the following:
+  // - Load page
+  // - Load extension; inject content script.
+  // - Navigate page; pagehide triggered.
+  // - Navigate back; pageshow triggered.
+  // - Close page; pagehide, unload triggered.
+  // At each of these last four events, the validity of the context is checked.
+
+  function contentScript() {
+    browser.test.sendMessage("content-script-ready");
+    window.wrappedJSObject.checkContextIsValid("Context is valid on execution");
+
+    window.addEventListener(
+      "pagehide",
+      () => {
+        window.wrappedJSObject.checkContextIsValid(
+          "Context is valid on pagehide"
+        );
+        browser.test.sendMessage("content-script-hide");
+      },
+      true
+    );
+    window.addEventListener("pageshow", () => {
+      window.wrappedJSObject.checkContextIsValid(
+        "Context is valid on pageshow"
+      );
+
+      // This unload listener is registered after pageshow, to ensure that the
+      // page can be stored in the bfcache at the previous pagehide.
+      window.addEventListener("unload", () => {
+        window.wrappedJSObject.checkContextIsValid(
+          "Context is valid on unload"
+        );
+        browser.test.sendMessage("content-script-unload");
+      });
+
+      browser.test.sendMessage("content-script-show");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/dummy*"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy?first"
+  );
+  await contentPage.spawn(extension.id, async extensionId => {
+    let context;
+    let checkContextIsValid = description => {
+      if (!context) {
+        let { DocumentManager } = ChromeUtils.import(
+          "resource://gre/modules/ExtensionContent.jsm",
+          null
+        );
+        context = DocumentManager.getContext(extensionId, this.content);
+      }
+      Assert.equal(
+        context.contentWindow,
+        this.content,
+        `${description}: contentWindow`
+      );
+      Assert.equal(context.active, true, `${description}: active`);
+    };
+    Cu.exportFunction(checkContextIsValid, this.content, {
+      defineAs: "checkContextIsValid",
+    });
+  });
+  await extension.startup();
+  await extension.awaitMessage("content-script-ready");
+
+  await contentPage.spawn(extension.id, async extensionId => {
+    // Navigate so that the content page is frozen in the bfcache.
+    this.content.location = "http://example.org/dummy?second";
+  });
+
+  await extension.awaitMessage("content-script-hide");
+  await contentPage.spawn(null, async () => {
+    // Navigate back so the content page is resurrected from the bfcache.
+    this.content.history.back();
+  });
+
+  await extension.awaitMessage("content-script-show");
+  await contentPage.close();
+  await extension.awaitMessage("content-script-hide");
+  await extension.awaitMessage("content-script-unload");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_context_isolation.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_context_isolation.js
new file mode 100644
index 0000000000..1b705e0a53
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_context_isolation.js
@@ -0,0 +1,160 @@
+"use strict";
+
+/* globals exportFunction */
+/* eslint-disable mozilla/balanced-listeners */
+
+const server = createHttpServer({ hosts: ["example.com", "example.org"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+server.registerPathHandler("/bfcachetestpage", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html;charset=utf-8", false);
+  response.write(`<!DOCTYPE html>
+<script>
+  window.addEventListener("pageshow", (event) => {
+    event.stopImmediatePropagation();
+    if (window.browserTestSendMessage) {
+      browserTestSendMessage("content-script-show");
+    }
+  });
+  window.addEventListener("pagehide", (event) => {
+    event.stopImmediatePropagation();
+    if (window.browserTestSendMessage) {
+      if (event.persisted) {
+        browserTestSendMessage("content-script-hide");
+      } else {
+        browserTestSendMessage("content-script-unload");
+      }
+    }
+  }, true);
+</script>`);
+});
+
+add_task(async function test_contentscript_context_isolation() {
+  function contentScript() {
+    browser.test.sendMessage("content-script-ready");
+
+    exportFunction(browser.test.sendMessage, window, {
+      defineAs: "browserTestSendMessage",
+    });
+
+    window.addEventListener("pageshow", () => {
+      browser.test.fail(
+        "pageshow should have been suppressed by stopImmediatePropagation"
+      );
+    });
+    window.addEventListener(
+      "pagehide",
+      () => {
+        browser.test.fail(
+          "pagehide should have been suppressed by stopImmediatePropagation"
+        );
+      },
+      true
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/bfcachetestpage"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/bfcachetestpage"
+  );
+  await extension.startup();
+  await extension.awaitMessage("content-script-ready");
+
+  // Get the content script context and check that it points to the correct window.
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { DocumentManager } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionContent.jsm",
+      null
+    );
+    this.context = DocumentManager.getContext(extensionId, this.content);
+
+    Assert.ok(this.context, "Got content script context");
+
+    Assert.equal(
+      this.context.contentWindow,
+      this.content,
+      "Context's contentWindow property is correct"
+    );
+
+    // Navigate so that the content page is hidden in the bfcache.
+
+    this.content.location = "http://example.org/dummy?noscripthere1";
+  });
+
+  await extension.awaitMessage("content-script-hide");
+
+  await contentPage.spawn(null, async () => {
+    Assert.equal(
+      this.context.contentWindow,
+      null,
+      "Context's contentWindow property is null"
+    );
+    Assert.ok(this.context.sandbox, "Context's sandbox exists");
+
+    // Navigate back so the content page is resurrected from the bfcache.
+    this.content.history.back();
+  });
+
+  await extension.awaitMessage("content-script-show");
+
+  await contentPage.spawn(null, async () => {
+    Assert.equal(
+      this.context.contentWindow,
+      this.content,
+      "Context's contentWindow property is correct"
+    );
+    Assert.ok(this.context.sandbox, "Context's sandbox exists before unload");
+
+    let contextUnloadedPromise = new Promise(resolve => {
+      this.context.callOnClose({ close: resolve });
+    });
+
+    // Now add an "unload" event listener, which should prevent a page from entering the bfcache.
+    await new Promise(resolve => {
+      this.content.addEventListener("unload", () => {
+        Assert.equal(
+          this.context.contentWindow,
+          this.content,
+          "Context's contentWindow property should be non-null at unload"
+        );
+        resolve();
+      });
+      this.content.location = "http://example.org/dummy?noscripthere2";
+    });
+
+    await contextUnloadedPromise;
+  });
+
+  await extension.awaitMessage("content-script-unload");
+
+  await contentPage.spawn(null, async () => {
+    Assert.equal(
+      this.context.sandbox,
+      null,
+      "Context's sandbox has been destroyed after unload"
+    );
+  });
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_create_iframe.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_create_iframe.js
new file mode 100644
index 0000000000..ff2622e4fb
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_create_iframe.js
@@ -0,0 +1,177 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_contentscript_create_iframe() {
+  function background() {
+    browser.runtime.onMessage.addListener((msg, sender) => {
+      let { name, availableAPIs, manifest, testGetManifest } = msg;
+      let hasExtTabsAPI = availableAPIs.indexOf("tabs") > 0;
+      let hasExtWindowsAPI = availableAPIs.indexOf("windows") > 0;
+
+      browser.test.assertFalse(
+        hasExtTabsAPI,
+        "the created iframe should not be able to use privileged APIs (tabs)"
+      );
+      browser.test.assertFalse(
+        hasExtWindowsAPI,
+        "the created iframe should not be able to use privileged APIs (windows)"
+      );
+
+      let {
+        applications: {
+          gecko: { id: expectedManifestGeckoId },
+        },
+      } = chrome.runtime.getManifest();
+      let {
+        applications: {
+          gecko: { id: actualManifestGeckoId },
+        },
+      } = manifest;
+
+      browser.test.assertEq(
+        actualManifestGeckoId,
+        expectedManifestGeckoId,
+        "the add-on manifest should be accessible from the created iframe"
+      );
+
+      let {
+        applications: {
+          gecko: { id: testGetManifestGeckoId },
+        },
+      } = testGetManifest;
+
+      browser.test.assertEq(
+        testGetManifestGeckoId,
+        expectedManifestGeckoId,
+        "GET_MANIFEST() returns manifest data before extension unload"
+      );
+
+      browser.test.sendMessage(name);
+    });
+  }
+
+  function contentScriptIframe() {
+    window.GET_MANIFEST = browser.runtime.getManifest.bind(null);
+
+    window.testGetManifestException = () => {
+      try {
+        window.GET_MANIFEST();
+      } catch (exception) {
+        return String(exception);
+      }
+    };
+
+    let testGetManifest = window.GET_MANIFEST();
+
+    let manifest = browser.runtime.getManifest();
+    let availableAPIs = Object.keys(browser).filter(key => browser[key]);
+
+    browser.runtime.sendMessage({
+      name: "content-script-iframe-loaded",
+      availableAPIs,
+      manifest,
+      testGetManifest,
+    });
+  }
+
+  const ID = "contentscript@tests.mozilla.org";
+  let extensionData = {
+    manifest: {
+      applications: { gecko: { id: ID } },
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+      web_accessible_resources: ["content_script_iframe.html"],
+    },
+
+    background,
+
+    files: {
+      "content_script.js"() {
+        let iframe = document.createElement("iframe");
+        iframe.src = browser.runtime.getURL("content_script_iframe.html");
+        document.body.appendChild(iframe);
+      },
+      "content_script_iframe.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script type="text/javascript" src="content_script_iframe.js"></script>
+          </head>
+        </html>`,
+      "content_script_iframe.js": contentScriptIframe,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  await extension.awaitMessage("content-script-iframe-loaded");
+
+  info("testing APIs availability once the extension is unloaded...");
+
+  await contentPage.spawn(null, () => {
+    this.iframeWindow = this.content[0];
+
+    Assert.ok(this.iframeWindow, "content script enabled iframe found");
+    Assert.ok(
+      /content_script_iframe\.html$/.test(this.iframeWindow.location),
+      "the found iframe has the expected URL"
+    );
+  });
+
+  await extension.unload();
+
+  info(
+    "test content script APIs not accessible from the frame once the extension is unloaded"
+  );
+
+  await contentPage.spawn(null, () => {
+    let win = Cu.waiveXrays(this.iframeWindow);
+    ok(
+      !Cu.isDeadWrapper(win.browser),
+      "the API object should not be a dead object"
+    );
+
+    let manifest;
+    let manifestException;
+    try {
+      manifest = win.browser.runtime.getManifest();
+    } catch (e) {
+      manifestException = e;
+    }
+
+    Assert.ok(!manifest, "manifest should be undefined");
+
+    Assert.equal(
+      manifestException.constructor.name,
+      "TypeError",
+      "expected exception received"
+    );
+
+    Assert.ok(
+      manifestException.message.endsWith("win.browser.runtime is undefined"),
+      "expected exception received"
+    );
+
+    let getManifestException = win.testGetManifestException();
+
+    Assert.equal(
+      getManifestException,
+      "TypeError: can't access dead object",
+      "expected exception received"
+    );
+  });
+
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_csp.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_csp.js
new file mode 100644
index 0000000000..cf770d91b4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_csp.js
@@ -0,0 +1,355 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { TestUtils } = ChromeUtils.import(
+  "resource://testing-common/TestUtils.jsm"
+);
+
+Services.prefs.setBoolPref("extensions.manifestV3.enabled", true);
+
+const server = createHttpServer({
+  hosts: ["example.com", "csplog.example.net"],
+});
+server.registerDirectory("/data/", do_get_file("data"));
+
+var gDefaultCSP = `default-src 'self' 'report-sample'; script-src 'self' 'report-sample';`;
+var gCSP = gDefaultCSP;
+const pageContent = `<!DOCTYPE html>
+  <html lang="en">
+  <head>
+    <meta charset="UTF-8">
+    <title></title>
+  </head>
+  <body>
+  <img id="testimg">
+  </body>
+  </html>`;
+
+server.registerPathHandler("/plain.html", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html");
+  if (gCSP) {
+    info(`Content-Security-Policy: ${gCSP}`);
+    response.setHeader("Content-Security-Policy", gCSP);
+  }
+  response.write(pageContent);
+});
+
+const BASE_URL = `http://example.com`;
+const pageURL = `${BASE_URL}/plain.html`;
+
+const CSP_REPORT_PATH = "/csp-report.sjs";
+
+function readUTF8InputStream(stream) {
+  let buffer = NetUtil.readInputStream(stream, stream.available());
+  return new TextDecoder().decode(buffer);
+}
+
+server.registerPathHandler(CSP_REPORT_PATH, (request, response) => {
+  response.setStatusLine(request.httpVersion, 204, "No Content");
+  let data = readUTF8InputStream(request.bodyInputStream);
+  Services.obs.notifyObservers(null, "extension-test-csp-report", data);
+});
+
+async function promiseCSPReport(test) {
+  let res = await TestUtils.topicObserved("extension-test-csp-report", test);
+  return JSON.parse(res[1]);
+}
+
+// Test functions loaded into extension content script.
+function testImage(data = {}) {
+  return new Promise(resolve => {
+    let img = window.document.getElementById("testimg");
+    img.onload = () => resolve(true);
+    img.onerror = () => {
+      browser.test.log(`img error: ${img.src}`);
+      resolve(false);
+    };
+    img.src = data.image_url;
+  });
+}
+
+function testFetch(data = {}) {
+  let f = data.content ? content.fetch : fetch;
+  return f(data.url)
+    .then(() => true)
+    .catch(e => {
+      browser.test.assertEq(
+        e.message,
+        "NetworkError when attempting to fetch resource.",
+        "expected fetch failure"
+      );
+      return false;
+    });
+}
+
+async function testEval(data = {}) {
+  try {
+    // eslint-disable-next-line no-eval
+    let ev = data.content ? window.eval : eval;
+    return ev("true");
+  } catch (e) {
+    return false;
+  }
+}
+
+async function testFunction(data = {}) {
+  try {
+    // eslint-disable-next-line no-eval
+    let fn = data.content ? window.Function : Function;
+    let sum = new fn("a", "b", "return a + b");
+    return sum(1, 1);
+  } catch (e) {
+    return 0;
+  }
+}
+
+function testScriptTag(data) {
+  return new Promise(resolve => {
+    let script = document.createElement("script");
+    script.src = data.url;
+    script.onload = () => {
+      resolve(true);
+    };
+    script.onerror = () => {
+      resolve(false);
+    };
+    document.body.appendChild(script);
+  });
+}
+
+// If the violation source is the extension the securitypolicyviolation event is not fired.
+// If the page is the source, the event is fired and both the content script or page scripts
+// will receive the event.  If we're expecting a moz-extension report  we'll  fail in the
+// event listener if we receive a report.  Otherwise we want to resolve in the listener to
+// ensure we've received the event for the test.
+function contentScript(report) {
+  return new Promise(resolve => {
+    if (!report || report["document-uri"] === "moz-extension") {
+      resolve();
+    }
+    // eslint-disable-next-line mozilla/balanced-listeners
+    document.addEventListener("securitypolicyviolation", e => {
+      browser.test.assertTrue(
+        e.documentURI !== "moz-extension",
+        `securitypolicyviolation: ${e.violatedDirective} ${e.documentURI}`
+      );
+      resolve();
+    });
+  });
+}
+
+let TESTS = [
+  // Image Tests
+  {
+    description:
+      "Image from content script using default extension csp. Image is allowed.",
+    pageCSP: `${gDefaultCSP} img-src 'none';`,
+    script: testImage,
+    data: { image_url: `${BASE_URL}/data/file_image_good.png` },
+    expect: true,
+  },
+  // Fetch Tests
+  {
+    description: "Fetch url in content script uses default extension csp.",
+    pageCSP: `${gDefaultCSP} connect-src 'none';`,
+    script: testFetch,
+    data: { url: `${BASE_URL}/data/file_image_good.png` },
+    expect: true,
+  },
+  {
+    description: "Fetch full url from content script uses page csp.",
+    pageCSP: `${gDefaultCSP} connect-src 'none';`,
+    script: testFetch,
+    data: {
+      content: true,
+      url: `${BASE_URL}/data/file_image_good.png`,
+    },
+    expect: false,
+    report: {
+      "blocked-uri": `${BASE_URL}/data/file_image_good.png`,
+      "document-uri": `${BASE_URL}/plain.html`,
+      "violated-directive": "connect-src",
+    },
+  },
+  {
+    description: "Fetch url from content script uses page csp.",
+    pageCSP: `${gDefaultCSP} connect-src *;`,
+    script: testFetch,
+    version: 3,
+    data: {
+      content: true,
+      url: `${BASE_URL}/data/file_image_good.png`,
+    },
+    expect: true,
+  },
+
+  // Eval tests.
+  {
+    description: "Eval from content script uses page csp with unsafe-eval.",
+    pageCSP: `default-src 'none'; script-src 'unsafe-eval';`,
+    script: testEval,
+    data: { content: true },
+    expect: true,
+  },
+  {
+    description: "Eval from content script uses page csp.",
+    pageCSP: `default-src 'self' 'report-sample'; script-src 'self';`,
+    version: 3,
+    script: testEval,
+    data: { content: true },
+    expect: false,
+    report: {
+      "blocked-uri": "eval",
+      "document-uri": "http://example.com/plain.html",
+      "violated-directive": "script-src",
+    },
+  },
+  {
+    description: "Eval in content script allowed by v2 csp.",
+    pageCSP: `script-src 'self' 'unsafe-eval';`,
+    script: testEval,
+    expect: true,
+  },
+  {
+    description: "Eval in content script disallowed by v3 csp.",
+    pageCSP: `script-src 'self' 'unsafe-eval';`,
+    version: 3,
+    script: testEval,
+    expect: false,
+  },
+  {
+    description: "Wrapped Eval in content script uses page csp.",
+    pageCSP: `script-src 'self' 'unsafe-eval';`,
+    version: 3,
+    script: async () => {
+      return window.wrappedJSObject.eval("true");
+    },
+    expect: true,
+  },
+  {
+    description: "Wrapped Eval in content script denied by page csp.",
+    pageCSP: `script-src 'self';`,
+    version: 3,
+    script: async () => {
+      try {
+        return window.wrappedJSObject.eval("true");
+      } catch (e) {
+        return false;
+      }
+    },
+    expect: false,
+  },
+
+  {
+    description: "Function from content script uses page csp.",
+    pageCSP: `default-src 'self'; script-src 'self' 'unsafe-eval';`,
+    script: testFunction,
+    data: { content: true },
+    expect: 2,
+  },
+  {
+    description: "Function from content script uses page csp.",
+    pageCSP: `default-src 'self' 'report-sample'; script-src 'self';`,
+    version: 3,
+    script: testFunction,
+    data: { content: true },
+    expect: 0,
+    report: {
+      "blocked-uri": "eval",
+      "document-uri": "http://example.com/plain.html",
+      "violated-directive": "script-src",
+    },
+  },
+  {
+    description: "Function in content script uses extension csp.",
+    pageCSP: `default-src 'self'; script-src 'self' 'unsafe-eval';`,
+    version: 3,
+    script: testFunction,
+    expect: 0,
+  },
+
+  // The javascript url tests are not included as we do not execute those,
+  // aparently even with the urlbar filtering pref flipped.
+  // (browser.urlbar.filter.javascript)
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=866522
+
+  // script tag injection tests
+  {
+    description: "remote script in content script passes in v2",
+    version: 2,
+    pageCSP: "script-src http://example.com:*;",
+    script: testScriptTag,
+    data: { url: `${BASE_URL}/data/file_script_good.js` },
+    expect: true,
+  },
+  {
+    description: "remote script in content script fails in v3",
+    version: 3,
+    pageCSP: "script-src http://example.com:*;",
+    script: testScriptTag,
+    data: { url: `${BASE_URL}/data/file_script_good.js` },
+    expect: false,
+  },
+];
+
+async function runCSPTest(test) {
+  // Set the CSP for the page loaded into the tab.
+  gCSP = `${test.pageCSP || gDefaultCSP} report-uri ${CSP_REPORT_PATH}`;
+  let data = {
+    manifest: {
+      manifest_version: test.version || 2,
+      content_scripts: [
+        {
+          matches: ["http://*/plain.html"],
+          run_at: "document_idle",
+          js: ["content_script.js"],
+        },
+      ],
+      permissions: ["<all_urls>"],
+    },
+
+    files: {
+      "content_script.js": `
+      (${contentScript})(${JSON.stringify(test.report)}).then(() => {
+        browser.test.sendMessage("violationEvent");
+      });
+      (${test.script})(${JSON.stringify(test.data)}).then(result => {
+        browser.test.sendMessage("result", result);
+      });
+      `,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(data);
+  await extension.startup();
+
+  let reportPromise = test.report && promiseCSPReport();
+  let contentPage = await ExtensionTestUtils.loadContentPage(pageURL);
+
+  info(`running: ${test.description}`);
+  await extension.awaitMessage("violationEvent");
+  let result = await extension.awaitMessage("result");
+  equal(result, test.expect, test.description);
+  if (test.report) {
+    let report = await reportPromise;
+    for (let key of Object.keys(test.report)) {
+      equal(
+        report["csp-report"][key],
+        test.report[key],
+        `csp-report ${key} matches`
+      );
+    }
+  }
+
+  await extension.unload();
+  await contentPage.close();
+  clearCache();
+}
+
+add_task(async function test_contentscript_csp() {
+  for (let test of TESTS) {
+    await runCSPTest(test);
+  }
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_css.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_css.js
new file mode 100644
index 0000000000..d94023387f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_css.js
@@ -0,0 +1,48 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_content_script_css() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/dummy"],
+          css: ["content.css"],
+          run_at: "document_start",
+        },
+      ],
+    },
+
+    files: {
+      "content.css": "body { max-width: 42px; }",
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+
+  function task() {
+    let style = this.content.getComputedStyle(this.content.document.body);
+    return style.maxWidth;
+  }
+
+  let maxWidth = await contentPage.spawn(null, task);
+  equal(maxWidth, "42px", "Stylesheet correctly applied");
+
+  await extension.unload();
+
+  maxWidth = await contentPage.spawn(null, task);
+  equal(maxWidth, "none", "Stylesheet correctly removed");
+
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_exporthelpers.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_exporthelpers.js
new file mode 100644
index 0000000000..f485a012c9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_exporthelpers.js
@@ -0,0 +1,98 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_contentscript_exportHelpers() {
+  function contentScript() {
+    browser.test.assertTrue(typeof cloneInto === "function");
+    browser.test.assertTrue(typeof createObjectIn === "function");
+    browser.test.assertTrue(typeof exportFunction === "function");
+
+    /* globals exportFunction, precisePi, reportPi */
+    let value = 3.14;
+    exportFunction(() => value, window, { defineAs: "precisePi" });
+
+    browser.test.assertEq(
+      "undefined",
+      typeof precisePi,
+      "exportFunction should export to the page's scope only"
+    );
+
+    browser.test.assertEq(
+      "undefined",
+      typeof window.precisePi,
+      "exportFunction should export to the page's scope only"
+    );
+
+    let results = [];
+    exportFunction(pi => results.push(pi), window, { defineAs: "reportPi" });
+
+    let s = document.createElement("script");
+    s.textContent = `(${function() {
+      let result1 = "unknown 1";
+      let result2 = "unknown 2";
+      try {
+        result1 = precisePi();
+      } catch (e) {
+        result1 = "err:" + e;
+      }
+      try {
+        result2 = window.precisePi();
+      } catch (e) {
+        result2 = "err:" + e;
+      }
+      reportPi(result1);
+      reportPi(result2);
+    }})();`;
+
+    document.documentElement.appendChild(s);
+    // Inline script ought to run synchronously.
+
+    browser.test.assertEq(
+      3.14,
+      results[0],
+      "exportFunction on window should define a global function"
+    );
+    browser.test.assertEq(
+      3.14,
+      results[1],
+      "exportFunction on window should export a property to window."
+    );
+
+    browser.test.assertEq(
+      2,
+      results.length,
+      "Expecting the number of results to match the number of method calls"
+    );
+
+    browser.test.notifyPass("export helper test completed");
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          js: ["contentscript.js"],
+          matches: ["http://example.com/data/file_sample.html"],
+          run_at: "document_start",
+        },
+      ],
+    },
+
+    files: {
+      "contentscript.js": contentScript,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  await extension.awaitFinish("export helper test completed");
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_in_background.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_in_background.js
new file mode 100644
index 0000000000..1a8aa6d706
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_in_background.js
@@ -0,0 +1,61 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerPathHandler("/dummyFrame", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+  response.write("");
+});
+
+add_task(async function connect_from_background_frame() {
+  async function background() {
+    const FRAME_URL = "http://example.com:8888/dummyFrame";
+    browser.runtime.onConnect.addListener(port => {
+      browser.test.assertEq(port.sender.tab, undefined, "Sender is not a tab");
+      browser.test.assertEq(port.sender.url, FRAME_URL, "Expected sender URL");
+      port.onMessage.addListener(msg => {
+        browser.test.assertEq("pong", msg, "Reply from content script");
+        port.disconnect();
+      });
+      port.postMessage("ping");
+    });
+
+    await browser.contentScripts.register({
+      matches: ["http://example.com/dummyFrame"],
+      js: [{ file: "contentscript.js" }],
+      allFrames: true,
+    });
+
+    let f = document.createElement("iframe");
+    f.src = FRAME_URL;
+    document.body.appendChild(f);
+  }
+
+  function contentScript() {
+    browser.test.log(`Running content script at ${document.URL}`);
+
+    let port = browser.runtime.connect();
+    port.onMessage.addListener(msg => {
+      browser.test.assertEq("ping", msg, "Expected message to content script");
+      port.postMessage("pong");
+    });
+    port.onDisconnect.addListener(() => {
+      browser.test.sendMessage("disconnected_in_content_script");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://example.com/*"],
+    },
+    files: {
+      "contentscript.js": contentScript,
+    },
+    background,
+  });
+  await extension.startup();
+  await extension.awaitMessage("disconnected_in_content_script");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_perf_observers.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_perf_observers.js
new file mode 100644
index 0000000000..484c41ad3f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_perf_observers.js
@@ -0,0 +1,71 @@
+"use strict";
+
+const server = createHttpServer({
+  hosts: ["a.example.com", "b.example.com", "c.example.com"],
+});
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_perf_observers_cors() {
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://b.example.com/"],
+      content_scripts: [
+        {
+          matches: ["http://a.example.com/file_sample.html"],
+          js: ["cs.js"],
+        },
+      ],
+    },
+    files: {
+      "cs.js"() {
+        let obs = new window.PerformanceObserver(list => {
+          list.getEntries().forEach(e => {
+            browser.test.sendMessage("observed", {
+              url: e.name,
+              time: e.connectEnd,
+              size: e.encodedBodySize,
+            });
+          });
+        });
+        obs.observe({ entryTypes: ["resource"] });
+
+        let b = document.createElement("link");
+        b.rel = "stylesheet";
+
+        // Simulate page including a cross-origin resource from b.example.com.
+        b.wrappedJSObject.href = "http://b.example.com/file_download.txt";
+        document.head.appendChild(b);
+
+        let c = document.createElement("link");
+        c.rel = "stylesheet";
+
+        // Simulate page including a cross-origin resource from c.example.com.
+        c.wrappedJSObject.href = "http://c.example.com/file_download.txt";
+        document.head.appendChild(c);
+      },
+    },
+  });
+
+  let page = await ExtensionTestUtils.loadContentPage(
+    "http://a.example.com/file_sample.html"
+  );
+  await extension.startup();
+
+  let b = await extension.awaitMessage("observed");
+  let c = await extension.awaitMessage("observed");
+
+  if (b.url.startsWith("http://c.")) {
+    [c, b] = [b, c];
+  }
+
+  ok(b.url.startsWith("http://b."), "Observed resource from b.example.com");
+  ok(b.time > 0, "connectionEnd available from b.example.com");
+  equal(b.size, 428, "encodedBodySize available from b.example.com");
+
+  ok(c.url.startsWith("http://c."), "Observed resource from c.example.com");
+  equal(c.time, 0, "connectionEnd == 0 from c.example.com");
+  equal(c.size, 0, "encodedBodySize == 0 from c.example.com");
+
+  await extension.unload();
+  await page.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_restrictSchemes.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_restrictSchemes.js
new file mode 100644
index 0000000000..e9b1dbe57c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_restrictSchemes.js
@@ -0,0 +1,70 @@
+"use strict";
+
+function makeExtension(id, isPrivileged) {
+  return ExtensionTestUtils.loadExtension({
+    isPrivileged,
+
+    manifest: {
+      applications: { gecko: { id } },
+
+      permissions: isPrivileged ? ["mozillaAddons"] : [],
+
+      content_scripts: [
+        {
+          matches: ["resource://foo/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js"() {
+        browser.test.assertEq(
+          "resource://foo/file_sample.html",
+          document.documentURI,
+          `Loaded content script into the correct document (extension: ${browser.runtime.id})`
+        );
+        browser.test.sendMessage(`content-script-${browser.runtime.id}`);
+      },
+    },
+  });
+}
+
+add_task(async function test_contentscript_restrictSchemes() {
+  let resProto = Services.io
+    .getProtocolHandler("resource")
+    .QueryInterface(Ci.nsIResProtocolHandler);
+  resProto.setSubstitutionWithFlags(
+    "foo",
+    Services.io.newFileURI(do_get_file("data")),
+    resProto.ALLOW_CONTENT_ACCESS
+  );
+
+  let unprivileged = makeExtension("unprivileged@tests.mozilla.org", false);
+  let privileged = makeExtension("privileged@tests.mozilla.org", true);
+
+  await unprivileged.startup();
+  await privileged.startup();
+
+  unprivileged.onMessage(
+    "content-script-unprivileged@tests.mozilla.org",
+    () => {
+      ok(
+        false,
+        "Unprivileged extension executed content script on resource URL"
+      );
+    }
+  );
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `resource://foo/file_sample.html`
+  );
+
+  await privileged.awaitMessage("content-script-privileged@tests.mozilla.org");
+
+  await contentPage.close();
+
+  await privileged.unload();
+  await unprivileged.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_scriptCreated.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_scriptCreated.js
new file mode 100644
index 0000000000..e0ed263065
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_scriptCreated.js
@@ -0,0 +1,61 @@
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+// Test that document_start content scripts don't block script-created
+// parsers.
+add_task(async function test_contentscript_scriptCreated() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_document_write.html"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+          match_about_blank: true,
+          all_frames: true,
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": function() {
+        if (window === top) {
+          addEventListener(
+            "message",
+            msg => {
+              browser.test.assertEq(
+                "ok",
+                msg.data,
+                "document.write() succeeded"
+              );
+              browser.test.sendMessage("content-script-done");
+            },
+            { once: true }
+          );
+        }
+      },
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_document_write.html`
+  );
+
+  await extension.awaitMessage("content-script-done");
+
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_teardown.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_teardown.js
new file mode 100644
index 0000000000..2bf7981657
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_teardown.js
@@ -0,0 +1,102 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_contentscript_reload_and_unload() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["contentscript.js"],
+        },
+      ],
+    },
+
+    files: {
+      "contentscript.js"() {
+        browser.test.sendMessage("contentscript-run");
+      },
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let events = [];
+  {
+    let { Management } = ChromeUtils.import(
+      "resource://gre/modules/Extension.jsm",
+      null
+    );
+    let record = (type, extensionContext) => {
+      let eventType = type == "proxy-context-load" ? "load" : "unload";
+      let url = extensionContext.uri.spec;
+      let extensionId = extensionContext.extension.id;
+      events.push({ eventType, url, extensionId });
+    };
+
+    Management.on("proxy-context-load", record);
+    Management.on("proxy-context-unload", record);
+    registerCleanupFunction(() => {
+      Management.off("proxy-context-load", record);
+      Management.off("proxy-context-unload", record);
+    });
+  }
+
+  const tabUrl = "http://example.com/data/file_sample.html";
+  let contentPage = await ExtensionTestUtils.loadContentPage(tabUrl);
+
+  await extension.awaitMessage("contentscript-run");
+
+  let contextEvents = events.splice(0);
+  equal(
+    contextEvents.length,
+    1,
+    "ExtensionContext state change after loading a content script"
+  );
+  equal(
+    contextEvents[0].eventType,
+    "load",
+    "Create ExtensionContext for content script"
+  );
+  equal(contextEvents[0].url, tabUrl, "ExtensionContext URL = page");
+
+  await contentPage.spawn(null, () => {
+    this.content.location.reload();
+  });
+  await extension.awaitMessage("contentscript-run");
+
+  contextEvents = events.splice(0);
+  equal(
+    contextEvents.length,
+    2,
+    "ExtensionContext state changes after reloading a content script"
+  );
+  equal(contextEvents[0].eventType, "unload", "Unload old ExtensionContext");
+  equal(contextEvents[0].url, tabUrl, "ExtensionContext URL = page");
+  equal(
+    contextEvents[1].eventType,
+    "load",
+    "Create new ExtensionContext for content script"
+  );
+  equal(contextEvents[1].url, tabUrl, "ExtensionContext URL = page");
+
+  await contentPage.close();
+
+  contextEvents = events.splice(0);
+  equal(
+    contextEvents.length,
+    1,
+    "ExtensionContext state change after unloading a content script"
+  );
+  equal(
+    contextEvents[0].eventType,
+    "unload",
+    "Unload ExtensionContext after closing the tab with the content script"
+  );
+  equal(contextEvents[0].url, tabUrl, "ExtensionContext URL = page");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_triggeringPrincipal.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_triggeringPrincipal.js
new file mode 100644
index 0000000000..f5df8e61d2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_triggeringPrincipal.js
@@ -0,0 +1,1373 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/**
+ * Tests that various types of inline content elements initiate requests
+ * with the triggering pringipal of the caller that requested the load,
+ * and that the correct security policies are applied to the resulting
+ * loads.
+ */
+
+const env = Cc["@mozilla.org/process/environment;1"].getService(
+  Ci.nsIEnvironment
+);
+
+// Make sure media pre-loading is enabled on Android so that our <audio> and
+// <video> elements trigger the expected requests.
+Services.prefs.setIntPref("media.autoplay.default", Ci.nsIAutoplay.ALLOWED);
+Services.prefs.setIntPref("media.preload.default", 3);
+
+// Increase the length of the code samples included in CSP reports so that we
+// can correctly validate them.
+Services.prefs.setIntPref(
+  "security.csp.reporting.script-sample.max-length",
+  4096
+);
+
+// Do not trunacate the blocked-uri in CSP reports for frame navigations.
+Services.prefs.setBoolPref(
+  "security.csp.truncate_blocked_uri_for_frame_navigations",
+  false
+);
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+const server = createHttpServer({
+  hosts: ["example.com", "csplog.example.net"],
+});
+
+server.registerDirectory("/data/", do_get_file("data"));
+
+var gContentSecurityPolicy = null;
+
+const BASE_URL = `http://example.com`;
+const CSP_REPORT_PATH = "/csp-report.sjs";
+
+/**
+ * Registers a static HTML document with the given content at the given
+ * path in our test HTTP server.
+ *
+ * @param {string} path
+ * @param {string} content
+ */
+function registerStaticPage(path, content) {
+  server.registerPathHandler(path, (request, response) => {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/html");
+    if (gContentSecurityPolicy) {
+      response.setHeader("Content-Security-Policy", gContentSecurityPolicy);
+    }
+    response.write(content);
+  });
+}
+
+/**
+ * A set of tags which are automatically closed in HTML documents, and
+ * do not require an explicit closing tag.
+ */
+const AUTOCLOSE_TAGS = new Set(["img", "input", "link", "source"]);
+
+/**
+ * An object describing the elements to create for a specific test.
+ *
+ * @typedef {object} ElementTestCase
+ * @property {Array} element
+ *        A recursive array, describing the element to create, in the
+ *        following format:
+ *
+ *          ["tagname", {attr: "attrValue"},
+ *            ["child-tagname", {attr: "value"}],
+ *            ...]
+ *
+ *        For each test, a DOM tree will be created with this structure.
+ *        A source attribute, with the name `test.srcAttr` and a value
+ *        based on the values of `test.src` and `opts`, will be added to
+ *        the first leaf node encountered.
+ * @property {string} src
+ *        The relative URL to use as the source of the element. Each
+ *        load of this URL will have a separate set of query parameters
+ *        appended to it, based on the values in `opts`.
+ * @property {string} [srcAttr = "src"]
+ *        The attribute in which to store the element's source URL.
+ * @property {string} [srcAttr = "src"]
+ *        The attribute in which to store the element's source URL.
+ * @property {boolean} [liveSrc = false]
+ *        If true, changing the source attribute after the element has
+ *        been inserted into the document is expected to trigger a new
+ *        load, and that configuration will be tested.
+ */
+
+/**
+ * Options for this specific configuration of an element test.
+ *
+ * @typedef {object} ElementTestOptions
+ * @property {string} origin
+ *        The origin with which the content is expected to load. This
+ *        may be one of "page", "contentScript", or "extension". The actual load
+ *        of the URL will be tested against the computed origin strings for
+ *        those two contexts.
+ * @property {string} source
+ *        An arbitrary string which uniquely identifies the source of
+ *        the load. For instance, each of these should have separate
+ *        origin strings:
+ *
+ *         - An element present in the initial page HTML.
+ *         - An element injected by a page script belonging to web
+ *           content.
+ *         - An element injected by an extension content script.
+ */
+
+/**
+ * Data describing a test element, which can be used to create a
+ * corresponding DOM tree.
+ *
+ * @typedef {object} ElementData
+ * @property {string} tagName
+ *        The tag name for the element.
+ * @property {object} attrs
+ *        A property containing key-value pairs for each of the
+ *        attribute's elements.
+ * @property {Array<ElementData>} children
+ *        A possibly empty array of element data for child elements.
+ */
+
+/**
+ * Returns data necessary to create test elements for the given test,
+ * with the given options.
+ *
+ * @param {ElementTestCase} test
+ *        An object describing the elements to create for a specific
+ *        test. This element will be created under various
+ *        circumstances, as described by `opts`.
+ * @param {ElementTestOptions} opts
+ *        Options for this specific configuration of the test.
+ * @returns {ElementData}
+ */
+function getElementData(test, opts) {
+  let baseURL = typeof BASE_URL !== "undefined" ? BASE_URL : location.href;
+
+  let { srcAttr, src } = test;
+
+  // Absolutify the URL, so it passes sanity checks that ignore
+  // triggering principals for relative URLs.
+  src = new URL(
+    src +
+      `?origin=${encodeURIComponent(opts.origin)}&source=${encodeURIComponent(
+        opts.source
+      )}`,
+    baseURL
+  ).href;
+
+  let haveSrc = false;
+  function rec(element) {
+    let [tagName, attrs, ...children] = element;
+
+    if (children.length) {
+      children = children.map(rec);
+    } else if (!haveSrc) {
+      attrs = Object.assign({ [srcAttr]: src }, attrs);
+      haveSrc = true;
+    }
+
+    return { tagName, attrs, children };
+  }
+  return rec(test.element);
+}
+
+/**
+ * The result type of the {@see createElement} function.
+ *
+ * @typedef {object} CreateElementResult
+ * @property {Element} elem
+ *        The root element of the created DOM tree.
+ * @property {Element} srcElem
+ *        The element in the tree to which the source attribute must be
+ *        added.
+ * @property {string} src
+ *        The value of the source element.
+ */
+
+/**
+ * Creates a DOM tree for a given test, in a given configuration, as
+ * understood by {@see getElementData}, but without the `test.srcAttr`
+ * attribute having been set. The caller must set the value of that
+ * attribute to the returned `src` value.
+ *
+ * There are many different ways most source values can be set
+ * (DOM attribute, DOM property, ...) and many different contexts
+ * (content script verses page script). Each test should be run with as
+ * many variants of these as possible.
+ *
+ * @param {ElementTestCase} test
+ *        A test object, as passed to {@see getElementData}.
+ * @param {ElementTestOptions} opts
+ *        An options object, as passed to {@see getElementData}.
+ * @returns {CreateElementResult}
+ */
+function createElement(test, opts) {
+  let srcElem;
+  let src;
+
+  function rec({ tagName, attrs, children }) {
+    let elem = document.createElement(tagName);
+
+    for (let [key, val] of Object.entries(attrs)) {
+      if (key === test.srcAttr) {
+        srcElem = elem;
+        src = val;
+      } else {
+        elem.setAttribute(key, val);
+      }
+    }
+    for (let child of children) {
+      elem.appendChild(rec(child));
+    }
+    return elem;
+  }
+  let elem = rec(getElementData(test, opts));
+
+  return { elem, srcElem, src };
+}
+
+/**
+ * Escapes any occurrences of &, ", < or > with XML entities.
+ *
+ * @param {string} str
+ *        The string to escape.
+ * @returns {string} The escaped string.
+ */
+function escapeXML(str) {
+  let replacements = {
+    "&": "&amp;",
+    '"': "&quot;",
+    "'": "&apos;",
+    "<": "&lt;",
+    ">": "&gt;",
+  };
+  return String(str).replace(/[&"''<>]/g, m => replacements[m]);
+}
+
+/**
+ * A tagged template function which escapes any XML metacharacters in
+ * interpolated values.
+ *
+ * @param {Array<string>} strings
+ *        An array of literal strings extracted from the templates.
+ * @param {Array} values
+ *        An array of interpolated values extracted from the template.
+ * @returns {string}
+ *        The result of the escaped values interpolated with the literal
+ *        strings.
+ */
+function escaped(strings, ...values) {
+  let result = [];
+
+  for (let [i, string] of strings.entries()) {
+    result.push(string);
+    if (i < values.length) {
+      result.push(escapeXML(values[i]));
+    }
+  }
+
+  return result.join("");
+}
+
+/**
+ * Converts the given test data, as accepted by {@see getElementData},
+ * to an HTML representation.
+ *
+ * @param {ElementTestCase} test
+ *        A test object, as passed to {@see getElementData}.
+ * @param {ElementTestOptions} opts
+ *        An options object, as passed to {@see getElementData}.
+ * @returns {string}
+ */
+function toHTML(test, opts) {
+  function rec({ tagName, attrs, children }) {
+    let html = [`<${tagName}`];
+    for (let [key, val] of Object.entries(attrs)) {
+      html.push(escaped` ${key}="${val}"`);
+    }
+
+    html.push(">");
+    if (!AUTOCLOSE_TAGS.has(tagName)) {
+      for (let child of children) {
+        html.push(rec(child));
+      }
+
+      html.push(`</${tagName}>`);
+    }
+    return html.join("");
+  }
+  return rec(getElementData(test, opts));
+}
+
+/**
+ * Injects various permutations of inline CSS into a content page, from both
+ * extension content script and content page contexts, and sends a "css-sources"
+ * message to the test harness describing the injected content for verification.
+ */
+function testInlineCSS() {
+  let urls = [];
+  let sources = [];
+
+  /**
+   * Constructs the URL of an image to be loaded by the given origin, and
+   * returns a CSS url() expression for it.
+   *
+   * The `name` parameter is an arbitrary name which should describe how the URL
+   * is loaded. The `opts` object may contain arbitrary properties which
+   * describe the load. Currently, only `inline` is recognized, and indicates
+   * that the URL is being used in an inline stylesheet which may be blocked by
+   * CSP.
+   *
+   * The URL and its parameters are recorded, and sent to the parent process for
+   * verification.
+   *
+   * @param {string} origin
+   * @param {string} name
+   * @param {object} [opts]
+   * @returns {string}
+   */
+  let i = 0;
+  let url = (origin, name, opts = {}) => {
+    let source = `${origin}-${name}`;
+
+    let { href } = new URL(
+      `css-${i++}.png?origin=${encodeURIComponent(
+        origin
+      )}&source=${encodeURIComponent(source)}`,
+      location.href
+    );
+
+    urls.push(Object.assign({}, opts, { href, origin, source }));
+    return `url("${href}")`;
+  };
+
+  /**
+   * Registers the given inline CSS source as being loaded by the given origin,
+   * and returns that CSS text.
+   *
+   * @param {string} origin
+   * @param {string} css
+   * @returns {string}
+   */
+  let source = (origin, css) => {
+    sources.push({ origin, css });
+    return css;
+  };
+
+  /**
+   * Saves the given function to be run after a short delay, just before sending
+   * the list of loaded sources to the parent process.
+   */
+  let laters = [];
+  let later = fn => {
+    laters.push(fn);
+  };
+
+  // Note: When accessing an element through `wrappedJSObject`, the operations
+  // occur in the content page context, using the content subject principal.
+  // When accessing it through X-ray wrappers, they happen in the content script
+  // context, using its subject principal.
+
+  {
+    let li = document.createElement("li");
+    li.setAttribute(
+      "style",
+      source(
+        "contentScript",
+        `background: ${url("contentScript", "li.style-first")}`
+      )
+    );
+    li.style.wrappedJSObject.listStyleImage = url(
+      "page",
+      "li.style.listStyleImage-second"
+    );
+    document.body.appendChild(li);
+  }
+
+  {
+    let li = document.createElement("li");
+    li.wrappedJSObject.setAttribute(
+      "style",
+      source(
+        "page",
+        `background: ${url("page", "li.style-first", { inline: true })}`
+      )
+    );
+    li.style.listStyleImage = url(
+      "contentScript",
+      "li.style.listStyleImage-second"
+    );
+    document.body.appendChild(li);
+  }
+
+  {
+    let li = document.createElement("li");
+    document.body.appendChild(li);
+    li.setAttribute(
+      "style",
+      source(
+        "contentScript",
+        `background: ${url("contentScript", "li.style-first")}`
+      )
+    );
+    later(() =>
+      li.wrappedJSObject.setAttribute(
+        "style",
+        source(
+          "page",
+          `background: ${url("page", "li.style-second", { inline: true })}`
+        )
+      )
+    );
+  }
+
+  {
+    let li = document.createElement("li");
+    document.body.appendChild(li);
+    li.wrappedJSObject.setAttribute(
+      "style",
+      source(
+        "page",
+        `background: ${url("page", "li.style-first", { inline: true })}`
+      )
+    );
+    later(() =>
+      li.setAttribute(
+        "style",
+        source(
+          "contentScript",
+          `background: ${url("contentScript", "li.style-second")}`
+        )
+      )
+    );
+  }
+
+  {
+    let li = document.createElement("li");
+    document.body.appendChild(li);
+    li.style.cssText = source(
+      "contentScript",
+      `background: ${url("contentScript", "li.style.cssText-first")}`
+    );
+
+    // TODO: This inline style should be blocked, since our style-src does not
+    // include 'unsafe-eval', but that is currently unimplemented.
+    later(() => {
+      li.style.wrappedJSObject.cssText = `background: ${url(
+        "page",
+        "li.style.cssText-second"
+      )}`;
+    });
+  }
+
+  // Creates a new element, inserts it into the page, and returns its CSS selector.
+  let divNum = 0;
+  function getSelector() {
+    let div = document.createElement("div");
+    div.id = `generated-div-${divNum++}`;
+    document.body.appendChild(div);
+    return `#${div.id}`;
+  }
+
+  for (let prop of ["textContent", "innerHTML"]) {
+    // Test creating <style> element from the extension side and then replacing
+    // its contents from the content side.
+    {
+      let sel = getSelector();
+      let style = document.createElement("style");
+      style[prop] = source(
+        "extension",
+        `${sel} { background: ${url("extension", `style-${prop}-first`)}; }`
+      );
+      document.head.appendChild(style);
+
+      later(() => {
+        style.wrappedJSObject[prop] = source(
+          "page",
+          `${sel} { background: ${url("page", `style-${prop}-second`, {
+            inline: true,
+          })}; }`
+        );
+      });
+    }
+
+    // Test creating <style> element from the extension side and then appending
+    // a text node to it. Regardless of whether the append happens from the
+    // content or extension side, this should cause the principal to be
+    // forgotten.
+    let testModifyAfterInject = (name, modifyFunc) => {
+      let sel = getSelector();
+      let style = document.createElement("style");
+      style[prop] = source(
+        "extension",
+        `${sel} { background: ${url(
+          "extension",
+          `style-${name}-${prop}-first`
+        )}; }`
+      );
+      document.head.appendChild(style);
+
+      later(() => {
+        modifyFunc(
+          style,
+          `${sel} { background: ${url("page", `style-${name}-${prop}-second`, {
+            inline: true,
+          })}; }`
+        );
+        source("page", style.textContent);
+      });
+    };
+
+    testModifyAfterInject("appendChild", (style, css) => {
+      style.appendChild(document.createTextNode(css));
+    });
+
+    // Test creating <style> element from the extension side and then appending
+    // to it using insertAdjacentHTML, with the same rules as above.
+    testModifyAfterInject("insertAdjacentHTML", (style, css) => {
+      // eslint-disable-next-line no-unsanitized/method
+      style.insertAdjacentHTML("beforeend", css);
+    });
+
+    // And again using insertAdjacentText.
+    testModifyAfterInject("insertAdjacentText", (style, css) => {
+      style.insertAdjacentText("beforeend", css);
+    });
+
+    // Test creating a style element and then accessing its CSSStyleSheet object.
+    {
+      let sel = getSelector();
+      let style = document.createElement("style");
+      style[prop] = source(
+        "extension",
+        `${sel} { background: ${url("extension", `style-${prop}-sheet`)}; }`
+      );
+      document.head.appendChild(style);
+
+      browser.test.assertThrows(
+        () => style.sheet.wrappedJSObject.cssRules,
+        /Not allowed to access cross-origin stylesheet/,
+        "Page content should not be able to access extension-generated CSS rules"
+      );
+
+      style.sheet.insertRule(
+        source(
+          "extension",
+          `${sel} { border-image: ${url(
+            "extension",
+            `style-${prop}-sheet-insertRule`
+          )}; }`
+        )
+      );
+    }
+  }
+
+  setTimeout(() => {
+    for (let fn of laters) {
+      fn();
+    }
+    browser.test.sendMessage("css-sources", { urls, sources });
+  });
+}
+
+/**
+ * A function which will be stringified, and run both as a page script
+ * and an extension content script, to test element injection under
+ * various configurations.
+ *
+ * @param {Array<ElementTestCase>} tests
+ *        A list of test objects, as understood by {@see getElementData}.
+ * @param {ElementTestOptions} baseOpts
+ *        A base options object, as understood by {@see getElementData},
+ *        which represents the default values for injections under this
+ *        context.
+ */
+function injectElements(tests, baseOpts) {
+  window.addEventListener(
+    "load",
+    () => {
+      if (typeof browser === "object") {
+        try {
+          testInlineCSS();
+        } catch (e) {
+          browser.test.fail(`Error: ${e} :: ${e.stack}`);
+        }
+      }
+
+      // Basic smoke test to check that SVG images do not try to create a document
+      // with an expanded principal, which would cause a crash.
+      let img = document.createElement("img");
+      img.src = "data:image/svg+xml,%3Csvg%2F%3E";
+      document.body.appendChild(img);
+
+      let rand = Math.random();
+
+      // Basic smoke test to check that we don't try to create stylesheets with an
+      // expanded principal, which would cause a crash when loading font sets.
+      let cssText = `
+      @font-face {
+          font-family: "DoesNotExist${rand}";
+          src: url("fonts/DoesNotExist.${rand}.woff") format("woff");
+          font-weight: normal;
+          font-style: normal;
+      }`;
+
+      let link = document.createElement("link");
+      link.rel = "stylesheet";
+      link.href = "data:text/css;base64," + btoa(cssText);
+      document.head.appendChild(link);
+
+      let style = document.createElement("style");
+      style.textContent = cssText;
+      document.head.appendChild(style);
+
+      let overrideOpts = opts => Object.assign({}, baseOpts, opts);
+      let opts = baseOpts;
+
+      // Build the full element with setAttr, then inject.
+      for (let test of tests) {
+        let { elem, srcElem, src } = createElement(test, opts);
+        srcElem.setAttribute(test.srcAttr, src);
+        document.body.appendChild(elem);
+      }
+
+      // Build the full element with a property setter.
+      opts = overrideOpts({ source: `${baseOpts.source}-prop` });
+      for (let test of tests) {
+        let { elem, srcElem, src } = createElement(test, opts);
+        srcElem[test.srcAttr] = src;
+        document.body.appendChild(elem);
+      }
+
+      // Build the element without the source attribute, inject, then set
+      // it.
+      opts = overrideOpts({ source: `${baseOpts.source}-attr-after-inject` });
+      for (let test of tests) {
+        let { elem, srcElem, src } = createElement(test, opts);
+        document.body.appendChild(elem);
+        srcElem.setAttribute(test.srcAttr, src);
+      }
+
+      // Build the element without the source attribute, inject, then set
+      // the corresponding property.
+      opts = overrideOpts({ source: `${baseOpts.source}-prop-after-inject` });
+      for (let test of tests) {
+        let { elem, srcElem, src } = createElement(test, opts);
+        document.body.appendChild(elem);
+        srcElem[test.srcAttr] = src;
+      }
+
+      // Build the element with a relative, rather than absolute, URL, and
+      // make sure it always has the page origin.
+      opts = overrideOpts({
+        source: `${baseOpts.source}-relative-url`,
+        origin: "page",
+      });
+      for (let test of tests) {
+        let { elem, srcElem, src } = createElement(test, opts);
+        // Note: This assumes that the content page and the src URL are
+        // always at the server root. If that changes, the test will
+        // timeout waiting for matching requests.
+        src = src.replace(/.*\//, "");
+        srcElem.setAttribute(test.srcAttr, src);
+        document.body.appendChild(elem);
+      }
+
+      // If we're in an extension content script, do some additional checks.
+      if (typeof browser !== "undefined") {
+        // Build the element without the source attribute, inject, then
+        // have content set it.
+        opts = overrideOpts({
+          source: `${baseOpts.source}-content-attr-after-inject`,
+          origin: "page",
+        });
+
+        for (let test of tests) {
+          let { elem, srcElem, src } = createElement(test, opts);
+
+          document.body.appendChild(elem);
+          window.wrappedJSObject.elem = srcElem;
+          window.wrappedJSObject.eval(
+            `elem.setAttribute(${JSON.stringify(
+              test.srcAttr
+            )}, ${JSON.stringify(src)})`
+          );
+        }
+
+        // Build the full element, then let content inject.
+        opts = overrideOpts({
+          source: `${baseOpts.source}-content-inject-after-attr`,
+        });
+        for (let test of tests) {
+          let { elem, srcElem, src } = createElement(test, opts);
+          srcElem.setAttribute(test.srcAttr, src);
+          window.wrappedJSObject.elem = elem;
+          window.wrappedJSObject.eval(`document.body.appendChild(elem)`);
+        }
+
+        // Build the element without the source attribute, let content set
+        // it, then inject.
+        opts = overrideOpts({
+          source: `${baseOpts.source}-inject-after-content-attr`,
+          origin: "page",
+        });
+
+        for (let test of tests) {
+          let { elem, srcElem, src } = createElement(test, opts);
+          window.wrappedJSObject.elem = srcElem;
+          window.wrappedJSObject.eval(
+            `elem.setAttribute(${JSON.stringify(
+              test.srcAttr
+            )}, ${JSON.stringify(src)})`
+          );
+          document.body.appendChild(elem);
+        }
+
+        // Build the element with a dummy source attribute, inject, then
+        // let content change it.
+        opts = overrideOpts({
+          source: `${baseOpts.source}-content-change-after-inject`,
+          origin: "page",
+        });
+
+        for (let test of tests) {
+          let { elem, srcElem, src } = createElement(test, opts);
+          srcElem.setAttribute(test.srcAttr, "meh.txt");
+          document.body.appendChild(elem);
+          window.wrappedJSObject.elem = srcElem;
+          window.wrappedJSObject.eval(
+            `elem.setAttribute(${JSON.stringify(
+              test.srcAttr
+            )}, ${JSON.stringify(src)})`
+          );
+        }
+      }
+    },
+    { once: true }
+  );
+}
+
+/**
+ * Stringifies the {@see injectElements} function for use as a page or
+ * content script.
+ *
+ * @param {Array<ElementTestCase>} tests
+ *        A list of test objects, as understood by {@see getElementData}.
+ * @param {ElementTestOptions} opts
+ *        A base options object, as understood by {@see getElementData},
+ *        which represents the default values for injections under this
+ *        context.
+ * @returns {string}
+ */
+function getInjectionScript(tests, opts) {
+  return `
+    ${getElementData}
+    ${createElement}
+    ${testInlineCSS}
+    (${injectElements})(${JSON.stringify(tests)},
+                        ${JSON.stringify(opts)});
+  `;
+}
+
+/**
+ * Extracts the "origin" query parameter from the given URL, and returns it,
+ * along with the URL sans origin parameter.
+ *
+ * @param {string} origURL
+ * @returns {object}
+ *        An object with `origin` and `baseURL` properties, containing the value
+ *        or the URL's "origin" query parameter and the URL with that parameter
+ *        removed, respectively.
+ */
+function getOriginBase(origURL) {
+  let url = new URL(origURL);
+  let origin = url.searchParams.get("origin");
+  url.searchParams.delete("origin");
+
+  return { origin, baseURL: url.href };
+}
+
+/**
+ * An object containing sets of base URLs and CSS sources which are present in
+ * the test page, sorted based on how they should be treated by CSP.
+ *
+ * @typedef {object} RequestedURLs
+ * @property {Set<string>} expectedURLs
+ *        A set of URLs which should be successfully requested by the content
+ *        page.
+ * @property {Set<string>} forbiddenURLs
+ *        A set of URLs which are present in the content page, but should never
+ *        generate requests.
+ * @property {Set<string>} blockedURLs
+ *        A set of URLs which are present in the content page, and should be
+ *        blocked by CSP, and reported in a CSP report.
+ * @property {Set<string>} blockedSources
+ *        A set of inline CSS sources which should be blocked by CSP, and
+ *        reported in a CSP report.
+ */
+
+/**
+ * Computes a list of expected and forbidden base URLs for the given
+ * sets of tests and sources. The base URL is the complete request URL
+ * with the `origin` query parameter removed.
+ *
+ * @param {Array<ElementTestCase>} tests
+ *        A list of tests, as understood by {@see getElementData}.
+ * @param {Object<string, object>} expectedSources
+ *        A set of sources for which each of the above tests is expected
+ *        to generate one request, if each of the properties in the
+ *        value object matches the value of the same property in the
+ *        test object.
+ * @param {Object<string, object>} [forbiddenSources = {}]
+ *        A set of sources for which requests should never be sent. Any
+ *        matching requests from these sources will cause the test to
+ *        fail.
+ * @returns {RequestedURLs}
+ */
+function computeBaseURLs(tests, expectedSources, forbiddenSources = {}) {
+  let expectedURLs = new Set();
+  let forbiddenURLs = new Set();
+
+  function* iterSources(test, sources) {
+    for (let [source, attrs] of Object.entries(sources)) {
+      // if a source defines attributes (e.g. liveSrc in PAGE_SOURCES etc.) then all
+      // attributes in the source must be matched by the test (see const TEST).
+      if (Object.keys(attrs).every(attr => attrs[attr] === test[attr])) {
+        yield `${BASE_URL}/${test.src}?source=${source}`;
+      }
+    }
+  }
+
+  for (let test of tests) {
+    for (let urlPrefix of iterSources(test, expectedSources)) {
+      expectedURLs.add(urlPrefix);
+    }
+    for (let urlPrefix of iterSources(test, forbiddenSources)) {
+      forbiddenURLs.add(urlPrefix);
+    }
+  }
+
+  return { expectedURLs, forbiddenURLs, blockedURLs: forbiddenURLs };
+}
+
+/**
+ * Generates a set of expected and forbidden URLs and sources based on the CSS
+ * injected by our content script.
+ *
+ * @param {object} message
+ *        The "css-sources" message sent by the content script, containing lists
+ *        of CSS sources injected into the page.
+ * @param {Array<object>} message.urls
+ *        A list of URLs present in styles injected by the content script.
+ * @param {string} message.urls.*.origin
+ *        The origin of the URL, one of "page", "contentScript", or "extension".
+ * @param {string} message.urls.*.href
+ *        The URL string.
+ * @param {boolean} message.urls.*.inline
+ *        If true, the URL is present in an inline stylesheet, which may be
+ *        blocked by CSP prior to parsing, depending on its origin.
+ * @param {Array<object>} message.sources
+ *        A list of inline CSS sources injected by the content script.
+ * @param {string} message.sources.*.origin
+ *        The origin of the CSS, one of "page", "contentScript", or "extension".
+ * @param {string} message.sources.*.css
+ *        The CSS source text.
+ * @param {boolean} [cspEnabled = false]
+ *        If true, a strict CSP is enabled for this page, and inline page
+ *        sources should be blocked. URLs present in these sources will not be
+ *        expected to generate a CSP report, the inline sources themselves will.
+ * @param {boolean} [contentCspEnabled = false]
+ * @returns {RequestedURLs}
+ */
+function computeExpectedForbiddenURLs(
+  { urls, sources },
+  cspEnabled = false,
+  contentCspEnabled = false
+) {
+  let expectedURLs = new Set();
+  let forbiddenURLs = new Set();
+  let blockedURLs = new Set();
+  let blockedSources = new Set();
+
+  for (let { href, origin, inline } of urls) {
+    let { baseURL } = getOriginBase(href);
+    if (cspEnabled && origin === "page") {
+      if (inline) {
+        forbiddenURLs.add(baseURL);
+      } else {
+        blockedURLs.add(baseURL);
+      }
+    } else if (contentCspEnabled && origin === "contentScript") {
+      if (inline) {
+        forbiddenURLs.add(baseURL);
+      }
+    } else {
+      expectedURLs.add(baseURL);
+    }
+  }
+
+  if (cspEnabled) {
+    for (let { origin, css } of sources) {
+      if (origin === "page") {
+        blockedSources.add(css);
+      }
+    }
+  }
+
+  return { expectedURLs, forbiddenURLs, blockedURLs, blockedSources };
+}
+
+/**
+ * Awaits the content loads for each of the given expected base URLs,
+ * and checks that their origin strings are as expected. Triggers a test
+ * failure if any of the given forbidden URLs is requested.
+ *
+ * @param {Promise<object>} urlsPromise
+ *        A promise which resolves to an object containing expected and
+ *        forbidden URL sets, as returned by {@see computeBaseURLs}.
+ * @param {object<string, string>} origins
+ *        A mapping of origin parameters as they appear in URL query
+ *        strings to the origin strings returned by corresponding
+ *        principals. These values are used to test requests against
+ *        their expected origins.
+ * @returns {Promise}
+ *        A promise which resolves when all requests have been
+ *        processed.
+ */
+function awaitLoads(urlsPromise, origins) {
+  return new Promise(resolve => {
+    let expectedURLs, forbiddenURLs;
+    let queuedChannels = [];
+
+    let observer;
+
+    function checkChannel(channel) {
+      let origURL = channel.URI.spec;
+      let { baseURL, origin } = getOriginBase(origURL);
+
+      if (forbiddenURLs.has(baseURL)) {
+        ok(false, `Got unexpected request for forbidden URL ${origURL}`);
+      }
+
+      if (expectedURLs.has(baseURL)) {
+        expectedURLs.delete(baseURL);
+
+        equal(
+          channel.loadInfo.triggeringPrincipal.origin,
+          origins[origin],
+          `Got expected origin for URL ${origURL}`
+        );
+
+        if (!expectedURLs.size) {
+          Services.obs.removeObserver(observer, "http-on-modify-request");
+          info("Got all expected requests");
+          resolve();
+        }
+      }
+    }
+
+    urlsPromise.then(urls => {
+      expectedURLs = new Set(urls.expectedURLs);
+      forbiddenURLs = new Set([...urls.forbiddenURLs, ...urls.blockedURLs]);
+
+      for (let channel of queuedChannels.splice(0)) {
+        checkChannel(channel.QueryInterface(Ci.nsIChannel));
+      }
+    });
+
+    observer = (channel, topic, data) => {
+      if (expectedURLs) {
+        checkChannel(channel.QueryInterface(Ci.nsIChannel));
+      } else {
+        queuedChannels.push(channel);
+      }
+    };
+    Services.obs.addObserver(observer, "http-on-modify-request");
+  });
+}
+
+function readUTF8InputStream(stream) {
+  let buffer = NetUtil.readInputStream(stream, stream.available());
+  return new TextDecoder().decode(buffer);
+}
+
+/**
+ * Awaits CSP reports for each of the given forbidden base URLs.
+ * Triggers a test failure if any of the given expected URLs triggers a
+ * report.
+ *
+ * @param {Promise<object>} urlsPromise
+ *        A promise which resolves to an object containing expected and
+ *        forbidden URL sets, as returned by {@see computeBaseURLs}.
+ * @returns {Promise}
+ *        A promise which resolves when all requests have been
+ *        processed.
+ */
+function awaitCSP(urlsPromise) {
+  return new Promise(resolve => {
+    let expectedURLs, blockedURLs, blockedSources;
+    let queuedRequests = [];
+
+    function checkRequest(request) {
+      let body = JSON.parse(readUTF8InputStream(request.bodyInputStream));
+      let report = body["csp-report"];
+
+      let origURL = report["blocked-uri"];
+      if (origURL !== "inline" && origURL !== "") {
+        let { baseURL } = getOriginBase(origURL);
+
+        if (expectedURLs.has(baseURL)) {
+          ok(false, `Got unexpected CSP report for allowed URL ${origURL}`);
+        }
+
+        if (blockedURLs.has(baseURL)) {
+          blockedURLs.delete(baseURL);
+
+          ok(true, `Got CSP report for forbidden URL ${origURL}`);
+        }
+      }
+
+      let source = report["script-sample"];
+      if (source) {
+        if (blockedSources.has(source)) {
+          blockedSources.delete(source);
+
+          ok(
+            true,
+            `Got CSP report for forbidden inline source ${JSON.stringify(
+              source
+            )}`
+          );
+        }
+      }
+
+      if (!blockedURLs.size && !blockedSources.size) {
+        ok(true, "Got all expected CSP reports");
+        resolve();
+      }
+    }
+
+    urlsPromise.then(urls => {
+      blockedURLs = new Set(urls.blockedURLs);
+      blockedSources = new Set(urls.blockedSources);
+      ({ expectedURLs } = urls);
+
+      for (let request of queuedRequests.splice(0)) {
+        checkRequest(request);
+      }
+    });
+
+    server.registerPathHandler(CSP_REPORT_PATH, (request, response) => {
+      response.setStatusLine(request.httpVersion, 204, "No Content");
+
+      if (expectedURLs) {
+        checkRequest(request);
+      } else {
+        queuedRequests.push(request);
+      }
+    });
+  });
+}
+
+/**
+ * A list of tests to run in each context, as understood by
+ * {@see getElementData}.
+ */
+const TESTS = [
+  {
+    element: ["audio", {}],
+    src: "audio.webm",
+  },
+  {
+    element: ["audio", {}, ["source", {}]],
+    src: "audio-source.webm",
+  },
+  // TODO: <frame> element, which requires a frameset document.
+  {
+    // the blocked-uri for frame-navigations is the pre-path URI. For the
+    // purpose of this test we do not strip the blocked-uri by setting the
+    // preference 'truncate_blocked_uri_for_frame_navigations'
+    element: ["iframe", {}],
+    src: "iframe.html",
+  },
+  {
+    element: ["img", {}],
+    src: "img.png",
+  },
+  {
+    element: ["img", {}],
+    src: "imgset.png",
+    srcAttr: "srcset",
+  },
+  {
+    element: ["input", { type: "image" }],
+    src: "input.png",
+  },
+  {
+    element: ["link", { rel: "stylesheet" }],
+    src: "link.css",
+    srcAttr: "href",
+  },
+  {
+    element: ["picture", {}, ["source", {}], ["img", {}]],
+    src: "picture.png",
+    srcAttr: "srcset",
+  },
+  {
+    element: ["script", {}],
+    src: "script.js",
+    liveSrc: false,
+  },
+  {
+    element: ["video", {}],
+    src: "video.webm",
+  },
+  {
+    element: ["video", {}, ["source", {}]],
+    src: "video-source.webm",
+  },
+];
+
+for (let test of TESTS) {
+  if (!test.srcAttr) {
+    test.srcAttr = "src";
+  }
+  if (!("liveSrc" in test)) {
+    test.liveSrc = true;
+  }
+}
+
+/**
+ * A set of sources for which each of the above tests is expected to
+ * generate one request, if each of the properties in the value object
+ * matches the value of the same property in the test object.
+ */
+// Sources which load with the page context.
+const PAGE_SOURCES = {
+  "contentScript-content-attr-after-inject": { liveSrc: true },
+  "contentScript-content-change-after-inject": { liveSrc: true },
+  "contentScript-inject-after-content-attr": {},
+  "contentScript-relative-url": {},
+  pageHTML: {},
+  pageScript: {},
+  "pageScript-attr-after-inject": {},
+  "pageScript-prop": {},
+  "pageScript-prop-after-inject": {},
+  "pageScript-relative-url": {},
+};
+// Sources which load with the extension context.
+const EXTENSION_SOURCES = {
+  contentScript: {},
+  "contentScript-attr-after-inject": { liveSrc: true },
+  "contentScript-content-inject-after-attr": {},
+  "contentScript-prop": {},
+  "contentScript-prop-after-inject": {},
+};
+// When our default content script CSP is applied, only
+// liveSrc: true are loading.  IOW, the "script" test above
+// will fail.
+const EXTENSION_SOURCES_CONTENT_CSP = {
+  contentScript: { liveSrc: true },
+  "contentScript-attr-after-inject": { liveSrc: true },
+  "contentScript-content-inject-after-attr": { liveSrc: true },
+  "contentScript-prop": { liveSrc: true },
+  "contentScript-prop-after-inject": { liveSrc: true },
+};
+// All sources.
+const SOURCES = Object.assign({}, PAGE_SOURCES, EXTENSION_SOURCES);
+
+registerStaticPage(
+  "/page.html",
+  `<!DOCTYPE html>
+  <html lang="en">
+  <head>
+    <meta charset="UTF-8">
+    <title></title>
+    <script nonce="deadbeef">
+      ${getInjectionScript(TESTS, { source: "pageScript", origin: "page" })}
+    </script>
+  </head>
+  <body>
+    ${TESTS.map(test =>
+      toHTML(test, { source: "pageHTML", origin: "page" })
+    ).join("\n  ")}
+  </body>
+  </html>`
+);
+
+function catchViolation() {
+  // eslint-disable-next-line mozilla/balanced-listeners
+  document.addEventListener("securitypolicyviolation", e => {
+    browser.test.assertTrue(
+      e.documentURI !== "moz-extension",
+      `securitypolicyviolation: ${e.violatedDirective} ${e.documentURI}`
+    );
+  });
+}
+
+const EXTENSION_DATA = {
+  manifest: {
+    content_scripts: [
+      {
+        matches: ["http://*/page.html"],
+        run_at: "document_start",
+        js: ["violation.js", "content_script.js"],
+      },
+    ],
+  },
+
+  files: {
+    "violation.js": catchViolation,
+    "content_script.js": getInjectionScript(TESTS, {
+      source: "contentScript",
+      origin: "contentScript",
+    }),
+  },
+};
+
+const pageURL = `${BASE_URL}/page.html`;
+const pageURI = Services.io.newURI(pageURL);
+
+// Merges the sets of expected URL and source data returned by separate
+// computedExpectedForbiddenURLs and computedBaseURLs calls.
+function mergeSources(a, b) {
+  return {
+    expectedURLs: new Set([...a.expectedURLs, ...b.expectedURLs]),
+    forbiddenURLs: new Set([...a.forbiddenURLs, ...b.forbiddenURLs]),
+    blockedURLs: new Set([...a.blockedURLs, ...b.blockedURLs]),
+    blockedSources: a.blockedSources || b.blockedSources,
+  };
+}
+
+// Returns a set of origin strings for the given extension and content page, for
+// use in verifying request triggering principals.
+function getOrigins(extension) {
+  return {
+    page: Services.scriptSecurityManager.createContentPrincipal(pageURI, {})
+      .origin,
+    contentScript: Cu.getObjectPrincipal(
+      Cu.Sandbox([extension.principal, pageURL])
+    ).origin,
+    extension: extension.principal.origin,
+  };
+}
+
+/**
+ * Tests that various types of inline content elements initiate requests
+ * with the triggering pringipal of the caller that requested the load.
+ */
+add_task(async function test_contentscript_triggeringPrincipals() {
+  let extension = ExtensionTestUtils.loadExtension(EXTENSION_DATA);
+  await extension.startup();
+
+  let urlsPromise = extension.awaitMessage("css-sources").then(msg => {
+    return mergeSources(
+      computeExpectedForbiddenURLs(msg),
+      computeBaseURLs(TESTS, SOURCES)
+    );
+  });
+
+  let origins = getOrigins(extension.extension);
+  let finished = awaitLoads(urlsPromise, origins);
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(pageURL);
+
+  await finished;
+
+  await extension.unload();
+  await contentPage.close();
+
+  clearCache();
+});
+
+/**
+ * Tests that the correct CSP is applied to loads of inline content
+ * depending on whether the load was initiated by an extension or the
+ * content page.
+ */
+add_task(async function test_contentscript_csp() {
+  // TODO bug 1408193: We currently don't get the full set of CSP reports when
+  // running in network scheduling chaos mode. It's not entirely clear why.
+  let chaosMode = parseInt(env.get("MOZ_CHAOSMODE"), 16);
+  let checkCSPReports = !(chaosMode === 0 || chaosMode & 0x02);
+
+  gContentSecurityPolicy = `default-src 'none' 'report-sample'; script-src 'nonce-deadbeef' 'unsafe-eval' 'report-sample'; report-uri ${CSP_REPORT_PATH};`;
+
+  let extension = ExtensionTestUtils.loadExtension(EXTENSION_DATA);
+  await extension.startup();
+
+  let urlsPromise = extension.awaitMessage("css-sources").then(msg => {
+    return mergeSources(
+      computeExpectedForbiddenURLs(msg, true),
+      computeBaseURLs(TESTS, EXTENSION_SOURCES, PAGE_SOURCES)
+    );
+  });
+
+  let origins = getOrigins(extension.extension);
+
+  let finished = Promise.all([
+    awaitLoads(urlsPromise, origins),
+    checkCSPReports && awaitCSP(urlsPromise),
+  ]);
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(pageURL);
+
+  await finished;
+
+  await extension.unload();
+  await contentPage.close();
+});
+
+/**
+ * Tests that the correct CSP is applied to loads of inline content
+ * depending on whether the load was initiated by an extension or the
+ * content page.
+ */
+add_task(async function test_extension_contentscript_csp() {
+  Services.prefs.setBoolPref("extensions.manifestV3.enabled", true);
+
+  // TODO bug 1408193: We currently don't get the full set of CSP reports when
+  // running in network scheduling chaos mode. It's not entirely clear why.
+  let chaosMode = parseInt(env.get("MOZ_CHAOSMODE"), 16);
+  let checkCSPReports = !(chaosMode === 0 || chaosMode & 0x02);
+
+  gContentSecurityPolicy = `default-src 'none' 'report-sample'; script-src 'nonce-deadbeef' 'unsafe-eval' 'report-sample'; report-uri ${CSP_REPORT_PATH};`;
+
+  let data = {
+    ...EXTENSION_DATA,
+    manifest: {
+      ...EXTENSION_DATA.manifest,
+      manifest_version: 3,
+    },
+  };
+  let extension = ExtensionTestUtils.loadExtension(data);
+  await extension.startup();
+
+  let urlsPromise = extension.awaitMessage("css-sources").then(msg => {
+    return mergeSources(
+      computeExpectedForbiddenURLs(msg, true, true),
+      computeBaseURLs(TESTS, EXTENSION_SOURCES_CONTENT_CSP, PAGE_SOURCES)
+    );
+  });
+
+  let origins = getOrigins(extension.extension);
+
+  let finished = Promise.all([
+    awaitLoads(urlsPromise, origins),
+    checkCSPReports && awaitCSP(urlsPromise),
+  ]);
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(pageURL);
+
+  await finished;
+
+  await extension.unload();
+  await contentPage.close();
+  Services.prefs.clearUserPref("extensions.manifestV3.enabled");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_unregister_during_loadContentScript.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_unregister_during_loadContentScript.js
new file mode 100644
index 0000000000..dd3ab7846d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_unregister_during_loadContentScript.js
@@ -0,0 +1,91 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function content_script_unregistered_during_loadContentScript() {
+  let content_scripts = [];
+
+  for (let i = 0; i < 10; i++) {
+    content_scripts.push({
+      matches: ["<all_urls>"],
+      js: ["dummy.js"],
+      run_at: "document_start",
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts,
+    },
+    files: {
+      "dummy.js": function() {
+        browser.test.sendMessage("content-script-executed");
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+  info("Wait for all the content scripts to be executed");
+  await Promise.all(
+    content_scripts.map(() => extension.awaitMessage("content-script-executed"))
+  );
+
+  const promiseDone = contentPage.spawn([extension.id], extensionId => {
+    const { ExtensionProcessScript } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionProcessScript.jsm"
+    );
+
+    return new Promise(resolve => {
+      // This recreates a scenario similar to Bug 1593240 and ensures that the
+      // related fix doesn't regress. Replacing loadContentScript with a
+      // function that unregisters all the content scripts make us sure that
+      // mutating the policy contentScripts doesn't trigger a crash due to
+      // the invalidation of the contentScripts iterator being used by the
+      // caller (ExtensionPolicyService::CheckContentScripts).
+      const { loadContentScript } = ExtensionProcessScript;
+      ExtensionProcessScript.loadContentScript = async (...args) => {
+        const policy = WebExtensionPolicy.getByID(extensionId);
+        let initial = policy.contentScripts.length;
+        let i = initial;
+        while (i) {
+          policy.unregisterContentScript(policy.contentScripts[--i]);
+        }
+        Services.tm.dispatchToMainThread(() =>
+          resolve({
+            initial,
+            final: policy.contentScripts.length,
+          })
+        );
+        // Call the real loadContentScript method.
+        return loadContentScript(...args);
+      };
+    });
+  });
+
+  info("Reload the webpage");
+  await contentPage.loadURL(`${BASE_URL}/file_sample.html`);
+  info("Wait for all the content scripts to be executed again");
+  await Promise.all(
+    content_scripts.map(() => extension.awaitMessage("content-script-executed"))
+  );
+  info("No crash triggered as expected");
+
+  Assert.deepEqual(
+    await promiseDone,
+    { initial: content_scripts.length, final: 0 },
+    "All content scripts unregistered as expected"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xml_prettyprint.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xml_prettyprint.js
new file mode 100644
index 0000000000..83cb2f86e9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xml_prettyprint.js
@@ -0,0 +1,75 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Services.prefs.setBoolPref("layout.xml.prettyprint", true);
+
+const BASE_XML = '<?xml version="1.0" encoding="UTF-8"?>';
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/test.xml", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/xml; charset=utf-8", false);
+  response.write(`${BASE_XML}\n<note></note>`);
+});
+
+// Make sure that XML pretty printer runs after content scripts
+// that runs at document_start (See Bug 1605657).
+add_task(async function content_script_on_xml_prettyprinted_document() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["<all_urls>"],
+          js: ["start.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+    files: {
+      "start.js": async function() {
+        const el = document.createElement("ext-el");
+        document.documentElement.append(el);
+        if (document.readyState !== "complete") {
+          await new Promise(resolve => {
+            document.addEventListener("DOMContentLoaded", resolve, {
+              once: true,
+            });
+          });
+        }
+        browser.test.sendMessage("content-script-done");
+      },
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/test.xml"
+  );
+
+  info("Wait content script and xml document to be fully loaded");
+  await extension.awaitMessage("content-script-done");
+
+  info("Verify the xml file is still pretty printed");
+  const res = await contentPage.spawn([], () => {
+    const doc = this.content.document;
+    const shadowRoot = doc.documentElement.openOrClosedShadowRoot;
+    const prettyPrintLink =
+      shadowRoot &&
+      shadowRoot.querySelector("link[href*='XMLPrettyPrint.css']");
+    return {
+      hasShadowRoot: !!shadowRoot,
+      hasPrettyPrintLink: !!prettyPrintLink,
+    };
+  });
+
+  Assert.deepEqual(
+    res,
+    { hasShadowRoot: true, hasPrettyPrintLink: true },
+    "The XML file has the pretty print shadowRoot"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xorigin_frame.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xorigin_frame.js
new file mode 100644
index 0000000000..cab508b040
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xorigin_frame.js
@@ -0,0 +1,85 @@
+"use strict";
+
+const server = createHttpServer({
+  hosts: ["example.net", "example.org"],
+});
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_process_switch_cross_origin_frame() {
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.org/*/file_iframe.html"],
+          all_frames: true,
+          js: ["cs.js"],
+        },
+      ],
+    },
+
+    background() {
+      browser.runtime.onConnect.addListener(port => {
+        port.onMessage.addListener(async () => {
+          let { url, frameId } = port.sender;
+
+          browser.test.assertTrue(frameId > 0, "sender frameId is ok");
+          browser.test.assertTrue(
+            url.endsWith("file_iframe.html"),
+            "url is ok"
+          );
+
+          port.postMessage(frameId);
+          port.disconnect();
+        });
+      });
+    },
+
+    files: {
+      "cs.js"() {
+        browser.test.assertEq(
+          location.href,
+          "http://example.org/data/file_iframe.html",
+          "url is ok"
+        );
+
+        let frameId;
+        let port = browser.runtime.connect();
+        port.onMessage.addListener(response => {
+          frameId = response;
+        });
+        port.onDisconnect.addListener(() => {
+          browser.test.sendMessage("content-script-loaded", frameId);
+        });
+        port.postMessage("hello");
+      },
+    },
+  });
+
+  await extension.startup();
+
+  const contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.net/data/file_with_xorigin_frame.html"
+  );
+
+  const browserProcessId =
+    contentPage.browser.browsingContext.currentWindowGlobal.domProcess.childID;
+
+  const scriptFrameId = await extension.awaitMessage("content-script-loaded");
+
+  const children = contentPage.browser.browsingContext.children.map(bc => ({
+    browsingContextId: bc.id,
+    processId: bc.currentWindowGlobal.domProcess.childID,
+  }));
+
+  Assert.equal(children.length, 1);
+  Assert.equal(scriptFrameId, children[0].browsingContextId);
+
+  if (contentPage.remoteSubframes) {
+    Assert.notEqual(browserProcessId, children[0].processId);
+  } else {
+    Assert.equal(browserProcessId, children[0].processId);
+  }
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xrays.js b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xrays.js
new file mode 100644
index 0000000000..7b92d5c4b7
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contentscript_xrays.js
@@ -0,0 +1,59 @@
+"use strict";
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function test_contentscript_xrays() {
+  async function contentScript() {
+    let unwrapped = window.wrappedJSObject;
+
+    browser.test.assertEq(
+      "undefined",
+      typeof test,
+      "Should not have named X-ray property access"
+    );
+    browser.test.assertEq(
+      undefined,
+      window.test,
+      "Should not have named X-ray property access"
+    );
+    browser.test.assertEq(
+      "object",
+      typeof unwrapped.test,
+      "Should always have non-X-ray named property access"
+    );
+
+    browser.test.notifyPass("contentScriptXrays");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  await extension.awaitFinish("contentScriptXrays");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contexts.js b/toolkit/components/extensions/test/xpcshell/test_ext_contexts.js
new file mode 100644
index 0000000000..7c06fe33a5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contexts.js
@@ -0,0 +1,198 @@
+"use strict";
+
+const global = this;
+
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+
+var { BaseContext, EventManager } = ExtensionCommon;
+
+class StubContext extends BaseContext {
+  constructor() {
+    let fakeExtension = { id: "test@web.extension" };
+    super("testEnv", fakeExtension);
+    this.sandbox = Cu.Sandbox(global);
+  }
+
+  logActivity(type, name, data) {
+    // no-op required by subclass
+  }
+
+  get cloneScope() {
+    return this.sandbox;
+  }
+
+  get principal() {
+    return Cu.getObjectPrincipal(this.sandbox);
+  }
+}
+
+add_task(async function test_post_unload_promises() {
+  let context = new StubContext();
+
+  let fail = result => {
+    ok(false, `Unexpected callback: ${result}`);
+  };
+
+  // Make sure promises resolve normally prior to unload.
+  let promises = [
+    context.wrapPromise(Promise.resolve()),
+    context.wrapPromise(Promise.reject({ message: "" })).catch(() => {}),
+  ];
+
+  await Promise.all(promises);
+
+  // Make sure promises that resolve after unload do not trigger
+  // resolution handlers.
+
+  context.wrapPromise(Promise.resolve("resolved")).then(fail);
+
+  context.wrapPromise(Promise.reject({ message: "rejected" })).then(fail, fail);
+
+  context.unload();
+
+  // The `setTimeout` ensures that we return to the event loop after
+  // promise resolution, which means we're guaranteed to return after
+  // any micro-tasks that get enqueued by the resolution handlers above.
+  await new Promise(resolve => setTimeout(resolve, 0));
+});
+
+add_task(async function test_post_unload_listeners() {
+  let context = new StubContext();
+
+  let fire;
+  let manager = new EventManager({
+    context,
+    name: "EventManager",
+    register: _fire => {
+      fire = () => {
+        _fire.async();
+      };
+      return () => {};
+    },
+  });
+
+  let fail = event => {
+    ok(false, `Unexpected event: ${event}`);
+  };
+
+  // Check that event listeners isn't called after it has been removed.
+  manager.addListener(fail);
+
+  let promise = new Promise(resolve => manager.addListener(resolve));
+
+  fire();
+
+  // The `fireSingleton` call ia dispatched asynchronously, so it won't
+  // have fired by this point. The `fail` listener that we remove now
+  // should not be called, even though the event has already been
+  // enqueued.
+  manager.removeListener(fail);
+
+  // Wait for the remaining listener to be called, which should always
+  // happen after the `fail` listener would normally be called.
+  await promise;
+
+  // Check that the event listener isn't called after the context has
+  // unloaded.
+  manager.addListener(fail);
+
+  // The `fire` callback always dispatches events
+  // asynchronously, so we need to test that any pending event callbacks
+  // aren't fired after the context unloads. We also need to test that
+  // any `fire` calls that happen *after* the context is unloaded also
+  // do not trigger callbacks.
+  fire();
+  Promise.resolve().then(fire);
+
+  context.unload();
+
+  // The `setTimeout` ensures that we return to the event loop after
+  // promise resolution, which means we're guaranteed to return after
+  // any micro-tasks that get enqueued by the resolution handlers above.
+  await new Promise(resolve => setTimeout(resolve, 0));
+});
+
+class Context extends BaseContext {
+  constructor(principal) {
+    let fakeExtension = { id: "test@web.extension" };
+    super("testEnv", fakeExtension);
+    Object.defineProperty(this, "principal", {
+      value: principal,
+      configurable: true,
+    });
+    this.sandbox = Cu.Sandbox(principal, { wantXrays: false });
+  }
+
+  logActivity(type, name, data) {
+    // no-op required by subclass
+  }
+
+  get cloneScope() {
+    return this.sandbox;
+  }
+}
+
+let ssm = Services.scriptSecurityManager;
+const PRINCIPAL1 = ssm.createContentPrincipalFromOrigin(
+  "http://www.example.org"
+);
+const PRINCIPAL2 = ssm.createContentPrincipalFromOrigin(
+  "http://www.somethingelse.org"
+);
+
+// Test that toJSON() works in the json sandbox
+add_task(async function test_stringify_toJSON() {
+  let context = new Context(PRINCIPAL1);
+  let obj = Cu.evalInSandbox(
+    "({hidden: true, toJSON() { return {visible: true}; } })",
+    context.sandbox
+  );
+
+  let stringified = context.jsonStringify(obj);
+  let expected = JSON.stringify({ visible: true });
+  equal(
+    stringified,
+    expected,
+    "Stringified object with toJSON() method is as expected"
+  );
+});
+
+// Test that stringifying in inaccessible property throws
+add_task(async function test_stringify_inaccessible() {
+  let context = new Context(PRINCIPAL1);
+  let sandbox = context.sandbox;
+  let sandbox2 = Cu.Sandbox(PRINCIPAL2);
+
+  Cu.waiveXrays(sandbox).subobj = Cu.evalInSandbox(
+    "({ subobject: true })",
+    sandbox2
+  );
+  let obj = Cu.evalInSandbox("({ local: true, nested: subobj })", sandbox);
+  Assert.throws(() => {
+    context.jsonStringify(obj);
+  }, /Permission denied to access property "toJSON"/);
+});
+
+add_task(async function test_stringify_accessible() {
+  // Test that an accessible property from another global is included
+  let principal = Cu.getObjectPrincipal(Cu.Sandbox([PRINCIPAL1, PRINCIPAL2]));
+  let context = new Context(principal);
+  let sandbox = context.sandbox;
+  let sandbox2 = Cu.Sandbox(PRINCIPAL2);
+
+  Cu.waiveXrays(sandbox).subobj = Cu.evalInSandbox(
+    "({ subobject: true })",
+    sandbox2
+  );
+  let obj = Cu.evalInSandbox("({ local: true, nested: subobj })", sandbox);
+  let stringified = context.jsonStringify(obj);
+
+  let expected = JSON.stringify({ local: true, nested: { subobject: true } });
+  equal(
+    stringified,
+    expected,
+    "Stringified object with accessible property is as expected"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contexts_gc.js b/toolkit/components/extensions/test/xpcshell/test_ext_contexts_gc.js
new file mode 100644
index 0000000000..521b7db4e9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contexts_gc.js
@@ -0,0 +1,273 @@
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+// Each of these tests do the following:
+// 1. Load document to create an extension context (instance of BaseContext).
+// 2. Get weak reference to that context.
+// 3. Unload the document.
+// 4. Force GC and check that the weak reference has been invalidated.
+
+async function reloadTopContext(contentPage) {
+  await contentPage.spawn(null, async () => {
+    let { TestUtils } = ChromeUtils.import(
+      "resource://testing-common/TestUtils.jsm"
+    );
+    let windowNukeObserved = TestUtils.topicObserved("inner-window-nuked");
+    info(`Reloading top-level document`);
+    this.content.location.reload();
+    await windowNukeObserved;
+    info(`Reloaded top-level document`);
+  });
+}
+
+async function assertContextReleased(contentPage, description) {
+  await contentPage.spawn(description, async assertionDescription => {
+    // Force GC, see https://searchfox.org/mozilla-central/rev/b0275bc977ad7fda615ef34b822bba938f2b16fd/testing/talos/talos/tests/devtools/addon/content/damp.js#84-98
+    // and https://searchfox.org/mozilla-central/rev/33c21c060b7f3a52477a73d06ebcb2bf313c4431/xpcom/base/nsMemoryReporterManager.cpp#2574-2585,2591-2594
+    let gcCount = 0;
+    while (gcCount < 30 && this.contextWeakRef.get() !== null) {
+      ++gcCount;
+      // The JS engine will sometimes hold IC stubs for function
+      // environments alive across multiple CCs, which can keep
+      // closed-over JS objects alive. A shrinking GC will throw those
+      // stubs away, and therefore side-step the problem.
+      Cu.forceShrinkingGC();
+      Cu.forceCC();
+      Cu.forceGC();
+      await new Promise(resolve => this.content.setTimeout(resolve, 0));
+    }
+
+    // The above loop needs to be repeated at most 3 times according to MinimizeMemoryUsage:
+    // https://searchfox.org/mozilla-central/rev/6f86cc3479f80ace97f62634e2c82a483d1ede40/xpcom/base/nsMemoryReporterManager.cpp#2644-2647
+    Assert.lessOrEqual(
+      gcCount,
+      3,
+      `Context should have been GCd within a few GC attempts.`
+    );
+
+    // Each test will set this.contextWeakRef before unloading the document.
+    Assert.ok(!this.contextWeakRef.get(), assertionDescription);
+  });
+}
+
+add_task(async function test_ContentScriptContextChild_in_child_frame() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_iframe.html"],
+          js: ["content_script.js"],
+          all_frames: true,
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": "browser.test.sendMessage('contentScriptLoaded');",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_toplevel.html`
+  );
+  await extension.awaitMessage("contentScriptLoaded");
+
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { DocumentManager } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionContent.jsm",
+      null
+    );
+    let frame = this.content.document.querySelector(
+      "iframe[src*='file_iframe.html']"
+    );
+    let context = DocumentManager.getContext(extensionId, frame.contentWindow);
+
+    Assert.ok(context, "Got content script context");
+
+    this.contextWeakRef = Cu.getWeakReference(context);
+    frame.remove();
+  });
+
+  await assertContextReleased(
+    contentPage,
+    "ContentScriptContextChild should have been released"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_ContentScriptContextChild_in_toplevel() {
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script.js"],
+          all_frames: true,
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": "browser.test.sendMessage('contentScriptLoaded');",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+  await extension.awaitMessage("contentScriptLoaded");
+
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { DocumentManager } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionContent.jsm",
+      null
+    );
+    let context = DocumentManager.getContext(extensionId, this.content);
+
+    Assert.ok(context, "Got content script context");
+
+    this.contextWeakRef = Cu.getWeakReference(context);
+  });
+
+  await reloadTopContext(contentPage);
+  await extension.awaitMessage("contentScriptLoaded");
+  await assertContextReleased(
+    contentPage,
+    "ContentScriptContextChild should have been released"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_ExtensionPageContextChild_in_child_frame() {
+  let extensionData = {
+    files: {
+      "iframe.html": `
+        <!DOCTYPE html><meta charset="utf8">
+        <script src="script.js"></script>
+      `,
+      "toplevel.html": `
+        <!DOCTYPE html><meta charset="utf8">
+        <iframe src="iframe.html"></iframe>
+      `,
+      "script.js": "browser.test.sendMessage('extensionPageLoaded');",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/toplevel.html`,
+    {
+      extension,
+      remote: extension.extension.remote,
+    }
+  );
+  await extension.awaitMessage("extensionPageLoaded");
+
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { ExtensionPageChild } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionPageChild.jsm"
+    );
+
+    let frame = this.content.document.querySelector(
+      "iframe[src*='iframe.html']"
+    );
+    let innerWindowID =
+      frame.browsingContext.currentWindowContext.innerWindowId;
+    let context = ExtensionPageChild.extensionContexts.get(innerWindowID);
+
+    Assert.ok(context, "Got extension page context for child frame");
+
+    this.contextWeakRef = Cu.getWeakReference(context);
+    frame.remove();
+  });
+
+  await assertContextReleased(
+    contentPage,
+    "ExtensionPageContextChild should have been released"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_ExtensionPageContextChild_in_toplevel() {
+  let extensionData = {
+    files: {
+      "toplevel.html": `
+        <!DOCTYPE html><meta charset="utf8">
+        <script src="script.js"></script>
+      `,
+      "script.js": "browser.test.sendMessage('extensionPageLoaded');",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/toplevel.html`,
+    {
+      extension,
+      remote: extension.extension.remote,
+    }
+  );
+  await extension.awaitMessage("extensionPageLoaded");
+
+  await contentPage.spawn(extension.id, async extensionId => {
+    let { ExtensionPageChild } = ChromeUtils.import(
+      "resource://gre/modules/ExtensionPageChild.jsm"
+    );
+
+    let innerWindowID = this.content.windowGlobalChild.innerWindowId;
+    let context = ExtensionPageChild.extensionContexts.get(innerWindowID);
+
+    Assert.ok(context, "Got extension page context for top-level document");
+
+    this.contextWeakRef = Cu.getWeakReference(context);
+  });
+
+  await reloadTopContext(contentPage);
+  await extension.awaitMessage("extensionPageLoaded");
+  // For some unknown reason, the context cannot forcidbly be released by the
+  // garbage collector unless we wait for a short while.
+  await contentPage.spawn(null, async () => {
+    let start = Date.now();
+    // The treshold was found after running this subtest only, 300 times
+    // in a release build (100 of xpcshell, xpcshell-e10s and xpcshell-remote).
+    // With treshold 8, almost half of the tests complete after a 17-18 ms delay.
+    // With treshold 7, over half of the tests complete after a 13-14 ms delay,
+    //  with 12 failures in 300 tests runs.
+    // Let's double that number to have a safety margin.
+    for (let i = 0; i < 15; ++i) {
+      await new Promise(resolve => this.content.setTimeout(resolve, 0));
+    }
+    info(`Going to GC after waiting for ${Date.now() - start} ms.`);
+  });
+  await assertContextReleased(
+    contentPage,
+    "ExtensionPageContextChild should have been released"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_contextual_identities.js b/toolkit/components/extensions/test/xpcshell/test_ext_contextual_identities.js
new file mode 100644
index 0000000000..1c1827c64f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_contextual_identities.js
@@ -0,0 +1,513 @@
+"use strict";
+
+do_get_profile();
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionPreferencesManager",
+  "resource://gre/modules/ExtensionPreferencesManager.jsm"
+);
+
+const CONTAINERS_PREF = "privacy.userContext.enabled";
+
+AddonTestUtils.init(this);
+
+add_task(async function startup() {
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_contextualIdentities_without_permissions() {
+  function background() {
+    browser.test.assertTrue(
+      !browser.contextualIdentities,
+      "contextualIdentities API is not available when the contextualIdentities permission is not required"
+    );
+    browser.test.notifyPass("contextualIdentities_without_permission");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    background,
+    manifest: {
+      applications: {
+        gecko: { id: "testing@thing.com" },
+      },
+      permissions: [],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("contextualIdentities_without_permission");
+  await extension.unload();
+});
+
+add_task(async function test_contextualIdentity_events() {
+  async function background() {
+    function createOneTimeListener(type) {
+      return new Promise((resolve, reject) => {
+        try {
+          browser.test.assertTrue(
+            type in browser.contextualIdentities,
+            `Found API object browser.contextualIdentities.${type}`
+          );
+          const listener = change => {
+            browser.test.assertTrue(
+              "contextualIdentity" in change,
+              `Found identity in change`
+            );
+            browser.contextualIdentities[type].removeListener(listener);
+            resolve(change);
+          };
+          browser.contextualIdentities[type].addListener(listener);
+        } catch (e) {
+          reject(e);
+        }
+      });
+    }
+
+    function assertExpected(expected, container) {
+      // Number of keys that are added by the APIs
+      const createdCount = 2;
+      for (let key of Object.keys(container)) {
+        browser.test.assertTrue(key in expected, `found property ${key}`);
+        browser.test.assertEq(
+          expected[key],
+          container[key],
+          `property value for ${key} is correct`
+        );
+      }
+      const hexMatch = /^#[0-9a-f]{6}$/;
+      browser.test.assertTrue(
+        hexMatch.test(expected.colorCode),
+        "Color code property was expected Hex shape"
+      );
+      const iconMatch = /^resource:\/\/usercontext-content\/[a-z]+[.]svg$/;
+      browser.test.assertTrue(
+        iconMatch.test(expected.iconUrl),
+        "Icon url property was expected shape"
+      );
+      browser.test.assertEq(
+        Object.keys(expected).length,
+        Object.keys(container).length + createdCount,
+        "all expected properties found"
+      );
+    }
+
+    let onCreatePromise = createOneTimeListener("onCreated");
+
+    let containerObj = { name: "foobar", color: "red", icon: "circle" };
+    let ci = await browser.contextualIdentities.create(containerObj);
+    browser.test.assertTrue(!!ci, "We have an identity");
+    const onCreateListenerResponse = await onCreatePromise;
+    const cookieStoreId = ci.cookieStoreId;
+    assertExpected(
+      onCreateListenerResponse.contextualIdentity,
+      Object.assign(containerObj, { cookieStoreId })
+    );
+
+    let onUpdatedPromise = createOneTimeListener("onUpdated");
+    let updateContainerObj = { name: "testing", color: "blue", icon: "dollar" };
+    ci = await browser.contextualIdentities.update(
+      cookieStoreId,
+      updateContainerObj
+    );
+    browser.test.assertTrue(!!ci, "We have an update identity");
+    const onUpdatedListenerResponse = await onUpdatedPromise;
+    assertExpected(
+      onUpdatedListenerResponse.contextualIdentity,
+      Object.assign(updateContainerObj, { cookieStoreId })
+    );
+
+    let onRemovePromise = createOneTimeListener("onRemoved");
+    ci = await browser.contextualIdentities.remove(
+      updateContainerObj.cookieStoreId
+    );
+    browser.test.assertTrue(!!ci, "We have an remove identity");
+    const onRemoveListenerResponse = await onRemovePromise;
+    assertExpected(
+      onRemoveListenerResponse.contextualIdentity,
+      Object.assign(updateContainerObj, { cookieStoreId })
+    );
+
+    browser.test.notifyPass("contextualIdentities_events");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    useAddonManager: "temporary",
+    manifest: {
+      applications: {
+        gecko: { id: "testing@thing.com" },
+      },
+      permissions: ["contextualIdentities"],
+    },
+  });
+
+  Services.prefs.setBoolPref(CONTAINERS_PREF, true);
+
+  await extension.startup();
+  await extension.awaitFinish("contextualIdentities_events");
+  await extension.unload();
+
+  Services.prefs.clearUserPref(CONTAINERS_PREF);
+});
+
+add_task(async function test_contextualIdentity_with_permissions() {
+  const initial = Services.prefs.getBoolPref(CONTAINERS_PREF);
+
+  async function background() {
+    let ci;
+    await browser.test.assertRejects(
+      browser.contextualIdentities.get("foobar"),
+      "Invalid contextual identity: foobar",
+      "API should reject here"
+    );
+    await browser.test.assertRejects(
+      browser.contextualIdentities.update("foobar", { name: "testing" }),
+      "Invalid contextual identity: foobar",
+      "API should reject for unknown updates"
+    );
+    await browser.test.assertRejects(
+      browser.contextualIdentities.remove("foobar"),
+      "Invalid contextual identity: foobar",
+      "API should reject for removing unknown containers"
+    );
+
+    ci = await browser.contextualIdentities.get("firefox-container-1");
+    browser.test.assertTrue(!!ci, "We have an identity");
+    browser.test.assertTrue("name" in ci, "We have an identity.name");
+    browser.test.assertTrue("color" in ci, "We have an identity.color");
+    browser.test.assertTrue("icon" in ci, "We have an identity.icon");
+    browser.test.assertEq("Personal", ci.name, "identity.name is correct");
+    browser.test.assertEq(
+      "firefox-container-1",
+      ci.cookieStoreId,
+      "identity.cookieStoreId is correct"
+    );
+
+    function listenForMessage(messageName, stateChangeBool) {
+      return new Promise(resolve => {
+        browser.test.onMessage.addListener(function listener(msg) {
+          browser.test.log(`Got message from background: ${msg}`);
+          if (msg === messageName + "-response") {
+            browser.test.onMessage.removeListener(listener);
+            resolve();
+          }
+        });
+        browser.test.log(
+          `Sending message to background: ${messageName} ${stateChangeBool}`
+        );
+        browser.test.sendMessage(messageName, stateChangeBool);
+      });
+    }
+
+    await listenForMessage("containers-state-change", false);
+
+    browser.test.assertRejects(
+      browser.contextualIdentities.query({}),
+      "Contextual identities are currently disabled",
+      "Throws when containers are disabled"
+    );
+
+    await listenForMessage("containers-state-change", true);
+
+    let cis = await browser.contextualIdentities.query({});
+    browser.test.assertEq(
+      4,
+      cis.length,
+      "by default we should have 4 containers"
+    );
+
+    cis = await browser.contextualIdentities.query({ name: "Personal" });
+    browser.test.assertEq(
+      1,
+      cis.length,
+      "by default we should have 1 container called Personal"
+    );
+
+    cis = await browser.contextualIdentities.query({ name: "foobar" });
+    browser.test.assertEq(
+      0,
+      cis.length,
+      "by default we should have 0 container called foobar"
+    );
+
+    ci = await browser.contextualIdentities.create({
+      name: "foobar",
+      color: "red",
+      icon: "gift",
+    });
+    browser.test.assertTrue(!!ci, "We have an identity");
+    browser.test.assertEq("foobar", ci.name, "identity.name is correct");
+    browser.test.assertEq("red", ci.color, "identity.color is correct");
+    browser.test.assertEq("gift", ci.icon, "identity.icon is correct");
+    browser.test.assertTrue(
+      !!ci.cookieStoreId,
+      "identity.cookieStoreId is correct"
+    );
+
+    browser.test.assertRejects(
+      browser.contextualIdentities.create({
+        name: "foobar",
+        color: "red",
+        icon: "firefox",
+      }),
+      "Invalid icon firefox for container",
+      "Create container called with an invalid icon"
+    );
+
+    browser.test.assertRejects(
+      browser.contextualIdentities.create({
+        name: "foobar",
+        color: "firefox-orange",
+        icon: "gift",
+      }),
+      "Invalid color name firefox-orange for container",
+      "Create container called with an invalid color"
+    );
+
+    cis = await browser.contextualIdentities.query({});
+    browser.test.assertEq(
+      5,
+      cis.length,
+      "we should still have have 5 containers"
+    );
+
+    ci = await browser.contextualIdentities.get(ci.cookieStoreId);
+    browser.test.assertTrue(!!ci, "We have an identity");
+    browser.test.assertEq("foobar", ci.name, "identity.name is correct");
+    browser.test.assertEq("red", ci.color, "identity.color is correct");
+    browser.test.assertEq("gift", ci.icon, "identity.icon is correct");
+
+    browser.test.assertRejects(
+      browser.contextualIdentities.update(ci.cookieStoreId, {
+        name: "foobar",
+        color: "red",
+        icon: "firefox",
+      }),
+      "Invalid icon firefox for container",
+      "Create container called with an invalid icon"
+    );
+
+    browser.test.assertRejects(
+      browser.contextualIdentities.update(ci.cookieStoreId, {
+        name: "foobar",
+        color: "firefox-orange",
+        icon: "gift",
+      }),
+      "Invalid color name firefox-orange for container",
+      "Create container called with an invalid color"
+    );
+
+    cis = await browser.contextualIdentities.query({});
+    browser.test.assertEq(5, cis.length, "now we have 5 identities");
+
+    ci = await browser.contextualIdentities.update(ci.cookieStoreId, {
+      name: "barfoo",
+      color: "blue",
+      icon: "cart",
+    });
+    browser.test.assertTrue(!!ci, "We have an identity");
+    browser.test.assertEq("barfoo", ci.name, "identity.name is correct");
+    browser.test.assertEq("blue", ci.color, "identity.color is correct");
+    browser.test.assertEq("cart", ci.icon, "identity.icon is correct");
+
+    ci = await browser.contextualIdentities.get(ci.cookieStoreId);
+    browser.test.assertTrue(!!ci, "We have an identity");
+    browser.test.assertEq("barfoo", ci.name, "identity.name is correct");
+    browser.test.assertEq("blue", ci.color, "identity.color is correct");
+    browser.test.assertEq("cart", ci.icon, "identity.icon is correct");
+
+    ci = await browser.contextualIdentities.remove(ci.cookieStoreId);
+    browser.test.assertTrue(!!ci, "We have an identity");
+    browser.test.assertEq("barfoo", ci.name, "identity.name is correct");
+    browser.test.assertEq("blue", ci.color, "identity.color is correct");
+    browser.test.assertEq("cart", ci.icon, "identity.icon is correct");
+
+    cis = await browser.contextualIdentities.query({});
+    browser.test.assertEq(4, cis.length, "we are back to 4 identities");
+
+    browser.test.notifyPass("contextualIdentities");
+  }
+
+  function makeExtension(id) {
+    return ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      background,
+      manifest: {
+        applications: {
+          gecko: { id },
+        },
+        permissions: ["contextualIdentities"],
+      },
+    });
+  }
+
+  let extension = makeExtension("containers-test@mozilla.org");
+
+  extension.onMessage("containers-state-change", stateBool => {
+    Cu.reportError(`Got message "containers-state-change", ${stateBool}`);
+    Services.prefs.setBoolPref(CONTAINERS_PREF, stateBool);
+    Cu.reportError("Changed pref");
+    extension.sendMessage("containers-state-change-response");
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("contextualIdentities");
+  equal(
+    Services.prefs.getBoolPref(CONTAINERS_PREF),
+    true,
+    "Pref should now be enabled, whatever it's initial state"
+  );
+  await extension.unload();
+  equal(
+    Services.prefs.getBoolPref(CONTAINERS_PREF),
+    initial,
+    "Pref should now be initial state"
+  );
+
+  Services.prefs.clearUserPref(CONTAINERS_PREF);
+});
+
+add_task(async function test_contextualIdentity_extensions_enable_containers() {
+  const initial = Services.prefs.getBoolPref(CONTAINERS_PREF);
+  async function background() {
+    let ci = await browser.contextualIdentities.get("firefox-container-1");
+    browser.test.assertTrue(!!ci, "We have an identity");
+
+    browser.test.notifyPass("contextualIdentities");
+  }
+  function makeExtension(id) {
+    return ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      background,
+      manifest: {
+        applications: {
+          gecko: { id },
+        },
+        permissions: ["contextualIdentities"],
+      },
+    });
+  }
+  async function testSetting(expect, message) {
+    let setting = await ExtensionPreferencesManager.getSetting(
+      "privacy.containers"
+    );
+    if (expect === null) {
+      equal(setting, null, message);
+    } else {
+      equal(setting.value, expect, message);
+    }
+  }
+  function testPref(expect, message) {
+    equal(Services.prefs.getBoolPref(CONTAINERS_PREF), expect, message);
+  }
+
+  let extension = makeExtension("containers-test@mozilla.org");
+  await extension.startup();
+  await extension.awaitFinish("contextualIdentities");
+  equal(
+    Services.prefs.getBoolPref(CONTAINERS_PREF),
+    true,
+    "Pref should now be enabled, whatever it's initial state"
+  );
+  await extension.unload();
+  await testSetting(null, "setting should be unset");
+  testPref(initial, "setting should be initial value");
+
+  // Lets set containers explicitly to be off and test we keep it that way after removal
+  Services.prefs.setBoolPref(CONTAINERS_PREF, false);
+
+  let extension1 = makeExtension("containers-test-1@mozilla.org");
+  await extension1.startup();
+  await extension1.awaitFinish("contextualIdentities");
+  await testSetting(extension1.id, "setting should be controlled");
+  testPref(true, "Pref should now be enabled, whatever it's initial state");
+
+  await extension1.unload();
+  await testSetting(null, "setting should be unset");
+  testPref(false, "Pref should be false");
+
+  // Lets set containers explicitly to be on and test we keep it that way after removal.
+  Services.prefs.setBoolPref(CONTAINERS_PREF, true);
+
+  let extension2 = makeExtension("containers-test-2@mozilla.org");
+  let extension3 = makeExtension("containers-test-3@mozilla.org");
+  await extension2.startup();
+  await extension2.awaitFinish("contextualIdentities");
+  await extension3.startup();
+  await extension3.awaitFinish("contextualIdentities");
+
+  // Flip the ordering to check it's still enabled
+  await testSetting(extension3.id, "setting should still be controlled by 3");
+  testPref(true, "Pref should now be enabled 1");
+  await extension3.unload();
+  await testSetting(extension2.id, "setting should still be controlled by 2");
+  testPref(true, "Pref should now be enabled 2");
+  await extension2.unload();
+  await testSetting(null, "setting should be unset");
+  testPref(true, "Pref should now be enabled 3");
+
+  Services.prefs.clearUserPref(CONTAINERS_PREF);
+});
+
+add_task(async function test_contextualIdentity_preference_change() {
+  async function background() {
+    let extensionInfo = await browser.management.getSelf();
+    if (extensionInfo.version == "1.0.0") {
+      const containers = await browser.contextualIdentities.query({});
+      browser.test.assertEq(
+        containers.length,
+        4,
+        "We still have the original containers"
+      );
+      await browser.contextualIdentities.create({
+        name: "foobar",
+        color: "red",
+        icon: "circle",
+      });
+    }
+    const containers = await browser.contextualIdentities.query({});
+    browser.test.assertEq(containers.length, 5, "We have a new container");
+    if (extensionInfo.version == "1.1.0") {
+      await browser.contextualIdentities.remove(containers[4].cookieStoreId);
+    }
+    browser.test.notifyPass("contextualIdentities");
+  }
+  function makeExtension(id, version) {
+    return ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      background,
+      manifest: {
+        version,
+        applications: {
+          gecko: { id },
+        },
+        permissions: ["contextualIdentities"],
+      },
+    });
+  }
+
+  Services.prefs.setBoolPref(CONTAINERS_PREF, false);
+  let extension = makeExtension("containers-pref-test@mozilla.org", "1.0.0");
+  await extension.startup();
+  await extension.awaitFinish("contextualIdentities");
+  equal(
+    Services.prefs.getBoolPref(CONTAINERS_PREF),
+    true,
+    "Pref should now be enabled, whatever it's initial state"
+  );
+
+  let extension2 = makeExtension("containers-pref-test@mozilla.org", "1.1.0");
+  await extension2.startup();
+  await extension2.awaitFinish("contextualIdentities");
+
+  await extension.unload();
+  equal(
+    Services.prefs.getBoolPref(CONTAINERS_PREF),
+    false,
+    "Pref should now be the initial state we set it to."
+  );
+
+  Services.prefs.clearUserPref(CONTAINERS_PREF);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_cookieBehaviors.js b/toolkit/components/extensions/test/xpcshell/test_ext_cookieBehaviors.js
new file mode 100644
index 0000000000..8edd61fc63
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_cookieBehaviors.js
@@ -0,0 +1,675 @@
+"use strict";
+
+const { UrlClassifierTestUtils } = ChromeUtils.import(
+  "resource://testing-common/UrlClassifierTestUtils.jsm"
+);
+
+const {
+  // cookieBehavior constants.
+  BEHAVIOR_REJECT,
+  BEHAVIOR_REJECT_TRACKER,
+
+  // lifetimePolicy constants.
+  ACCEPT_SESSION,
+} = Ci.nsICookieService;
+
+function createPage({ script, body = "" } = {}) {
+  if (script) {
+    body += `<script src="${script}"></script>`;
+  }
+
+  return `<!DOCTYPE html>
+    <html>
+      <head>
+        <meta charset="utf-8">
+      </head>
+      <body>
+        ${body}
+      </body>
+    </html>`;
+}
+
+const server = createHttpServer({ hosts: ["example.com", "itisatracker.org"] });
+server.registerDirectory("/data/", do_get_file("data"));
+server.registerPathHandler("/test-cookies", (request, response) => {
+  response.setHeader("Cache-Control", "no-cache", false);
+  response.setHeader("Content-Type", "text/json", false);
+  response.setHeader("Set-Cookie", "myKey=myCookie", true);
+  response.write('{"success": true}');
+});
+server.registerPathHandler("/subframe.html", (request, response) => {
+  response.write(createPage());
+});
+server.registerPathHandler("/page-with-tracker.html", (request, response) => {
+  response.write(
+    createPage({
+      body: `<iframe src="http://itisatracker.org/test-cookies"></iframe>`,
+    })
+  );
+});
+server.registerPathHandler("/sw.js", (request, response) => {
+  response.setHeader("Content-Type", "text/javascript", false);
+  response.write("");
+});
+
+function assertCookiesForHost(url, cookiesCount, message) {
+  const { host } = new URL(url);
+  const cookies = Services.cookies.cookies.filter(
+    cookie => cookie.host === host
+  );
+  equal(cookies.length, cookiesCount, message);
+  return cookies;
+}
+
+// Test that the indexedDB and localStorage are allowed in an extension page
+// and that the indexedDB is allowed in a extension worker.
+add_task(async function test_ext_page_allowed_storage() {
+  function testWebStorages() {
+    const url = window.location.href;
+
+    try {
+      // In a webpage accessing indexedDB throws on cookiesBehavior reject,
+      // here we verify that doesn't happen for an extension page.
+      browser.test.assertTrue(
+        indexedDB,
+        "IndexedDB global should be accessible"
+      );
+
+      // In a webpage localStorage is undefined on cookiesBehavior reject,
+      // here we verify that doesn't happen for an extension page.
+      browser.test.assertTrue(
+        localStorage,
+        "localStorage global should be defined"
+      );
+
+      const worker = new Worker("worker.js");
+      worker.onmessage = event => {
+        browser.test.assertTrue(
+          event.data.pass,
+          "extension page worker have access to indexedDB"
+        );
+
+        browser.test.sendMessage("test-storage:done", url);
+      };
+
+      worker.postMessage({});
+    } catch (err) {
+      browser.test.fail(`Unexpected error: ${err}`);
+      browser.test.sendMessage("test-storage:done", url);
+    }
+  }
+
+  function testWorker() {
+    this.onmessage = () => {
+      try {
+        void indexedDB;
+        postMessage({ pass: true });
+      } catch (err) {
+        postMessage({ pass: false });
+        throw err;
+      }
+    };
+  }
+
+  async function createExtension() {
+    let extension = ExtensionTestUtils.loadExtension({
+      files: {
+        "test_web_storages.js": testWebStorages,
+        "worker.js": testWorker,
+        "page_subframe.html": createPage({ script: "test_web_storages.js" }),
+        "page_with_subframe.html": createPage({
+          body: '<iframe src="page_subframe.html"></iframe>',
+        }),
+        "page.html": createPage({
+          script: "test_web_storages.js",
+        }),
+      },
+    });
+
+    await extension.startup();
+
+    const EXT_BASE_URL = `moz-extension://${extension.uuid}/`;
+
+    return { extension, EXT_BASE_URL };
+  }
+
+  const cookieBehaviors = [
+    "BEHAVIOR_LIMIT_FOREIGN",
+    "BEHAVIOR_REJECT_FOREIGN",
+    "BEHAVIOR_REJECT",
+    "BEHAVIOR_REJECT_TRACKER",
+    "BEHAVIOR_REJECT_TRACKER_AND_PARTITION_FOREIGN",
+  ];
+  equal(
+    cookieBehaviors.length,
+    Ci.nsICookieService.BEHAVIOR_LAST,
+    "all behaviors should be covered"
+  );
+
+  for (const behavior of cookieBehaviors) {
+    info(
+      `Test extension page access to indexedDB & localStorage with ${behavior}`
+    );
+    ok(
+      behavior in Ci.nsICookieService,
+      `${behavior} is a valid CookieBehavior`
+    );
+    Services.prefs.setIntPref(
+      "network.cookie.cookieBehavior",
+      Ci.nsICookieService[behavior]
+    );
+
+    // Create a new extension to ensure that the cookieBehavior just set is going to be
+    // used for the requests triggered by the extension page.
+    const { extension, EXT_BASE_URL } = await createExtension();
+    const extPage = await ExtensionTestUtils.loadContentPage("about:blank", {
+      extension,
+      remote: extension.extension.remote,
+    });
+
+    info("Test from a top level extension page");
+    await extPage.loadURL(`${EXT_BASE_URL}page.html`);
+
+    let testedFromURL = await extension.awaitMessage("test-storage:done");
+    equal(
+      testedFromURL,
+      `${EXT_BASE_URL}page.html`,
+      "Got the results from the expected url"
+    );
+
+    info("Test from a sub frame extension page");
+    await extPage.loadURL(`${EXT_BASE_URL}page_with_subframe.html`);
+
+    testedFromURL = await extension.awaitMessage("test-storage:done");
+    equal(
+      testedFromURL,
+      `${EXT_BASE_URL}page_subframe.html`,
+      "Got the results from the expected url"
+    );
+
+    await extPage.close();
+    await extension.unload();
+  }
+});
+
+add_task(async function test_ext_page_3rdparty_cookies() {
+  // Disable tracking protection to test cookies on BEHAVIOR_REJECT_TRACKER
+  // (otherwise tracking protection would block the tracker iframe and
+  // we would not be actually checking the cookie behavior).
+  Services.prefs.setBoolPref("privacy.trackingprotection.enabled", false);
+  await UrlClassifierTestUtils.addTestTrackers();
+  registerCleanupFunction(function() {
+    UrlClassifierTestUtils.cleanupTestTrackers();
+    Services.prefs.clearUserPref("privacy.trackingprotection.enabled");
+    Services.cookies.removeAll();
+  });
+
+  function testRequestScript() {
+    browser.test.onMessage.addListener((msg, url) => {
+      const done = () => {
+        browser.test.sendMessage(`${msg}:done`);
+      };
+
+      switch (msg) {
+        case "xhr": {
+          let req = new XMLHttpRequest();
+          req.onload = done;
+          req.open("GET", url);
+          req.send();
+          break;
+        }
+        case "fetch": {
+          window.fetch(url).then(done);
+          break;
+        }
+        case "worker fetch": {
+          const worker = new Worker("test_worker.js");
+          worker.onmessage = evt => {
+            if (evt.data.requestDone) {
+              done();
+            }
+          };
+          worker.postMessage({ url });
+          break;
+        }
+        default: {
+          browser.test.fail(`Received an unexpected message: ${msg}`);
+          done();
+        }
+      }
+    });
+
+    browser.test.sendMessage("testRequestScript:ready", window.location.href);
+  }
+
+  function testWorker() {
+    this.onmessage = evt => {
+      fetch(evt.data.url).then(() => {
+        postMessage({ requestDone: true });
+      });
+    };
+  }
+
+  async function createExtension() {
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        permissions: ["http://example.com/*", "http://itisatracker.org/*"],
+      },
+      files: {
+        "test_worker.js": testWorker,
+        "test_request.js": testRequestScript,
+        "page_subframe.html": createPage({ script: "test_request.js" }),
+        "page_with_subframe.html": createPage({
+          body: '<iframe src="page_subframe.html"></iframe>',
+        }),
+        "page.html": createPage({ script: "test_request.js" }),
+      },
+    });
+
+    await extension.startup();
+
+    const EXT_BASE_URL = `moz-extension://${extension.uuid}`;
+
+    return { extension, EXT_BASE_URL };
+  }
+
+  const testUrl = "http://example.com/test-cookies";
+  const testRequests = ["xhr", "fetch", "worker fetch"];
+  const tests = [
+    { behavior: "BEHAVIOR_ACCEPT", cookiesCount: 1 },
+    { behavior: "BEHAVIOR_REJECT_FOREIGN", cookiesCount: 1 },
+    { behavior: "BEHAVIOR_REJECT", cookiesCount: 0 },
+    { behavior: "BEHAVIOR_LIMIT_FOREIGN", cookiesCount: 1 },
+    { behavior: "BEHAVIOR_REJECT_TRACKER", cookiesCount: 1 },
+  ];
+
+  function clearAllCookies() {
+    Services.cookies.removeAll();
+    let cookies = Services.cookies.cookies;
+    equal(cookies.length, 0, "There shouldn't be any cookies after clearing");
+  }
+
+  async function runTestRequests(extension, cookiesCount, msg) {
+    for (const testRequest of testRequests) {
+      clearAllCookies();
+      extension.sendMessage(testRequest, testUrl);
+      await extension.awaitMessage(`${testRequest}:done`);
+      assertCookiesForHost(
+        testUrl,
+        cookiesCount,
+        `${msg}: cookies count on ${testRequest} "${testUrl}"`
+      );
+    }
+  }
+
+  for (const { behavior, cookiesCount } of tests) {
+    info(`Test cookies on http requests with ${behavior}`);
+    ok(
+      behavior in Ci.nsICookieService,
+      `${behavior} is a valid CookieBehavior`
+    );
+    Services.prefs.setIntPref(
+      "network.cookie.cookieBehavior",
+      Ci.nsICookieService[behavior]
+    );
+
+    // Create a new extension to ensure that the cookieBehavior just set is going to be
+    // used for the requests triggered by the extension page.
+    const { extension, EXT_BASE_URL } = await createExtension();
+
+    // Run all the test requests on a top level extension page.
+    let extPage = await ExtensionTestUtils.loadContentPage(
+      `${EXT_BASE_URL}/page.html`,
+      {
+        extension,
+        remote: extension.extension.remote,
+      }
+    );
+    await extension.awaitMessage("testRequestScript:ready");
+    await runTestRequests(
+      extension,
+      cookiesCount,
+      `Test top level extension page on ${behavior}`
+    );
+    await extPage.close();
+
+    // Rerun all the test requests on a sub frame extension page.
+    extPage = await ExtensionTestUtils.loadContentPage(
+      `${EXT_BASE_URL}/page_with_subframe.html`,
+      {
+        extension,
+        remote: extension.extension.remote,
+      }
+    );
+    await extension.awaitMessage("testRequestScript:ready");
+    await runTestRequests(
+      extension,
+      cookiesCount,
+      `Test sub frame extension page on ${behavior}`
+    );
+    await extPage.close();
+
+    await extension.unload();
+  }
+
+  // Test tracking url blocking from a webpage subframe.
+  info(
+    "Testing blocked tracker cookies in webpage subframe on BEHAVIOR_REJECT_TRACKERS"
+  );
+  Services.prefs.setIntPref(
+    "network.cookie.cookieBehavior",
+    BEHAVIOR_REJECT_TRACKER
+  );
+
+  const trackerURL = "http://itisatracker.org/test-cookies";
+  const { extension, EXT_BASE_URL } = await createExtension();
+  const extPage = await ExtensionTestUtils.loadContentPage(
+    `${EXT_BASE_URL}/_generated_background_page.html`,
+    {
+      extension,
+      remote: extension.extension.remote,
+    }
+  );
+  clearAllCookies();
+
+  await extPage.spawn(
+    "http://example.com/page-with-tracker.html",
+    async iframeURL => {
+      const iframe = this.content.document.createElement("iframe");
+      iframe.setAttribute("src", iframeURL);
+      return new Promise(resolve => {
+        iframe.onload = () => resolve();
+        this.content.document.body.appendChild(iframe);
+      });
+    }
+  );
+
+  assertCookiesForHost(
+    trackerURL,
+    0,
+    "Test cookies on web subframe inside top level extension page on BEHAVIOR_REJECT_TRACKER"
+  );
+  clearAllCookies();
+
+  await extPage.close();
+  await extension.unload();
+});
+
+// Test that a webpage embedded as a subframe of an extension page is not allowed to use
+// IndexedDB and register a ServiceWorker when it shouldn't be based on the cookieBehavior.
+add_task(
+  async function test_webpage_subframe_storage_respect_cookiesBehavior() {
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        permissions: ["http://example.com/*"],
+        web_accessible_resources: ["subframe.html"],
+      },
+      files: {
+        "toplevel.html": createPage({
+          body: `
+          <iframe id="ext" src="subframe.html"></iframe>
+          <iframe id="web" src="http://example.com/subframe.html"></iframe>
+        `,
+        }),
+        "subframe.html": createPage(),
+      },
+    });
+
+    Services.prefs.setIntPref("network.cookie.cookieBehavior", BEHAVIOR_REJECT);
+
+    await extension.startup();
+
+    let extensionPage = await ExtensionTestUtils.loadContentPage(
+      `moz-extension://${extension.uuid}/toplevel.html`,
+      {
+        extension,
+        remote: extension.extension.remote,
+      }
+    );
+
+    let results = await extensionPage.spawn(null, async () => {
+      let extFrame = this.content.document.querySelector("iframe#ext");
+      let webFrame = this.content.document.querySelector("iframe#web");
+
+      function testIDB(win) {
+        try {
+          void win.indexedDB;
+          return { success: true };
+        } catch (err) {
+          return { error: `${err}` };
+        }
+      }
+
+      async function testServiceWorker(win) {
+        try {
+          await win.navigator.serviceWorker.register("sw.js");
+          return { success: true };
+        } catch (err) {
+          return { error: `${err}` };
+        }
+      }
+
+      return {
+        extTopLevel: testIDB(this.content),
+        extSubFrame: testIDB(extFrame.contentWindow),
+        webSubFrame: testIDB(webFrame.contentWindow),
+        webServiceWorker: await testServiceWorker(webFrame.contentWindow),
+      };
+    });
+
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      "http://example.com/subframe.html"
+    );
+
+    results.extSubFrameContent = await contentPage.spawn(
+      extension.uuid,
+      uuid => {
+        return new Promise(resolve => {
+          let frame = this.content.document.createElement("iframe");
+          frame.setAttribute("src", `moz-extension://${uuid}/subframe.html`);
+          frame.onload = () => {
+            try {
+              void frame.contentWindow.indexedDB;
+              resolve({ success: true });
+            } catch (err) {
+              resolve({ error: `${err}` });
+            }
+          };
+          this.content.document.body.appendChild(frame);
+        });
+      }
+    );
+
+    Assert.deepEqual(
+      results.extTopLevel,
+      { success: true },
+      "IndexedDB allowed in a top level extension page"
+    );
+
+    Assert.deepEqual(
+      results.extSubFrame,
+      { success: true },
+      "IndexedDB allowed in a subframe extension page with a top level extension page"
+    );
+
+    Assert.deepEqual(
+      results.webSubFrame,
+      { error: "SecurityError: The operation is insecure." },
+      "IndexedDB not allowed in a subframe webpage with a top level extension page"
+    );
+    Assert.deepEqual(
+      results.webServiceWorker,
+      { error: "SecurityError: The operation is insecure." },
+      "IndexedDB and Cache not allowed in a service worker registered in the subframe webpage extension page"
+    );
+
+    Assert.deepEqual(
+      results.extSubFrameContent,
+      { success: true },
+      "IndexedDB allowed in a subframe extension page with a top level webpage"
+    );
+
+    await extensionPage.close();
+    await contentPage.close();
+
+    await extension.unload();
+  }
+);
+
+// Test that the webpage's indexedDB and localStorage are still not allowed from a content script
+// when the cookie behavior doesn't allow it, even when they are allowed in the extension pages.
+add_task(async function test_content_script_on_cookieBehaviorReject() {
+  Services.prefs.setIntPref("network.cookie.cookieBehavior", BEHAVIOR_REJECT);
+
+  function contentScript() {
+    // Ensure that when the current cookieBehavior doesn't allow a webpage to use indexedDB
+    // or localStorage, then a WebExtension content script is not allowed to use it as well.
+    browser.test.assertThrows(
+      () => indexedDB,
+      /The operation is insecure/,
+      "a content script can't use indexedDB from a page where it is disallowed"
+    );
+
+    browser.test.assertThrows(
+      () => localStorage,
+      /The operation is insecure/,
+      "a content script can't use localStorage from a page where it is disallowed"
+    );
+
+    browser.test.notifyPass("cs_disallowed_storage");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  await extension.awaitFinish("cs_disallowed_storage");
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(function clear_cookieBehavior_pref() {
+  Services.prefs.clearUserPref("network.cookie.cookieBehavior");
+});
+
+// Test that localStorage is not in session-only mode for the extension pages,
+// even when the session-only mode has been globally enabled, but that the
+// lifetime policy currently set is respected in webpage subframes embedded in
+// an extension page.
+add_task(async function test_localStorage_on_session_lifetimePolicy() {
+  // localStorage in session-only mode.
+  Services.prefs.setIntPref("network.cookie.lifetimePolicy", ACCEPT_SESSION);
+
+  function extPageScript() {
+    localStorage.setItem("test-key", "test-value");
+
+    browser.test.sendMessage("bg_localStorage_set");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://example.com/*", "http://itisatracker.org/*"],
+    },
+    files: {
+      "ext.js": extPageScript,
+      "ext.html": createPage({
+        body: `<iframe src="http://example.com"></iframe>`,
+        script: "ext.js",
+      }),
+    },
+  });
+
+  await extension.startup();
+
+  let extensionPage = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/ext.html`,
+    {
+      extension,
+      remote: extension.extension.remote,
+    }
+  );
+  await extension.awaitMessage("bg_localStorage_set");
+
+  const results = await extensionPage.spawn(null, async () => {
+    const iframe = this.content.document.querySelector("iframe").contentWindow;
+    const { localStorage } = this.content;
+
+    await this.content.fetch("http://itisatracker.org/test-cookies");
+    await iframe.fetch("http://example.com/test-cookies");
+
+    return {
+      topLevel: {
+        isSessionOnly: localStorage.isSessionOnly,
+        domStorageLength: localStorage.length,
+        domStorageStoredValue: localStorage.getItem("test-key"),
+      },
+      webFrame: {
+        isSessionOnly: iframe.localStorage.isSessionOnly,
+      },
+    };
+  });
+
+  equal(
+    results.topLevel.isSessionOnly,
+    false,
+    "the extension localStorage is not set in session-only mode"
+  );
+  equal(
+    results.topLevel.domStorageLength,
+    1,
+    "the extension storage contains the expected number of keys"
+  );
+  equal(
+    results.topLevel.domStorageStoredValue,
+    "test-value",
+    "the extension storage contains the expected data"
+  );
+
+  equal(
+    results.webFrame.isSessionOnly,
+    true,
+    "the webpage sub frame localStorage is in session-only mode"
+  );
+
+  let cookies = assertCookiesForHost(
+    "http://example.com",
+    1,
+    "Got a cookie from the extension page request"
+  );
+  ok(
+    cookies[0].isSession,
+    "Got a session cookie from the extension page request"
+  );
+
+  cookies = assertCookiesForHost(
+    "http://itisatracker.org",
+    1,
+    "Got a cookie from the web page request"
+  );
+  ok(cookies[0].isSession, "Got a session cookie from the web page request");
+
+  await extensionPage.close();
+
+  await extension.unload();
+});
+
+add_task(function clear_lifetimePolicy_pref() {
+  Services.prefs.clearUserPref("network.cookie.lifetimePolicy");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_cookies_firstParty.js b/toolkit/components/extensions/test/xpcshell/test_ext_cookies_firstParty.js
new file mode 100644
index 0000000000..700794b46c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_cookies_firstParty.js
@@ -0,0 +1,334 @@
+"use strict";
+
+const server = createHttpServer({
+  hosts: ["example.org", "example.net", "example.com"],
+});
+
+function promiseSetCookies() {
+  return new Promise(resolve => {
+    server.registerPathHandler("/setCookies", (request, response) => {
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.setHeader("Set-Cookie", "none=a; sameSite=none", true);
+      response.setHeader("Set-Cookie", "lax=b; sameSite=lax", true);
+      response.setHeader("Set-Cookie", "strict=c; sameSite=strict", true);
+      response.write("<html></html>");
+      resolve();
+    });
+  });
+}
+
+function promiseLoadedCookies() {
+  return new Promise(resolve => {
+    let cookies;
+
+    server.registerPathHandler("/checkCookies", (request, response) => {
+      cookies = request.hasHeader("Cookie") ? request.getHeader("Cookie") : "";
+
+      response.setStatusLine(request.httpVersion, 302, "Moved Permanently");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.setHeader("Location", "/ready");
+    });
+
+    server.registerPathHandler("/navigate", (request, response) => {
+      cookies = request.hasHeader("Cookie") ? request.getHeader("Cookie") : "";
+
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.write(
+        "<html><script>location = '/checkCookies';</script></html>"
+      );
+    });
+
+    server.registerPathHandler("/fetch", (request, response) => {
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.write("<html><script>fetch('/checkCookies');</script></html>");
+    });
+
+    server.registerPathHandler("/nestedfetch", (request, response) => {
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.write(
+        "<html><iframe src='http://example.net/nestedfetch2'></iframe></html>"
+      );
+    });
+
+    server.registerPathHandler("/nestedfetch2", (request, response) => {
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.write(
+        "<html><iframe src='http://example.org/fetch'></iframe></html>"
+      );
+    });
+
+    server.registerPathHandler("/ready", (request, response) => {
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.write("<html></html>");
+
+      resolve(cookies);
+    });
+  });
+}
+
+add_task(async function setup() {
+  Services.prefs.setIntPref("network.cookie.cookieBehavior", 0);
+  Services.prefs.setBoolPref("network.cookie.sameSite.laxByDefault", true);
+
+  // We don't want to have 'secure' cookies because our test http server doesn't run in https.
+  Services.prefs.setBoolPref(
+    "network.cookie.sameSite.noneRequiresSecure",
+    false
+  );
+
+  // Let's set 3 cookies before loading the extension.
+  let cookiesPromise = promiseSetCookies();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.org/setCookies"
+  );
+  await cookiesPromise;
+  await contentPage.close();
+  Assert.equal(Services.cookies.cookies.length, 3);
+});
+
+add_task(async function test_cookies_firstParty() {
+  async function pageScript() {
+    const ifr = document.createElement("iframe");
+    ifr.src = "http://example.org/" + location.search.slice(1);
+    document.body.appendChild(ifr);
+  }
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["*://example.org/"],
+    },
+    files: {
+      "page.html": `<body><script src="page.js"></script></body>`,
+      "page.js": pageScript,
+    },
+  });
+
+  await extension.startup();
+
+  // This page will load example.org in an iframe.
+  let url = `moz-extension://${extension.uuid}/page.html`;
+  let cookiesPromise = promiseLoadedCookies();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    url + "?checkCookies",
+    { extension }
+  );
+
+  // Let's check the cookies received during the last loading.
+  Assert.equal(await cookiesPromise, "none=a; lax=b; strict=c");
+  await contentPage.close();
+
+  // Let's navigate.
+  cookiesPromise = promiseLoadedCookies();
+  contentPage = await ExtensionTestUtils.loadContentPage(url + "?navigate", {
+    extension,
+  });
+
+  // Let's check the cookies received during the last loading.
+  Assert.equal(await cookiesPromise, "none=a; lax=b; strict=c");
+  await contentPage.close();
+
+  // Let's run a fetch()
+  cookiesPromise = promiseLoadedCookies();
+  contentPage = await ExtensionTestUtils.loadContentPage(url + "?fetch", {
+    extension,
+  });
+
+  // Let's check the cookies received during the last loading.
+  Assert.equal(await cookiesPromise, "none=a; lax=b; strict=c");
+  await contentPage.close();
+
+  // Let's run a fetch() from a nested iframe (extension -> example.net ->
+  // example.org -> fetch)
+  cookiesPromise = promiseLoadedCookies();
+  contentPage = await ExtensionTestUtils.loadContentPage(url + "?nestedfetch", {
+    extension,
+  });
+
+  // Let's check the cookies received during the last loading.
+  Assert.equal(await cookiesPromise, "none=a");
+  await contentPage.close();
+
+  // Let's run a fetch() from a nested iframe (extension -> example.org -> fetch)
+  cookiesPromise = promiseLoadedCookies();
+  contentPage = await ExtensionTestUtils.loadContentPage(
+    url + "?nestedfetch2",
+    {
+      extension,
+    }
+  );
+
+  // Let's check the cookies received during the last loading.
+  Assert.equal(await cookiesPromise, "none=a; lax=b; strict=c");
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_cookies_iframes() {
+  server.registerPathHandler("/echocookies", (request, response) => {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+    response.write(
+      request.hasHeader("Cookie") ? request.getHeader("Cookie") : ""
+    );
+  });
+
+  server.registerPathHandler("/contentScriptHere", (request, response) => {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+    response.write("<html></html>");
+  });
+
+  server.registerPathHandler("/pageWithFrames", (request, response) => {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+
+    response.write(`
+      <html>
+        <iframe src="http://example.com/contentScriptHere"></iframe>
+        <iframe src="http://example.net/contentScriptHere"></iframe>
+      </html>
+    `);
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["*://example.org/"],
+      content_scripts: [
+        {
+          js: ["contentScript.js"],
+          matches: [
+            "*://example.com/contentScriptHere",
+            "*://example.net/contentScriptHere",
+          ],
+          run_at: "document_end",
+          all_frames: true,
+        },
+      ],
+    },
+    files: {
+      "contentScript.js": async () => {
+        const res = await fetch("http://example.org/echocookies");
+        const cookies = await res.text();
+        browser.test.assertEq(
+          "none=a",
+          cookies,
+          "expected cookies in content script"
+        );
+        browser.test.sendMessage("extfetch:" + location.hostname);
+      },
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/pageWithFrames"
+  );
+  await Promise.all([
+    extension.awaitMessage("extfetch:example.com"),
+    extension.awaitMessage("extfetch:example.net"),
+  ]);
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_cookies_background() {
+  async function background() {
+    const res = await fetch("http://example.org/echocookies", {
+      credentials: "include",
+    });
+    const cookies = await res.text();
+    browser.test.sendMessage("fetchcookies", cookies);
+  }
+
+  const tests = [
+    {
+      permissions: ["http://example.org/*"],
+      cookies: "none=a; lax=b; strict=c",
+    },
+    {
+      permissions: [],
+      cookies: "none=a",
+    },
+  ];
+
+  for (let test of tests) {
+    let extension = ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        permissions: test.permissions,
+      },
+    });
+
+    server.registerPathHandler("/echocookies", (request, response) => {
+      response.setStatusLine(request.httpVersion, 200, "OK");
+      response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+      response.setHeader(
+        "Access-Control-Allow-Origin",
+        `moz-extension://${extension.uuid}`,
+        false
+      );
+      response.setHeader("Access-Control-Allow-Credentials", "true", false);
+      response.write(
+        request.hasHeader("Cookie") ? request.getHeader("Cookie") : ""
+      );
+    });
+
+    await extension.startup();
+    equal(
+      await extension.awaitMessage("fetchcookies"),
+      test.cookies,
+      "extension with permissions can see SameSite-restricted cookies"
+    );
+
+    await extension.unload();
+  }
+});
+
+add_task(async function test_cookies_contentScript() {
+  server.registerPathHandler("/empty", (request, response) => {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+    response.write("<html><body></body></html>");
+  });
+
+  async function contentScript() {
+    let res = await fetch("http://example.org/checkCookies");
+    browser.test.assertEq(location.origin + "/ready", res.url, "request OK");
+    browser.test.sendMessage("fetch-done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          run_at: "document_end",
+          js: ["contentscript.js"],
+          matches: ["*://*/*"],
+        },
+      ],
+    },
+    files: {
+      "contentscript.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+
+  let cookiesPromise = promiseLoadedCookies();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.org/empty"
+  );
+  await extension.awaitMessage("fetch-done");
+
+  // Let's check the cookies received during the last loading.
+  Assert.equal(await cookiesPromise, "none=a; lax=b; strict=c");
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_cookies_samesite.js b/toolkit/components/extensions/test/xpcshell/test_ext_cookies_samesite.js
new file mode 100644
index 0000000000..2847698340
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_cookies_samesite.js
@@ -0,0 +1,109 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.org"] });
+server.registerPathHandler("/sameSiteCookiesApiTest", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_samesite_cookies() {
+  function contentScript() {
+    document.cookie = "test1=whatever";
+    document.cookie = "test2=whatever; SameSite=lax";
+    document.cookie = "test3=whatever; SameSite=strict";
+    browser.runtime.sendMessage("do-check-cookies");
+  }
+  async function background() {
+    await new Promise(resolve => {
+      browser.runtime.onMessage.addListener(msg => {
+        browser.test.assertEq("do-check-cookies", msg, "expected message");
+        resolve();
+      });
+    });
+
+    const url = "https://example.org/";
+
+    // Baseline. Every cookie must have the expected sameSite.
+    let cookie = await browser.cookies.get({ url, name: "test1" });
+    browser.test.assertEq(
+      "no_restriction",
+      cookie.sameSite,
+      "Expected sameSite for test1"
+    );
+
+    cookie = await browser.cookies.get({ url, name: "test2" });
+    browser.test.assertEq(
+      "lax",
+      cookie.sameSite,
+      "Expected sameSite for test2"
+    );
+
+    cookie = await browser.cookies.get({ url, name: "test3" });
+    browser.test.assertEq(
+      "strict",
+      cookie.sameSite,
+      "Expected sameSite for test3"
+    );
+
+    // Testing cookies.getAll + cookies.set
+    let cookies = await browser.cookies.getAll({ url, name: "test3" });
+    browser.test.assertEq(1, cookies.length, "There is only one test3 cookie");
+
+    cookie = await browser.cookies.set({
+      url,
+      name: "test3",
+      value: "newvalue",
+    });
+    browser.test.assertEq(
+      "no_restriction",
+      cookie.sameSite,
+      "sameSite defaults to no_restriction"
+    );
+
+    for (let sameSite of ["no_restriction", "lax", "strict"]) {
+      cookie = await browser.cookies.set({ url, name: "test3", sameSite });
+      browser.test.assertEq(
+        sameSite,
+        cookie.sameSite,
+        `Expected sameSite=${sameSite} in return value of cookies.set`
+      );
+      cookies = await browser.cookies.getAll({ url, name: "test3" });
+      browser.test.assertEq(
+        1,
+        cookies.length,
+        `test3 is still the only cookie after setting sameSite=${sameSite}`
+      );
+      browser.test.assertEq(
+        sameSite,
+        cookies[0].sameSite,
+        `test3 was updated to sameSite=${sameSite}`
+      );
+    }
+
+    browser.test.notifyPass("cookies");
+  }
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["cookies", "*://example.org/"],
+      content_scripts: [
+        {
+          matches: ["*://example.org/sameSiteCookiesApiTest*"],
+          js: ["contentscript.js"],
+        },
+      ],
+    },
+    files: {
+      "contentscript.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.org/sameSiteCookiesApiTest"
+  );
+  await extension.awaitFinish("cookies");
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_debugging_utils.js b/toolkit/components/extensions/test/xpcshell/test_ext_debugging_utils.js
new file mode 100644
index 0000000000..a0a552f64f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_debugging_utils.js
@@ -0,0 +1,316 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { ExtensionParent } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionParent.jsm"
+);
+
+add_task(async function testExtensionDebuggingUtilsCleanup() {
+  const extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.sendMessage("background.ready");
+    },
+  });
+
+  const expectedEmptyDebugUtils = {
+    hiddenXULWindow: null,
+    cacheSize: 0,
+  };
+
+  let { hiddenXULWindow, debugBrowserPromises } = ExtensionParent.DebugUtils;
+
+  deepEqual(
+    { hiddenXULWindow, cacheSize: debugBrowserPromises.size },
+    expectedEmptyDebugUtils,
+    "No ExtensionDebugUtils resources has been allocated yet"
+  );
+
+  await extension.startup();
+
+  await extension.awaitMessage("background.ready");
+
+  hiddenXULWindow = ExtensionParent.DebugUtils.hiddenXULWindow;
+  deepEqual(
+    { hiddenXULWindow, cacheSize: debugBrowserPromises.size },
+    expectedEmptyDebugUtils,
+    "No debugging resources has been yet allocated once the extension is running"
+  );
+
+  const fakeAddonActor = {
+    addonId: extension.id,
+  };
+
+  const anotherAddonActor = {
+    addonId: extension.id,
+  };
+
+  const waitFirstBrowser = ExtensionParent.DebugUtils.getExtensionProcessBrowser(
+    fakeAddonActor
+  );
+  const waitSecondBrowser = ExtensionParent.DebugUtils.getExtensionProcessBrowser(
+    anotherAddonActor
+  );
+
+  const addonDebugBrowser = await waitFirstBrowser;
+  equal(
+    addonDebugBrowser.isRemoteBrowser,
+    extension.extension.remote,
+    "The addon debugging browser has the expected remote type"
+  );
+
+  equal(
+    await waitSecondBrowser,
+    addonDebugBrowser,
+    "Two addon debugging actors related to the same addon get the same browser element "
+  );
+
+  equal(
+    debugBrowserPromises.size,
+    1,
+    "The expected resources has been allocated"
+  );
+
+  const nonExistentAddonActor = {
+    addonId: "non-existent-addon@test",
+  };
+
+  const waitRejection = ExtensionParent.DebugUtils.getExtensionProcessBrowser(
+    nonExistentAddonActor
+  );
+
+  await Assert.rejects(
+    waitRejection,
+    /Extension not found/,
+    "Reject with the expected message for non existent addons"
+  );
+
+  equal(
+    debugBrowserPromises.size,
+    1,
+    "No additional debugging resources has been allocated"
+  );
+
+  await ExtensionParent.DebugUtils.releaseExtensionProcessBrowser(
+    fakeAddonActor
+  );
+
+  equal(
+    debugBrowserPromises.size,
+    1,
+    "The addon debugging browser is cached until all the related actors have released it"
+  );
+
+  await ExtensionParent.DebugUtils.releaseExtensionProcessBrowser(
+    anotherAddonActor
+  );
+
+  hiddenXULWindow = ExtensionParent.DebugUtils.hiddenXULWindow;
+
+  deepEqual(
+    { hiddenXULWindow, cacheSize: debugBrowserPromises.size },
+    expectedEmptyDebugUtils,
+    "All the allocated debugging resources has been cleared"
+  );
+
+  await extension.unload();
+});
+
+add_task(async function testExtensionDebuggingUtilsAddonReloaded() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "test-reloaded@test.mozilla.com",
+        },
+      },
+    },
+    background() {
+      browser.test.sendMessage("background.ready");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("background.ready");
+
+  let fakeAddonActor = {
+    addonId: extension.id,
+  };
+
+  const addonDebugBrowser = await ExtensionParent.DebugUtils.getExtensionProcessBrowser(
+    fakeAddonActor
+  );
+  equal(
+    addonDebugBrowser.isRemoteBrowser,
+    extension.extension.remote,
+    "The addon debugging browser has the expected remote type"
+  );
+  equal(
+    ExtensionParent.DebugUtils.debugBrowserPromises.size,
+    1,
+    "Got the expected number of requested debug browsers"
+  );
+
+  const { chromeDocument } = ExtensionParent.DebugUtils.hiddenXULWindow;
+
+  ok(
+    addonDebugBrowser.parentElement === chromeDocument.documentElement,
+    "The addon debugging browser is part of the hiddenXULWindow chromeDocument"
+  );
+
+  await extension.unload();
+
+  // Install an extension with the same id to recreate for the DebugUtils
+  // conditions similar to an addon reloaded while the Addon Debugger is opened.
+  extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "test-reloaded@test.mozilla.com",
+        },
+      },
+    },
+    background() {
+      browser.test.sendMessage("background.ready");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("background.ready");
+
+  equal(
+    ExtensionParent.DebugUtils.debugBrowserPromises.size,
+    1,
+    "Got the expected number of requested debug browsers"
+  );
+
+  const newAddonDebugBrowser = await ExtensionParent.DebugUtils.getExtensionProcessBrowser(
+    fakeAddonActor
+  );
+
+  equal(
+    addonDebugBrowser,
+    newAddonDebugBrowser,
+    "The existent debugging browser has been reused"
+  );
+
+  equal(
+    newAddonDebugBrowser.isRemoteBrowser,
+    extension.extension.remote,
+    "The addon debugging browser has the expected remote type"
+  );
+
+  await ExtensionParent.DebugUtils.releaseExtensionProcessBrowser(
+    fakeAddonActor
+  );
+
+  equal(
+    ExtensionParent.DebugUtils.debugBrowserPromises.size,
+    0,
+    "All the addon debugging browsers has been released"
+  );
+
+  await extension.unload();
+});
+
+add_task(async function testExtensionDebuggingUtilsWithMultipleAddons() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "test-addon-1@test.mozilla.com",
+        },
+      },
+    },
+    background() {
+      browser.test.sendMessage("background.ready");
+    },
+  });
+  let anotherExtension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "test-addon-2@test.mozilla.com",
+        },
+      },
+    },
+    background() {
+      browser.test.sendMessage("background.ready");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("background.ready");
+
+  await anotherExtension.startup();
+  await anotherExtension.awaitMessage("background.ready");
+
+  const fakeAddonActor = {
+    addonId: extension.id,
+  };
+
+  const anotherFakeAddonActor = {
+    addonId: anotherExtension.id,
+  };
+
+  const { DebugUtils } = ExtensionParent;
+  const debugBrowser = await DebugUtils.getExtensionProcessBrowser(
+    fakeAddonActor
+  );
+  const anotherDebugBrowser = await DebugUtils.getExtensionProcessBrowser(
+    anotherFakeAddonActor
+  );
+
+  const chromeDocument = DebugUtils.hiddenXULWindow.chromeDocument;
+
+  equal(
+    ExtensionParent.DebugUtils.debugBrowserPromises.size,
+    2,
+    "Got the expected number of debug browsers requested"
+  );
+  ok(
+    debugBrowser.parentElement === chromeDocument.documentElement,
+    "The first debug browser is part of the hiddenXUL chromeDocument"
+  );
+  ok(
+    anotherDebugBrowser.parentElement === chromeDocument.documentElement,
+    "The second debug browser is part of the hiddenXUL chromeDocument"
+  );
+
+  await ExtensionParent.DebugUtils.releaseExtensionProcessBrowser(
+    fakeAddonActor
+  );
+
+  equal(
+    ExtensionParent.DebugUtils.debugBrowserPromises.size,
+    1,
+    "Got the expected number of debug browsers requested"
+  );
+
+  ok(
+    anotherDebugBrowser.parentElement === chromeDocument.documentElement,
+    "The second debug browser is still part of the hiddenXUL chromeDocument"
+  );
+
+  ok(
+    debugBrowser.parentElement == null,
+    "The first debug browser has been removed from the hiddenXUL chromeDocument"
+  );
+
+  await ExtensionParent.DebugUtils.releaseExtensionProcessBrowser(
+    anotherFakeAddonActor
+  );
+
+  ok(
+    anotherDebugBrowser.parentElement == null,
+    "The second debug browser has been removed from the hiddenXUL chromeDocument"
+  );
+  equal(
+    ExtensionParent.DebugUtils.debugBrowserPromises.size,
+    0,
+    "All the addon debugging browsers has been released"
+  );
+
+  await extension.unload();
+  await anotherExtension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_dns.js b/toolkit/components/extensions/test/xpcshell/test_ext_dns.js
new file mode 100644
index 0000000000..d7f9d6efe9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_dns.js
@@ -0,0 +1,176 @@
+"use strict";
+
+// Some test machines and android are not returning ipv6, turn it
+// off to get consistent test results.
+Services.prefs.setBoolPref("network.dns.disableIPv6", true);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+function getExtension(background = undefined) {
+  let manifest = {
+    permissions: ["dns", "proxy"],
+  };
+  return ExtensionTestUtils.loadExtension({
+    manifest,
+    background() {
+      browser.test.onMessage.addListener(async (msg, data) => {
+        if (msg == "proxy") {
+          await browser.proxy.settings.set({ value: data });
+          browser.test.sendMessage("proxied");
+          return;
+        }
+        browser.test.log(`=== dns resolve test ${JSON.stringify(data)}`);
+        browser.dns
+          .resolve(data.hostname, data.flags)
+          .then(result => {
+            browser.test.log(
+              `=== dns resolve result ${JSON.stringify(result)}`
+            );
+            browser.test.sendMessage("resolved", result);
+          })
+          .catch(e => {
+            browser.test.log(`=== dns resolve error ${e.message}`);
+            browser.test.sendMessage("resolved", { message: e.message });
+          });
+      });
+      browser.test.sendMessage("ready");
+    },
+    incognitoOverride: "spanning",
+    useAddonManager: "temporary",
+  });
+}
+
+const tests = [
+  {
+    request: {
+      hostname: "localhost",
+    },
+    expect: {
+      addresses: ["127.0.0.1"], // ipv6 disabled , "::1"
+    },
+  },
+  {
+    request: {
+      hostname: "localhost",
+      flags: ["offline"],
+    },
+    expect: {
+      addresses: ["127.0.0.1"], // ipv6 disabled , "::1"
+    },
+  },
+  {
+    request: {
+      hostname: "test.example",
+    },
+    expect: {
+      // android will error with offline
+      error: /NS_ERROR_UNKNOWN_HOST|NS_ERROR_OFFLINE/,
+    },
+  },
+  {
+    request: {
+      hostname: "127.0.0.1",
+      flags: ["canonical_name"],
+    },
+    expect: {
+      canonicalName: "127.0.0.1",
+      addresses: ["127.0.0.1"],
+    },
+  },
+  {
+    request: {
+      hostname: "localhost",
+      flags: ["disable_ipv6"],
+    },
+    expect: {
+      addresses: ["127.0.0.1"],
+    },
+  },
+];
+
+add_task(async function startup() {
+  await AddonTestUtils.promiseStartupManager();
+});
+
+add_task(async function test_dns_resolve() {
+  let extension = getExtension();
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  for (let test of tests) {
+    extension.sendMessage("resolve", test.request);
+    let result = await extension.awaitMessage("resolved");
+    if (test.expect.error) {
+      ok(
+        test.expect.error.test(result.message),
+        `expected error ${result.message}`
+      );
+    } else {
+      equal(
+        result.canonicalName,
+        test.expect.canonicalName,
+        "canonicalName match"
+      );
+      // It seems there are platform differences happening that make this
+      // testing difficult. We're going to rely on other existing dns tests to validate
+      // the dns service itself works and only validate that we're getting generally
+      // expected results in the webext api.
+      ok(
+        result.addresses.length >= test.expect.addresses.length,
+        "expected number of addresses returned"
+      );
+      if (test.expect.addresses.length && result.addresses.length) {
+        ok(
+          result.addresses.includes(test.expect.addresses[0]),
+          "got expected ip address"
+        );
+      }
+    }
+  }
+
+  await extension.unload();
+});
+
+add_task(async function test_dns_resolve_socks() {
+  let extension = getExtension();
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  extension.sendMessage("proxy", {
+    proxyType: "manual",
+    socks: "127.0.0.1",
+    socksVersion: 5,
+    proxyDNS: true,
+  });
+  await extension.awaitMessage("proxied");
+  equal(
+    Services.prefs.getIntPref("network.proxy.type"),
+    1 /* PROXYCONFIG_MANUAL */,
+    "manual proxy"
+  );
+  equal(
+    Services.prefs.getStringPref("network.proxy.socks"),
+    "127.0.0.1",
+    "socks proxy"
+  );
+  ok(
+    Services.prefs.getBoolPref("network.proxy.socks_remote_dns"),
+    "socks remote dns"
+  );
+  extension.sendMessage("resolve", {
+    hostname: "mozilla.org",
+  });
+  let result = await extension.awaitMessage("resolved");
+  ok(
+    /NS_ERROR_UNKNOWN_PROXY_HOST/.test(result.message),
+    `expected error ${result.message}`
+  );
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_downloads.js b/toolkit/components/extensions/test/xpcshell/test_ext_downloads.js
new file mode 100644
index 0000000000..f65df707e1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_downloads.js
@@ -0,0 +1,38 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_downloads_api_namespace_and_permissions() {
+  function backgroundScript() {
+    browser.test.assertTrue(!!browser.downloads, "`downloads` API is present.");
+    browser.test.assertTrue(
+      !!browser.downloads.FilenameConflictAction,
+      "`downloads.FilenameConflictAction` enum is present."
+    );
+    browser.test.assertTrue(
+      !!browser.downloads.InterruptReason,
+      "`downloads.InterruptReason` enum is present."
+    );
+    browser.test.assertTrue(
+      !!browser.downloads.DangerType,
+      "`downloads.DangerType` enum is present."
+    );
+    browser.test.assertTrue(
+      !!browser.downloads.State,
+      "`downloads.State` enum is present."
+    );
+    browser.test.notifyPass("downloads tests");
+  }
+
+  let extensionData = {
+    background: backgroundScript,
+    manifest: {
+      permissions: ["downloads", "downloads.open"],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitFinish("downloads tests");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_downloads_cookies.js b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_cookies.js
new file mode 100644
index 0000000000..aa91cd7c88
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_cookies.js
@@ -0,0 +1,216 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { UrlClassifierTestUtils } = ChromeUtils.import(
+  "resource://testing-common/UrlClassifierTestUtils.jsm"
+);
+
+// Value for network.cookie.cookieBehavior to reject all third-party cookies.
+const { BEHAVIOR_REJECT_FOREIGN } = Ci.nsICookieService;
+
+const server = createHttpServer({ hosts: ["example.net", "itisatracker.org"] });
+server.registerPathHandler("/setcookies", (request, response) => {
+  response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+  response.setHeader("Set-Cookie", "c_none=1; sameSite=none", true);
+  response.setHeader("Set-Cookie", "c_lax=1; sameSite=lax", true);
+  response.setHeader("Set-Cookie", "c_strict=1; sameSite=strict", true);
+});
+
+server.registerPathHandler("/download", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+
+  let cookies = request.hasHeader("Cookie") ? request.getHeader("Cookie") : "";
+  // Assign the result through the MIME-type, to make it easier to read the
+  // result via the downloads API.
+  response.setHeader("Content-Type", `dummy/${encodeURIComponent(cookies)}`);
+  // Response of length 7.
+  response.write("1234567");
+});
+
+server.registerPathHandler("/redirect", (request, response) => {
+  response.setStatusLine(request.httpVersion, 302, "Found");
+  response.setHeader("Location", "/download");
+});
+
+function createDownloadTestExtension(extraPermissions = []) {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["downloads", ...extraPermissions],
+    },
+    incognitoOverride: "spanning",
+    background() {
+      async function getCookiesForDownload(url) {
+        let donePromise = new Promise(resolve => {
+          browser.downloads.onChanged.addListener(async delta => {
+            if (delta.state?.current === "complete") {
+              resolve(delta.id);
+            }
+          });
+        });
+        // TODO bug 1653636: Remove this when the correct browsing mode is used.
+        const incognito = browser.extension.inIncognitoContext;
+        let downloadId = await browser.downloads.download({ url, incognito });
+        browser.test.assertEq(await donePromise, downloadId, "got download");
+        let [download] = await browser.downloads.search({ id: downloadId });
+        browser.test.log(`Download results: ${JSON.stringify(download)}`);
+
+        // Delete the file since we aren't interested in it.
+        // TODO bug 1654819: On Windows the file may be recreated.
+        await browser.downloads.removeFile(download.id);
+        // Sanity check to verify that we got the result from /download.
+        browser.test.assertEq(7, download.fileSize, "download succeeded");
+
+        // The "/download" endpoint mirrors received cookies via Content-Type.
+        let cookies = decodeURIComponent(download.mime.replace("dummy/", ""));
+        return cookies;
+      }
+
+      browser.test.onMessage.addListener(async url => {
+        browser.test.sendMessage("result", await getCookiesForDownload(url));
+      });
+    },
+  });
+}
+
+async function downloadAndGetCookies(extension, url) {
+  extension.sendMessage(url);
+  return extension.awaitMessage("result");
+}
+
+add_task(async function setup() {
+  const nsIFile = Ci.nsIFile;
+  const downloadDir = FileUtils.getDir("TmpD", ["downloads"]);
+  downloadDir.createUnique(nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  Services.prefs.setIntPref("browser.download.folderList", 2);
+  Services.prefs.setComplexValue("browser.download.dir", nsIFile, downloadDir);
+
+  // Support sameSite=none despite the server using http instead of https.
+  Services.prefs.setBoolPref(
+    "network.cookie.sameSite.noneRequiresSecure",
+    false
+  );
+  async function loadAndClose(url) {
+    let contentPage = await ExtensionTestUtils.loadContentPage(url);
+    await contentPage.close();
+  }
+  // Generate cookies for use in this test.
+  await loadAndClose("http://example.net/setcookies");
+  await loadAndClose("http://itisatracker.org/setcookies");
+
+  await UrlClassifierTestUtils.addTestTrackers();
+  registerCleanupFunction(() => {
+    UrlClassifierTestUtils.cleanupTestTrackers();
+    Services.cookies.removeAll();
+
+    Services.prefs.clearUserPref("browser.download.folderList");
+    Services.prefs.clearUserPref("browser.download.dir");
+
+    downloadDir.remove(false);
+  });
+});
+
+// Checks that (sameSite) cookies are included in download requests.
+add_task(async function download_cookies_basic() {
+  let extension = createDownloadTestExtension(["*://example.net/*"]);
+  await extension.startup();
+
+  equal(
+    await downloadAndGetCookies(extension, "http://example.net/download"),
+    "c_none=1; c_lax=1; c_strict=1",
+    "Cookies for downloads.download with sameSite cookies"
+  );
+
+  equal(
+    await downloadAndGetCookies(extension, "http://example.net/redirect"),
+    "c_none=1; c_lax=1; c_strict=1",
+    "Cookies for downloads.download with redirect"
+  );
+
+  await runWithPrefs(
+    [["network.cookie.cookieBehavior", BEHAVIOR_REJECT_FOREIGN]],
+    async () => {
+      equal(
+        await downloadAndGetCookies(extension, "http://example.net/download"),
+        "c_none=1; c_lax=1; c_strict=1",
+        "Cookies for downloads.download with all third-party cookies disabled"
+      );
+    }
+  );
+
+  await extension.unload();
+});
+
+// Checks that (sameSite) cookies are included even when tracking protection
+// would block cookies from third-party requests.
+add_task(async function download_cookies_from_tracker_url() {
+  let extension = createDownloadTestExtension(["*://itisatracker.org/*"]);
+  await extension.startup();
+
+  equal(
+    await downloadAndGetCookies(extension, "http://itisatracker.org/download"),
+    "c_none=1; c_lax=1; c_strict=1",
+    "Cookies for downloads.download of itisatracker.org"
+  );
+
+  await extension.unload();
+});
+
+// Checks that (sameSite) cookies are included even without host permissions.
+add_task(async function download_cookies_without_host_permissions() {
+  let extension = createDownloadTestExtension();
+  await extension.startup();
+
+  equal(
+    await downloadAndGetCookies(extension, "http://example.net/download"),
+    "c_none=1; c_lax=1; c_strict=1",
+    "Cookies for downloads.download without host permissions"
+  );
+
+  equal(
+    await downloadAndGetCookies(extension, "http://itisatracker.org/download"),
+    "c_none=1; c_lax=1; c_strict=1",
+    "Cookies for downloads.download of itisatracker.org"
+  );
+
+  await runWithPrefs(
+    [["network.cookie.cookieBehavior", BEHAVIOR_REJECT_FOREIGN]],
+    async () => {
+      equal(
+        await downloadAndGetCookies(extension, "http://example.net/download"),
+        "c_none=1; c_lax=1; c_strict=1",
+        "Cookies for downloads.download with all third-party cookies disabled"
+      );
+    }
+  );
+
+  await extension.unload();
+});
+
+// Checks that (sameSite) cookies from private browsing are included.
+add_task(async function download_cookies_in_perma_private_browsing() {
+  Services.prefs.setBoolPref("browser.privatebrowsing.autostart", true);
+  let extension = createDownloadTestExtension(["*://example.net/*"]);
+  await extension.startup();
+
+  equal(
+    await downloadAndGetCookies(extension, "http://example.net/download"),
+    "",
+    "Initially no cookies in permanent private browsing mode"
+  );
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.net/setcookies",
+    { privateBrowsing: true }
+  );
+
+  equal(
+    await downloadAndGetCookies(extension, "http://example.net/download"),
+    "c_none=1; c_lax=1; c_strict=1",
+    "Cookies for downloads.download in perma-private-browsing mode"
+  );
+
+  await extension.unload();
+  await contentPage.close();
+  Services.prefs.clearUserPref("browser.privatebrowsing.autostart");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_downloads_download.js b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_download.js
new file mode 100644
index 0000000000..a9edb9d13e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_download.js
@@ -0,0 +1,680 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+const { Downloads } = ChromeUtils.import(
+  "resource://gre/modules/Downloads.jsm"
+);
+
+const gServer = createHttpServer();
+gServer.registerDirectory("/data/", do_get_file("data"));
+
+gServer.registerPathHandler("/dir/", (_, res) => res.write("length=8"));
+
+const WINDOWS = AppConstants.platform == "win";
+
+const BASE = `http://localhost:${gServer.identity.primaryPort}/`;
+const FILE_NAME = "file_download.txt";
+const FILE_NAME_W_SPACES = "file   download.txt";
+const FILE_URL = BASE + "data/" + FILE_NAME;
+const FILE_NAME_UNIQUE = "file_download(1).txt";
+const FILE_LEN = 46;
+
+let downloadDir;
+
+function setup() {
+  downloadDir = FileUtils.getDir("TmpD", ["downloads"]);
+  downloadDir.createUnique(
+    Ci.nsIFile.DIRECTORY_TYPE,
+    FileUtils.PERMS_DIRECTORY
+  );
+  info(`Using download directory ${downloadDir.path}`);
+
+  Services.prefs.setIntPref("browser.download.folderList", 2);
+  Services.prefs.setComplexValue(
+    "browser.download.dir",
+    Ci.nsIFile,
+    downloadDir
+  );
+
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("browser.download.folderList");
+    Services.prefs.clearUserPref("browser.download.dir");
+
+    let entries = downloadDir.directoryEntries;
+    while (entries.hasMoreElements()) {
+      let entry = entries.nextFile;
+      ok(false, `Leftover file ${entry.path} in download directory`);
+      entry.remove(false);
+    }
+
+    downloadDir.remove(false);
+  });
+}
+
+function backgroundScript() {
+  let blobUrl;
+  browser.test.onMessage.addListener(async (msg, ...args) => {
+    if (msg == "download.request") {
+      let options = args[0];
+
+      if (options.blobme) {
+        let blob = new Blob(options.blobme);
+        delete options.blobme;
+        blobUrl = options.url = window.URL.createObjectURL(blob);
+      }
+
+      try {
+        let id = await browser.downloads.download(options);
+        browser.test.sendMessage("download.done", { status: "success", id });
+      } catch (error) {
+        browser.test.sendMessage("download.done", {
+          status: "error",
+          errmsg: error.message,
+        });
+      }
+    } else if (msg == "killTheBlob") {
+      window.URL.revokeObjectURL(blobUrl);
+      blobUrl = null;
+    }
+  });
+
+  browser.test.sendMessage("ready");
+}
+
+// This function is a bit of a sledgehammer, it looks at every download
+// the browser knows about and waits for all active downloads to complete.
+// But we only start one at a time and only do a handful in total, so
+// this lets us test download() without depending on anything else.
+async function waitForDownloads() {
+  let list = await Downloads.getList(Downloads.ALL);
+  let downloads = await list.getAll();
+
+  let inprogress = downloads.filter(dl => !dl.stopped);
+  return Promise.all(inprogress.map(dl => dl.whenSucceeded()));
+}
+
+// Create a file in the downloads directory.
+function touch(filename) {
+  let file = downloadDir.clone();
+  file.append(filename);
+  file.create(Ci.nsIFile.NORMAL_FILE_TYPE, FileUtils.PERMS_FILE);
+}
+
+// Remove a file in the downloads directory.
+function remove(filename, recursive = false) {
+  let file = downloadDir.clone();
+  file.append(filename);
+  file.remove(recursive);
+}
+
+add_task(async function test_downloads() {
+  setup();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["downloads"],
+    },
+    incognitoOverride: "spanning",
+  });
+
+  function download(options) {
+    extension.sendMessage("download.request", options);
+    return extension.awaitMessage("download.done");
+  }
+
+  async function testDownload(options, localFile, expectedSize, description) {
+    let msg = await download(options);
+    equal(
+      msg.status,
+      "success",
+      `downloads.download() works with ${description}`
+    );
+
+    await waitForDownloads();
+
+    let localPath = downloadDir.clone();
+    let parts = Array.isArray(localFile) ? localFile : [localFile];
+
+    parts.map(p => localPath.append(p));
+    equal(
+      localPath.fileSize,
+      expectedSize,
+      "Downloaded file has expected size"
+    );
+    localPath.remove(false);
+  }
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  info("extension started");
+
+  // Call download() with just the url property.
+  await testDownload({ url: FILE_URL }, FILE_NAME, FILE_LEN, "just source");
+
+  // Call download() with a filename property.
+  await testDownload(
+    {
+      url: FILE_URL,
+      filename: "newpath.txt",
+    },
+    "newpath.txt",
+    FILE_LEN,
+    "source and filename"
+  );
+
+  // Call download() with a filename with subdirs.
+  await testDownload(
+    {
+      url: FILE_URL,
+      filename: "sub/dir/file",
+    },
+    ["sub", "dir", "file"],
+    FILE_LEN,
+    "source and filename with subdirs"
+  );
+
+  // Call download() with a filename with existing subdirs.
+  await testDownload(
+    {
+      url: FILE_URL,
+      filename: "sub/dir/file2",
+    },
+    ["sub", "dir", "file2"],
+    FILE_LEN,
+    "source and filename with existing subdirs"
+  );
+
+  // Only run Windows path separator test on Windows.
+  if (WINDOWS) {
+    // Call download() with a filename with Windows path separator.
+    await testDownload(
+      {
+        url: FILE_URL,
+        filename: "sub\\dir\\file3",
+      },
+      ["sub", "dir", "file3"],
+      FILE_LEN,
+      "filename with Windows path separator"
+    );
+  }
+  remove("sub", true);
+
+  // Call download(), filename with subdir, skipping parts.
+  await testDownload(
+    {
+      url: FILE_URL,
+      filename: "skip//part",
+    },
+    ["skip", "part"],
+    FILE_LEN,
+    "source, filename, with subdir, skipping parts"
+  );
+  remove("skip", true);
+
+  // Check conflictAction of "uniquify".
+  touch(FILE_NAME);
+  await testDownload(
+    {
+      url: FILE_URL,
+      conflictAction: "uniquify",
+    },
+    FILE_NAME_UNIQUE,
+    FILE_LEN,
+    "conflictAction=uniquify"
+  );
+  // todo check that preexisting file was not modified?
+  remove(FILE_NAME);
+
+  // Check conflictAction of "overwrite".
+  touch(FILE_NAME);
+  await testDownload(
+    {
+      url: FILE_URL,
+      conflictAction: "overwrite",
+    },
+    FILE_NAME,
+    FILE_LEN,
+    "conflictAction=overwrite"
+  );
+
+  // Try to download in invalid url
+  await download({ url: "this is not a valid URL" }).then(msg => {
+    equal(msg.status, "error", "downloads.download() fails with invalid url");
+    ok(
+      /not a valid URL/.test(msg.errmsg),
+      "error message for invalid url is correct"
+    );
+  });
+
+  // Try to download to an empty path.
+  await download({
+    url: FILE_URL,
+    filename: "",
+  }).then(msg => {
+    equal(
+      msg.status,
+      "error",
+      "downloads.download() fails with empty filename"
+    );
+    equal(
+      msg.errmsg,
+      "filename must not be empty",
+      "error message for empty filename is correct"
+    );
+  });
+
+  // Try to download to an absolute path.
+  const absolutePath = OS.Path.join(
+    WINDOWS ? "\\tmp" : "/tmp",
+    "file_download.txt"
+  );
+  await download({
+    url: FILE_URL,
+    filename: absolutePath,
+  }).then(msg => {
+    equal(
+      msg.status,
+      "error",
+      "downloads.download() fails with absolute filename"
+    );
+    equal(
+      msg.errmsg,
+      "filename must not be an absolute path",
+      `error message for absolute path (${absolutePath}) is correct`
+    );
+  });
+
+  if (WINDOWS) {
+    await download({
+      url: FILE_URL,
+      filename: "C:\\file_download.txt",
+    }).then(msg => {
+      equal(
+        msg.status,
+        "error",
+        "downloads.download() fails with absolute filename"
+      );
+      equal(
+        msg.errmsg,
+        "filename must not be an absolute path",
+        "error message for absolute path with drive letter is correct"
+      );
+    });
+  }
+
+  // Try to download to a relative path containing ..
+  await download({
+    url: FILE_URL,
+    filename: OS.Path.join("..", "file_download.txt"),
+  }).then(msg => {
+    equal(
+      msg.status,
+      "error",
+      "downloads.download() fails with back-references"
+    );
+    equal(
+      msg.errmsg,
+      "filename must not contain back-references (..)",
+      "error message for back-references is correct"
+    );
+  });
+
+  // Try to download to a long relative path containing ..
+  await download({
+    url: FILE_URL,
+    filename: OS.Path.join("foo", "..", "..", "file_download.txt"),
+  }).then(msg => {
+    equal(
+      msg.status,
+      "error",
+      "downloads.download() fails with back-references"
+    );
+    equal(
+      msg.errmsg,
+      "filename must not contain back-references (..)",
+      "error message for back-references is correct"
+    );
+  });
+
+  // Test illegal characters.
+  await download({
+    url: FILE_URL,
+    filename: "like:this",
+  }).then(msg => {
+    equal(msg.status, "error", "downloads.download() fails with illegal chars");
+    equal(
+      msg.errmsg,
+      "filename must not contain illegal characters",
+      "error message correct"
+    );
+  });
+
+  // Try to download a blob url
+  const BLOB_STRING = "Hello, world";
+  await testDownload(
+    {
+      blobme: [BLOB_STRING],
+      filename: FILE_NAME,
+    },
+    FILE_NAME,
+    BLOB_STRING.length,
+    "blob url"
+  );
+  extension.sendMessage("killTheBlob");
+
+  // Try to download a blob url without a given filename
+  await testDownload(
+    {
+      blobme: [BLOB_STRING],
+    },
+    "download",
+    BLOB_STRING.length,
+    "blob url with no filename"
+  );
+  extension.sendMessage("killTheBlob");
+
+  // Download a normal URL with an empty filename part.
+  await testDownload(
+    {
+      url: BASE + "dir/",
+    },
+    "download",
+    8,
+    "normal url with empty filename"
+  );
+
+  // Download a filename with multiple spaces, url is ignored for this test.
+  await testDownload(
+    {
+      url: FILE_URL,
+      filename: "a   file.txt",
+    },
+    "a   file.txt",
+    FILE_LEN,
+    "filename with multiple spaces"
+  );
+
+  // Download a normal URL with a leafname containing multiple spaces.
+  // Note: spaces are compressed by file name normalization.
+  await testDownload(
+    {
+      url: BASE + "data/" + FILE_NAME_W_SPACES,
+    },
+    FILE_NAME_W_SPACES.replace(/\s+/, " "),
+    FILE_LEN,
+    "leafname with multiple spaces"
+  );
+
+  // Check that the "incognito" property is supported.
+  await testDownload(
+    {
+      url: FILE_URL,
+      incognito: false,
+    },
+    FILE_NAME,
+    FILE_LEN,
+    "incognito=false"
+  );
+
+  await testDownload(
+    {
+      url: FILE_URL,
+      incognito: true,
+    },
+    FILE_NAME,
+    FILE_LEN,
+    "incognito=true"
+  );
+
+  await extension.unload();
+});
+
+async function testHttpErrors(allowHttpErrors) {
+  const server = createHttpServer();
+  const url = `http://localhost:${server.identity.primaryPort}/error`;
+  const content = "HTTP Error test";
+
+  server.registerPathHandler("/error", (request, response) => {
+    response.setStatusLine(
+      "1.1",
+      parseInt(request.queryString, 10),
+      "Some Error"
+    );
+    response.setHeader("Content-Type", "text/plain", false);
+    response.setHeader("Content-Length", content.length.toString());
+    response.write(content);
+  });
+
+  function background(code) {
+    let dlid = 0;
+    let expectedState;
+    browser.test.onMessage.addListener(async options => {
+      try {
+        expectedState = options.allowHttpErrors ? "complete" : "interrupted";
+        dlid = await browser.downloads.download(options);
+      } catch (err) {
+        browser.test.fail(`Unexpected error in downloads.download(): ${err}`);
+      }
+    });
+    function onChanged({ id, state }) {
+      if (dlid !== id || !state || state.current === "in_progress") {
+        return;
+      }
+      browser.test.assertEq(state.current, expectedState, "correct state");
+      browser.downloads.search({ id }).then(([download]) => {
+        browser.test.sendMessage("done", download.error);
+      });
+    }
+    browser.downloads.onChanged.addListener(onChanged);
+  }
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["downloads"],
+    },
+    background,
+  });
+  await extension.startup();
+
+  async function download(code, expected_when_disallowed) {
+    const options = {
+      url: url + "?" + code,
+      filename: `test-${code}`,
+      conflictAction: "overwrite",
+      allowHttpErrors,
+    };
+    extension.sendMessage(options);
+    const rv = await extension.awaitMessage("done");
+
+    if (allowHttpErrors) {
+      const localPath = downloadDir.clone();
+      localPath.append(options.filename);
+      equal(
+        localPath.fileSize,
+        // The 20x No content errors will not produce any response body,
+        // only "true" errors do.
+        code >= 400 ? content.length : 0,
+        "Downloaded file has expected size" + code
+      );
+      localPath.remove(false);
+
+      ok(!rv, "error must be ignored and hence false-y");
+      return;
+    }
+
+    equal(
+      rv,
+      expected_when_disallowed,
+      "error must have the correct InterruptReason"
+    );
+  }
+
+  await download(204, "SERVER_BAD_CONTENT"); // No Content
+  await download(205, "SERVER_BAD_CONTENT"); // Reset Content
+  await download(404, "SERVER_BAD_CONTENT"); // Not Found
+  await download(403, "SERVER_FORBIDDEN"); // Forbidden
+  await download(402, "SERVER_UNAUTHORIZED"); // Unauthorized
+  await download(407, "SERVER_UNAUTHORIZED"); // Proxy auth required
+  await download(504, "SERVER_FAILED"); //General errors, here Gateway Timeout
+
+  await extension.unload();
+}
+
+add_task(function test_download_disallowed_http_errors() {
+  return testHttpErrors(false);
+});
+
+add_task(function test_download_allowed_http_errors() {
+  return testHttpErrors(true);
+});
+
+add_task(async function test_download_http_details() {
+  const server = createHttpServer();
+  const url = `http://localhost:${server.identity.primaryPort}/post-log`;
+
+  let received;
+  server.registerPathHandler("/post-log", (request, response) => {
+    received = request;
+    response.setHeader("Set-Cookie", "monster=", false);
+  });
+
+  // Confirm received vs. expected values.
+  function confirm(method, headers = {}, body) {
+    equal(received.method, method, "method is correct");
+
+    for (let name in headers) {
+      ok(received.hasHeader(name), `header ${name} received`);
+      equal(
+        received.getHeader(name),
+        headers[name],
+        `header ${name} is correct`
+      );
+    }
+
+    if (body) {
+      const str = NetUtil.readInputStreamToString(
+        received.bodyInputStream,
+        received.bodyInputStream.available()
+      );
+      equal(str, body, "body is correct");
+    }
+  }
+
+  function background() {
+    browser.test.onMessage.addListener(async options => {
+      try {
+        await browser.downloads.download(options);
+      } catch (err) {
+        browser.test.sendMessage("done", { err: err.message });
+      }
+    });
+    browser.downloads.onChanged.addListener(({ state }) => {
+      if (state && state.current === "complete") {
+        browser.test.sendMessage("done", { ok: true });
+      }
+    });
+  }
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["downloads"],
+    },
+    background,
+    incognitoOverride: "spanning",
+  });
+  await extension.startup();
+
+  function download(options) {
+    options.url = url;
+    options.conflictAction = "overwrite";
+
+    extension.sendMessage(options);
+    return extension.awaitMessage("done");
+  }
+
+  // Test that site cookies are sent with download requests,
+  // and "incognito" downloads use a separate cookie jar.
+  let testDownloadCookie = async function(incognito) {
+    let result = await download({ incognito });
+    ok(result.ok, `preflight to set cookies with incognito=${incognito}`);
+    ok(!received.hasHeader("cookie"), "first request has no cookies");
+
+    result = await download({ incognito });
+    ok(result.ok, `download with cookie with incognito=${incognito}`);
+    equal(
+      received.getHeader("cookie"),
+      "monster=",
+      "correct cookie header sent for second download"
+    );
+  };
+
+  await testDownloadCookie(false);
+  await testDownloadCookie(true);
+
+  // Test method option.
+  let result = await download({});
+  ok(result.ok, "download works without the method option, defaults to GET");
+  confirm("GET");
+
+  result = await download({ method: "PUT" });
+  ok(!result.ok, "download rejected with PUT method");
+  ok(
+    /method: Invalid enumeration/.test(result.err),
+    "descriptive error message"
+  );
+
+  result = await download({ method: "POST" });
+  ok(result.ok, "download works with POST method");
+  confirm("POST");
+
+  // Test body option values.
+  result = await download({ body: [] });
+  ok(!result.ok, "download rejected because of non-string body");
+  ok(/body: Expected string/.test(result.err), "descriptive error message");
+
+  result = await download({ method: "POST", body: "of work" });
+  ok(result.ok, "download works with POST method and body");
+  confirm("POST", { "Content-Length": 7 }, "of work");
+
+  // Test custom headers.
+  result = await download({ headers: [{ name: "X-Custom" }] });
+  ok(!result.ok, "download rejected because of missing header value");
+  ok(/"value" is required/.test(result.err), "descriptive error message");
+
+  result = await download({ headers: [{ name: "X-Custom", value: "13" }] });
+  ok(result.ok, "download works with a custom header");
+  confirm("GET", { "X-Custom": "13" });
+
+  // Test Referer header.
+  const referer = "http://example.org/test";
+  result = await download({ headers: [{ name: "Referer", value: referer }] });
+  ok(result.ok, "download works with Referer header");
+  confirm("GET", { Referer: referer });
+
+  // Test forbidden headers.
+  result = await download({ headers: [{ name: "DNT", value: "1" }] });
+  ok(!result.ok, "download rejected because of forbidden header name DNT");
+  ok(/Forbidden request header/.test(result.err), "descriptive error message");
+
+  result = await download({
+    headers: [{ name: "Proxy-Connection", value: "keep" }],
+  });
+  ok(
+    !result.ok,
+    "download rejected because of forbidden header name prefix Proxy-"
+  );
+  ok(/Forbidden request header/.test(result.err), "descriptive error message");
+
+  result = await download({ headers: [{ name: "Sec-ret", value: "13" }] });
+  ok(
+    !result.ok,
+    "download rejected because of forbidden header name prefix Sec-"
+  );
+  ok(/Forbidden request header/.test(result.err), "descriptive error message");
+
+  remove("post-log");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_downloads_misc.js b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_misc.js
new file mode 100644
index 0000000000..9de40a8c9c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_misc.js
@@ -0,0 +1,1069 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { Downloads } = ChromeUtils.import(
+  "resource://gre/modules/Downloads.jsm"
+);
+
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+
+const { TestUtils } = ChromeUtils.import(
+  "resource://testing-common/TestUtils.jsm"
+);
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const ROOT = `http://localhost:${server.identity.primaryPort}`;
+const BASE = `${ROOT}/data`;
+const TXT_FILE = "file_download.txt";
+const TXT_URL = BASE + "/" + TXT_FILE;
+
+// Keep these in sync with code in interruptible.sjs
+const INT_PARTIAL_LEN = 15;
+const INT_TOTAL_LEN = 31;
+
+const TEST_DATA = "This is 31 bytes of sample data";
+const TOTAL_LEN = TEST_DATA.length;
+const PARTIAL_LEN = 15;
+
+// A handler to let us systematically test pausing/resuming/canceling
+// of downloads.  This target represents a small text file but a simple
+// GET will stall after sending part of the data, to give the test code
+// a chance to pause or do other operations on an in-progress download.
+// A resumed download (ie, a GET with a Range: header) will allow the
+// download to complete.
+function handleRequest(request, response) {
+  response.setHeader("Content-Type", "text/plain", false);
+
+  if (request.hasHeader("Range")) {
+    let start, end;
+    let matches = request
+      .getHeader("Range")
+      .match(/^\s*bytes=(\d+)?-(\d+)?\s*$/);
+    if (matches != null) {
+      start = matches[1] ? parseInt(matches[1], 10) : 0;
+      end = matches[2] ? parseInt(matches[2], 10) : TOTAL_LEN - 1;
+    }
+
+    if (end == undefined || end >= TOTAL_LEN) {
+      response.setStatusLine(
+        request.httpVersion,
+        416,
+        "Requested Range Not Satisfiable"
+      );
+      response.setHeader("Content-Range", `*/${TOTAL_LEN}`, false);
+      response.finish();
+      return;
+    }
+
+    response.setStatusLine(request.httpVersion, 206, "Partial Content");
+    response.setHeader("Content-Range", `${start}-${end}/${TOTAL_LEN}`, false);
+    response.write(TEST_DATA.slice(start, end + 1));
+  } else if (request.queryString.includes("stream")) {
+    response.processAsync();
+    response.setHeader("Content-Length", "10000", false);
+    response.write("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
+    setInterval(() => {
+      response.write("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
+    }, 50);
+  } else {
+    response.processAsync();
+    response.setHeader("Content-Length", `${TOTAL_LEN}`, false);
+    response.write(TEST_DATA.slice(0, PARTIAL_LEN));
+  }
+
+  registerCleanupFunction(() => {
+    try {
+      response.finish();
+    } catch (e) {
+      // This will throw, but we don't care at this point.
+    }
+  });
+}
+
+server.registerPrefixHandler("/interruptible/", handleRequest);
+
+let interruptibleCount = 0;
+function getInterruptibleUrl(filename = "interruptible.html") {
+  let n = interruptibleCount++;
+  return `${ROOT}/interruptible/${filename}?count=${n}`;
+}
+
+function backgroundScript() {
+  let events = new Set();
+  let eventWaiter = null;
+
+  browser.downloads.onCreated.addListener(data => {
+    events.add({ type: "onCreated", data });
+    if (eventWaiter) {
+      eventWaiter();
+    }
+  });
+
+  browser.downloads.onChanged.addListener(data => {
+    events.add({ type: "onChanged", data });
+    if (eventWaiter) {
+      eventWaiter();
+    }
+  });
+
+  browser.downloads.onErased.addListener(data => {
+    events.add({ type: "onErased", data });
+    if (eventWaiter) {
+      eventWaiter();
+    }
+  });
+
+  // Returns a promise that will resolve when the given list of expected
+  // events have all been seen.  By default, succeeds only if the exact list
+  // of expected events is seen in the given order.  options.exact can be
+  // set to false to allow other events and options.inorder can be set to
+  // false to allow the events to arrive in any order.
+  function waitForEvents(expected, options = {}) {
+    function compare(a, b) {
+      if (typeof b == "object" && b != null) {
+        if (typeof a != "object") {
+          return false;
+        }
+        return Object.keys(b).every(fld => compare(a[fld], b[fld]));
+      }
+      return a == b;
+    }
+
+    const exact = "exact" in options ? options.exact : true;
+    const inorder = "inorder" in options ? options.inorder : true;
+    return new Promise((resolve, reject) => {
+      function check() {
+        function fail(msg) {
+          browser.test.fail(msg);
+          reject(new Error(msg));
+        }
+        if (events.size < expected.length) {
+          return;
+        }
+        if (exact && expected.length < events.size) {
+          fail(
+            `Got ${events.size} events but only expected ${expected.length}`
+          );
+          return;
+        }
+
+        let remaining = new Set(events);
+        if (inorder) {
+          for (let event of events) {
+            if (compare(event, expected[0])) {
+              expected.shift();
+              remaining.delete(event);
+            }
+          }
+        } else {
+          expected = expected.filter(val => {
+            for (let remainingEvent of remaining) {
+              if (compare(remainingEvent, val)) {
+                remaining.delete(remainingEvent);
+                return false;
+              }
+            }
+            return true;
+          });
+        }
+
+        // Events that did occur have been removed from expected so if
+        // expected is empty, we're done.  If we didn't see all the
+        // expected events and we're not looking for an exact match,
+        // then we just may not have seen the event yet, so return without
+        // failing and check() will be called again when a new event arrives.
+        if (!expected.length) {
+          events = remaining;
+          eventWaiter = null;
+          resolve();
+        } else if (exact) {
+          fail(
+            `Mismatched event: expecting ${JSON.stringify(
+              expected[0]
+            )} but got ${JSON.stringify(Array.from(remaining)[0])}`
+          );
+        }
+      }
+      eventWaiter = check;
+      check();
+    });
+  }
+
+  browser.test.onMessage.addListener(async (msg, ...args) => {
+    let match = msg.match(/(\w+).request$/);
+    if (!match) {
+      return;
+    }
+
+    let what = match[1];
+    if (what == "waitForEvents") {
+      try {
+        await waitForEvents(...args);
+        browser.test.sendMessage("waitForEvents.done", { status: "success" });
+      } catch (error) {
+        browser.test.sendMessage("waitForEvents.done", {
+          status: "error",
+          errmsg: error.message,
+        });
+      }
+    } else if (what == "clearEvents") {
+      events = new Set();
+      browser.test.sendMessage("clearEvents.done", { status: "success" });
+    } else {
+      try {
+        let result = await browser.downloads[what](...args);
+        browser.test.sendMessage(`${what}.done`, { status: "success", result });
+      } catch (error) {
+        browser.test.sendMessage(`${what}.done`, {
+          status: "error",
+          errmsg: error.message,
+        });
+      }
+    }
+  });
+
+  browser.test.sendMessage("ready");
+}
+
+let downloadDir;
+let extension;
+
+async function waitForCreatedPartFile(baseFilename = "interruptible.html") {
+  const partFilePath = `${downloadDir.path}/${baseFilename}.part`;
+
+  info(`Wait for ${partFilePath} to be created`);
+  let lastError;
+  await TestUtils.waitForCondition(
+    async () =>
+      OS.File.stat(partFilePath).then(
+        () => true,
+        err => {
+          lastError = err;
+          return false;
+        }
+      ),
+    `Wait for the ${partFilePath} to exists before pausing the download`
+  ).catch(err => {
+    if (lastError) {
+      throw lastError;
+    }
+    throw err;
+  });
+}
+
+async function clearDownloads(callback) {
+  let list = await Downloads.getList(Downloads.ALL);
+  let downloads = await list.getAll();
+
+  await Promise.all(downloads.map(download => list.remove(download)));
+
+  return downloads;
+}
+
+function runInExtension(what, ...args) {
+  extension.sendMessage(`${what}.request`, ...args);
+  return extension.awaitMessage(`${what}.done`);
+}
+
+// This is pretty simplistic, it looks for a progress update for a
+// download of the given url in which the total bytes are exactly equal
+// to the given value.  Unless you know exactly how data will arrive from
+// the server (eg see interruptible.sjs), it probably isn't very useful.
+async function waitForProgress(url, testFn) {
+  let list = await Downloads.getList(Downloads.ALL);
+
+  return new Promise(resolve => {
+    const view = {
+      onDownloadChanged(download) {
+        if (download.source.url == url && testFn(download.currentBytes)) {
+          list.removeView(view);
+          resolve(download.currentBytes);
+        }
+      },
+    };
+    list.addView(view);
+  });
+}
+
+add_task(async function setup() {
+  const nsIFile = Ci.nsIFile;
+  downloadDir = FileUtils.getDir("TmpD", ["downloads"]);
+  downloadDir.createUnique(nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  info(`downloadDir ${downloadDir.path}`);
+
+  Services.prefs.setIntPref("browser.download.folderList", 2);
+  Services.prefs.setComplexValue("browser.download.dir", nsIFile, downloadDir);
+
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("browser.download.folderList");
+    Services.prefs.clearUserPref("browser.download.dir");
+    downloadDir.remove(true);
+
+    return clearDownloads();
+  });
+
+  await clearDownloads().then(downloads => {
+    info(`removed ${downloads.length} pre-existing downloads from history`);
+  });
+
+  extension = ExtensionTestUtils.loadExtension({
+    background: backgroundScript,
+    manifest: {
+      permissions: ["downloads"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+});
+
+add_task(async function test_events() {
+  let msg = await runInExtension("download", { url: TXT_URL });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onCreated", data: { id, url: TXT_URL } },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "in_progress",
+          current: "complete",
+        },
+      },
+    },
+  ]);
+  equal(msg.status, "success", "got onCreated and onChanged events");
+});
+
+add_task(async function test_cancel() {
+  let url = getInterruptibleUrl();
+  info(url);
+  let msg = await runInExtension("download", { url });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  let progressPromise = waitForProgress(url, bytes => bytes == INT_PARTIAL_LEN);
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onCreated", data: { id } },
+  ]);
+  equal(msg.status, "success", "got created and changed events");
+
+  await progressPromise;
+  info(`download reached ${INT_PARTIAL_LEN} bytes`);
+
+  msg = await runInExtension("cancel", id);
+  equal(msg.status, "success", "cancel() succeeded");
+
+  // TODO bug 1256243: This sequence of events is bogus
+  msg = await runInExtension("waitForEvents", [
+    {
+      type: "onChanged",
+      data: {
+        state: {
+          previous: "in_progress",
+          current: "interrupted",
+        },
+        paused: {
+          previous: false,
+          current: true,
+        },
+      },
+    },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        error: {
+          previous: null,
+          current: "USER_CANCELED",
+        },
+      },
+    },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        paused: {
+          previous: true,
+          current: false,
+        },
+      },
+    },
+  ]);
+  equal(
+    msg.status,
+    "success",
+    "got onChanged events corresponding to cancel()"
+  );
+
+  msg = await runInExtension("search", { error: "USER_CANCELED" });
+  equal(msg.status, "success", "search() succeeded");
+  equal(msg.result.length, 1, "search() found 1 download");
+  equal(msg.result[0].id, id, "download.id is correct");
+  equal(msg.result[0].state, "interrupted", "download.state is correct");
+  equal(msg.result[0].paused, false, "download.paused is correct");
+  equal(
+    msg.result[0].estimatedEndTime,
+    null,
+    "download.estimatedEndTime is correct"
+  );
+  equal(msg.result[0].canResume, false, "download.canResume is correct");
+  equal(msg.result[0].error, "USER_CANCELED", "download.error is correct");
+  equal(
+    msg.result[0].totalBytes,
+    INT_TOTAL_LEN,
+    "download.totalBytes is correct"
+  );
+  equal(msg.result[0].exists, false, "download.exists is correct");
+
+  msg = await runInExtension("pause", id);
+  equal(msg.status, "error", "cannot pause a canceled download");
+
+  msg = await runInExtension("resume", id);
+  equal(msg.status, "error", "cannot resume a canceled download");
+});
+
+add_task(async function test_pauseresume() {
+  const filename = "pauseresume.html";
+  let url = getInterruptibleUrl(filename);
+  let msg = await runInExtension("download", { url });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  let progressPromise = waitForProgress(url, bytes => bytes == INT_PARTIAL_LEN);
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onCreated", data: { id } },
+  ]);
+  equal(msg.status, "success", "got created and changed events");
+
+  await progressPromise;
+  info(`download reached ${INT_PARTIAL_LEN} bytes`);
+
+  // Prevent intermittent timeouts due to the part file not yet created
+  // (e.g. see Bug 1573360).
+  await waitForCreatedPartFile(filename);
+
+  info("Pause the download item");
+  msg = await runInExtension("pause", id);
+  equal(msg.status, "success", "pause() succeeded");
+
+  msg = await runInExtension("waitForEvents", [
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "in_progress",
+          current: "interrupted",
+        },
+        paused: {
+          previous: false,
+          current: true,
+        },
+        canResume: {
+          previous: false,
+          current: true,
+        },
+      },
+    },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        error: {
+          previous: null,
+          current: "USER_CANCELED",
+        },
+      },
+    },
+  ]);
+  equal(msg.status, "success", "got onChanged event corresponding to pause");
+
+  msg = await runInExtension("search", { paused: true });
+  equal(msg.status, "success", "search() succeeded");
+  equal(msg.result.length, 1, "search() found 1 download");
+  equal(msg.result[0].id, id, "download.id is correct");
+  equal(msg.result[0].state, "interrupted", "download.state is correct");
+  equal(msg.result[0].paused, true, "download.paused is correct");
+  equal(
+    msg.result[0].estimatedEndTime,
+    null,
+    "download.estimatedEndTime is correct"
+  );
+  equal(msg.result[0].canResume, true, "download.canResume is correct");
+  equal(msg.result[0].error, "USER_CANCELED", "download.error is correct");
+  equal(
+    msg.result[0].bytesReceived,
+    INT_PARTIAL_LEN,
+    "download.bytesReceived is correct"
+  );
+  equal(
+    msg.result[0].totalBytes,
+    INT_TOTAL_LEN,
+    "download.totalBytes is correct"
+  );
+  equal(msg.result[0].exists, false, "download.exists is correct");
+
+  msg = await runInExtension("search", { error: "USER_CANCELED" });
+  equal(msg.status, "success", "search() succeeded");
+  let found = msg.result.filter(item => item.id == id);
+  equal(found.length, 1, "search() by error found the paused download");
+
+  msg = await runInExtension("pause", id);
+  equal(msg.status, "error", "cannot pause an already paused download");
+
+  msg = await runInExtension("resume", id);
+  equal(msg.status, "success", "resume() succeeded");
+
+  msg = await runInExtension("waitForEvents", [
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "interrupted",
+          current: "in_progress",
+        },
+        paused: {
+          previous: true,
+          current: false,
+        },
+        canResume: {
+          previous: true,
+          current: false,
+        },
+        error: {
+          previous: "USER_CANCELED",
+          current: null,
+        },
+      },
+    },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "in_progress",
+          current: "complete",
+        },
+      },
+    },
+  ]);
+  equal(msg.status, "success", "got onChanged events for resume and complete");
+
+  msg = await runInExtension("search", { id });
+  equal(msg.status, "success", "search() succeeded");
+  equal(msg.result.length, 1, "search() found 1 download");
+  equal(msg.result[0].state, "complete", "download.state is correct");
+  equal(msg.result[0].paused, false, "download.paused is correct");
+  equal(
+    msg.result[0].estimatedEndTime,
+    null,
+    "download.estimatedEndTime is correct"
+  );
+  equal(msg.result[0].canResume, false, "download.canResume is correct");
+  equal(msg.result[0].error, null, "download.error is correct");
+  equal(
+    msg.result[0].bytesReceived,
+    INT_TOTAL_LEN,
+    "download.bytesReceived is correct"
+  );
+  equal(
+    msg.result[0].totalBytes,
+    INT_TOTAL_LEN,
+    "download.totalBytes is correct"
+  );
+  equal(msg.result[0].exists, true, "download.exists is correct");
+
+  msg = await runInExtension("pause", id);
+  equal(msg.status, "error", "cannot pause a completed download");
+
+  msg = await runInExtension("resume", id);
+  equal(msg.status, "error", "cannot resume a completed download");
+});
+
+add_task(async function test_pausecancel() {
+  let url = getInterruptibleUrl();
+  let msg = await runInExtension("download", { url });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  let progressPromise = waitForProgress(url, bytes => bytes == INT_PARTIAL_LEN);
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onCreated", data: { id } },
+  ]);
+  equal(msg.status, "success", "got created and changed events");
+
+  await progressPromise;
+  info(`download reached ${INT_PARTIAL_LEN} bytes`);
+
+  msg = await runInExtension("pause", id);
+  equal(msg.status, "success", "pause() succeeded");
+
+  msg = await runInExtension("waitForEvents", [
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "in_progress",
+          current: "interrupted",
+        },
+        paused: {
+          previous: false,
+          current: true,
+        },
+        canResume: {
+          previous: false,
+          current: true,
+        },
+      },
+    },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        error: {
+          previous: null,
+          current: "USER_CANCELED",
+        },
+      },
+    },
+  ]);
+  equal(msg.status, "success", "got onChanged event corresponding to pause");
+
+  msg = await runInExtension("search", { paused: true });
+  equal(msg.status, "success", "search() succeeded");
+  equal(msg.result.length, 1, "search() found 1 download");
+  equal(msg.result[0].id, id, "download.id is correct");
+  equal(msg.result[0].state, "interrupted", "download.state is correct");
+  equal(msg.result[0].paused, true, "download.paused is correct");
+  equal(
+    msg.result[0].estimatedEndTime,
+    null,
+    "download.estimatedEndTime is correct"
+  );
+  equal(msg.result[0].canResume, true, "download.canResume is correct");
+  equal(msg.result[0].error, "USER_CANCELED", "download.error is correct");
+  equal(
+    msg.result[0].bytesReceived,
+    INT_PARTIAL_LEN,
+    "download.bytesReceived is correct"
+  );
+  equal(
+    msg.result[0].totalBytes,
+    INT_TOTAL_LEN,
+    "download.totalBytes is correct"
+  );
+  equal(msg.result[0].exists, false, "download.exists is correct");
+
+  msg = await runInExtension("search", { error: "USER_CANCELED" });
+  equal(msg.status, "success", "search() succeeded");
+  let found = msg.result.filter(item => item.id == id);
+  equal(found.length, 1, "search() by error found the paused download");
+
+  msg = await runInExtension("cancel", id);
+  equal(msg.status, "success", "cancel() succeeded");
+
+  msg = await runInExtension("waitForEvents", [
+    {
+      type: "onChanged",
+      data: {
+        id,
+        paused: {
+          previous: true,
+          current: false,
+        },
+        canResume: {
+          previous: true,
+          current: false,
+        },
+      },
+    },
+  ]);
+  equal(msg.status, "success", "got onChanged event for cancel");
+
+  msg = await runInExtension("search", { id });
+  equal(msg.status, "success", "search() succeeded");
+  equal(msg.result.length, 1, "search() found 1 download");
+  equal(msg.result[0].state, "interrupted", "download.state is correct");
+  equal(msg.result[0].paused, false, "download.paused is correct");
+  equal(
+    msg.result[0].estimatedEndTime,
+    null,
+    "download.estimatedEndTime is correct"
+  );
+  equal(msg.result[0].canResume, false, "download.canResume is correct");
+  equal(msg.result[0].error, "USER_CANCELED", "download.error is correct");
+  equal(
+    msg.result[0].totalBytes,
+    INT_TOTAL_LEN,
+    "download.totalBytes is correct"
+  );
+  equal(msg.result[0].exists, false, "download.exists is correct");
+});
+
+add_task(async function test_pause_resume_cancel_badargs() {
+  let BAD_ID = 1000;
+
+  let msg = await runInExtension("pause", BAD_ID);
+  equal(msg.status, "error", "pause() failed with a bad download id");
+  ok(/Invalid download id/.test(msg.errmsg), "error message is descriptive");
+
+  msg = await runInExtension("resume", BAD_ID);
+  equal(msg.status, "error", "resume() failed with a bad download id");
+  ok(/Invalid download id/.test(msg.errmsg), "error message is descriptive");
+
+  msg = await runInExtension("cancel", BAD_ID);
+  equal(msg.status, "error", "cancel() failed with a bad download id");
+  ok(/Invalid download id/.test(msg.errmsg), "error message is descriptive");
+});
+
+add_task(async function test_file_removal() {
+  let msg = await runInExtension("download", { url: TXT_URL });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onCreated", data: { id, url: TXT_URL } },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "in_progress",
+          current: "complete",
+        },
+      },
+    },
+  ]);
+
+  equal(msg.status, "success", "got onCreated and onChanged events");
+
+  msg = await runInExtension("removeFile", id);
+  equal(msg.status, "success", "removeFile() succeeded");
+
+  msg = await runInExtension("removeFile", id);
+  equal(
+    msg.status,
+    "error",
+    "removeFile() fails since the file was already removed."
+  );
+  ok(
+    /file doesn't exist/.test(msg.errmsg),
+    "removeFile() failed on removed file."
+  );
+
+  msg = await runInExtension("removeFile", 1000);
+  ok(
+    /Invalid download id/.test(msg.errmsg),
+    "removeFile() failed due to non-existent id"
+  );
+});
+
+add_task(async function test_removal_of_incomplete_download() {
+  const filename = "remove-incomplete.html";
+  let url = getInterruptibleUrl(filename);
+  let msg = await runInExtension("download", { url });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  let progressPromise = waitForProgress(url, bytes => bytes == INT_PARTIAL_LEN);
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onCreated", data: { id } },
+  ]);
+  equal(msg.status, "success", "got created and changed events");
+
+  await progressPromise;
+  info(`download reached ${INT_PARTIAL_LEN} bytes`);
+
+  // Prevent intermittent timeouts due to the part file not yet created
+  // (e.g. see Bug 1573360).
+  await waitForCreatedPartFile(filename);
+
+  msg = await runInExtension("pause", id);
+  equal(msg.status, "success", "pause() succeeded");
+
+  msg = await runInExtension("waitForEvents", [
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "in_progress",
+          current: "interrupted",
+        },
+        paused: {
+          previous: false,
+          current: true,
+        },
+        canResume: {
+          previous: false,
+          current: true,
+        },
+      },
+    },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        error: {
+          previous: null,
+          current: "USER_CANCELED",
+        },
+      },
+    },
+  ]);
+  equal(msg.status, "success", "got onChanged event corresponding to pause");
+
+  msg = await runInExtension("removeFile", id);
+  equal(msg.status, "error", "removeFile() on paused download failed");
+
+  ok(
+    /Cannot remove incomplete download/.test(msg.errmsg),
+    "removeFile() failed due to download being incomplete"
+  );
+
+  msg = await runInExtension("resume", id);
+  equal(msg.status, "success", "resume() succeeded");
+
+  msg = await runInExtension("waitForEvents", [
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "interrupted",
+          current: "in_progress",
+        },
+        paused: {
+          previous: true,
+          current: false,
+        },
+        canResume: {
+          previous: true,
+          current: false,
+        },
+        error: {
+          previous: "USER_CANCELED",
+          current: null,
+        },
+      },
+    },
+    {
+      type: "onChanged",
+      data: {
+        id,
+        state: {
+          previous: "in_progress",
+          current: "complete",
+        },
+      },
+    },
+  ]);
+  equal(msg.status, "success", "got onChanged events for resume and complete");
+
+  msg = await runInExtension("removeFile", id);
+  equal(
+    msg.status,
+    "success",
+    "removeFile() succeeded following completion of resumed download."
+  );
+});
+
+// Test erase().  We don't do elaborate testing of the query handling
+// since it uses the exact same engine as search() which is tested
+// more thoroughly in test_chrome_ext_downloads_search.html
+add_task(async function test_erase() {
+  await clearDownloads();
+
+  await runInExtension("clearEvents");
+
+  async function download() {
+    let msg = await runInExtension("download", { url: TXT_URL });
+    equal(msg.status, "success", "download succeeded");
+    let id = msg.result;
+
+    msg = await runInExtension(
+      "waitForEvents",
+      [
+        {
+          type: "onChanged",
+          data: { id, state: { current: "complete" } },
+        },
+      ],
+      { exact: false }
+    );
+    equal(msg.status, "success", "download finished");
+
+    return id;
+  }
+
+  let ids = {};
+  ids.dl1 = await download();
+  ids.dl2 = await download();
+  ids.dl3 = await download();
+
+  let msg = await runInExtension("search", {});
+  equal(msg.status, "success", "search succeeded");
+  equal(msg.result.length, 3, "search found 3 downloads");
+
+  msg = await runInExtension("clearEvents");
+
+  msg = await runInExtension("erase", { id: ids.dl1 });
+  equal(msg.status, "success", "erase by id succeeded");
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onErased", data: ids.dl1 },
+  ]);
+  equal(msg.status, "success", "received onErased event");
+
+  msg = await runInExtension("search", {});
+  equal(msg.status, "success", "search succeeded");
+  equal(msg.result.length, 2, "search found 2 downloads");
+
+  msg = await runInExtension("erase", {});
+  equal(msg.status, "success", "erase everything succeeded");
+
+  msg = await runInExtension(
+    "waitForEvents",
+    [
+      { type: "onErased", data: ids.dl2 },
+      { type: "onErased", data: ids.dl3 },
+    ],
+    { inorder: false }
+  );
+  equal(msg.status, "success", "received 2 onErased events");
+
+  msg = await runInExtension("search", {});
+  equal(msg.status, "success", "search succeeded");
+  equal(msg.result.length, 0, "search found 0 downloads");
+});
+
+function loadImage(img, data) {
+  return new Promise(resolve => {
+    img.src = data;
+    img.onload = resolve;
+  });
+}
+
+add_task(async function test_getFileIcon() {
+  let webNav = Services.appShell.createWindowlessBrowser(false);
+  let docShell = webNav.docShell;
+
+  let system = Services.scriptSecurityManager.getSystemPrincipal();
+  docShell.createAboutBlankContentViewer(system, system);
+
+  let img = webNav.document.createElement("img");
+
+  let msg = await runInExtension("download", { url: TXT_URL });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  msg = await runInExtension("getFileIcon", id);
+  equal(msg.status, "success", "getFileIcon() succeeded");
+  await loadImage(img, msg.result);
+  equal(img.height, 32, "returns an icon with the right height");
+  equal(img.width, 32, "returns an icon with the right width");
+
+  msg = await runInExtension("waitForEvents", [
+    { type: "onCreated", data: { id, url: TXT_URL } },
+    { type: "onChanged" },
+  ]);
+  equal(msg.status, "success", "got events");
+
+  msg = await runInExtension("getFileIcon", id);
+  equal(msg.status, "success", "getFileIcon() succeeded");
+  await loadImage(img, msg.result);
+  equal(img.height, 32, "returns an icon with the right height after download");
+  equal(img.width, 32, "returns an icon with the right width after download");
+
+  msg = await runInExtension("getFileIcon", id + 100);
+  equal(msg.status, "error", "getFileIcon() failed");
+  ok(msg.errmsg.includes("Invalid download id"), "download id is invalid");
+
+  msg = await runInExtension("getFileIcon", id, { size: 127 });
+  equal(msg.status, "success", "getFileIcon() succeeded");
+  await loadImage(img, msg.result);
+  equal(img.height, 127, "returns an icon with the right custom height");
+  equal(img.width, 127, "returns an icon with the right custom width");
+
+  msg = await runInExtension("getFileIcon", id, { size: 1 });
+  equal(msg.status, "success", "getFileIcon() succeeded");
+  await loadImage(img, msg.result);
+  equal(img.height, 1, "returns an icon with the right custom height");
+  equal(img.width, 1, "returns an icon with the right custom width");
+
+  msg = await runInExtension("getFileIcon", id, { size: "foo" });
+  equal(msg.status, "error", "getFileIcon() fails");
+  ok(msg.errmsg.includes("Error processing size"), "size is not a number");
+
+  msg = await runInExtension("getFileIcon", id, { size: 0 });
+  equal(msg.status, "error", "getFileIcon() fails");
+  ok(msg.errmsg.includes("Error processing size"), "size is too small");
+
+  msg = await runInExtension("getFileIcon", id, { size: 128 });
+  equal(msg.status, "error", "getFileIcon() fails");
+  ok(msg.errmsg.includes("Error processing size"), "size is too big");
+
+  webNav.close();
+});
+
+add_task(async function test_estimatedendtime() {
+  // Note we are not testing the actual value calculation of estimatedEndTime,
+  // only whether it is null/non-null at the appropriate times.
+
+  let url = `${getInterruptibleUrl()}&stream=1`;
+  let msg = await runInExtension("download", { url });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+
+  let previousBytes = await waitForProgress(url, bytes => bytes > 0);
+  await waitForProgress(url, bytes => bytes > previousBytes);
+
+  msg = await runInExtension("search", { id });
+  equal(msg.status, "success", "search() succeeded");
+  equal(msg.result.length, 1, "search() found 1 download");
+  ok(msg.result[0].estimatedEndTime, "download.estimatedEndTime is correct");
+  ok(msg.result[0].bytesReceived > 0, "download.bytesReceived is correct");
+
+  msg = await runInExtension("cancel", id);
+
+  msg = await runInExtension("search", { id });
+  equal(msg.status, "success", "search() succeeded");
+  equal(msg.result.length, 1, "search() found 1 download");
+  ok(!msg.result[0].estimatedEndTime, "download.estimatedEndTime is correct");
+});
+
+add_task(async function test_byExtension() {
+  let msg = await runInExtension("download", { url: TXT_URL });
+  equal(msg.status, "success", "download() succeeded");
+  const id = msg.result;
+  msg = await runInExtension("search", { id });
+
+  equal(msg.result.length, 1, "search() found 1 download");
+  equal(
+    msg.result[0].byExtensionName,
+    "Generated extension",
+    "download.byExtensionName is correct"
+  );
+  equal(
+    msg.result[0].byExtensionId,
+    extension.id,
+    "download.byExtensionId is correct"
+  );
+});
+
+add_task(async function cleanup() {
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_downloads_private.js b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_private.js
new file mode 100644
index 0000000000..b80e5f3274
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_private.js
@@ -0,0 +1,308 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE = `http://localhost:${server.identity.primaryPort}/data`;
+const TXT_FILE = "file_download.txt";
+const TXT_URL = BASE + "/" + TXT_FILE;
+
+add_task(function setup() {
+  let downloadDir = FileUtils.getDir("TmpD", ["downloads"]);
+  downloadDir.createUnique(
+    Ci.nsIFile.DIRECTORY_TYPE,
+    FileUtils.PERMS_DIRECTORY
+  );
+  info(`Using download directory ${downloadDir.path}`);
+
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+  Services.prefs.setIntPref("browser.download.folderList", 2);
+  Services.prefs.setComplexValue(
+    "browser.download.dir",
+    Ci.nsIFile,
+    downloadDir
+  );
+
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+    Services.prefs.clearUserPref("browser.download.folderList");
+    Services.prefs.clearUserPref("browser.download.dir");
+
+    let entries = downloadDir.directoryEntries;
+    while (entries.hasMoreElements()) {
+      let entry = entries.nextFile;
+      ok(false, `Leftover file ${entry.path} in download directory`);
+      entry.remove(false);
+    }
+
+    downloadDir.remove(false);
+  });
+});
+
+add_task(async function test_private_download() {
+  let pb_extension = ExtensionTestUtils.loadExtension({
+    background: async function() {
+      function promiseEvent(eventTarget, accept) {
+        return new Promise(resolve => {
+          eventTarget.addListener(function listener(data) {
+            if (accept && !accept(data)) {
+              return;
+            }
+            eventTarget.removeListener(listener);
+            resolve(data);
+          });
+        });
+      }
+      let startTestPromise = promiseEvent(browser.test.onMessage);
+      let removeTestPromise = promiseEvent(
+        browser.test.onMessage,
+        msg => msg == "remove"
+      );
+      let onCreatedPromise = promiseEvent(browser.downloads.onCreated);
+      let onDonePromise = promiseEvent(
+        browser.downloads.onChanged,
+        delta => delta.state && delta.state.current === "complete"
+      );
+
+      browser.test.sendMessage("ready");
+      let { url, filename } = await startTestPromise;
+
+      browser.test.log("Starting private download");
+      let downloadId = await browser.downloads.download({
+        url,
+        filename,
+        incognito: true,
+      });
+      browser.test.sendMessage("downloadId", downloadId);
+
+      browser.test.log("Waiting for downloads.onCreated");
+      let createdItem = await onCreatedPromise;
+
+      browser.test.log("Waiting for completion notification");
+      await onDonePromise;
+
+      // test_ext_downloads_download.js already tests whether the file exists
+      // in the file system. Here we will only verify that the  downloads API
+      // behaves in a meaningful way.
+
+      let [downloadItem] = await browser.downloads.search({ id: downloadId });
+      browser.test.assertEq(url, createdItem.url, "onCreated url should match");
+      browser.test.assertEq(url, downloadItem.url, "download url should match");
+      browser.test.assertTrue(
+        createdItem.incognito,
+        "created download should be private"
+      );
+      browser.test.assertTrue(
+        downloadItem.incognito,
+        "stored download should be private"
+      );
+
+      await removeTestPromise;
+      browser.test.log("Removing downloaded file");
+      browser.test.assertTrue(downloadItem.exists, "downloaded file exists");
+      await browser.downloads.removeFile(downloadId);
+
+      // Disabled because the assertion fails - https://bugzil.la/1381031
+      // let [downloadItem2] = await browser.downloads.search({id: downloadId});
+      // browser.test.assertFalse(downloadItem2.exists, "file should be deleted");
+
+      browser.test.log("Erasing private download from history");
+      let erasePromise = promiseEvent(browser.downloads.onErased);
+      await browser.downloads.erase({ id: downloadId });
+      browser.test.assertEq(
+        downloadId,
+        await erasePromise,
+        "onErased should be fired for the erased private download"
+      );
+
+      browser.test.notifyPass("private download test done");
+    },
+    manifest: {
+      applications: { gecko: { id: "@spanning" } },
+      permissions: ["downloads"],
+    },
+    incognitoOverride: "spanning",
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "@not_allowed" } },
+      permissions: ["downloads", "downloads.open"],
+    },
+    background: async function() {
+      browser.downloads.onCreated.addListener(() => {
+        browser.test.fail("download-onCreated");
+      });
+      browser.downloads.onChanged.addListener(() => {
+        browser.test.fail("download-onChanged");
+      });
+      browser.downloads.onErased.addListener(() => {
+        browser.test.fail("download-onErased");
+      });
+      browser.test.onMessage.addListener(async (msg, data) => {
+        if (msg == "download") {
+          let { url, filename, downloadId } = data;
+          await browser.test.assertRejects(
+            browser.downloads.download({
+              url,
+              filename,
+              incognito: true,
+            }),
+            /private browsing access not allowed/,
+            "cannot download using incognito without permission."
+          );
+
+          let downloads = await browser.downloads.search({ id: downloadId });
+          browser.test.assertEq(
+            downloads.length,
+            0,
+            "cannot search for incognito downloads"
+          );
+          let erasing = await browser.downloads.erase({ id: downloadId });
+          browser.test.assertEq(
+            erasing.length,
+            0,
+            "cannot erase incognito download"
+          );
+
+          await browser.test.assertRejects(
+            browser.downloads.removeFile(downloadId),
+            /Invalid download id/,
+            "cannot remove incognito download"
+          );
+          await browser.test.assertRejects(
+            browser.downloads.pause(downloadId),
+            /Invalid download id/,
+            "cannot pause incognito download"
+          );
+          await browser.test.assertRejects(
+            browser.downloads.resume(downloadId),
+            /Invalid download id/,
+            "cannot resume incognito download"
+          );
+          await browser.test.assertRejects(
+            browser.downloads.cancel(downloadId),
+            /Invalid download id/,
+            "cannot cancel incognito download"
+          );
+          await browser.test.assertRejects(
+            browser.downloads.removeFile(downloadId),
+            /Invalid download id/,
+            "cannot remove incognito download"
+          );
+          await browser.test.assertRejects(
+            browser.downloads.show(downloadId),
+            /Invalid download id/,
+            "cannot show incognito download"
+          );
+          await browser.test.assertRejects(
+            browser.downloads.getFileIcon(downloadId),
+            /Invalid download id/,
+            "cannot show incognito download"
+          );
+        }
+        if (msg == "download.open") {
+          let { downloadId } = data;
+          await browser.test.assertRejects(
+            browser.downloads.open(downloadId),
+            /Invalid download id/,
+            "cannot open incognito download"
+          );
+        }
+        browser.test.sendMessage("continue");
+      });
+    },
+  });
+
+  await extension.startup();
+  await pb_extension.startup();
+  await pb_extension.awaitMessage("ready");
+  pb_extension.sendMessage({
+    url: TXT_URL,
+    filename: TXT_FILE,
+  });
+  let downloadId = await pb_extension.awaitMessage("downloadId");
+  extension.sendMessage("download", {
+    url: TXT_URL,
+    filename: TXT_FILE,
+    downloadId,
+  });
+  await extension.awaitMessage("continue");
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("download.open", { downloadId });
+    await extension.awaitMessage("continue");
+  });
+  pb_extension.sendMessage("remove");
+
+  await pb_extension.awaitFinish("private download test done");
+  await pb_extension.unload();
+  await extension.unload();
+});
+
+// Regression test for https://bugzilla.mozilla.org/show_bug.cgi?id=1649463
+add_task(async function download_blob_in_perma_private_browsing() {
+  Services.prefs.setBoolPref("browser.privatebrowsing.autostart", true);
+
+  // This script creates a blob:-URL and checks that the URL can be downloaded.
+  async function testScript() {
+    const blobUrl = URL.createObjectURL(new Blob(["data here"]));
+    const downloadId = await new Promise(resolve => {
+      browser.downloads.onChanged.addListener(delta => {
+        browser.test.log(`downloads.onChanged = ${JSON.stringify(delta)}`);
+        if (delta.state && delta.state.current !== "in_progress") {
+          resolve(delta.id);
+        }
+      });
+      browser.downloads.download({
+        url: blobUrl,
+        filename: "some-blob-download.txt",
+      });
+    });
+
+    let [downloadItem] = await browser.downloads.search({ id: downloadId });
+    browser.test.log(`Downloaded ${JSON.stringify(downloadItem)}`);
+    browser.test.assertEq(downloadItem.url, blobUrl, "expected blob URL");
+    // TODO bug 1653636: should be true because of perma-private browsing.
+    // browser.test.assertTrue(downloadItem.incognito, "download is private");
+    browser.test.assertFalse(
+      downloadItem.incognito,
+      "download is private [skipped - to be fixed in bug 1653636]"
+    );
+    browser.test.assertTrue(downloadItem.exists, "download exists");
+    await browser.downloads.removeFile(downloadId);
+
+    browser.test.sendMessage("downloadDone");
+  }
+  let pb_extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "@private-download-ext" } },
+      permissions: ["downloads"],
+    },
+    background: testScript,
+    incognitoOverride: "spanning",
+    files: {
+      "test_part2.html": `
+        <!DOCTYPE html><meta charset="utf-8">
+        <script src="test_part2.js"></script>
+      `,
+      "test_part2.js": testScript,
+    },
+  });
+  await pb_extension.startup();
+
+  info("Testing download of blob:-URL from extension's background page");
+  await pb_extension.awaitMessage("downloadDone");
+
+  info("Testing download of blob:-URL with different userContextId");
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${pb_extension.uuid}/test_part2.html`,
+    { extension: pb_extension, userContextId: 2 }
+  );
+  await pb_extension.awaitMessage("downloadDone");
+  await contentPage.close();
+
+  await pb_extension.unload();
+  Services.prefs.clearUserPref("browser.privatebrowsing.autostart");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_downloads_search.js b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_search.js
new file mode 100644
index 0000000000..f28a4c881f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_search.js
@@ -0,0 +1,682 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { Downloads } = ChromeUtils.import(
+  "resource://gre/modules/Downloads.jsm"
+);
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE = `http://localhost:${server.identity.primaryPort}/data`;
+const TXT_FILE = "file_download.txt";
+const TXT_URL = BASE + "/" + TXT_FILE;
+const TXT_LEN = 46;
+const HTML_FILE = "file_download.html";
+const HTML_URL = BASE + "/" + HTML_FILE;
+const HTML_LEN = 117;
+const EMPTY_FILE = "empty_file_download.txt";
+const EMPTY_URL = BASE + "/" + EMPTY_FILE;
+const EMPTY_LEN = 0;
+const BIG_LEN = 1000; // something bigger both TXT_LEN and HTML_LEN
+
+function backgroundScript() {
+  let complete = new Map();
+
+  function waitForComplete(id) {
+    if (complete.has(id)) {
+      return complete.get(id).promise;
+    }
+
+    let promise = new Promise(resolve => {
+      complete.set(id, { resolve });
+    });
+    complete.get(id).promise = promise;
+    return promise;
+  }
+
+  browser.downloads.onChanged.addListener(change => {
+    if (change.state && change.state.current == "complete") {
+      // Make sure we have a promise.
+      waitForComplete(change.id);
+      complete.get(change.id).resolve();
+    }
+  });
+
+  browser.test.onMessage.addListener(async (msg, ...args) => {
+    if (msg == "download.request") {
+      try {
+        let id = await browser.downloads.download(args[0]);
+        browser.test.sendMessage("download.done", { status: "success", id });
+      } catch (error) {
+        browser.test.sendMessage("download.done", {
+          status: "error",
+          errmsg: error.message,
+        });
+      }
+    } else if (msg == "search.request") {
+      try {
+        let downloads = await browser.downloads.search(args[0]);
+        browser.test.sendMessage("search.done", {
+          status: "success",
+          downloads,
+        });
+      } catch (error) {
+        browser.test.sendMessage("search.done", {
+          status: "error",
+          errmsg: error.message,
+        });
+      }
+    } else if (msg == "waitForComplete.request") {
+      await waitForComplete(args[0]);
+      browser.test.sendMessage("waitForComplete.done");
+    }
+  });
+
+  browser.test.sendMessage("ready");
+}
+
+async function clearDownloads(callback) {
+  let list = await Downloads.getList(Downloads.ALL);
+  let downloads = await list.getAll();
+
+  await Promise.all(downloads.map(download => list.remove(download)));
+
+  return downloads;
+}
+
+add_task(async function test_search() {
+  const nsIFile = Ci.nsIFile;
+  let downloadDir = FileUtils.getDir("TmpD", ["downloads"]);
+  downloadDir.createUnique(nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  info(`downloadDir ${downloadDir.path}`);
+
+  function downloadPath(filename) {
+    let path = downloadDir.clone();
+    path.append(filename);
+    return path.path;
+  }
+
+  Services.prefs.setIntPref("browser.download.folderList", 2);
+  Services.prefs.setComplexValue("browser.download.dir", nsIFile, downloadDir);
+  Services.prefs.setBoolPref("privacy.reduceTimerPrecision", false);
+
+  registerCleanupFunction(async () => {
+    Services.prefs.clearUserPref("browser.download.folderList");
+    Services.prefs.clearUserPref("browser.download.dir");
+    Services.prefs.clearUserPref("privacy.reduceTimerPrecision");
+    await cleanupDir(downloadDir);
+    await clearDownloads();
+  });
+
+  await clearDownloads().then(downloads => {
+    info(`removed ${downloads.length} pre-existing downloads from history`);
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: backgroundScript,
+    manifest: {
+      permissions: ["downloads"],
+    },
+  });
+
+  async function download(options) {
+    extension.sendMessage("download.request", options);
+    let result = await extension.awaitMessage("download.done");
+
+    if (result.status == "success") {
+      info(`wait for onChanged event to indicate ${result.id} is complete`);
+      extension.sendMessage("waitForComplete.request", result.id);
+
+      await extension.awaitMessage("waitForComplete.done");
+    }
+
+    return result;
+  }
+
+  function search(query) {
+    extension.sendMessage("search.request", query);
+    return extension.awaitMessage("search.done");
+  }
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  // Do some downloads...
+  const time1 = new Date();
+
+  let downloadIds = {};
+  let msg = await download({ url: TXT_URL });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.txt1 = msg.id;
+
+  const TXT_FILE2 = "NewFile.txt";
+  msg = await download({ url: TXT_URL, filename: TXT_FILE2 });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.txt2 = msg.id;
+
+  msg = await download({ url: EMPTY_URL });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.txt3 = msg.id;
+
+  const time2 = new Date();
+
+  msg = await download({ url: HTML_URL });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.html1 = msg.id;
+
+  const HTML_FILE2 = "renamed.html";
+  msg = await download({ url: HTML_URL, filename: HTML_FILE2 });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.html2 = msg.id;
+
+  const time3 = new Date();
+
+  // Search for each individual download and check
+  // the corresponding DownloadItem.
+  async function checkDownloadItem(id, expect) {
+    let item = await search({ id });
+    equal(item.status, "success", "search() succeeded");
+    equal(item.downloads.length, 1, "search() found exactly 1 download");
+
+    Object.keys(expect).forEach(function(field) {
+      equal(
+        item.downloads[0][field],
+        expect[field],
+        `DownloadItem.${field} is correct"`
+      );
+    });
+  }
+  await checkDownloadItem(downloadIds.txt1, {
+    url: TXT_URL,
+    filename: downloadPath(TXT_FILE),
+    mime: "text/plain",
+    state: "complete",
+    bytesReceived: TXT_LEN,
+    totalBytes: TXT_LEN,
+    fileSize: TXT_LEN,
+    exists: true,
+  });
+
+  await checkDownloadItem(downloadIds.txt2, {
+    url: TXT_URL,
+    filename: downloadPath(TXT_FILE2),
+    mime: "text/plain",
+    state: "complete",
+    bytesReceived: TXT_LEN,
+    totalBytes: TXT_LEN,
+    fileSize: TXT_LEN,
+    exists: true,
+  });
+
+  await checkDownloadItem(downloadIds.txt3, {
+    url: EMPTY_URL,
+    filename: downloadPath(EMPTY_FILE),
+    mime: "text/plain",
+    state: "complete",
+    bytesReceived: EMPTY_LEN,
+    totalBytes: EMPTY_LEN,
+    fileSize: EMPTY_LEN,
+    exists: true,
+  });
+
+  await checkDownloadItem(downloadIds.html1, {
+    url: HTML_URL,
+    filename: downloadPath(HTML_FILE),
+    mime: "text/html",
+    state: "complete",
+    bytesReceived: HTML_LEN,
+    totalBytes: HTML_LEN,
+    fileSize: HTML_LEN,
+    exists: true,
+  });
+
+  await checkDownloadItem(downloadIds.html2, {
+    url: HTML_URL,
+    filename: downloadPath(HTML_FILE2),
+    mime: "text/html",
+    state: "complete",
+    bytesReceived: HTML_LEN,
+    totalBytes: HTML_LEN,
+    fileSize: HTML_LEN,
+    exists: true,
+  });
+
+  async function checkSearch(query, expected, description, exact) {
+    let item = await search(query);
+    equal(item.status, "success", "search() succeeded");
+    equal(
+      item.downloads.length,
+      expected.length,
+      `search() for ${description} found exactly ${expected.length} downloads`
+    );
+
+    let receivedIds = item.downloads.map(i => i.id);
+    if (exact) {
+      receivedIds.forEach((id, idx) => {
+        equal(
+          id,
+          downloadIds[expected[idx]],
+          `search() for ${description} returned ${expected[idx]} in position ${idx}`
+        );
+      });
+    } else {
+      Object.keys(downloadIds).forEach(key => {
+        const id = downloadIds[key];
+        const thisExpected = expected.includes(key);
+        equal(
+          receivedIds.includes(id),
+          thisExpected,
+          `search() for ${description} ${
+            thisExpected ? "includes" : "does not include"
+          } ${key}`
+        );
+      });
+    }
+  }
+
+  // Check that search with an invalid id returns nothing.
+  // NB: for now ids are not persistent and we start numbering them at 1
+  //     so a sufficiently large number will be unused.
+  const INVALID_ID = 1000;
+  await checkSearch({ id: INVALID_ID }, [], "invalid id");
+
+  // Check that search on url works.
+  await checkSearch({ url: TXT_URL }, ["txt1", "txt2"], "url");
+
+  // Check that regexp on url works.
+  const HTML_REGEX = "[download]{8}.html+$";
+  await checkSearch({ urlRegex: HTML_REGEX }, ["html1", "html2"], "url regexp");
+
+  // Check that compatible url+regexp works
+  await checkSearch(
+    { url: HTML_URL, urlRegex: HTML_REGEX },
+    ["html1", "html2"],
+    "compatible url+urlRegex"
+  );
+
+  // Check that incompatible url+regexp works
+  await checkSearch(
+    { url: TXT_URL, urlRegex: HTML_REGEX },
+    [],
+    "incompatible url+urlRegex"
+  );
+
+  // Check that search on filename works.
+  await checkSearch({ filename: downloadPath(TXT_FILE) }, ["txt1"], "filename");
+
+  // Check that regexp on filename works.
+  await checkSearch({ filenameRegex: HTML_REGEX }, ["html1"], "filename regex");
+
+  // Check that compatible filename+regexp works
+  await checkSearch(
+    { filename: downloadPath(HTML_FILE), filenameRegex: HTML_REGEX },
+    ["html1"],
+    "compatible filename+filename regex"
+  );
+
+  // Check that incompatible filename+regexp works
+  await checkSearch(
+    { filename: downloadPath(TXT_FILE), filenameRegex: HTML_REGEX },
+    [],
+    "incompatible filename+filename regex"
+  );
+
+  // Check that simple positive search terms work.
+  await checkSearch(
+    { query: ["file_download"] },
+    ["txt1", "txt2", "txt3", "html1", "html2"],
+    "term file_download"
+  );
+  await checkSearch({ query: ["NewFile"] }, ["txt2"], "term NewFile");
+
+  // Check that positive search terms work case-insensitive.
+  await checkSearch({ query: ["nEwfILe"] }, ["txt2"], "term nEwfiLe");
+
+  // Check that negative search terms work.
+  await checkSearch({ query: ["-txt"] }, ["html1", "html2"], "term -txt");
+
+  // Check that positive and negative search terms together work.
+  await checkSearch(
+    { query: ["html", "-renamed"] },
+    ["html1"],
+    "positive and negative terms"
+  );
+
+  async function checkSearchWithDate(query, expected, description) {
+    const fields = Object.keys(query);
+    if (fields.length != 1 || !(query[fields[0]] instanceof Date)) {
+      throw new Error("checkSearchWithDate expects exactly one Date field");
+    }
+    const field = fields[0];
+    const date = query[field];
+
+    let newquery = {};
+
+    // Check as a Date
+    newquery[field] = date;
+    await checkSearch(newquery, expected, `${description} as Date`);
+
+    // Check as numeric milliseconds
+    newquery[field] = date.valueOf();
+    await checkSearch(newquery, expected, `${description} as numeric ms`);
+
+    // Check as stringified milliseconds
+    newquery[field] = date.valueOf().toString();
+    await checkSearch(newquery, expected, `${description} as string ms`);
+
+    // Check as ISO string
+    newquery[field] = date.toISOString();
+    await checkSearch(newquery, expected, `${description} as iso string`);
+  }
+
+  // Check startedBefore
+  await checkSearchWithDate({ startedBefore: time1 }, [], "before time1");
+  await checkSearchWithDate(
+    { startedBefore: time2 },
+    ["txt1", "txt2", "txt3"],
+    "before time2"
+  );
+  await checkSearchWithDate(
+    { startedBefore: time3 },
+    ["txt1", "txt2", "txt3", "html1", "html2"],
+    "before time3"
+  );
+
+  // Check startedAfter
+  await checkSearchWithDate(
+    { startedAfter: time1 },
+    ["txt1", "txt2", "txt3", "html1", "html2"],
+    "after time1"
+  );
+  await checkSearchWithDate(
+    { startedAfter: time2 },
+    ["html1", "html2"],
+    "after time2"
+  );
+  await checkSearchWithDate({ startedAfter: time3 }, [], "after time3");
+
+  // Check simple search on totalBytes
+  await checkSearch({ totalBytes: TXT_LEN }, ["txt1", "txt2"], "totalBytes");
+  await checkSearch({ totalBytes: HTML_LEN }, ["html1", "html2"], "totalBytes");
+
+  // Check simple test on totalBytes{Greater,Less}
+  // (NB: TXT_LEN < HTML_LEN < BIG_LEN)
+  await checkSearch(
+    { totalBytesGreater: 0 },
+    ["txt1", "txt2", "html1", "html2"],
+    "totalBytesGreater than 0"
+  );
+  await checkSearch(
+    { totalBytesGreater: TXT_LEN },
+    ["html1", "html2"],
+    `totalBytesGreater than ${TXT_LEN}`
+  );
+  await checkSearch(
+    { totalBytesGreater: HTML_LEN },
+    [],
+    `totalBytesGreater than ${HTML_LEN}`
+  );
+  await checkSearch(
+    { totalBytesLess: TXT_LEN },
+    ["txt3"],
+    `totalBytesLess than ${TXT_LEN}`
+  );
+  await checkSearch(
+    { totalBytesLess: HTML_LEN },
+    ["txt1", "txt2", "txt3"],
+    `totalBytesLess than ${HTML_LEN}`
+  );
+  await checkSearch(
+    { totalBytesLess: BIG_LEN },
+    ["txt1", "txt2", "txt3", "html1", "html2"],
+    `totalBytesLess than ${BIG_LEN}`
+  );
+
+  // Bug 1503760 check if 0 byte files with no search query are returned.
+  await checkSearch(
+    {},
+    ["txt1", "txt2", "txt3", "html1", "html2"],
+    "totalBytesGreater than -1"
+  );
+
+  // Check good combinations of totalBytes*.
+  await checkSearch(
+    { totalBytes: HTML_LEN, totalBytesGreater: TXT_LEN },
+    ["html1", "html2"],
+    "totalBytes and totalBytesGreater"
+  );
+  await checkSearch(
+    { totalBytes: TXT_LEN, totalBytesLess: HTML_LEN },
+    ["txt1", "txt2"],
+    "totalBytes and totalBytesGreater"
+  );
+  await checkSearch(
+    { totalBytes: HTML_LEN, totalBytesLess: BIG_LEN, totalBytesGreater: 0 },
+    ["html1", "html2"],
+    "totalBytes and totalBytesLess and totalBytesGreater"
+  );
+
+  // Check bad combination of totalBytes*.
+  await checkSearch(
+    { totalBytesLess: TXT_LEN, totalBytesGreater: HTML_LEN },
+    [],
+    "bad totalBytesLess, totalBytesGreater combination"
+  );
+  await checkSearch(
+    { totalBytes: TXT_LEN, totalBytesGreater: HTML_LEN },
+    [],
+    "bad totalBytes, totalBytesGreater combination"
+  );
+  await checkSearch(
+    { totalBytes: HTML_LEN, totalBytesLess: TXT_LEN },
+    [],
+    "bad totalBytes, totalBytesLess combination"
+  );
+
+  // Check mime.
+  await checkSearch(
+    { mime: "text/plain" },
+    ["txt1", "txt2", "txt3"],
+    "mime text/plain"
+  );
+  await checkSearch(
+    { mime: "text/html" },
+    ["html1", "html2"],
+    "mime text/htmlplain"
+  );
+  await checkSearch({ mime: "video/webm" }, [], "mime video/webm");
+
+  // Check fileSize.
+  await checkSearch({ fileSize: TXT_LEN }, ["txt1", "txt2"], "fileSize");
+  await checkSearch({ fileSize: HTML_LEN }, ["html1", "html2"], "fileSize");
+
+  // Fields like bytesReceived, paused, state, exists are meaningful
+  // for downloads that are in progress but have not yet completed.
+  // todo: add tests for these when we have better support for in-progress
+  // downloads (e.g., after pause(), resume() and cancel() are implemented)
+
+  // Check multiple query properties.
+  // We could make this testing arbitrarily complicated...
+  // We already tested combining fields with obvious interactions above
+  // (e.g., filename and filenameRegex or startTime and startedBefore/After)
+  // so now just throw as many fields as we can at a single search and
+  // make sure a simple case still works.
+  await checkSearch(
+    {
+      url: TXT_URL,
+      urlRegex: "download",
+      filename: downloadPath(TXT_FILE),
+      filenameRegex: "download",
+      query: ["download"],
+      startedAfter: time1.valueOf().toString(),
+      startedBefore: time2.valueOf().toString(),
+      totalBytes: TXT_LEN,
+      totalBytesGreater: 0,
+      totalBytesLess: BIG_LEN,
+      mime: "text/plain",
+      fileSize: TXT_LEN,
+    },
+    ["txt1"],
+    "many properties"
+  );
+
+  // Check simple orderBy (forward and backward).
+  await checkSearch(
+    { orderBy: ["startTime"] },
+    ["txt1", "txt2", "txt3", "html1", "html2"],
+    "orderBy startTime",
+    true
+  );
+  await checkSearch(
+    { orderBy: ["-startTime"] },
+    ["html2", "html1", "txt3", "txt2", "txt1"],
+    "orderBy -startTime",
+    true
+  );
+
+  // Check orderBy with multiple fields.
+  // NB: TXT_URL and HTML_URL differ only in extension and .html precedes .txt
+  // EMPTY_URL begins with e which precedes f
+  await checkSearch(
+    { orderBy: ["url", "-startTime"] },
+    ["txt3", "html2", "html1", "txt2", "txt1"],
+    "orderBy with multiple fields",
+    true
+  );
+
+  // Check orderBy with limit.
+  await checkSearch(
+    { orderBy: ["url"], limit: 1 },
+    ["txt3"],
+    "orderBy with limit",
+    true
+  );
+
+  // Check bad arguments.
+  async function checkBadSearch(query, pattern, description) {
+    let item = await search(query);
+    equal(item.status, "error", "search() failed");
+    ok(
+      pattern.test(item.errmsg),
+      `error message for ${description} was correct (${item.errmsg}).`
+    );
+  }
+
+  await checkBadSearch(
+    "myquery",
+    /Incorrect argument type/,
+    "query is not an object"
+  );
+  await checkBadSearch(
+    { bogus: "boo" },
+    /Unexpected property/,
+    "query contains an unknown field"
+  );
+  await checkBadSearch(
+    { query: "query string" },
+    /Expected array/,
+    "query.query is a string"
+  );
+  await checkBadSearch(
+    { startedBefore: "i am not a time" },
+    /Type error/,
+    "query.startedBefore is not a valid time"
+  );
+  await checkBadSearch(
+    { startedAfter: "i am not a time" },
+    /Type error/,
+    "query.startedAfter is not a valid time"
+  );
+  await checkBadSearch(
+    { endedBefore: "i am not a time" },
+    /Type error/,
+    "query.endedBefore is not a valid time"
+  );
+  await checkBadSearch(
+    { endedAfter: "i am not a time" },
+    /Type error/,
+    "query.endedAfter is not a valid time"
+  );
+  await checkBadSearch(
+    { urlRegex: "[" },
+    /Invalid urlRegex/,
+    "query.urlRegexp is not a valid regular expression"
+  );
+  await checkBadSearch(
+    { filenameRegex: "[" },
+    /Invalid filenameRegex/,
+    "query.filenameRegexp is not a valid regular expression"
+  );
+  await checkBadSearch(
+    { orderBy: "startTime" },
+    /Expected array/,
+    "query.orderBy is not an array"
+  );
+  await checkBadSearch(
+    { orderBy: ["bogus"] },
+    /Invalid orderBy field/,
+    "query.orderBy references a non-existent field"
+  );
+
+  await extension.unload();
+});
+
+// Test that downloads with totalBytes of -1 (ie, that have not yet started)
+// work properly.  See bug 1519762 for details of a past regression in
+// this area.
+add_task(async function test_inprogress() {
+  let resume,
+    resumePromise = new Promise(resolve => {
+      resume = resolve;
+    });
+  let hit = false;
+  server.registerPathHandler("/data/slow", async (request, response) => {
+    hit = true;
+    response.processAsync();
+    await resumePromise;
+    response.setHeader("Content-type", "text/plain");
+    response.write("");
+    response.finish();
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["downloads"],
+    },
+    background() {
+      browser.test.onMessage.addListener(async (msg, url) => {
+        let id = await browser.downloads.download({ url });
+        let full = await browser.downloads.search({ id });
+
+        browser.test.assertEq(
+          full.length,
+          1,
+          "Found new download in search results"
+        );
+        browser.test.assertEq(
+          full[0].totalBytes,
+          -1,
+          "New download still has totalBytes == -1"
+        );
+
+        browser.downloads.onChanged.addListener(info => {
+          if (info.id == id && info.state && info.state.current == "complete") {
+            browser.test.notifyPass("done");
+          }
+        });
+
+        browser.test.sendMessage("started");
+      });
+    },
+  });
+
+  await extension.startup();
+  extension.sendMessage("go", `${BASE}/slow`);
+  await extension.awaitMessage("started");
+  resume();
+  await extension.awaitFinish("done");
+  await extension.unload();
+  Assert.ok(hit, "slow path was actually hit");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_downloads_urlencoded.js b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_urlencoded.js
new file mode 100644
index 0000000000..9a63369efb
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_downloads_urlencoded.js
@@ -0,0 +1,235 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { Downloads } = ChromeUtils.import(
+  "resource://gre/modules/Downloads.jsm"
+);
+
+function backgroundScript() {
+  let complete = new Map();
+
+  function waitForComplete(id) {
+    if (complete.has(id)) {
+      return complete.get(id).promise;
+    }
+
+    let promise = new Promise(resolve => {
+      complete.set(id, { resolve });
+    });
+    complete.get(id).promise = promise;
+    return promise;
+  }
+
+  browser.downloads.onChanged.addListener(change => {
+    if (change.state && change.state.current == "complete") {
+      // Make sure we have a promise.
+      waitForComplete(change.id);
+      complete.get(change.id).resolve();
+    }
+  });
+
+  browser.test.onMessage.addListener(async (msg, ...args) => {
+    if (msg == "download.request") {
+      try {
+        let id = await browser.downloads.download(args[0]);
+        browser.test.sendMessage("download.done", { status: "success", id });
+      } catch (error) {
+        browser.test.sendMessage("download.done", {
+          status: "error",
+          errmsg: error.message,
+        });
+      }
+    } else if (msg == "search.request") {
+      try {
+        let downloads = await browser.downloads.search(args[0]);
+        browser.test.sendMessage("search.done", {
+          status: "success",
+          downloads,
+        });
+      } catch (error) {
+        browser.test.sendMessage("search.done", {
+          status: "error",
+          errmsg: error.message,
+        });
+      }
+    } else if (msg == "waitForComplete.request") {
+      await waitForComplete(args[0]);
+      browser.test.sendMessage("waitForComplete.done");
+    }
+  });
+
+  browser.test.sendMessage("ready");
+}
+
+async function clearDownloads(callback) {
+  let list = await Downloads.getList(Downloads.ALL);
+  let downloads = await list.getAll();
+
+  await Promise.all(downloads.map(download => list.remove(download)));
+
+  return downloads;
+}
+
+add_task(async function test_decoded_filename_download() {
+  const server = createHttpServer();
+  server.registerPrefixHandler("/data/", (_, res) => res.write("length=8"));
+
+  const BASE = `http://localhost:${server.identity.primaryPort}/data`;
+  const FILE_NAME_ENCODED_1 = "file%2Fencode.txt";
+  const FILE_NAME_DECODED_1 = "file_encode.txt";
+  const FILE_NAME_ENCODED_URL_1 = BASE + "/" + FILE_NAME_ENCODED_1;
+  const FILE_NAME_ENCODED_2 = "file%F0%9F%9A%B2encoded.txt";
+  const FILE_NAME_DECODED_2 = "file\u{0001F6B2}encoded.txt";
+  const FILE_NAME_ENCODED_URL_2 = BASE + "/" + FILE_NAME_ENCODED_2;
+  const FILE_NAME_ENCODED_3 = "file%X%20encode.txt";
+  const FILE_NAME_DECODED_3 = "file%X encode.txt";
+  const FILE_NAME_ENCODED_URL_3 = BASE + "/" + FILE_NAME_ENCODED_3;
+  const FILE_ENCODED_LEN = 8;
+
+  const nsIFile = Ci.nsIFile;
+  let downloadDir = FileUtils.getDir("TmpD", ["downloads"]);
+  downloadDir.createUnique(nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+  info(`downloadDir ${downloadDir.path}`);
+
+  function downloadPath(filename) {
+    let path = downloadDir.clone();
+    path.append(filename);
+    return path.path;
+  }
+
+  Services.prefs.setIntPref("browser.download.folderList", 2);
+  Services.prefs.setComplexValue("browser.download.dir", nsIFile, downloadDir);
+
+  registerCleanupFunction(async () => {
+    Services.prefs.clearUserPref("browser.download.folderList");
+    Services.prefs.clearUserPref("browser.download.dir");
+    await cleanupDir(downloadDir);
+    await clearDownloads();
+  });
+
+  await clearDownloads().then(downloads => {
+    info(`removed ${downloads.length} pre-existing downloads from history`);
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: backgroundScript,
+    manifest: {
+      permissions: ["downloads"],
+    },
+  });
+
+  async function download(options) {
+    extension.sendMessage("download.request", options);
+    let result = await extension.awaitMessage("download.done");
+
+    if (result.status == "success") {
+      info(`wait for onChanged event to indicate ${result.id} is complete`);
+      extension.sendMessage("waitForComplete.request", result.id);
+
+      await extension.awaitMessage("waitForComplete.done");
+    }
+
+    return result;
+  }
+
+  function search(query) {
+    extension.sendMessage("search.request", query);
+    return extension.awaitMessage("search.done");
+  }
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  let downloadIds = {};
+  let msg = await download({ url: FILE_NAME_ENCODED_URL_1 });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.fileEncoded1 = msg.id;
+
+  msg = await download({ url: FILE_NAME_ENCODED_URL_2 });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.fileEncoded2 = msg.id;
+
+  msg = await download({ url: FILE_NAME_ENCODED_URL_3 });
+  equal(msg.status, "success", "download() succeeded");
+  downloadIds.fileEncoded3 = msg.id;
+
+  // Search for each individual download and check
+  // the corresponding DownloadItem.
+  async function checkDownloadItem(id, expect) {
+    let item = await search({ id });
+    equal(item.status, "success", "search() succeeded");
+    equal(item.downloads.length, 1, "search() found exactly 1 download");
+    Object.keys(expect).forEach(function(field) {
+      equal(
+        item.downloads[0][field],
+        expect[field],
+        `DownloadItem.${field} is correct"`
+      );
+    });
+  }
+
+  await checkDownloadItem(downloadIds.fileEncoded1, {
+    url: FILE_NAME_ENCODED_URL_1,
+    filename: downloadPath(FILE_NAME_DECODED_1),
+    state: "complete",
+    bytesReceived: FILE_ENCODED_LEN,
+    totalBytes: FILE_ENCODED_LEN,
+    fileSize: FILE_ENCODED_LEN,
+    exists: true,
+  });
+
+  await checkDownloadItem(downloadIds.fileEncoded2, {
+    url: FILE_NAME_ENCODED_URL_2,
+    filename: downloadPath(FILE_NAME_DECODED_2),
+    state: "complete",
+    bytesReceived: FILE_ENCODED_LEN,
+    totalBytes: FILE_ENCODED_LEN,
+    fileSize: FILE_ENCODED_LEN,
+    exists: true,
+  });
+
+  await checkDownloadItem(downloadIds.fileEncoded3, {
+    url: FILE_NAME_ENCODED_URL_3,
+    filename: downloadPath(FILE_NAME_DECODED_3),
+    state: "complete",
+    bytesReceived: FILE_ENCODED_LEN,
+    totalBytes: FILE_ENCODED_LEN,
+    fileSize: FILE_ENCODED_LEN,
+    exists: true,
+  });
+
+  // Searching for downloads by the decoded filename works correctly.
+  async function checkSearch(query, expected, description) {
+    let item = await search(query);
+    equal(item.status, "success", "search() succeeded");
+    equal(
+      item.downloads.length,
+      expected.length,
+      `search() for ${description} found exactly ${expected.length} downloads`
+    );
+    equal(
+      item.downloads[0].id,
+      downloadIds[expected[0]],
+      `search() for ${description} returned ${expected[0]} in position ${0}`
+    );
+  }
+
+  await checkSearch(
+    { filename: downloadPath(FILE_NAME_DECODED_1) },
+    ["fileEncoded1"],
+    "filename"
+  );
+  await checkSearch(
+    { filename: downloadPath(FILE_NAME_DECODED_2) },
+    ["fileEncoded2"],
+    "filename"
+  );
+  await checkSearch(
+    { filename: downloadPath(FILE_NAME_DECODED_3) },
+    ["fileEncoded3"],
+    "filename"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_error_location.js b/toolkit/components/extensions/test/xpcshell/test_ext_error_location.js
new file mode 100644
index 0000000000..ab18c9c371
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_error_location.js
@@ -0,0 +1,48 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_error_location() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      let { fileName } = new Error();
+
+      browser.test.sendMessage("fileName", fileName);
+
+      browser.runtime.sendMessage("Meh.", () => {});
+
+      await browser.test.assertRejects(
+        browser.runtime.sendMessage("Meh"),
+        error => {
+          return error.fileName === fileName && error.lineNumber === 9;
+        }
+      );
+
+      browser.test.notifyPass("error-location");
+    },
+  });
+
+  let fileName;
+  const { messages } = await promiseConsoleOutput(async () => {
+    await extension.startup();
+
+    fileName = await extension.awaitMessage("fileName");
+
+    await extension.awaitFinish("error-location");
+
+    await extension.unload();
+  });
+
+  let [msg] = messages.filter(m => m.message.includes("Unchecked lastError"));
+
+  equal(msg.sourceName, fileName, "Message source");
+  equal(msg.lineNumber, 6, "Message line");
+
+  let frame = msg.stack;
+  if (frame) {
+    equal(frame.source, fileName, "Frame source");
+    equal(frame.line, 6, "Frame line");
+    equal(frame.column, 23, "Frame column");
+    equal(frame.functionDisplayName, "background", "Frame function name");
+  }
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_eventpage_warning.js b/toolkit/components/extensions/test/xpcshell/test_ext_eventpage_warning.js
new file mode 100644
index 0000000000..ba53803f43
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_eventpage_warning.js
@@ -0,0 +1,90 @@
+"use strict";
+
+AddonTestUtils.init(this);
+// This test expects and checks deprecation warnings.
+ExtensionTestUtils.failOnSchemaWarnings(false);
+
+function createEventPageExtension(eventPage) {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      background: eventPage,
+    },
+    files: {
+      "event_page_script.js"() {
+        browser.test.log("running event page as background script");
+        browser.test.sendMessage("running", 1);
+      },
+      "event-page.html": `<!DOCTYPE html>
+        <html><head>
+          <meta charset="utf-8">
+          <script src="event_page_script.js"><\/script>
+        </head></html>`,
+    },
+  });
+}
+
+add_task(async function test_eventpages() {
+  let testCases = [
+    {
+      message: "testing event page running as a background page",
+      eventPage: {
+        page: "event-page.html",
+        persistent: false,
+      },
+    },
+    {
+      message: "testing event page scripts running as a background page",
+      eventPage: {
+        scripts: ["event_page_script.js"],
+        persistent: false,
+      },
+    },
+    {
+      message: "testing additional unrecognized properties on background page",
+      eventPage: {
+        scripts: ["event_page_script.js"],
+        nonExistentProp: true,
+      },
+    },
+    {
+      message: "testing persistent background page",
+      eventPage: {
+        page: "event-page.html",
+        persistent: true,
+      },
+    },
+    {
+      message:
+        "testing scripts with persistent background running as a background page",
+      eventPage: {
+        scripts: ["event_page_script.js"],
+        persistent: true,
+      },
+    },
+  ];
+
+  let { messages } = await promiseConsoleOutput(async () => {
+    for (let test of testCases) {
+      info(test.message);
+
+      let extension = createEventPageExtension(test.eventPage);
+      await extension.startup();
+      let x = await extension.awaitMessage("running");
+      equal(x, 1, "got correct value from extension");
+      await extension.unload();
+    }
+  });
+  AddonTestUtils.checkMessages(
+    messages,
+    {
+      expected: [
+        { message: /Event pages are not currently supported./ },
+        { message: /Event pages are not currently supported./ },
+        {
+          message: /Reading manifest: Warning processing background.nonExistentProp: An unexpected property was found/,
+        },
+      ],
+    },
+    true
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_experiments.js b/toolkit/components/extensions/test/xpcshell/test_ext_experiments.js
new file mode 100644
index 0000000000..1393888eca
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_experiments.js
@@ -0,0 +1,358 @@
+"use strict";
+
+/* globals browser */
+const { AddonSettings } = ChromeUtils.import(
+  "resource://gre/modules/addons/AddonSettings.jsm"
+);
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  AddonTestUtils.overrideCertDB();
+  await ExtensionTestUtils.startAddonManager();
+});
+
+let fooExperimentAPIs = {
+  foo: {
+    schema: "schema.json",
+    parent: {
+      scopes: ["addon_parent"],
+      script: "parent.js",
+      paths: [["experiments", "foo", "parent"]],
+    },
+    child: {
+      scopes: ["addon_child"],
+      script: "child.js",
+      paths: [["experiments", "foo", "child"]],
+    },
+  },
+};
+
+let fooExperimentFiles = {
+  "schema.json": JSON.stringify([
+    {
+      namespace: "experiments.foo",
+      types: [
+        {
+          id: "Meh",
+          type: "object",
+          properties: {},
+        },
+      ],
+      functions: [
+        {
+          name: "parent",
+          type: "function",
+          async: true,
+          parameters: [],
+        },
+        {
+          name: "child",
+          type: "function",
+          parameters: [],
+          returns: { type: "string" },
+        },
+      ],
+    },
+  ]),
+
+  /* globals ExtensionAPI */
+  "parent.js": () => {
+    this.foo = class extends ExtensionAPI {
+      getAPI(context) {
+        return {
+          experiments: {
+            foo: {
+              parent() {
+                return Promise.resolve("parent");
+              },
+            },
+          },
+        };
+      }
+    };
+  },
+
+  "child.js": () => {
+    this.foo = class extends ExtensionAPI {
+      getAPI(context) {
+        return {
+          experiments: {
+            foo: {
+              child() {
+                return "child";
+              },
+            },
+          },
+        };
+      }
+    };
+  },
+};
+
+async function testFooExperiment() {
+  browser.test.assertEq(
+    "object",
+    typeof browser.experiments,
+    "typeof browser.experiments"
+  );
+
+  browser.test.assertEq(
+    "object",
+    typeof browser.experiments.foo,
+    "typeof browser.experiments.foo"
+  );
+
+  browser.test.assertEq(
+    "function",
+    typeof browser.experiments.foo.child,
+    "typeof browser.experiments.foo.child"
+  );
+
+  browser.test.assertEq(
+    "function",
+    typeof browser.experiments.foo.parent,
+    "typeof browser.experiments.foo.parent"
+  );
+
+  browser.test.assertEq(
+    "child",
+    browser.experiments.foo.child(),
+    "foo.child()"
+  );
+
+  browser.test.assertEq(
+    "parent",
+    await browser.experiments.foo.parent(),
+    "await foo.parent()"
+  );
+}
+
+async function testFooFailExperiment() {
+  browser.test.assertEq(
+    "object",
+    typeof browser.experiments,
+    "typeof browser.experiments"
+  );
+
+  browser.test.assertEq(
+    "undefined",
+    typeof browser.experiments.foo,
+    "typeof browser.experiments.foo"
+  );
+}
+
+add_task(async function test_bundled_experiments() {
+  let testCases = [
+    { isSystem: true, temporarilyInstalled: true, shouldHaveExperiments: true },
+    {
+      isSystem: true,
+      temporarilyInstalled: false,
+      shouldHaveExperiments: true,
+    },
+    {
+      isPrivileged: true,
+      temporarilyInstalled: true,
+      shouldHaveExperiments: true,
+    },
+    {
+      isPrivileged: true,
+      temporarilyInstalled: false,
+      shouldHaveExperiments: true,
+    },
+    {
+      isPrivileged: false,
+      temporarilyInstalled: true,
+      shouldHaveExperiments: AddonSettings.EXPERIMENTS_ENABLED,
+    },
+    {
+      isPrivileged: false,
+      temporarilyInstalled: false,
+      shouldHaveExperiments: AppConstants.MOZ_APP_NAME == "thunderbird",
+    },
+  ];
+
+  async function background(shouldHaveExperiments) {
+    if (shouldHaveExperiments) {
+      await testFooExperiment();
+    } else {
+      await testFooFailExperiment();
+    }
+
+    browser.test.notifyPass("background.experiments.foo");
+  }
+
+  for (let testCase of testCases) {
+    let extension = ExtensionTestUtils.loadExtension({
+      isPrivileged: testCase.isPrivileged,
+      isSystem: testCase.isSystem,
+      temporarilyInstalled: testCase.temporarilyInstalled,
+
+      manifest: {
+        experiment_apis: fooExperimentAPIs,
+      },
+
+      background: `
+        ${testFooExperiment}
+        ${testFooFailExperiment}
+        (${background})(${testCase.shouldHaveExperiments});
+      `,
+
+      files: fooExperimentFiles,
+    });
+
+    await extension.startup();
+
+    await extension.awaitFinish("background.experiments.foo");
+
+    await extension.unload();
+  }
+});
+
+add_task(async function test_unbundled_experiments() {
+  async function background() {
+    await testFooExperiment();
+
+    browser.test.assertEq(
+      "object",
+      typeof browser.experiments.crunk,
+      "typeof browser.experiments.crunk"
+    );
+
+    browser.test.assertEq(
+      "function",
+      typeof browser.experiments.crunk.child,
+      "typeof browser.experiments.crunk.child"
+    );
+
+    browser.test.assertEq(
+      "function",
+      typeof browser.experiments.crunk.parent,
+      "typeof browser.experiments.crunk.parent"
+    );
+
+    browser.test.assertEq(
+      "crunk-child",
+      browser.experiments.crunk.child(),
+      "crunk.child()"
+    );
+
+    browser.test.assertEq(
+      "crunk-parent",
+      await browser.experiments.crunk.parent(),
+      "await crunk.parent()"
+    );
+
+    browser.test.notifyPass("background.experiments.crunk");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+
+    manifest: {
+      experiment_apis: fooExperimentAPIs,
+
+      permissions: ["experiments.crunk"],
+    },
+
+    background: `
+      ${testFooExperiment}
+      (${background})();
+    `,
+
+    files: fooExperimentFiles,
+  });
+
+  let apiExtension = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+
+    manifest: {
+      applications: { gecko: { id: "crunk@experiments.addons.mozilla.org" } },
+
+      experiment_apis: {
+        crunk: {
+          schema: "schema.json",
+          parent: {
+            scopes: ["addon_parent"],
+            script: "parent.js",
+            paths: [["experiments", "crunk", "parent"]],
+          },
+          child: {
+            scopes: ["addon_child"],
+            script: "child.js",
+            paths: [["experiments", "crunk", "child"]],
+          },
+        },
+      },
+    },
+
+    files: {
+      "schema.json": JSON.stringify([
+        {
+          namespace: "experiments.crunk",
+          types: [
+            {
+              id: "Meh",
+              type: "object",
+              properties: {},
+            },
+          ],
+          functions: [
+            {
+              name: "parent",
+              type: "function",
+              async: true,
+              parameters: [],
+            },
+            {
+              name: "child",
+              type: "function",
+              parameters: [],
+              returns: { type: "string" },
+            },
+          ],
+        },
+      ]),
+
+      "parent.js": () => {
+        this.crunk = class extends ExtensionAPI {
+          getAPI(context) {
+            return {
+              experiments: {
+                crunk: {
+                  parent() {
+                    return Promise.resolve("crunk-parent");
+                  },
+                },
+              },
+            };
+          }
+        };
+      },
+
+      "child.js": () => {
+        this.crunk = class extends ExtensionAPI {
+          getAPI(context) {
+            return {
+              experiments: {
+                crunk: {
+                  child() {
+                    return "crunk-child";
+                  },
+                },
+              },
+            };
+          }
+        };
+      },
+    },
+  });
+
+  await apiExtension.startup();
+  await extension.startup();
+
+  await extension.awaitFinish("background.experiments.crunk");
+
+  await extension.unload();
+  await apiExtension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_extension.js b/toolkit/components/extensions/test/xpcshell/test_ext_extension.js
new file mode 100644
index 0000000000..72fa161965
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extension.js
@@ -0,0 +1,80 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_is_allowed_incognito_access() {
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  async function background() {
+    let allowed = await browser.extension.isAllowedIncognitoAccess();
+
+    browser.test.assertEq(true, allowed, "isAllowedIncognitoAccess is true");
+    browser.test.notifyPass("isAllowedIncognitoAccess");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    incognitoOverride: "spanning",
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("isAllowedIncognitoAccess");
+  await extension.unload();
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+});
+
+add_task(async function test_is_denied_incognito_access() {
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  async function background() {
+    let allowed = await browser.extension.isAllowedIncognitoAccess();
+
+    browser.test.assertEq(false, allowed, "isAllowedIncognitoAccess is false");
+    browser.test.notifyPass("isNotAllowedIncognitoAccess");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("isNotAllowedIncognitoAccess");
+  await extension.unload();
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+});
+
+add_task(async function test_in_incognito_context_false() {
+  function background() {
+    browser.test.assertEq(
+      false,
+      browser.extension.inIncognitoContext,
+      "inIncognitoContext returned false"
+    );
+    browser.test.notifyPass("inIncognitoContext");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("inIncognitoContext");
+  await extension.unload();
+});
+
+add_task(async function test_is_allowed_file_scheme_access() {
+  async function background() {
+    let allowed = await browser.extension.isAllowedFileSchemeAccess();
+
+    browser.test.assertEq(false, allowed, "isAllowedFileSchemeAccess is false");
+    browser.test.notifyPass("isAllowedFileSchemeAccess");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("isAllowedFileSchemeAccess");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_extensionPreferencesManager.js b/toolkit/components/extensions/test/xpcshell/test_ext_extensionPreferencesManager.js
new file mode 100644
index 0000000000..19e046e12d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extensionPreferencesManager.js
@@ -0,0 +1,887 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionPreferencesManager",
+  "resource://gre/modules/ExtensionPreferencesManager.jsm"
+);
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionSettingsStore",
+  "resource://gre/modules/ExtensionSettingsStore.jsm"
+);
+ChromeUtils.defineModuleGetter(
+  this,
+  "Preferences",
+  "resource://gre/modules/Preferences.jsm"
+);
+var { PromiseUtils } = ChromeUtils.import(
+  "resource://gre/modules/PromiseUtils.jsm"
+);
+
+const {
+  createAppInfo,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+let lastSetPref;
+
+const STORE_TYPE = "prefs";
+
+// Test settings to use with the preferences manager.
+const SETTINGS = {
+  multiple_prefs: {
+    prefNames: ["my.pref.1", "my.pref.2", "my.pref.3"],
+
+    initalValues: ["value1", "value2", "value3"],
+
+    valueFn(pref, value) {
+      return `${pref}-${value}`;
+    },
+
+    setCallback(value) {
+      let prefs = {};
+      for (let pref of this.prefNames) {
+        prefs[pref] = this.valueFn(pref, value);
+      }
+      return prefs;
+    },
+  },
+
+  singlePref: {
+    prefNames: ["my.single.pref"],
+
+    initalValues: ["value1"],
+
+    onPrefsChanged(item) {
+      lastSetPref = item;
+    },
+
+    valueFn(pref, value) {
+      return value;
+    },
+
+    setCallback(value) {
+      return { [this.prefNames[0]]: this.valueFn(null, value) };
+    },
+  },
+};
+
+ExtensionPreferencesManager.addSetting(
+  "multiple_prefs",
+  SETTINGS.multiple_prefs
+);
+ExtensionPreferencesManager.addSetting("singlePref", SETTINGS.singlePref);
+
+// Set initial values for prefs.
+for (let setting in SETTINGS) {
+  setting = SETTINGS[setting];
+  for (let i = 0; i < setting.prefNames.length; i++) {
+    Preferences.set(setting.prefNames[i], setting.initalValues[i]);
+  }
+}
+
+function checkPrefs(settingObj, value, msg) {
+  for (let pref of settingObj.prefNames) {
+    equal(Preferences.get(pref), settingObj.valueFn(pref, value), msg);
+  }
+}
+
+function checkOnPrefsChanged(setting, value, msg) {
+  if (value) {
+    deepEqual(lastSetPref, value, msg);
+    lastSetPref = null;
+  } else {
+    ok(!lastSetPref, msg);
+  }
+}
+
+add_task(async function test_preference_manager() {
+  await promiseStartupManager();
+
+  // Create an array of test framework extension wrappers to install.
+  let testExtensions = [
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {},
+    }),
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {},
+    }),
+  ];
+
+  for (let extension of testExtensions) {
+    await extension.startup();
+  }
+
+  // Create an array actual Extension objects which correspond to the
+  // test framework extension wrappers.
+  let extensions = testExtensions.map(extension => extension.extension);
+
+  for (let setting in SETTINGS) {
+    let settingObj = SETTINGS[setting];
+    let newValue1 = "newValue1";
+    let levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+      extensions[1].id,
+      setting
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        null,
+        "onPrefsChanged has not been called yet"
+      );
+    }
+    equal(
+      levelOfControl,
+      "controllable_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl with no settings set."
+    );
+
+    let prefsChanged = await ExtensionPreferencesManager.setSetting(
+      extensions[1].id,
+      setting,
+      newValue1
+    );
+    ok(prefsChanged, "setSetting returns true when the pref(s) have been set.");
+    checkPrefs(
+      settingObj,
+      newValue1,
+      "setSetting sets the prefs for the first extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        { id: extensions[1].id, value: newValue1, key: setting },
+        "onPrefsChanged is called when pref changes"
+      );
+    }
+    levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+      extensions[1].id,
+      setting
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl when a pref has been set."
+    );
+
+    let checkSetting = await ExtensionPreferencesManager.getSetting(setting);
+    equal(
+      checkSetting.value,
+      newValue1,
+      "getSetting returns the expected value."
+    );
+
+    let newValue2 = "newValue2";
+    prefsChanged = await ExtensionPreferencesManager.setSetting(
+      extensions[0].id,
+      setting,
+      newValue2
+    );
+    ok(
+      !prefsChanged,
+      "setSetting returns false when the pref(s) have not been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue1,
+      "setSetting does not set the pref(s) for an earlier extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        null,
+        "onPrefsChanged isn't called without control change"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.disableSetting(
+      extensions[0].id,
+      setting
+    );
+    ok(
+      !prefsChanged,
+      "disableSetting returns false when the pref(s) have not been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue1,
+      "disableSetting does not change the pref(s) for the non-top extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        null,
+        "onPrefsChanged isn't called without control change on disable"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.enableSetting(
+      extensions[0].id,
+      setting
+    );
+    ok(
+      !prefsChanged,
+      "enableSetting returns false when the pref(s) have not been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue1,
+      "enableSetting does not change the pref(s) for the non-top extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        null,
+        "onPrefsChanged isn't called without control change on enable"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.removeSetting(
+      extensions[0].id,
+      setting
+    );
+    ok(
+      !prefsChanged,
+      "removeSetting returns false when the pref(s) have not been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue1,
+      "removeSetting does not change the pref(s) for the non-top extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        null,
+        "onPrefsChanged isn't called without control change on remove"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.setSetting(
+      extensions[0].id,
+      setting,
+      newValue2
+    );
+    ok(
+      !prefsChanged,
+      "setSetting returns false when the pref(s) have not been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue1,
+      "setSetting does not set the pref(s) for an earlier extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        null,
+        "onPrefsChanged isn't called without control change again"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.disableSetting(
+      extensions[1].id,
+      setting
+    );
+    ok(
+      prefsChanged,
+      "disableSetting returns true when the pref(s) have been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue2,
+      "disableSetting sets the pref(s) to the next value when disabling the top extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        { id: extensions[0].id, key: setting, value: newValue2 },
+        "onPrefsChanged is called when control changes on disable"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.enableSetting(
+      extensions[1].id,
+      setting
+    );
+    ok(
+      prefsChanged,
+      "enableSetting returns true when the pref(s) have been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue1,
+      "enableSetting sets the pref(s) to the previous value(s)."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        { id: extensions[1].id, key: setting, value: newValue1 },
+        "onPrefsChanged is called when control changes on enable"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.removeSetting(
+      extensions[1].id,
+      setting
+    );
+    ok(
+      prefsChanged,
+      "removeSetting returns true when the pref(s) have been set."
+    );
+    checkPrefs(
+      settingObj,
+      newValue2,
+      "removeSetting sets the pref(s) to the next value when removing the top extension."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        { id: extensions[0].id, key: setting, value: newValue2 },
+        "onPrefsChanged is called when control changes on remove"
+      );
+    }
+
+    prefsChanged = await ExtensionPreferencesManager.removeSetting(
+      extensions[0].id,
+      setting
+    );
+    ok(
+      prefsChanged,
+      "removeSetting returns true when the pref(s) have been set."
+    );
+    if (settingObj.onPrefsChanged) {
+      checkOnPrefsChanged(
+        setting,
+        { key: setting, initialValue: { "my.single.pref": "value1" } },
+        "onPrefsChanged is called when control is entirely removed"
+      );
+    }
+    for (let i = 0; i < settingObj.prefNames.length; i++) {
+      equal(
+        Preferences.get(settingObj.prefNames[i]),
+        settingObj.initalValues[i],
+        "removeSetting sets the pref(s) to the initial value(s) when removing the last extension."
+      );
+    }
+
+    checkSetting = await ExtensionPreferencesManager.getSetting(setting);
+    equal(
+      checkSetting,
+      null,
+      "getSetting returns null when nothing has been set."
+    );
+  }
+
+  // Tests for unsetAll.
+  let newValue3 = "newValue3";
+  for (let setting in SETTINGS) {
+    let settingObj = SETTINGS[setting];
+    await ExtensionPreferencesManager.setSetting(
+      extensions[0].id,
+      setting,
+      newValue3
+    );
+    checkPrefs(settingObj, newValue3, "setSetting set the pref.");
+  }
+
+  let setSettings = await ExtensionSettingsStore.getAllForExtension(
+    extensions[0].id,
+    STORE_TYPE
+  );
+  deepEqual(
+    setSettings,
+    Object.keys(SETTINGS),
+    "Expected settings were set for extension."
+  );
+  await ExtensionPreferencesManager.disableAll(extensions[0].id);
+
+  for (let setting in SETTINGS) {
+    let settingObj = SETTINGS[setting];
+    for (let i = 0; i < settingObj.prefNames.length; i++) {
+      equal(
+        Preferences.get(settingObj.prefNames[i]),
+        settingObj.initalValues[i],
+        "disableAll unset the pref."
+      );
+    }
+  }
+
+  setSettings = await ExtensionSettingsStore.getAllForExtension(
+    extensions[0].id,
+    STORE_TYPE
+  );
+  deepEqual(
+    setSettings,
+    Object.keys(SETTINGS),
+    "disableAll retains the settings."
+  );
+
+  await ExtensionPreferencesManager.enableAll(extensions[0].id);
+  for (let setting in SETTINGS) {
+    let settingObj = SETTINGS[setting];
+    checkPrefs(settingObj, newValue3, "enableAll re-set the pref.");
+  }
+
+  await ExtensionPreferencesManager.removeAll(extensions[0].id);
+
+  for (let setting in SETTINGS) {
+    let settingObj = SETTINGS[setting];
+    for (let i = 0; i < settingObj.prefNames.length; i++) {
+      equal(
+        Preferences.get(settingObj.prefNames[i]),
+        settingObj.initalValues[i],
+        "removeAll unset the pref."
+      );
+    }
+  }
+
+  setSettings = await ExtensionSettingsStore.getAllForExtension(
+    extensions[0].id,
+    STORE_TYPE
+  );
+  deepEqual(setSettings, [], "removeAll removed all settings.");
+
+  // Tests for preventing automatic changes to manually edited prefs.
+  for (let setting in SETTINGS) {
+    let apiValue = "newValue";
+    let manualValue = "something different";
+    let settingObj = SETTINGS[setting];
+    let extension = extensions[1];
+    await ExtensionPreferencesManager.setSetting(
+      extension.id,
+      setting,
+      apiValue
+    );
+
+    let checkResetPrefs = method => {
+      let prefNames = settingObj.prefNames;
+      for (let i = 0; i < prefNames.length; i++) {
+        if (i === 0) {
+          equal(
+            Preferences.get(prefNames[0]),
+            manualValue,
+            `${method} did not change a manually set pref.`
+          );
+        } else {
+          equal(
+            Preferences.get(prefNames[i]),
+            settingObj.valueFn(prefNames[i], apiValue),
+            `${method} did not change another pref when a pref was manually set.`
+          );
+        }
+      }
+    };
+
+    // Manually set the preference to a different value.
+    Preferences.set(settingObj.prefNames[0], manualValue);
+
+    await ExtensionPreferencesManager.disableAll(extension.id);
+    checkResetPrefs("disableAll");
+
+    await ExtensionPreferencesManager.enableAll(extension.id);
+    checkResetPrefs("enableAll");
+
+    await ExtensionPreferencesManager.removeAll(extension.id);
+    checkResetPrefs("removeAll");
+  }
+
+  // Test with an uninitialized pref.
+  let setting = "singlePref";
+  let settingObj = SETTINGS[setting];
+  let pref = settingObj.prefNames[0];
+  let newValue = "newValue";
+  Preferences.reset(pref);
+  await ExtensionPreferencesManager.setSetting(
+    extensions[1].id,
+    setting,
+    newValue
+  );
+  equal(
+    Preferences.get(pref),
+    settingObj.valueFn(pref, newValue),
+    "Uninitialized pref is set."
+  );
+  await ExtensionPreferencesManager.removeSetting(extensions[1].id, setting);
+  ok(!Preferences.has(pref), "removeSetting removed the pref.");
+
+  // Test levelOfControl with a locked pref.
+  setting = "multiple_prefs";
+  let prefToLock = SETTINGS[setting].prefNames[0];
+  Preferences.lock(prefToLock, 1);
+  ok(Preferences.locked(prefToLock), `Preference ${prefToLock} is locked.`);
+  let levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+    extensions[1].id,
+    setting
+  );
+  equal(
+    levelOfControl,
+    "not_controllable",
+    "getLevelOfControl returns correct levelOfControl when a pref is locked."
+  );
+
+  for (let extension of testExtensions) {
+    await extension.unload();
+  }
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_preference_manager_set_when_disabled() {
+  await promiseStartupManager();
+
+  let id = "@set-disabled-pref";
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id } },
+    },
+  });
+
+  await extension.startup();
+
+  // We test both a default pref and a user-set pref.  Get the default
+  // value off the pref we'll use.  We fake the default pref by setting
+  // a value on it before creating the setting.
+  Services.prefs.setBoolPref("bar", true);
+
+  function isUndefinedPref(pref) {
+    try {
+      Services.prefs.getStringPref(pref);
+      return false;
+    } catch (e) {
+      return true;
+    }
+  }
+  ok(isUndefinedPref("foo"), "test pref is not set");
+
+  await ExtensionSettingsStore.initialize();
+  let lastItemChange = PromiseUtils.defer();
+  ExtensionPreferencesManager.addSetting("some-pref", {
+    prefNames: ["foo", "bar"],
+    onPrefsChanged(item) {
+      lastItemChange.resolve(item);
+      lastItemChange = PromiseUtils.defer();
+    },
+    setCallback(value) {
+      return { [this.prefNames[0]]: value, [this.prefNames[1]]: false };
+    },
+  });
+
+  await ExtensionPreferencesManager.setSetting(id, "some-pref", "my value");
+
+  let item = ExtensionSettingsStore.getSetting("prefs", "some-pref");
+  equal(item.value, "my value", "The value has been set");
+  equal(
+    Services.prefs.getStringPref("foo"),
+    "my value",
+    "The user pref has been set"
+  );
+  equal(
+    Services.prefs.getBoolPref("bar"),
+    false,
+    "The default pref has been set"
+  );
+
+  await ExtensionPreferencesManager.disableSetting(id, "some-pref");
+
+  // test that a disabled setting has been returned to the default value.  In this
+  // case the pref is not a default pref, so it will be undefined.
+  item = ExtensionSettingsStore.getSetting("prefs", "some-pref");
+  equal(item.value, undefined, "The value is back to default");
+  equal(item.initialValue.foo, undefined, "The initialValue is correct");
+  ok(isUndefinedPref("foo"), "user pref is not set");
+  equal(
+    Services.prefs.getBoolPref("bar"),
+    true,
+    "The default pref has been restored to the default"
+  );
+
+  // test that setSetting() will enable a disabled setting
+  await ExtensionPreferencesManager.setSetting(id, "some-pref", "new value");
+
+  item = ExtensionSettingsStore.getSetting("prefs", "some-pref");
+  equal(item.value, "new value", "The value is set again");
+  equal(
+    Services.prefs.getStringPref("foo"),
+    "new value",
+    "The user pref is set again"
+  );
+  equal(
+    Services.prefs.getBoolPref("bar"),
+    false,
+    "The default pref has been set again"
+  );
+
+  // Force settings to be serialized and reloaded to mimick what happens
+  // with settings through a restart of Firefox.  Bug 1576266.
+  await ExtensionSettingsStore._reloadFile(true);
+
+  // Now unload the extension to test prefs are reset properly.
+  let promise = lastItemChange.promise;
+  await extension.unload();
+
+  // Test that the pref is unset when an extension is uninstalled.
+  item = await promise;
+  deepEqual(
+    item,
+    { key: "some-pref", initialValue: { bar: true } },
+    "The value has been reset"
+  );
+  ok(isUndefinedPref("foo"), "user pref is not set");
+  equal(
+    Services.prefs.getBoolPref("bar"),
+    true,
+    "The default pref has been restored to the default"
+  );
+  Services.prefs.clearUserPref("bar");
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_preference_default_upgraded() {
+  await promiseStartupManager();
+
+  let id = "@upgrade-pref";
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id } },
+    },
+  });
+
+  await extension.startup();
+
+  // We set the default value for a pref here so it will be
+  // picked up by EPM.
+  let defaultPrefs = Services.prefs.getDefaultBranch(null);
+  defaultPrefs.setStringPref("bar", "initial default");
+
+  await ExtensionSettingsStore.initialize();
+  ExtensionPreferencesManager.addSetting("some-pref", {
+    prefNames: ["bar"],
+    setCallback(value) {
+      return { [this.prefNames[0]]: value };
+    },
+  });
+
+  await ExtensionPreferencesManager.setSetting(id, "some-pref", "new value");
+  let item = ExtensionSettingsStore.getSetting("prefs", "some-pref");
+  equal(item.value, "new value", "The value is set");
+
+  defaultPrefs.setStringPref("bar", "new default");
+
+  item = ExtensionSettingsStore.getSetting("prefs", "some-pref");
+  equal(item.value, "new value", "The value is still set");
+
+  let prefsChanged = await ExtensionPreferencesManager.removeSetting(
+    id,
+    "some-pref"
+  );
+  ok(prefsChanged, "pref changed on removal of setting.");
+  equal(Preferences.get("bar"), "new default", "default value is correct");
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
+
+add_task(async function test_preference_select() {
+  await promiseStartupManager();
+
+  let extensionData = {
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id: "@one" } },
+    },
+  };
+  let one = ExtensionTestUtils.loadExtension(extensionData);
+
+  await one.startup();
+
+  // We set the default value for a pref here so it will be
+  // picked up by EPM.
+  let defaultPrefs = Services.prefs.getDefaultBranch(null);
+  defaultPrefs.setStringPref("bar", "initial default");
+
+  await ExtensionSettingsStore.initialize();
+  ExtensionPreferencesManager.addSetting("some-pref", {
+    prefNames: ["bar"],
+    setCallback(value) {
+      return { [this.prefNames[0]]: value };
+    },
+  });
+
+  ok(
+    await ExtensionPreferencesManager.setSetting(
+      one.id,
+      "some-pref",
+      "new value"
+    ),
+    "setting was changed"
+  );
+  let item = await ExtensionPreferencesManager.getSetting("some-pref");
+  equal(item.value, "new value", "The value is set");
+
+  // User-set the setting.
+  await ExtensionPreferencesManager.selectSetting(null, "some-pref");
+  item = await ExtensionPreferencesManager.getSetting("some-pref");
+  deepEqual(
+    item,
+    { key: "some-pref", initialValue: {} },
+    "The value is user-set"
+  );
+
+  // Extensions installed before cannot gain control again.
+  let levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+    one.id,
+    "some-pref"
+  );
+  equal(
+    levelOfControl,
+    "not_controllable",
+    "getLevelOfControl returns correct levelOfControl when user-set."
+  );
+
+  // Enabling the top-precedence addon does not take over a user-set setting.
+  await ExtensionPreferencesManager.disableSetting(one.id, "some-pref");
+  await ExtensionPreferencesManager.enableSetting(one.id, "some-pref");
+  item = await ExtensionPreferencesManager.getSetting("some-pref");
+  deepEqual(
+    item,
+    { key: "some-pref", initialValue: {} },
+    "The value is user-set"
+  );
+
+  // Upgrading does not override the user-set setting.
+  extensionData.manifest.version = "2.0";
+  extensionData.manifest.incognito = "not_allowed";
+  await one.upgrade(extensionData);
+  levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+    one.id,
+    "some-pref"
+  );
+  equal(
+    levelOfControl,
+    "not_controllable",
+    "getLevelOfControl returns correct levelOfControl when user-set after addon upgrade."
+  );
+
+  // We can re-select the extension.
+  await ExtensionPreferencesManager.selectSetting(one.id, "some-pref");
+  item = await ExtensionPreferencesManager.getSetting("some-pref");
+  deepEqual(item.value, "new value", "The value is extension set");
+
+  // An extension installed after user-set can take over the setting.
+  await ExtensionPreferencesManager.selectSetting(null, "some-pref");
+  item = await ExtensionPreferencesManager.getSetting("some-pref");
+  deepEqual(
+    item,
+    { key: "some-pref", initialValue: {} },
+    "The value is user-set"
+  );
+
+  let two = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id: "@two" } },
+    },
+  });
+
+  await two.startup();
+  levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+    two.id,
+    "some-pref"
+  );
+  equal(
+    levelOfControl,
+    "controllable_by_this_extension",
+    "getLevelOfControl returns correct levelOfControl when user-set after addon install."
+  );
+
+  await ExtensionPreferencesManager.setSetting(
+    two.id,
+    "some-pref",
+    "another value"
+  );
+  item = ExtensionSettingsStore.getSetting("prefs", "some-pref");
+  equal(item.value, "another value", "The value is set");
+
+  // A new installed extension can override a user selected extension.
+  let three = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id: "@three" } },
+    },
+  });
+
+  // user selects specific extension to take control
+  await ExtensionPreferencesManager.selectSetting(one.id, "some-pref");
+
+  // two cannot control
+  levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+    two.id,
+    "some-pref"
+  );
+  equal(
+    levelOfControl,
+    "not_controllable",
+    "getLevelOfControl returns correct levelOfControl when user-set after addon install."
+  );
+
+  // three can control after install
+  await three.startup();
+  levelOfControl = await ExtensionPreferencesManager.getLevelOfControl(
+    three.id,
+    "some-pref"
+  );
+  equal(
+    levelOfControl,
+    "controllable_by_this_extension",
+    "getLevelOfControl returns correct levelOfControl when user-set after addon install."
+  );
+
+  await ExtensionPreferencesManager.setSetting(
+    three.id,
+    "some-pref",
+    "third value"
+  );
+  item = ExtensionSettingsStore.getSetting("prefs", "some-pref");
+  equal(item.value, "third value", "The value is set");
+
+  // We have returned to precedence based settings.
+  await ExtensionPreferencesManager.removeSetting(three.id, "some-pref");
+  await ExtensionPreferencesManager.removeSetting(two.id, "some-pref");
+  item = await ExtensionPreferencesManager.getSetting("some-pref");
+  equal(item.value, "new value", "The value is extension set");
+
+  await one.unload();
+  await two.unload();
+  await three.unload();
+  await promiseShutdownManager();
+});
+
+add_task(async function test_preference_select() {
+  let prefNames = await ExtensionPreferencesManager.getManagedPrefDetails();
+  // Just check a subset of settings that are in this test file.
+  Assert.ok(prefNames.size > 0, "some prefs exist");
+  for (let settingName in SETTINGS) {
+    let setting = SETTINGS[settingName];
+    for (let prefName of setting.prefNames) {
+      Assert.equal(
+        prefNames.get(prefName),
+        settingName,
+        "setting retrieved prefNames"
+      );
+    }
+  }
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_extensionSettingsStore.js b/toolkit/components/extensions/test/xpcshell/test_ext_extensionSettingsStore.js
new file mode 100644
index 0000000000..e4baa79a2c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extensionSettingsStore.js
@@ -0,0 +1,1089 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionSettingsStore",
+  "resource://gre/modules/ExtensionSettingsStore.jsm"
+);
+
+const {
+  createAppInfo,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+// Allow for unsigned addons.
+AddonTestUtils.overrideCertDB();
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+const ITEMS = {
+  key1: [
+    { key: "key1", value: "val1", id: "@first" },
+    { key: "key1", value: "val2", id: "@second" },
+    { key: "key1", value: "val3", id: "@third" },
+  ],
+  key2: [
+    { key: "key2", value: "val1-2", id: "@first" },
+    { key: "key2", value: "val2-2", id: "@second" },
+    { key: "key2", value: "val3-2", id: "@third" },
+  ],
+};
+const KEY_LIST = Object.keys(ITEMS);
+const TEST_TYPE = "myType";
+
+let callbackCount = 0;
+
+function initialValue(key) {
+  callbackCount++;
+  return `key:${key}`;
+}
+
+add_task(async function test_settings_store() {
+  await promiseStartupManager();
+
+  // Create an array of test framework extension wrappers to install.
+  let testExtensions = [
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {
+        applications: { gecko: { id: "@first" } },
+      },
+    }),
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {
+        applications: { gecko: { id: "@second" } },
+      },
+    }),
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {
+        applications: { gecko: { id: "@third" } },
+      },
+    }),
+  ];
+
+  for (let extension of testExtensions) {
+    await extension.startup();
+  }
+
+  // Create an array actual Extension objects which correspond to the
+  // test framework extension wrappers.
+  let extensions = testExtensions.map(extension => extension.extension);
+
+  let expectedCallbackCount = 0;
+
+  await Assert.rejects(
+    ExtensionSettingsStore.getLevelOfControl(1, TEST_TYPE, "key"),
+    /The ExtensionSettingsStore was accessed before the initialize promise resolved/,
+    "Accessing the SettingsStore before it is initialized throws an error."
+  );
+
+  // Initialize the SettingsStore.
+  await ExtensionSettingsStore.initialize();
+
+  // Add a setting for the second oldest extension, where it is the only setting for a key.
+  for (let key of KEY_LIST) {
+    let extensionIndex = 1;
+    let itemToAdd = ITEMS[key][extensionIndex];
+    let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controllable_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl with no settings set for a key."
+    );
+    let item = await ExtensionSettingsStore.addSetting(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      itemToAdd.key,
+      itemToAdd.value,
+      initialValue
+    );
+    expectedCallbackCount++;
+    equal(
+      callbackCount,
+      expectedCallbackCount,
+      "initialValueCallback called the expected number of times."
+    );
+    deepEqual(
+      item,
+      itemToAdd,
+      "Adding initial item for a key returns that item."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      itemToAdd,
+      "getSetting returns correct item with only one item in the list."
+    );
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl with only one item in the list."
+    );
+    ok(
+      ExtensionSettingsStore.hasSetting(
+        extensions[extensionIndex].id,
+        TEST_TYPE,
+        key
+      ),
+      "hasSetting returns the correct value when an extension has a setting set."
+    );
+    item = await ExtensionSettingsStore.getSetting(
+      TEST_TYPE,
+      key,
+      extensions[extensionIndex].id
+    );
+    deepEqual(
+      item,
+      itemToAdd,
+      "getSetting with id returns correct item with only one item in the list."
+    );
+  }
+
+  // Add a setting for the oldest extension.
+  for (let key of KEY_LIST) {
+    let extensionIndex = 0;
+    let itemToAdd = ITEMS[key][extensionIndex];
+    let item = await ExtensionSettingsStore.addSetting(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      itemToAdd.key,
+      itemToAdd.value,
+      initialValue
+    );
+    equal(
+      callbackCount,
+      expectedCallbackCount,
+      "initialValueCallback called the expected number of times."
+    );
+    equal(
+      item,
+      null,
+      "An older extension adding a setting for a key returns null"
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      ITEMS[key][1],
+      "getSetting returns correct item with more than one item in the list."
+    );
+    let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_other_extensions",
+      "getLevelOfControl returns correct levelOfControl when another extension is in control."
+    );
+    item = await ExtensionSettingsStore.getSetting(
+      TEST_TYPE,
+      key,
+      extensions[extensionIndex].id
+    );
+    deepEqual(
+      item,
+      itemToAdd,
+      "getSetting with id returns correct item with more than one item in the list."
+    );
+  }
+
+  // Reload the settings store to emulate a browser restart.
+  await ExtensionSettingsStore._reloadFile();
+
+  // Add a setting for the newest extension.
+  for (let key of KEY_LIST) {
+    let extensionIndex = 2;
+    let itemToAdd = ITEMS[key][extensionIndex];
+    let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controllable_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl for a more recent extension."
+    );
+    let item = await ExtensionSettingsStore.addSetting(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      itemToAdd.key,
+      itemToAdd.value,
+      initialValue
+    );
+    equal(
+      callbackCount,
+      expectedCallbackCount,
+      "initialValueCallback called the expected number of times."
+    );
+    deepEqual(
+      item,
+      itemToAdd,
+      "Adding item for most recent extension returns that item."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      itemToAdd,
+      "getSetting returns correct item with more than one item in the list."
+    );
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl when this extension is in control."
+    );
+    item = await ExtensionSettingsStore.getSetting(
+      TEST_TYPE,
+      key,
+      extensions[extensionIndex].id
+    );
+    deepEqual(
+      item,
+      itemToAdd,
+      "getSetting with id returns correct item with more than one item in the list."
+    );
+  }
+
+  for (let extension of extensions) {
+    let items = await ExtensionSettingsStore.getAllForExtension(
+      extension.id,
+      TEST_TYPE
+    );
+    deepEqual(items, KEY_LIST, "getAllForExtension returns expected keys.");
+  }
+
+  // Attempting to remove a setting that has not been set should *not* throw an exception.
+  let removeResult = await ExtensionSettingsStore.removeSetting(
+    extensions[0].id,
+    "myType",
+    "unset_key"
+  );
+  equal(
+    removeResult,
+    null,
+    "Removing a setting that was not previously set returns null."
+  );
+
+  // Attempting to disable a setting that has not been set should throw an exception.
+  Assert.throws(
+    () =>
+      ExtensionSettingsStore.disable(extensions[0].id, "myType", "unset_key"),
+    /Cannot alter the setting for myType:unset_key as it does not exist/,
+    "disable rejects with an unset key."
+  );
+
+  // Attempting to enable a setting that has not been set should throw an exception.
+  Assert.throws(
+    () =>
+      ExtensionSettingsStore.enable(extensions[0].id, "myType", "unset_key"),
+    /Cannot alter the setting for myType:unset_key as it does not exist/,
+    "enable rejects with an unset key."
+  );
+
+  let expectedKeys = KEY_LIST;
+  // Disable the non-top item for a key.
+  for (let key of KEY_LIST) {
+    let extensionIndex = 0;
+    let item = await ExtensionSettingsStore.addSetting(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key,
+      "new value",
+      initialValue
+    );
+    equal(
+      callbackCount,
+      expectedCallbackCount,
+      "initialValueCallback called the expected number of times."
+    );
+    equal(item, null, "Updating non-top item for a key returns null");
+    item = await ExtensionSettingsStore.disable(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(item, null, "Disabling non-top item for a key returns null.");
+    let allForExtension = await ExtensionSettingsStore.getAllForExtension(
+      extensions[extensionIndex].id,
+      TEST_TYPE
+    );
+    deepEqual(
+      allForExtension,
+      expectedKeys,
+      "getAllForExtension returns expected keys after a disable."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      ITEMS[key][2],
+      "getSetting returns correct item after a disable."
+    );
+    let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_other_extensions",
+      "getLevelOfControl returns correct levelOfControl after disabling of non-top item."
+    );
+  }
+
+  // Re-enable the non-top item for a key.
+  for (let key of KEY_LIST) {
+    let extensionIndex = 0;
+    let item = await ExtensionSettingsStore.enable(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(item, null, "Enabling non-top item for a key returns null.");
+    let allForExtension = await ExtensionSettingsStore.getAllForExtension(
+      extensions[extensionIndex].id,
+      TEST_TYPE
+    );
+    deepEqual(
+      allForExtension,
+      expectedKeys,
+      "getAllForExtension returns expected keys after an enable."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      ITEMS[key][2],
+      "getSetting returns correct item after an enable."
+    );
+    let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_other_extensions",
+      "getLevelOfControl returns correct levelOfControl after enabling of non-top item."
+    );
+  }
+
+  // Remove the non-top item for a key.
+  for (let key of KEY_LIST) {
+    let extensionIndex = 0;
+    let item = await ExtensionSettingsStore.removeSetting(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(item, null, "Removing non-top item for a key returns null.");
+    expectedKeys = expectedKeys.filter(expectedKey => expectedKey != key);
+    let allForExtension = await ExtensionSettingsStore.getAllForExtension(
+      extensions[extensionIndex].id,
+      TEST_TYPE
+    );
+    deepEqual(
+      allForExtension,
+      expectedKeys,
+      "getAllForExtension returns expected keys after a removal."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      ITEMS[key][2],
+      "getSetting returns correct item after a removal."
+    );
+    let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[extensionIndex].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_other_extensions",
+      "getLevelOfControl returns correct levelOfControl after removal of non-top item."
+    );
+    ok(
+      !ExtensionSettingsStore.hasSetting(
+        extensions[extensionIndex].id,
+        TEST_TYPE,
+        key
+      ),
+      "hasSetting returns the correct value when an extension does not have a setting set."
+    );
+  }
+
+  for (let key of KEY_LIST) {
+    // Disable the top item for a key.
+    let item = await ExtensionSettingsStore.disable(
+      extensions[2].id,
+      TEST_TYPE,
+      key
+    );
+    deepEqual(
+      item,
+      ITEMS[key][1],
+      "Disabling top item for a key returns the new top item."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      ITEMS[key][1],
+      "getSetting returns correct item after a disable."
+    );
+    let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[2].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controllable_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl after disabling of top item."
+    );
+
+    // Re-enable the top item for a key.
+    item = await ExtensionSettingsStore.enable(
+      extensions[2].id,
+      TEST_TYPE,
+      key
+    );
+    deepEqual(
+      item,
+      ITEMS[key][2],
+      "Re-enabling top item for a key returns the old top item."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      ITEMS[key][2],
+      "getSetting returns correct item after an enable."
+    );
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[2].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl after re-enabling top item."
+    );
+
+    // Remove the top item for a key.
+    item = await ExtensionSettingsStore.removeSetting(
+      extensions[2].id,
+      TEST_TYPE,
+      key
+    );
+    deepEqual(
+      item,
+      ITEMS[key][1],
+      "Removing top item for a key returns the new top item."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      ITEMS[key][1],
+      "getSetting returns correct item after a removal."
+    );
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[2].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controllable_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl after removal of top item."
+    );
+
+    // Add a setting for the current top item.
+    let itemToAdd = { key, value: `new-${key}`, id: "@second" };
+    item = await ExtensionSettingsStore.addSetting(
+      extensions[1].id,
+      TEST_TYPE,
+      itemToAdd.key,
+      itemToAdd.value,
+      initialValue
+    );
+    equal(
+      callbackCount,
+      expectedCallbackCount,
+      "initialValueCallback called the expected number of times."
+    );
+    deepEqual(
+      item,
+      itemToAdd,
+      "Updating top item for a key returns that item."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      itemToAdd,
+      "getSetting returns correct item after updating."
+    );
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl after updating."
+    );
+
+    // Disable the last remaining item for a key.
+    let expectedItem = { key, initialValue: initialValue(key) };
+    // We're using the callback to set the expected value, so we need to increment the
+    // expectedCallbackCount.
+    expectedCallbackCount++;
+    item = await ExtensionSettingsStore.disable(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    deepEqual(
+      item,
+      expectedItem,
+      "Disabling last item for a key returns the initial value."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      expectedItem,
+      "getSetting returns the initial value after all are disabled."
+    );
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controllable_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl after all are disabled."
+    );
+
+    // Re-enable the last remaining item for a key.
+    item = await ExtensionSettingsStore.enable(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    deepEqual(
+      item,
+      itemToAdd,
+      "Re-enabling last item for a key returns the old value."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(
+      item,
+      itemToAdd,
+      "getSetting returns expected value after re-enabling."
+    );
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controlled_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl after re-enabling."
+    );
+
+    // Remove the last remaining item for a key.
+    item = await ExtensionSettingsStore.removeSetting(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    deepEqual(
+      item,
+      expectedItem,
+      "Removing last item for a key returns the initial value."
+    );
+    item = await ExtensionSettingsStore.getSetting(TEST_TYPE, key);
+    deepEqual(item, null, "getSetting returns null after all are removed.");
+    levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      levelOfControl,
+      "controllable_by_this_extension",
+      "getLevelOfControl returns correct levelOfControl after all are removed."
+    );
+
+    // Attempting to remove a setting that has had all extensions removed should *not* throw an exception.
+    removeResult = await ExtensionSettingsStore.removeSetting(
+      extensions[1].id,
+      TEST_TYPE,
+      key
+    );
+    equal(
+      removeResult,
+      null,
+      "Removing a setting that has had all extensions removed returns null."
+    );
+  }
+
+  // Test adding a setting with a value in callbackArgument.
+  let extensionIndex = 0;
+  let testKey = "callbackArgumentKey";
+  let callbackArgumentValue = Date.now();
+  // Add the setting.
+  let item = await ExtensionSettingsStore.addSetting(
+    extensions[extensionIndex].id,
+    TEST_TYPE,
+    testKey,
+    1,
+    initialValue,
+    callbackArgumentValue
+  );
+  expectedCallbackCount++;
+  equal(
+    callbackCount,
+    expectedCallbackCount,
+    "initialValueCallback called the expected number of times."
+  );
+  // Remove the setting which should return the initial value.
+  let expectedItem = {
+    key: testKey,
+    initialValue: initialValue(callbackArgumentValue),
+  };
+  // We're using the callback to set the expected value, so we need to increment the
+  // expectedCallbackCount.
+  expectedCallbackCount++;
+  item = await ExtensionSettingsStore.removeSetting(
+    extensions[extensionIndex].id,
+    TEST_TYPE,
+    testKey
+  );
+  deepEqual(
+    item,
+    expectedItem,
+    "Removing last item for a key returns the initial value."
+  );
+  item = await ExtensionSettingsStore.getSetting(TEST_TYPE, testKey);
+  deepEqual(item, null, "getSetting returns null after all are removed.");
+
+  item = await ExtensionSettingsStore.getSetting(TEST_TYPE, "not a key");
+  equal(
+    item,
+    null,
+    "getSetting returns a null item if the setting does not have any records."
+  );
+  let levelOfControl = await ExtensionSettingsStore.getLevelOfControl(
+    extensions[1].id,
+    TEST_TYPE,
+    "not a key"
+  );
+  equal(
+    levelOfControl,
+    "controllable_by_this_extension",
+    "getLevelOfControl returns correct levelOfControl if the setting does not have any records."
+  );
+
+  for (let extension of testExtensions) {
+    await extension.unload();
+  }
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_settings_store_setByUser() {
+  await promiseStartupManager();
+
+  // Create an array of test framework extension wrappers to install.
+  let testExtensions = [
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {
+        applications: { gecko: { id: "@first" } },
+      },
+    }),
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {
+        applications: { gecko: { id: "@second" } },
+      },
+    }),
+  ];
+
+  let type = "some_type";
+  let key = "some_key";
+
+  for (let extension of testExtensions) {
+    await extension.startup();
+  }
+
+  // Create an array actual Extension objects which correspond to the
+  // test framework extension wrappers.
+  let [one, two] = testExtensions.map(extension => extension.extension);
+  let initialCallback = () => "initial";
+
+  // Initialize the SettingsStore.
+  await ExtensionSettingsStore.initialize();
+
+  equal(
+    null,
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting is initially null"
+  );
+
+  let item = await ExtensionSettingsStore.addSetting(
+    one.id,
+    type,
+    key,
+    "one",
+    initialCallback
+  );
+  deepEqual(
+    { key, value: "one", id: one.id },
+    item,
+    "addSetting returns the first set item"
+  );
+
+  item = await ExtensionSettingsStore.addSetting(
+    two.id,
+    type,
+    key,
+    "two",
+    initialCallback
+  );
+  deepEqual(
+    { key, value: "two", id: two.id },
+    item,
+    "addSetting returns the second set item"
+  );
+
+  // a user-set selection reverts to precedence order when new
+  // extension sets the setting.
+  ExtensionSettingsStore.select(
+    ExtensionSettingsStore.SETTING_USER_SET,
+    type,
+    key
+  );
+  deepEqual(
+    { key, initialValue: "initial" },
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the initial value after being set by user"
+  );
+
+  let three = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id: "@third" } },
+    },
+  });
+  await three.startup();
+
+  item = await ExtensionSettingsStore.addSetting(
+    three.id,
+    type,
+    key,
+    "three",
+    initialCallback
+  );
+  deepEqual(
+    { key, value: "three", id: three.id },
+    item,
+    "addSetting returns the third set item"
+  );
+  deepEqual(
+    item,
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the third set item"
+  );
+
+  ExtensionSettingsStore.select(
+    ExtensionSettingsStore.SETTING_USER_SET,
+    type,
+    key
+  );
+  deepEqual(
+    { key, initialValue: "initial" },
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the initial value after being set by user"
+  );
+
+  item = ExtensionSettingsStore.select(one.id, type, key);
+  deepEqual(
+    { key, value: "one", id: one.id },
+    item,
+    "selecting an extension returns the first set item after enable"
+  );
+
+  // Disabling a selected item returns to precedence order
+  ExtensionSettingsStore.disable(one.id, type, key);
+  deepEqual(
+    { key, value: "three", id: three.id },
+    ExtensionSettingsStore.getSetting(type, key),
+    "returning to precedence order sets the third set item"
+  );
+
+  // Test that disabling all then enabling one does not take over a user-set setting.
+  ExtensionSettingsStore.select(
+    ExtensionSettingsStore.SETTING_USER_SET,
+    type,
+    key
+  );
+  deepEqual(
+    { key, initialValue: "initial" },
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the initial value after being set by user"
+  );
+
+  ExtensionSettingsStore.disable(three.id, type, key);
+  ExtensionSettingsStore.disable(two.id, type, key);
+  deepEqual(
+    { key, initialValue: "initial" },
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the initial value after disabling all extensions"
+  );
+
+  ExtensionSettingsStore.enable(three.id, type, key);
+  deepEqual(
+    { key, initialValue: "initial" },
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the initial value after enabling one extension"
+  );
+
+  // Ensure that calling addSetting again will not reset a user-set value when
+  // the extension install date is older than the user-set date.
+  item = await ExtensionSettingsStore.addSetting(
+    three.id,
+    type,
+    key,
+    "three",
+    initialCallback
+  );
+  deepEqual(
+    { key, initialValue: "initial" },
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the initial value after calling addSetting for old addon"
+  );
+
+  item = ExtensionSettingsStore.enable(three.id, type, key);
+  equal(undefined, item, "enabling the active item does not return an item");
+  deepEqual(
+    { key, initialValue: "initial" },
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns the initial value after enabling one extension"
+  );
+
+  ExtensionSettingsStore.removeSetting(three.id, type, key);
+  ExtensionSettingsStore.removeSetting(two.id, type, key);
+  ExtensionSettingsStore.removeSetting(one.id, type, key);
+
+  equal(
+    null,
+    ExtensionSettingsStore.getSetting(type, key),
+    "getSetting returns null after removing all settings"
+  );
+
+  for (let extension of testExtensions) {
+    await extension.unload();
+  }
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_settings_store_add_disabled() {
+  await promiseStartupManager();
+
+  let id = "@add-on-disable";
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id } },
+    },
+  });
+
+  await extension.startup();
+  await ExtensionSettingsStore.initialize();
+
+  await ExtensionSettingsStore.addSetting(
+    id,
+    "foo",
+    "bar",
+    "set",
+    () => "not set"
+  );
+
+  let item = ExtensionSettingsStore.getSetting("foo", "bar");
+  equal(item.id, id, "The add-on is in control");
+  equal(item.value, "set", "The value is set");
+
+  ExtensionSettingsStore.disable(id, "foo", "bar");
+  item = ExtensionSettingsStore.getSetting("foo", "bar");
+  equal(item.id, undefined, "The add-on is not in control");
+  equal(item.initialValue, "not set", "The value is not set");
+
+  await ExtensionSettingsStore.addSetting(
+    id,
+    "foo",
+    "bar",
+    "set",
+    () => "not set"
+  );
+  item = ExtensionSettingsStore.getSetting("foo", "bar");
+  equal(item.id, id, "The add-on is in control");
+  equal(item.value, "set", "The value is set");
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_settings_uninstall_remove() {
+  await promiseStartupManager();
+
+  let id = "@add-on-uninstall";
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      applications: { gecko: { id } },
+    },
+  });
+
+  await extension.startup();
+  await ExtensionSettingsStore.initialize();
+
+  await ExtensionSettingsStore.addSetting(
+    id,
+    "foo",
+    "bar",
+    "set",
+    () => "not set"
+  );
+
+  let item = ExtensionSettingsStore.getSetting("foo", "bar");
+  equal(item.id, id, "The add-on is in control");
+  equal(item.value, "set", "The value is set");
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+
+  item = ExtensionSettingsStore.getSetting("foo", "bar");
+  equal(item, null, "The add-on setting was removed");
+});
+
+add_task(async function test_exceptions() {
+  await ExtensionSettingsStore.initialize();
+
+  await Assert.rejects(
+    ExtensionSettingsStore.addSetting(
+      1,
+      TEST_TYPE,
+      "key_not_a_function",
+      "val1",
+      "not a function"
+    ),
+    /initialValueCallback must be a function/,
+    "addSetting rejects with a callback that is not a function."
+  );
+});
+
+add_task(async function test_get_all_settings() {
+  await promiseStartupManager();
+
+  let testExtensions = [
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {
+        applications: { gecko: { id: "@first" } },
+      },
+    }),
+    ExtensionTestUtils.loadExtension({
+      useAddonManager: "temporary",
+      manifest: {
+        applications: { gecko: { id: "@second" } },
+      },
+    }),
+  ];
+
+  for (let extension of testExtensions) {
+    await extension.startup();
+  }
+
+  await ExtensionSettingsStore.initialize();
+
+  let items = ExtensionSettingsStore.getAllSettings("foo", "bar");
+  equal(items.length, 0, "There are no addons controlling this setting yet");
+
+  await ExtensionSettingsStore.addSetting(
+    "@first",
+    "foo",
+    "bar",
+    "set",
+    () => "not set"
+  );
+
+  items = ExtensionSettingsStore.getAllSettings("foo", "bar");
+  equal(items.length, 1, "The add-on setting has 1 addon trying to control it");
+
+  await ExtensionSettingsStore.addSetting(
+    "@second",
+    "foo",
+    "bar",
+    "setting",
+    () => "not set"
+  );
+
+  let item = ExtensionSettingsStore.getSetting("foo", "bar");
+  equal(item.id, "@second", "The second add-on is in control");
+  equal(item.value, "setting", "The second value is set");
+
+  items = ExtensionSettingsStore.getAllSettings("foo", "bar");
+  equal(
+    items.length,
+    2,
+    "The add-on setting has 2 addons trying to control it"
+  );
+
+  await ExtensionSettingsStore.removeSetting("@first", "foo", "bar");
+
+  items = ExtensionSettingsStore.getAllSettings("foo", "bar");
+  equal(items.length, 1, "There is only 1 addon controlling this setting");
+
+  await ExtensionSettingsStore.removeSetting("@second", "foo", "bar");
+
+  items = ExtensionSettingsStore.getAllSettings("foo", "bar");
+  equal(
+    items.length,
+    0,
+    "There is no longer any addon controlling this setting"
+  );
+
+  for (let extension of testExtensions) {
+    await extension.unload();
+  }
+
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_extension_content_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_extension_content_telemetry.js
new file mode 100644
index 0000000000..8044a07c71
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extension_content_telemetry.js
@@ -0,0 +1,151 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const HISTOGRAM = "WEBEXT_CONTENT_SCRIPT_INJECTION_MS";
+const HISTOGRAM_KEYED = "WEBEXT_CONTENT_SCRIPT_INJECTION_MS_BY_ADDONID";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function test_telemetry() {
+  function contentScript() {
+    browser.test.sendMessage("content-script-run");
+  }
+
+  Services.prefs.setBoolPref(
+    "toolkit.telemetry.testing.overrideProductsCheck",
+    true
+  );
+
+  let extension1 = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_end",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+  let extension2 = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_end",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  clearHistograms();
+
+  let process = IS_OOP ? "content" : "parent";
+  ok(
+    !(HISTOGRAM in getSnapshots(process)),
+    `No data recorded for histogram: ${HISTOGRAM}.`
+  );
+  ok(
+    !(HISTOGRAM_KEYED in getKeyedSnapshots(process)),
+    `No data recorded for keyed histogram: ${HISTOGRAM_KEYED}.`
+  );
+
+  await extension1.startup();
+  let extensionId = extension1.extension.id;
+
+  info(`Started extension with id ${extensionId}`);
+
+  ok(
+    !(HISTOGRAM in getSnapshots(process)),
+    `No data recorded for histogram after startup: ${HISTOGRAM}.`
+  );
+  ok(
+    !(HISTOGRAM_KEYED in getKeyedSnapshots(process)),
+    `No data recorded for keyed histogram: ${HISTOGRAM_KEYED}.`
+  );
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+  await extension1.awaitMessage("content-script-run");
+  await promiseTelemetryRecorded(HISTOGRAM, process, 1);
+  await promiseKeyedTelemetryRecorded(HISTOGRAM_KEYED, process, extensionId, 1);
+
+  equal(
+    valueSum(getSnapshots(process)[HISTOGRAM].values),
+    1,
+    `Data recorded for histogram: ${HISTOGRAM}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId].values),
+    1,
+    `Data recorded for histogram: ${HISTOGRAM_KEYED} with key ${extensionId}.`
+  );
+
+  await contentPage.close();
+  await extension1.unload();
+
+  await extension2.startup();
+  let extensionId2 = extension2.extension.id;
+
+  info(`Started extension with id ${extensionId2}`);
+
+  equal(
+    valueSum(getSnapshots(process)[HISTOGRAM].values),
+    1,
+    `No new data recorded for histogram after extension2 startup: ${HISTOGRAM}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId].values),
+    1,
+    `No new data recorded for histogram after extension2 startup: ${HISTOGRAM_KEYED} with key ${extensionId}.`
+  );
+  ok(
+    !(extensionId2 in getKeyedSnapshots(process)[HISTOGRAM_KEYED]),
+    `No data recorded for histogram after startup: ${HISTOGRAM_KEYED} with key ${extensionId2}.`
+  );
+
+  contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+  await extension2.awaitMessage("content-script-run");
+  await promiseTelemetryRecorded(HISTOGRAM, process, 2);
+  await promiseKeyedTelemetryRecorded(
+    HISTOGRAM_KEYED,
+    process,
+    extensionId2,
+    1
+  );
+
+  equal(
+    valueSum(getSnapshots(process)[HISTOGRAM].values),
+    2,
+    `Data recorded for histogram: ${HISTOGRAM}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId].values),
+    1,
+    `No new data recorded for histogram: ${HISTOGRAM_KEYED} with key ${extensionId}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId2].values),
+    1,
+    `Data recorded for histogram: ${HISTOGRAM_KEYED} with key ${extensionId2}.`
+  );
+
+  await contentPage.close();
+  await extension2.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_extension_startup_failure.js b/toolkit/components/extensions/test/xpcshell/test_ext_extension_startup_failure.js
new file mode 100644
index 0000000000..5e995b3aa6
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extension_startup_failure.js
@@ -0,0 +1,46 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { ExtensionTestCommon } = ChromeUtils.import(
+  "resource://testing-common/ExtensionTestCommon.jsm"
+);
+
+add_task(async function extension_startup_early_error() {
+  const EXTENSION_ID = "@extension-with-package-error";
+  let extension = ExtensionTestCommon.generate({
+    manifest: {
+      applications: { gecko: { id: EXTENSION_ID } },
+    },
+  });
+
+  extension.initLocale = async function() {
+    // Simulate error that happens during startup.
+    extension.packagingError("dummy error");
+  };
+
+  let startupPromise = extension.startup();
+
+  let policy = WebExtensionPolicy.getByID(EXTENSION_ID);
+  ok(policy, "WebExtensionPolicy instantiated at startup");
+  let readyPromise = policy.readyPromise;
+  ok(readyPromise, "WebExtensionPolicy.readyPromise is set");
+
+  await Assert.rejects(
+    startupPromise,
+    /dummy error/,
+    "Extension with packaging error should fail to load"
+  );
+
+  Assert.equal(
+    WebExtensionPolicy.getByID(EXTENSION_ID),
+    null,
+    "WebExtensionPolicy should be unregistered"
+  );
+
+  Assert.equal(
+    await readyPromise,
+    null,
+    "policy.readyPromise should be resolved with null"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_extension_startup_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_extension_startup_telemetry.js
new file mode 100644
index 0000000000..fe1fab4ea2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extension_startup_telemetry.js
@@ -0,0 +1,93 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const HISTOGRAM = "WEBEXT_EXTENSION_STARTUP_MS";
+const HISTOGRAM_KEYED = "WEBEXT_EXTENSION_STARTUP_MS_BY_ADDONID";
+
+function processSnapshot(snapshot) {
+  return snapshot.sum > 0;
+}
+
+function processKeyedSnapshot(snapshot) {
+  let res = {};
+  for (let key of Object.keys(snapshot)) {
+    res[key] = snapshot[key].sum > 0;
+  }
+  return res;
+}
+
+add_task(async function test_telemetry() {
+  Services.prefs.setBoolPref(
+    "toolkit.telemetry.testing.overrideProductsCheck",
+    true
+  );
+
+  let extension1 = ExtensionTestUtils.loadExtension({});
+  let extension2 = ExtensionTestUtils.loadExtension({});
+
+  clearHistograms();
+
+  assertHistogramEmpty(HISTOGRAM);
+  assertKeyedHistogramEmpty(HISTOGRAM_KEYED);
+
+  await extension1.startup();
+
+  assertHistogramSnapshot(
+    HISTOGRAM,
+    { processSnapshot, expectedValue: true },
+    `Data recorded for first extension for histogram: ${HISTOGRAM}.`
+  );
+
+  assertHistogramSnapshot(
+    HISTOGRAM_KEYED,
+    {
+      keyed: true,
+      processSnapshot: processKeyedSnapshot,
+      expectedValue: {
+        [extension1.extension.id]: true,
+      },
+    },
+    `Data recorded for first extension for histogram ${HISTOGRAM_KEYED}`
+  );
+
+  let histogram = Services.telemetry.getHistogramById(HISTOGRAM);
+  let histogramKeyed = Services.telemetry.getKeyedHistogramById(
+    HISTOGRAM_KEYED
+  );
+  let histogramSum = histogram.snapshot().sum;
+  let histogramSumExt1 = histogramKeyed.snapshot()[extension1.extension.id].sum;
+
+  await extension2.startup();
+
+  assertHistogramSnapshot(
+    HISTOGRAM,
+    {
+      processSnapshot: snapshot => snapshot.sum > histogramSum,
+      expectedValue: true,
+    },
+    `Data recorded for second extension for histogram: ${HISTOGRAM}.`
+  );
+
+  assertHistogramSnapshot(
+    HISTOGRAM_KEYED,
+    {
+      keyed: true,
+      processSnapshot: processKeyedSnapshot,
+      expectedValue: {
+        [extension1.extension.id]: true,
+        [extension2.extension.id]: true,
+      },
+    },
+    `Data recorded for second extension for histogram ${HISTOGRAM_KEYED}`
+  );
+
+  equal(
+    histogramKeyed.snapshot()[extension1.extension.id].sum,
+    histogramSumExt1,
+    `Data recorder for first extension is unchanged on the keyed histogram ${HISTOGRAM_KEYED}`
+  );
+
+  await extension1.unload();
+  await extension2.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_file_access.js b/toolkit/components/extensions/test/xpcshell/test_ext_file_access.js
new file mode 100644
index 0000000000..c05188cd38
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_file_access.js
@@ -0,0 +1,193 @@
+"use strict";
+
+const FILE_DUMMY_URL = Services.io.newFileURI(
+  do_get_file("data/dummy_page.html")
+).spec;
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+// XHR/fetch from content script to the page itself is allowed.
+add_task(async function content_script_xhr_to_self() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["file:///*"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+    files: {
+      "content_script.js": async () => {
+        let response = await fetch(document.URL);
+        browser.test.assertEq(200, response.status, "expected load");
+        let responseText = await response.text();
+        browser.test.assertTrue(
+          responseText.includes("<p>Page</p>"),
+          `expected file content in response of ${response.url}`
+        );
+
+        // Now with content.fetch:
+        response = await content.fetch(document.URL);
+        browser.test.assertEq(200, response.status, "expected load (content)");
+
+        browser.test.sendMessage("done");
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(FILE_DUMMY_URL);
+  await extension.awaitMessage("done");
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+// XHR/fetch for other file is not allowed, even with file://-permissions.
+add_task(async function content_script_xhr_to_other_file_not_allowed() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["file:///*"],
+      content_scripts: [
+        {
+          matches: ["file:///*"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+    files: {
+      "content_script.js": async () => {
+        let otherFileUrl = document.URL.replace(
+          "dummy_page.html",
+          "file_sample.html"
+        );
+        let x = new XMLHttpRequest();
+        x.open("GET", otherFileUrl);
+        await new Promise(resolve => {
+          x.onloadend = resolve;
+          x.send();
+        });
+        browser.test.assertEq(0, x.status, "expected error");
+        browser.test.assertEq("", x.responseText, "request should fail");
+
+        // Now with content.XMLHttpRequest.
+        x = new content.XMLHttpRequest();
+        x.open("GET", otherFileUrl);
+        x.onloadend = () => {
+          browser.test.assertEq(0, x.status, "expected error (content)");
+          browser.test.sendMessage("done");
+        };
+        x.send();
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(FILE_DUMMY_URL);
+  await extension.awaitMessage("done");
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+// "file://" permission does not grant access to files in the extension page.
+add_task(async function file_access_from_extension_page_not_allowed() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["file:///*"],
+      description: FILE_DUMMY_URL,
+    },
+    async background() {
+      const FILE_DUMMY_URL = browser.runtime.getManifest().description;
+
+      await browser.test.assertRejects(
+        fetch(FILE_DUMMY_URL),
+        /NetworkError when attempting to fetch resource/,
+        "block request to file from background page despite file permission"
+      );
+
+      // Regression test for bug 1420296 .
+      await browser.test.assertRejects(
+        fetch(FILE_DUMMY_URL, { mode: "same-origin" }),
+        /NetworkError when attempting to fetch resource/,
+        "block request to file from background page despite 'same-origin' mode"
+      );
+
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("done");
+
+  await extension.unload();
+});
+
+// webRequest listeners should see subresource requests from file:-principals.
+add_task(async function webRequest_script_request_from_file_principals() {
+  // Extension without file:-permission should not see the request.
+  let extensionWithoutFilePermission = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://example.net/", "webRequest"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.fail(`Unexpected request from ${details.originUrl}`);
+        },
+        { urls: ["http://example.net/intercept_by_webRequest.js"] }
+      );
+    },
+  });
+
+  // Extension with <all_urls> (which matches the resource URL at example.net
+  // and the origin at file://*/*) can see the request.
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["<all_urls>", "webRequest", "webRequestBlocking"],
+      web_accessible_resources: ["testDONE.html"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        ({ originUrl }) => {
+          browser.test.assertTrue(
+            /^file:.*file_do_load_script_subresource.html/.test(originUrl),
+            `expected script to be loaded from a local file (${originUrl})`
+          );
+          let redirectUrl = browser.runtime.getURL("testDONE.html");
+          return {
+            redirectUrl: `data:text/javascript,location.href='${redirectUrl}';`,
+          };
+        },
+        { urls: ["http://example.net/intercept_by_webRequest.js"] },
+        ["blocking"]
+      );
+    },
+    files: {
+      "testDONE.html": `<!DOCTYPE html><script src="testDONE.js"></script>`,
+      "testDONE.js"() {
+        browser.test.sendMessage("webRequest_redirect_completed");
+      },
+    },
+  });
+
+  await extensionWithoutFilePermission.startup();
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    Services.io.newFileURI(
+      do_get_file("data/file_do_load_script_subresource.html")
+    ).spec
+  );
+  await extension.awaitMessage("webRequest_redirect_completed");
+  await contentPage.close();
+
+  await extension.unload();
+  await extensionWithoutFilePermission.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_geckoProfiler_control.js b/toolkit/components/extensions/test/xpcshell/test_ext_geckoProfiler_control.js
new file mode 100644
index 0000000000..69c24cfc4b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_geckoProfiler_control.js
@@ -0,0 +1,208 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+
+let getExtension = () => {
+  return ExtensionTestUtils.loadExtension({
+    background: async function() {
+      const runningListener = isRunning => {
+        if (isRunning) {
+          browser.test.sendMessage("started");
+        } else {
+          browser.test.sendMessage("stopped");
+        }
+      };
+
+      browser.test.onMessage.addListener(async (message, data) => {
+        let result;
+        switch (message) {
+          case "start":
+            result = await browser.geckoProfiler.start({
+              bufferSize: 10000,
+              windowLength: 20,
+              interval: 0.5,
+              features: ["js"],
+              threads: ["GeckoMain"],
+            });
+            browser.test.assertEq(undefined, result, "start returns nothing.");
+            break;
+          case "stop":
+            result = await browser.geckoProfiler.stop();
+            browser.test.assertEq(undefined, result, "stop returns nothing.");
+            break;
+          case "pause":
+            result = await browser.geckoProfiler.pause();
+            browser.test.assertEq(undefined, result, "pause returns nothing.");
+            browser.test.sendMessage("paused");
+            break;
+          case "resume":
+            result = await browser.geckoProfiler.resume();
+            browser.test.assertEq(undefined, result, "resume returns nothing.");
+            browser.test.sendMessage("resumed");
+            break;
+          case "test profile":
+            result = await browser.geckoProfiler.getProfile();
+            browser.test.assertTrue(
+              "libs" in result,
+              "The profile contains libs."
+            );
+            browser.test.assertTrue(
+              "meta" in result,
+              "The profile contains meta."
+            );
+            browser.test.assertTrue(
+              "threads" in result,
+              "The profile contains threads."
+            );
+            browser.test.assertTrue(
+              result.threads.some(t => t.name == "GeckoMain"),
+              "The profile contains a GeckoMain thread."
+            );
+            browser.test.sendMessage("tested profile");
+            break;
+          case "test dump to file":
+            try {
+              await browser.geckoProfiler.dumpProfileToFile(data.fileName);
+              browser.test.sendMessage("tested dump to file", {});
+            } catch (e) {
+              browser.test.sendMessage("tested dump to file", {
+                error: e.message,
+              });
+            }
+            break;
+          case "test profile as array buffer":
+            let arrayBuffer = await browser.geckoProfiler.getProfileAsArrayBuffer();
+            browser.test.assertTrue(
+              arrayBuffer.byteLength >= 2,
+              "The profile array buffer contains data."
+            );
+            let textDecoder = new TextDecoder();
+            let profile = JSON.parse(textDecoder.decode(arrayBuffer));
+            browser.test.assertTrue(
+              "libs" in profile,
+              "The profile contains libs."
+            );
+            browser.test.assertTrue(
+              "meta" in profile,
+              "The profile contains meta."
+            );
+            browser.test.assertTrue(
+              "threads" in profile,
+              "The profile contains threads."
+            );
+            browser.test.assertTrue(
+              profile.threads.some(t => t.name == "GeckoMain"),
+              "The profile contains a GeckoMain thread."
+            );
+            browser.test.sendMessage("tested profile as array buffer");
+            break;
+          case "remove runningListener":
+            browser.geckoProfiler.onRunning.removeListener(runningListener);
+            browser.test.sendMessage("removed runningListener");
+            break;
+        }
+      });
+
+      browser.test.sendMessage("ready");
+
+      browser.geckoProfiler.onRunning.addListener(runningListener);
+    },
+
+    manifest: {
+      permissions: ["geckoProfiler"],
+      applications: {
+        gecko: {
+          id: "profilertest@mozilla.com",
+        },
+      },
+    },
+  });
+};
+
+let verifyProfileData = bytes => {
+  let textDecoder = new TextDecoder();
+  let profile = JSON.parse(textDecoder.decode(bytes));
+  ok("libs" in profile, "The profile contains libs.");
+  ok("meta" in profile, "The profile contains meta.");
+  ok("threads" in profile, "The profile contains threads.");
+  ok(
+    profile.threads.some(t => t.name == "GeckoMain"),
+    "The profile contains a GeckoMain thread."
+  );
+};
+
+add_task(async function testProfilerControl() {
+  const acceptedExtensionIdsPref =
+    "extensions.geckoProfiler.acceptedExtensionIds";
+  Services.prefs.setCharPref(
+    acceptedExtensionIdsPref,
+    "profilertest@mozilla.com"
+  );
+
+  let extension = getExtension();
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  await extension.awaitMessage("stopped");
+
+  extension.sendMessage("start");
+  await extension.awaitMessage("started");
+
+  extension.sendMessage("test profile");
+  await extension.awaitMessage("tested profile");
+
+  const profilerPath = OS.Path.join(OS.Constants.Path.profileDir, "profiler");
+  let data, fileName, targetPath;
+
+  // test with file name only
+  fileName = "bar.profile";
+  targetPath = OS.Path.join(profilerPath, fileName);
+  extension.sendMessage("test dump to file", { fileName });
+  data = await extension.awaitMessage("tested dump to file");
+  equal(data.error, undefined, "No error thrown");
+  ok(await OS.File.exists(targetPath), "Saved gecko profile exists.");
+  verifyProfileData(await OS.File.read(targetPath));
+
+  // test overwriting the formerly created file
+  extension.sendMessage("test dump to file", { fileName });
+  data = await extension.awaitMessage("tested dump to file");
+  equal(data.error, undefined, "No error thrown");
+  ok(await OS.File.exists(targetPath), "Saved gecko profile exists.");
+  verifyProfileData(await OS.File.read(targetPath));
+
+  // test with a POSIX path, which is not allowed
+  fileName = "foo/bar.profile";
+  targetPath = OS.Path.join(profilerPath, ...fileName.split("/"));
+  extension.sendMessage("test dump to file", { fileName });
+  data = await extension.awaitMessage("tested dump to file");
+  equal(data.error, "Path cannot contain a subdirectory.");
+  ok(!(await OS.File.exists(targetPath)), "Gecko profile hasn't been saved.");
+
+  // test with a non POSIX path which is not allowed
+  fileName = "foo\\bar.profile";
+  targetPath = OS.Path.join(profilerPath, ...fileName.split("\\"));
+  extension.sendMessage("test dump to file", { fileName });
+  data = await extension.awaitMessage("tested dump to file");
+  equal(data.error, "Path cannot contain a subdirectory.");
+  ok(!(await OS.File.exists(targetPath)), "Gecko profile hasn't been saved.");
+
+  extension.sendMessage("test profile as array buffer");
+  await extension.awaitMessage("tested profile as array buffer");
+
+  extension.sendMessage("pause");
+  await extension.awaitMessage("paused");
+
+  extension.sendMessage("resume");
+  await extension.awaitMessage("resumed");
+
+  extension.sendMessage("stop");
+  await extension.awaitMessage("stopped");
+
+  extension.sendMessage("remove runningListener");
+  await extension.awaitMessage("removed runningListener");
+
+  await extension.unload();
+
+  Services.prefs.clearUserPref(acceptedExtensionIdsPref);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_geckoProfiler_schema.js b/toolkit/components/extensions/test/xpcshell/test_ext_geckoProfiler_schema.js
new file mode 100644
index 0000000000..d0bbf7e60f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_geckoProfiler_schema.js
@@ -0,0 +1,56 @@
+"use strict";
+
+add_task(async function() {
+  const acceptedExtensionIdsPref =
+    "extensions.geckoProfiler.acceptedExtensionIds";
+  Services.prefs.setCharPref(
+    acceptedExtensionIdsPref,
+    "profilertest@mozilla.com"
+  );
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: () => {
+      browser.test.sendMessage(
+        "features",
+        Object.values(browser.geckoProfiler.ProfilerFeature)
+      );
+    },
+    manifest: {
+      permissions: ["geckoProfiler"],
+      applications: {
+        gecko: {
+          id: "profilertest@mozilla.com",
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+  let acceptedFeatures = await extension.awaitMessage("features");
+  await extension.unload();
+
+  Services.prefs.clearUserPref(acceptedExtensionIdsPref);
+
+  const allFeaturesAcceptedByProfiler = Services.profiler.GetAllFeatures();
+  ok(
+    allFeaturesAcceptedByProfiler.length >= 2,
+    "Either we've massively reduced the profiler's feature set, or something is wrong."
+  );
+
+  // Check that the list of available values in the ProfilerFeature enum
+  // matches the list of features supported by the profiler.
+  for (const feature of allFeaturesAcceptedByProfiler) {
+    ok(
+      acceptedFeatures.includes(feature),
+      `The schema of the geckoProfiler.start() method should accept the "${feature}" feature.`
+    );
+  }
+  for (const feature of acceptedFeatures) {
+    ok(
+      // Bug 1594566 - ignore Responsiveness until the extension is updated
+      allFeaturesAcceptedByProfiler.includes(feature) ||
+        feature == "responsiveness",
+      `The schema of the geckoProfiler.start() method mentions a "${feature}" feature which is not supported by the profiler.`
+    );
+  }
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_geturl.js b/toolkit/components/extensions/test/xpcshell/test_ext_geturl.js
new file mode 100644
index 0000000000..63b1016293
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_geturl.js
@@ -0,0 +1,61 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_contentscript() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.runtime.onMessage.addListener(([url1, url2]) => {
+        let url3 = browser.runtime.getURL("test_file.html");
+        let url4 = browser.extension.getURL("test_file.html");
+
+        browser.test.assertTrue(url1 !== undefined, "url1 defined");
+
+        browser.test.assertTrue(
+          url1.startsWith("moz-extension://"),
+          "url1 has correct scheme"
+        );
+        browser.test.assertTrue(
+          url1.endsWith("test_file.html"),
+          "url1 has correct leaf name"
+        );
+
+        browser.test.assertEq(url1, url2, "url2 matches");
+        browser.test.assertEq(url1, url3, "url3 matches");
+        browser.test.assertEq(url1, url4, "url4 matches");
+
+        browser.test.notifyPass("geturl");
+      });
+    },
+
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+    },
+
+    files: {
+      "content_script.js"() {
+        let url1 = browser.runtime.getURL("test_file.html");
+        let url2 = browser.extension.getURL("test_file.html");
+        browser.runtime.sendMessage([url1, url2]);
+      },
+    },
+  });
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  await extension.awaitFinish("geturl");
+
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_i18n.js b/toolkit/components/extensions/test/xpcshell/test_ext_i18n.js
new file mode 100644
index 0000000000..9709df842d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_i18n.js
@@ -0,0 +1,574 @@
+"use strict";
+
+const { Preferences } = ChromeUtils.import(
+  "resource://gre/modules/Preferences.jsm"
+);
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+var originalReqLocales = Services.locale.requestedLocales;
+
+registerCleanupFunction(() => {
+  Preferences.reset("intl.accept_languages");
+  Services.locale.requestedLocales = originalReqLocales;
+});
+
+add_task(async function test_i18n() {
+  function runTests(assertEq) {
+    let _ = browser.i18n.getMessage.bind(browser.i18n);
+
+    let url = browser.runtime.getURL("/");
+    assertEq(
+      url,
+      `moz-extension://${_("@@extension_id")}/`,
+      "@@extension_id builtin message"
+    );
+
+    assertEq("Foo.", _("Foo"), "Simple message in selected locale.");
+
+    assertEq("(bar)", _("bar"), "Simple message fallback in default locale.");
+
+    assertEq("", _("some-unknown-locale-string"), "Unknown locale string.");
+
+    assertEq("", _("@@unknown_builtin_string"), "Unknown built-in string.");
+    assertEq(
+      "",
+      _("@@bidi_unknown_builtin_string"),
+      "Unknown built-in bidi string."
+    );
+
+    assertEq("Føo.", _("Föo"), "Multi-byte message in selected locale.");
+
+    let substitutions = [];
+    substitutions[4] = "5";
+    substitutions[13] = "14";
+
+    assertEq(
+      "'$0' '14' '' '5' '$$$$' '$'.",
+      _("basic_substitutions", substitutions),
+      "Basic numeric substitutions"
+    );
+
+    assertEq(
+      "'$0' '' 'just a string' '' '$$$$' '$'.",
+      _("basic_substitutions", "just a string"),
+      "Basic numeric substitutions, with non-array value"
+    );
+
+    let values = _("named_placeholder_substitutions", [
+      "(subst $1 $2)",
+      "(2 $1 $2)",
+    ]).split("\n");
+
+    assertEq(
+      "_foo_ (subst $1 $2) _bar_",
+      values[0],
+      "Named and numeric substitution"
+    );
+
+    assertEq(
+      "(2 $1 $2)",
+      values[1],
+      "Numeric substitution amid named placeholders"
+    );
+
+    assertEq("$bad name$", values[2], "Named placeholder with invalid key");
+
+    assertEq("", values[3], "Named placeholder with an invalid value");
+
+    assertEq(
+      "Accepted, but shouldn't break.",
+      values[4],
+      "Named placeholder with a strange content value"
+    );
+
+    assertEq("$foo", values[5], "Non-placeholder token that should be ignored");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      default_locale: "jp",
+
+      content_scripts: [
+        { matches: ["http://*/*/file_sample.html"], js: ["content.js"] },
+      ],
+    },
+
+    files: {
+      "_locales/en_US/messages.json": {
+        foo: {
+          message: "Foo.",
+          description: "foo",
+        },
+
+        föo: {
+          message: "Føo.",
+          description: "foo",
+        },
+
+        basic_substitutions: {
+          message: "'$0' '$14' '$1' '$5' '$$$$$' '$$'.",
+          description: "foo",
+        },
+
+        Named_placeholder_substitutions: {
+          message:
+            "$Foo$\n$2\n$bad name$\n$bad_value$\n$bad_content_value$\n$foo",
+          description: "foo",
+          placeholders: {
+            foO: {
+              content: "_foo_ $1 _bar_",
+              description: "foo",
+            },
+
+            "bad name": {
+              content: "Nope.",
+              description: "bad name",
+            },
+
+            bad_value: "Nope.",
+
+            bad_content_value: {
+              content: ["Accepted, but shouldn't break."],
+              description: "bad value",
+            },
+          },
+        },
+
+        broken_placeholders: {
+          message: "$broken$",
+          description: "broken placeholders",
+          placeholders: "foo.",
+        },
+      },
+
+      "_locales/jp/messages.json": {
+        foo: {
+          message: "(foo)",
+          description: "foo",
+        },
+
+        bar: {
+          message: "(bar)",
+          description: "bar",
+        },
+      },
+
+      "content.js":
+        "new " +
+        function(runTestsFn) {
+          runTestsFn((...args) => {
+            browser.runtime.sendMessage(["assertEq", ...args]);
+          });
+
+          browser.runtime.sendMessage(["content-script-finished"]);
+        } +
+        `(${runTests})`,
+    },
+
+    background:
+      "new " +
+      function(runTestsFn) {
+        browser.runtime.onMessage.addListener(([msg, ...args]) => {
+          if (msg == "assertEq") {
+            browser.test.assertEq(...args);
+          } else {
+            browser.test.sendMessage(msg, ...args);
+          }
+        });
+
+        runTestsFn(browser.test.assertEq.bind(browser.test));
+      } +
+      `(${runTests})`,
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+  await extension.awaitMessage("content-script-finished");
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_i18n_negotiation() {
+  function runTests(expected) {
+    let _ = browser.i18n.getMessage.bind(browser.i18n);
+
+    browser.test.assertEq(expected, _("foo"), "Got expected message");
+  }
+
+  let extensionData = {
+    manifest: {
+      default_locale: "en_US",
+
+      content_scripts: [
+        { matches: ["http://*/*/file_sample.html"], js: ["content.js"] },
+      ],
+    },
+
+    files: {
+      "_locales/en_US/messages.json": {
+        foo: {
+          message: "English.",
+          description: "foo",
+        },
+      },
+
+      "_locales/jp/messages.json": {
+        foo: {
+          message: "\u65e5\u672c\u8a9e",
+          description: "foo",
+        },
+      },
+
+      "content.js":
+        "new " +
+        function(runTestsFn) {
+          browser.test.onMessage.addListener(expected => {
+            runTestsFn(expected);
+
+            browser.test.sendMessage("content-script-finished");
+          });
+          browser.test.sendMessage("content-ready");
+        } +
+        `(${runTests})`,
+    },
+
+    background:
+      "new " +
+      function(runTestsFn) {
+        browser.test.onMessage.addListener(expected => {
+          runTestsFn(expected);
+
+          browser.test.sendMessage("background-script-finished");
+        });
+      } +
+      `(${runTests})`,
+  };
+
+  // At the moment extension language negotiation is tied to Firefox language
+  // negotiation result. That means that to test an extension in `fr`, we need
+  // to mock `fr` being available in Firefox and then request it.
+  //
+  // In the future, we should provide some way for tests to decouple their
+  // language selection from that of Firefox.
+  Services.locale.availableLocales = ["en-US", "fr", "jp"];
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  for (let [lang, msg] of [
+    ["en-US", "English."],
+    ["jp", "\u65e5\u672c\u8a9e"],
+  ]) {
+    Services.locale.requestedLocales = [lang];
+
+    let extension = ExtensionTestUtils.loadExtension(extensionData);
+    await extension.startup();
+    await extension.awaitMessage("content-ready");
+
+    extension.sendMessage(msg);
+    await extension.awaitMessage("background-script-finished");
+    await extension.awaitMessage("content-script-finished");
+
+    await extension.unload();
+  }
+  Services.locale.requestedLocales = originalReqLocales;
+
+  await contentPage.close();
+});
+
+add_task(async function test_get_accept_languages() {
+  function checkResults(source, results, expected) {
+    browser.test.assertEq(
+      expected.length,
+      results.length,
+      `got expected number of languages in ${source}`
+    );
+    results.forEach((lang, index) => {
+      browser.test.assertEq(
+        expected[index],
+        lang,
+        `got expected language in ${source}`
+      );
+    });
+  }
+
+  function background(checkResultsFn) {
+    browser.test.onMessage.addListener(([msg, expected]) => {
+      browser.i18n.getAcceptLanguages().then(results => {
+        checkResultsFn("background", results, expected);
+
+        browser.test.sendMessage("background-done");
+      });
+    });
+  }
+
+  function content(checkResultsFn) {
+    browser.test.onMessage.addListener(([msg, expected]) => {
+      browser.i18n.getAcceptLanguages().then(results => {
+        checkResultsFn("contentScript", results, expected);
+
+        browser.test.sendMessage("content-done");
+      });
+    });
+    browser.test.sendMessage("content-loaded");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          run_at: "document_start",
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    background: `(${background})(${checkResults})`,
+
+    files: {
+      "content_script.js": `(${content})(${checkResults})`,
+    },
+  });
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  await extension.startup();
+  await extension.awaitMessage("content-loaded");
+
+  let expectedLangs = ["en-US", "en"];
+  extension.sendMessage(["expect-results", expectedLangs]);
+  await extension.awaitMessage("background-done");
+  await extension.awaitMessage("content-done");
+
+  expectedLangs = ["en-US", "en", "fr-CA", "fr"];
+  Preferences.set("intl.accept_languages", expectedLangs.toString());
+  extension.sendMessage(["expect-results", expectedLangs]);
+  await extension.awaitMessage("background-done");
+  await extension.awaitMessage("content-done");
+  Preferences.reset("intl.accept_languages");
+
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_get_ui_language() {
+  function getResults() {
+    return {
+      getUILanguage: browser.i18n.getUILanguage(),
+      getMessage: browser.i18n.getMessage("@@ui_locale"),
+    };
+  }
+
+  function checkResults(source, results, expected) {
+    browser.test.assertEq(
+      expected,
+      results.getUILanguage,
+      `Got expected getUILanguage result in ${source}`
+    );
+    browser.test.assertEq(
+      expected,
+      results.getMessage,
+      `Got expected getMessage result in ${source}`
+    );
+  }
+
+  function background(getResultsFn, checkResultsFn) {
+    browser.test.onMessage.addListener(([msg, expected]) => {
+      checkResultsFn("background", getResultsFn(), expected);
+
+      browser.test.sendMessage("background-done");
+    });
+  }
+
+  function content(getResultsFn, checkResultsFn) {
+    browser.test.onMessage.addListener(([msg, expected]) => {
+      checkResultsFn("contentScript", getResultsFn(), expected);
+
+      browser.test.sendMessage("content-done");
+    });
+    browser.test.sendMessage("content-loaded");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          run_at: "document_start",
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    background: `(${background})(${getResults}, ${checkResults})`,
+
+    files: {
+      "content_script.js": `(${content})(${getResults}, ${checkResults})`,
+    },
+  });
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  await extension.startup();
+  await extension.awaitMessage("content-loaded");
+
+  extension.sendMessage(["expect-results", "en-US"]);
+
+  await extension.awaitMessage("background-done");
+  await extension.awaitMessage("content-done");
+
+  // We don't currently have a good way to mock this.
+  if (false) {
+    Services.locale.requestedLocales = ["he"];
+
+    extension.sendMessage(["expect-results", "he"]);
+
+    await extension.awaitMessage("background-done");
+    await extension.awaitMessage("content-done");
+  }
+
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_detect_language() {
+  if (AppConstants.MOZ_BUILD_APP !== "browser") {
+    // This is not supported on Android.
+    return;
+  }
+
+  const af_string =
+    " aam skukuza die naam beteken hy wat skoonvee of hy wat alles onderstebo keer wysig " +
+    "bosveldkampe boskampe is kleiner afgeleë ruskampe wat oor min fasiliteite beskik daar is geen restaurante " +
+    "of winkels nie en slegs oornagbesoekers word toegelaat bateleur";
+  // String with intermixed French/English text
+  const fr_en_string =
+    "France is the largest country in Western Europe and the third-largest in Europe as a whole. " +
+    "A accès aux chiens et aux frontaux qui lui ont été il peut consulter et modifier ses collections et exporter " +
+    "Cet article concerne le pays européen aujourd’hui appelé République française. Pour d’autres usages du nom France, " +
+    "Pour une aide rapide et effective, veuiller trouver votre aide dans le menu ci-dessus." +
+    "Motoring events began soon after the construction of the first successful gasoline-fueled automobiles. The quick brown fox jumped over the lazy dog";
+
+  function checkResult(source, result, expected) {
+    browser.test.assertEq(
+      expected.isReliable,
+      result.isReliable,
+      "result.confident is true"
+    );
+    browser.test.assertEq(
+      expected.languages.length,
+      result.languages.length,
+      `result.languages contains the expected number of languages in ${source}`
+    );
+    expected.languages.forEach((lang, index) => {
+      browser.test.assertEq(
+        lang.percentage,
+        result.languages[index].percentage,
+        `element ${index} of result.languages array has the expected percentage in ${source}`
+      );
+      browser.test.assertEq(
+        lang.language,
+        result.languages[index].language,
+        `element ${index} of result.languages array has the expected language in ${source}`
+      );
+    });
+  }
+
+  function backgroundScript(checkResultFn) {
+    browser.test.onMessage.addListener(([msg, expected]) => {
+      browser.i18n.detectLanguage(msg).then(result => {
+        checkResultFn("background", result, expected);
+        browser.test.sendMessage("background-done");
+      });
+    });
+  }
+
+  function content(checkResultFn) {
+    browser.test.onMessage.addListener(([msg, expected]) => {
+      browser.i18n.detectLanguage(msg).then(result => {
+        checkResultFn("contentScript", result, expected);
+        browser.test.sendMessage("content-done");
+      });
+    });
+    browser.test.sendMessage("content-loaded");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          run_at: "document_start",
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    background: `(${backgroundScript})(${checkResult})`,
+
+    files: {
+      "content_script.js": `(${content})(${checkResult})`,
+    },
+  });
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  await extension.startup();
+  await extension.awaitMessage("content-loaded");
+
+  let expected = {
+    isReliable: true,
+    languages: [
+      {
+        language: "fr",
+        percentage: 67,
+      },
+      {
+        language: "en",
+        percentage: 32,
+      },
+    ],
+  };
+  extension.sendMessage([fr_en_string, expected]);
+  await extension.awaitMessage("background-done");
+  await extension.awaitMessage("content-done");
+
+  expected = {
+    isReliable: true,
+    languages: [
+      {
+        language: "af",
+        percentage: 99,
+      },
+    ],
+  };
+  extension.sendMessage([af_string, expected]);
+  await extension.awaitMessage("background-done");
+  await extension.awaitMessage("content-done");
+
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_i18n_css.js b/toolkit/components/extensions/test/xpcshell/test_ext_i18n_css.js
new file mode 100644
index 0000000000..c644ba9782
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_i18n_css.js
@@ -0,0 +1,197 @@
+"use strict";
+
+const { Preferences } = ChromeUtils.import(
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+const {
+  createAppInfo,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+// Some multibyte characters. This sample was taken from the encoding/api-basics.html web platform test.
+const MULTIBYTE_STRING = "z\xA2\u6C34\uD834\uDD1E\uF8FF\uDBFF\uDFFD\uFFFE";
+let getCSS = (a, b) => `a { content: '${a}'; } b { content: '${b}'; }`;
+
+let extensionData = {
+  background: function() {
+    function backgroundFetch(url) {
+      return new Promise((resolve, reject) => {
+        let xhr = new XMLHttpRequest();
+        xhr.overrideMimeType("text/plain");
+        xhr.open("GET", url);
+        xhr.onload = () => {
+          resolve(xhr.responseText);
+        };
+        xhr.onerror = reject;
+        xhr.send();
+      });
+    }
+
+    Promise.all([
+      backgroundFetch("foo.css"),
+      backgroundFetch("bar.CsS?x#y"),
+      backgroundFetch("foo.txt"),
+    ]).then(results => {
+      browser.test.assertEq(
+        "body { max-width: 42px; }",
+        results[0],
+        "CSS file localized"
+      );
+      browser.test.assertEq(
+        "body { max-width: 42px; }",
+        results[1],
+        "CSS file localized"
+      );
+
+      browser.test.assertEq(
+        "body { __MSG_foo__; }",
+        results[2],
+        "Text file not localized"
+      );
+
+      browser.test.notifyPass("i18n-css");
+    });
+
+    browser.test.sendMessage("ready", browser.runtime.getURL("/"));
+  },
+
+  manifest: {
+    applications: {
+      gecko: {
+        id: "i18n_css@mochi.test",
+      },
+    },
+
+    web_accessible_resources: [
+      "foo.css",
+      "foo.txt",
+      "locale.css",
+      "multibyte.css",
+    ],
+
+    content_scripts: [
+      {
+        matches: ["http://*/*/file_sample.html"],
+        css: ["foo.css"],
+        run_at: "document_start",
+      },
+      {
+        matches: ["http://*/*/file_sample.html"],
+        js: ["content.js"],
+      },
+    ],
+
+    default_locale: "en",
+  },
+
+  files: {
+    "_locales/en/messages.json": JSON.stringify({
+      foo: {
+        message: "max-width: 42px",
+        description: "foo",
+      },
+      multibyteKey: {
+        message: MULTIBYTE_STRING,
+      },
+    }),
+
+    "content.js": function() {
+      let style = getComputedStyle(document.body);
+      browser.test.sendMessage("content-maxWidth", style.maxWidth);
+    },
+
+    "foo.css": "body { __MSG_foo__; }",
+    "bar.CsS": "body { __MSG_foo__; }",
+    "foo.txt": "body { __MSG_foo__; }",
+    "locale.css":
+      '* { content: "__MSG_@@ui_locale__ __MSG_@@bidi_dir__ __MSG_@@bidi_reversed_dir__ __MSG_@@bidi_start_edge__ __MSG_@@bidi_end_edge__" }',
+    "multibyte.css": getCSS("__MSG_multibyteKey__", MULTIBYTE_STRING),
+  },
+};
+
+async function test_i18n_css(options = {}) {
+  extensionData.useAddonManager = options.useAddonManager;
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+  let baseURL = await extension.awaitMessage("ready");
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  let css = await contentPage.fetch(baseURL + "foo.css");
+
+  equal(
+    css,
+    "body { max-width: 42px; }",
+    "CSS file localized in mochitest scope"
+  );
+
+  let maxWidth = await extension.awaitMessage("content-maxWidth");
+
+  equal(maxWidth, "42px", "stylesheet correctly applied");
+
+  css = await contentPage.fetch(baseURL + "locale.css");
+  equal(
+    css,
+    '* { content: "en-US ltr rtl left right" }',
+    "CSS file localized in mochitest scope"
+  );
+
+  css = await contentPage.fetch(baseURL + "multibyte.css");
+  equal(
+    css,
+    getCSS(MULTIBYTE_STRING, MULTIBYTE_STRING),
+    "CSS file contains multibyte string"
+  );
+
+  await contentPage.close();
+
+  // We don't currently have a good way to mock this.
+  if (false) {
+    const DIR = "intl.l10n.pseudo";
+
+    // We don't wind up actually switching the chrome registry locale, since we
+    // don't have a chrome package for Hebrew. So just override it, and force
+    // RTL directionality.
+    const origReqLocales = Services.locale.requestedLocales;
+    Services.locale.requestedLocales = ["he"];
+    Preferences.set(DIR, "bidi");
+
+    css = await fetch(baseURL + "locale.css");
+    equal(
+      css,
+      '* { content: "he rtl ltr right left" }',
+      "CSS file localized in mochitest scope"
+    );
+
+    Services.locale.requestedLocales = origReqLocales;
+    Preferences.reset(DIR);
+  }
+
+  await extension.awaitFinish("i18n-css");
+  await extension.unload();
+}
+
+add_task(async function startup() {
+  await promiseStartupManager();
+});
+add_task(test_i18n_css);
+add_task(async function test_i18n_css_xpi() {
+  await test_i18n_css({ useAddonManager: "temporary" });
+});
+add_task(async function startup() {
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_idle.js b/toolkit/components/extensions/test/xpcshell/test_ext_idle.js
new file mode 100644
index 0000000000..8225278a7f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_idle.js
@@ -0,0 +1,270 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { MockRegistrar } = ChromeUtils.import(
+  "resource://testing-common/MockRegistrar.jsm"
+);
+
+let idleService = {
+  _observers: new Set(),
+  _activity: {
+    addCalls: [],
+    removeCalls: [],
+    observerFires: [],
+  },
+  _reset: function() {
+    this._observers.clear();
+    this._activity.addCalls = [];
+    this._activity.removeCalls = [];
+    this._activity.observerFires = [];
+  },
+  _fireObservers: function(state) {
+    for (let observer of this._observers.values()) {
+      observer.observe(observer, state, null);
+      this._activity.observerFires.push(state);
+    }
+  },
+  QueryInterface: ChromeUtils.generateQI(["nsIUserIdleService"]),
+  idleTime: 19999,
+  addIdleObserver: function(observer, time) {
+    this._observers.add(observer);
+    this._activity.addCalls.push(time);
+  },
+  removeIdleObserver: function(observer, time) {
+    this._observers.delete(observer);
+    this._activity.removeCalls.push(time);
+  },
+};
+
+function checkActivity(expectedActivity) {
+  let { expectedAdd, expectedRemove, expectedFires } = expectedActivity;
+  let { addCalls, removeCalls, observerFires } = idleService._activity;
+  equal(
+    expectedAdd.length,
+    addCalls.length,
+    "idleService.addIdleObserver was called the expected number of times"
+  );
+  equal(
+    expectedRemove.length,
+    removeCalls.length,
+    "idleService.removeIdleObserver was called the expected number of times"
+  );
+  equal(
+    expectedFires.length,
+    observerFires.length,
+    "idle observer was fired the expected number of times"
+  );
+  deepEqual(
+    addCalls,
+    expectedAdd,
+    "expected interval passed to idleService.addIdleObserver"
+  );
+  deepEqual(
+    removeCalls,
+    expectedRemove,
+    "expected interval passed to idleService.removeIdleObserver"
+  );
+  deepEqual(
+    observerFires,
+    expectedFires,
+    "expected topic passed to idle observer"
+  );
+}
+
+add_task(async function setup() {
+  let fakeIdleService = MockRegistrar.register(
+    "@mozilla.org/widget/useridleservice;1",
+    idleService
+  );
+  registerCleanupFunction(() => {
+    MockRegistrar.unregister(fakeIdleService);
+  });
+});
+
+add_task(async function testQueryStateActive() {
+  function background() {
+    browser.idle.queryState(20).then(
+      status => {
+        browser.test.assertEq("active", status, "Idle status is active");
+        browser.test.notifyPass("idle");
+      },
+      err => {
+        browser.test.fail(`Error: ${err} :: ${err.stack}`);
+        browser.test.notifyFail("idle");
+      }
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["idle"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("idle");
+  await extension.unload();
+});
+
+add_task(async function testQueryStateIdle() {
+  function background() {
+    browser.idle.queryState(15).then(
+      status => {
+        browser.test.assertEq("idle", status, "Idle status is idle");
+        browser.test.notifyPass("idle");
+      },
+      err => {
+        browser.test.fail(`Error: ${err} :: ${err.stack}`);
+        browser.test.notifyFail("idle");
+      }
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["idle"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("idle");
+  await extension.unload();
+});
+
+add_task(async function testOnlySetDetectionInterval() {
+  function background() {
+    browser.idle.setDetectionInterval(99);
+    browser.test.sendMessage("detectionIntervalSet");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["idle"],
+    },
+  });
+
+  idleService._reset();
+  await extension.startup();
+  await extension.awaitMessage("detectionIntervalSet");
+  idleService._fireObservers("idle");
+  checkActivity({ expectedAdd: [], expectedRemove: [], expectedFires: [] });
+  await extension.unload();
+});
+
+add_task(async function testSetDetectionIntervalBeforeAddingListener() {
+  function background() {
+    browser.idle.setDetectionInterval(99);
+    browser.idle.onStateChanged.addListener(newState => {
+      browser.test.assertEq(
+        "idle",
+        newState,
+        "listener fired with the expected state"
+      );
+      browser.test.sendMessage("listenerFired");
+    });
+    browser.test.sendMessage("listenerAdded");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["idle"],
+    },
+  });
+
+  idleService._reset();
+  await extension.startup();
+  await extension.awaitMessage("listenerAdded");
+  idleService._fireObservers("idle");
+  await extension.awaitMessage("listenerFired");
+  checkActivity({
+    expectedAdd: [99],
+    expectedRemove: [],
+    expectedFires: ["idle"],
+  });
+  // Defer unloading the extension so the asynchronous event listener
+  // reply finishes.
+  await new Promise(resolve => setTimeout(resolve, 0));
+  await extension.unload();
+});
+
+add_task(async function testSetDetectionIntervalAfterAddingListener() {
+  function background() {
+    browser.idle.onStateChanged.addListener(newState => {
+      browser.test.assertEq(
+        "idle",
+        newState,
+        "listener fired with the expected state"
+      );
+      browser.test.sendMessage("listenerFired");
+    });
+    browser.idle.setDetectionInterval(99);
+    browser.test.sendMessage("detectionIntervalSet");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["idle"],
+    },
+  });
+
+  idleService._reset();
+  await extension.startup();
+  await extension.awaitMessage("detectionIntervalSet");
+  idleService._fireObservers("idle");
+  await extension.awaitMessage("listenerFired");
+  checkActivity({
+    expectedAdd: [60, 99],
+    expectedRemove: [60],
+    expectedFires: ["idle"],
+  });
+
+  // Defer unloading the extension so the asynchronous event listener
+  // reply finishes.
+  await new Promise(resolve => setTimeout(resolve, 0));
+  await extension.unload();
+});
+
+add_task(async function testOnlyAddingListener() {
+  function background() {
+    browser.idle.onStateChanged.addListener(newState => {
+      browser.test.assertEq(
+        "active",
+        newState,
+        "listener fired with the expected state"
+      );
+      browser.test.sendMessage("listenerFired");
+    });
+    browser.test.sendMessage("listenerAdded");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["idle"],
+    },
+  });
+
+  idleService._reset();
+  await extension.startup();
+  await extension.awaitMessage("listenerAdded");
+  idleService._fireObservers("active");
+  await extension.awaitMessage("listenerFired");
+  // check that "idle-daily" topic does not cause a listener to fire
+  idleService._fireObservers("idle-daily");
+  checkActivity({
+    expectedAdd: [60],
+    expectedRemove: [],
+    expectedFires: ["active", "idle-daily"],
+  });
+
+  // Defer unloading the extension so the asynchronous event listener
+  // reply finishes.
+  await new Promise(resolve => setTimeout(resolve, 0));
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_incognito.js b/toolkit/components/extensions/test/xpcshell/test_ext_incognito.js
new file mode 100644
index 0000000000..9b17a633e9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_incognito.js
@@ -0,0 +1,302 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { AddonManager } = ChromeUtils.import(
+  "resource://gre/modules/AddonManager.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+AddonTestUtils.usePrivilegedSignatures = id => id.startsWith("privileged");
+
+// Assert on the expected "addonsManager.action" telemetry events (and optional filter events to verify
+// by using a given actionType).
+function assertActionAMTelemetryEvent(
+  expectedActionEvents,
+  assertMessage,
+  { actionType } = {}
+) {
+  const snapshot = Services.telemetry.snapshotEvents(
+    Ci.nsITelemetry.DATASET_PRERELEASE_CHANNELS,
+    true
+  );
+
+  ok(
+    snapshot.parent && !!snapshot.parent.length,
+    "Got parent telemetry events in the snapshot"
+  );
+
+  const events = snapshot.parent
+    .filter(([timestamp, category, method, object, value, extra]) => {
+      return (
+        category === "addonsManager" &&
+        method === "action" &&
+        (!actionType ? true : extra && extra.action === actionType)
+      );
+    })
+    .map(([timestamp, category, method, object, value, extra]) => {
+      return { method, object, value, extra };
+    });
+
+  Assert.deepEqual(events, expectedActionEvents, assertMessage);
+}
+
+async function runIncognitoTest(
+  extensionData,
+  privateBrowsingAllowed,
+  allowPrivateBrowsingByDefault
+) {
+  Services.prefs.setBoolPref(
+    "extensions.allowPrivateBrowsingByDefault",
+    allowPrivateBrowsingByDefault
+  );
+
+  let wrapper = ExtensionTestUtils.loadExtension(extensionData);
+  await wrapper.startup();
+  let { extension } = wrapper;
+
+  if (!allowPrivateBrowsingByDefault) {
+    // Check the permission if we're not allowPrivateBrowsingByDefault.
+    equal(
+      extension.permissions.has("internal:privateBrowsingAllowed"),
+      privateBrowsingAllowed,
+      "privateBrowsingAllowed in serialized extension"
+    );
+  }
+  equal(
+    extension.privateBrowsingAllowed,
+    privateBrowsingAllowed,
+    "privateBrowsingAllowed in extension"
+  );
+  equal(
+    extension.policy.privateBrowsingAllowed,
+    privateBrowsingAllowed,
+    "privateBrowsingAllowed on policy"
+  );
+
+  await wrapper.unload();
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+}
+
+add_task(async function test_extension_incognito_spanning() {
+  await runIncognitoTest({}, false, false);
+  await runIncognitoTest({}, true, true);
+});
+
+// Test that when we are restricted, we can override the restriction for tests.
+add_task(async function test_extension_incognito_override_spanning() {
+  let extensionData = {
+    incognitoOverride: "spanning",
+  };
+  await runIncognitoTest(extensionData, true, false);
+});
+
+// This tests that a privileged extension will always have private browsing.
+add_task(async function test_extension_incognito_privileged() {
+  let extensionData = {
+    isPrivileged: true,
+  };
+  await runIncognitoTest(extensionData, true, true);
+  await runIncognitoTest(extensionData, true, false);
+});
+
+// We only test spanning upgrades since that is the only allowed
+// incognito type prior to feature being turned on.
+add_task(async function test_extension_incognito_spanning_grandfathered() {
+  await AddonTestUtils.promiseStartupManager();
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", true);
+  Services.prefs.setBoolPref("extensions.incognito.migrated", false);
+
+  // This extension gets disabled before the "upgrade", it should not
+  // get grandfathered permissions.
+  const disabledAddonId = "disabled-ext@mozilla.com";
+  let disabledWrapper = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: disabledAddonId } },
+      incognito: "spanning",
+    },
+    useAddonManager: "permanent",
+  });
+  await disabledWrapper.startup();
+  let disabledPolicy = WebExtensionPolicy.getByID(disabledAddonId);
+
+  // Verify policy settings.
+  equal(
+    disabledPolicy.permissions.includes("internal:privateBrowsingAllowed"),
+    false,
+    "privateBrowsingAllowed is not in permissions for disabled addon"
+  );
+  equal(
+    disabledPolicy.privateBrowsingAllowed,
+    true,
+    "privateBrowsingAllowed in disabled addon"
+  );
+
+  let disabledAddon = await AddonManager.getAddonByID(disabledAddonId);
+  await disabledAddon.disable();
+
+  // This extension gets grandfathered permissions for private browsing.
+  let addonId = "grandfathered@mozilla.com";
+  let wrapper = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: addonId } },
+      incognito: "spanning",
+    },
+    useAddonManager: "permanent",
+  });
+  await wrapper.startup();
+  let policy = WebExtensionPolicy.getByID(addonId);
+
+  // Verify policy settings.
+  equal(
+    policy.permissions.includes("internal:privateBrowsingAllowed"),
+    false,
+    "privateBrowsingAllowed is not in permissions"
+  );
+  equal(
+    policy.privateBrowsingAllowed,
+    true,
+    "privateBrowsingAllowed in extension"
+  );
+
+  // Turn on incognito support and update the browser.
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+  // Disable the addonsManager telemetry event category, to ensure that it will
+  // be enabled automatically during the AddonManager/XPIProvider startup and
+  // the telemetry event recorded (See Bug 1540112 for a rationale).
+  Services.telemetry.setEventRecordingEnabled("addonsManager", false);
+  await AddonTestUtils.promiseRestartManager("2");
+  await wrapper.awaitStartup();
+
+  // Did it upgrade?
+  ok(
+    Services.prefs.getBoolPref("extensions.incognito.migrated", false),
+    "pref marked as migrated"
+  );
+
+  // Verify policy settings.
+  policy = WebExtensionPolicy.getByID(addonId);
+  ok(
+    policy.permissions.includes("internal:privateBrowsingAllowed"),
+    "privateBrowsingAllowed is in permissions"
+  );
+  equal(
+    policy.privateBrowsingAllowed,
+    true,
+    "privateBrowsingAllowed in extension"
+  );
+
+  // Verify the disabled addon did not get permissions.
+  disabledAddon = await AddonManager.getAddonByID(disabledAddonId);
+  await disabledAddon.enable();
+  disabledPolicy = WebExtensionPolicy.getByID(disabledAddonId);
+
+  // Verify policy settings.
+  equal(
+    disabledPolicy.permissions.includes("internal:privateBrowsingAllowed"),
+    false,
+    "privateBrowsingAllowed is not in permissions for disabled addon"
+  );
+  equal(
+    disabledPolicy.privateBrowsingAllowed,
+    false,
+    "privateBrowsingAllowed in disabled addon"
+  );
+
+  await wrapper.unload();
+  await disabledWrapper.unload();
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+  Services.prefs.clearUserPref("extensions.incognito.migrated");
+
+  const expectedEvents = [
+    {
+      method: "action",
+      object: "appUpgrade",
+      value: "on",
+      extra: { addonId, action: "privateBrowsingAllowed" },
+    },
+  ];
+
+  assertActionAMTelemetryEvent(
+    expectedEvents,
+    "Got the expected telemetry events for the grandfathered extensions",
+    { actionType: "privateBrowsingAllowed" }
+  );
+});
+
+add_task(async function test_extension_privileged_not_allowed() {
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  let addonId = "privileged_not_allowed@mochi.test";
+  let extensionData = {
+    manifest: {
+      version: "1.0",
+      applications: { gecko: { id: addonId } },
+      incognito: "not_allowed",
+    },
+    useAddonManager: "permanent",
+    isPrivileged: true,
+  };
+  let wrapper = ExtensionTestUtils.loadExtension(extensionData);
+  await wrapper.startup();
+  let policy = WebExtensionPolicy.getByID(addonId);
+  equal(
+    policy.extension.isPrivileged,
+    true,
+    "The test extension is privileged"
+  );
+  equal(
+    policy.privateBrowsingAllowed,
+    false,
+    "privateBrowsingAllowed is false"
+  );
+
+  await wrapper.unload();
+});
+
+// Test that we remove pb permission if an extension is updated to not_allowed.
+add_task(async function test_extension_upgrade_not_allowed() {
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  let addonId = "upgrade@mochi.test";
+  let extensionData = {
+    manifest: {
+      version: "1.0",
+      applications: { gecko: { id: addonId } },
+      incognito: "spanning",
+    },
+    useAddonManager: "permanent",
+    incognitoOverride: "spanning",
+  };
+  let wrapper = ExtensionTestUtils.loadExtension(extensionData);
+  await wrapper.startup();
+
+  let policy = WebExtensionPolicy.getByID(addonId);
+
+  equal(
+    policy.privateBrowsingAllowed,
+    true,
+    "privateBrowsingAllowed in extension"
+  );
+
+  extensionData.manifest.version = "2.0";
+  extensionData.manifest.incognito = "not_allowed";
+  await wrapper.upgrade(extensionData);
+
+  equal(wrapper.version, "2.0", "Expected extension version");
+  policy = WebExtensionPolicy.getByID(addonId);
+  equal(
+    policy.privateBrowsingAllowed,
+    false,
+    "privateBrowsingAllowed is false"
+  );
+
+  await wrapper.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_indexedDB_principal.js b/toolkit/components/extensions/test/xpcshell/test_ext_indexedDB_principal.js
new file mode 100644
index 0000000000..e520c48f26
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_indexedDB_principal.js
@@ -0,0 +1,101 @@
+"use strict";
+
+AddonTestUtils.init(this);
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+add_task(async function test_indexedDB_principal() {
+  Services.prefs.setBoolPref("privacy.firstparty.isolate", true);
+
+  await AddonTestUtils.promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {},
+    async background() {
+      browser.test.onMessage.addListener(async msg => {
+        if (msg == "create-storage") {
+          let request = window.indexedDB.open("TestDatabase");
+          request.onupgradeneeded = function(e) {
+            let db = e.target.result;
+            db.createObjectStore("TestStore");
+          };
+          request.onsuccess = function(e) {
+            let db = e.target.result;
+            let tx = db.transaction("TestStore", "readwrite");
+            let store = tx.objectStore("TestStore");
+            tx.oncomplete = () => browser.test.sendMessage("storage-created");
+            store.add("foo", "bar");
+            tx.onerror = function(e) {
+              browser.test.fail(`Failed with error ${tx.error.message}`);
+              // Don't wait for timeout
+              browser.test.sendMessage("storage-created");
+            };
+          };
+          request.onerror = function(e) {
+            browser.test.fail(`Failed with error ${request.error.message}`);
+            // Don't wait for timeout
+            browser.test.sendMessage("storage-created");
+          };
+          return;
+        }
+        if (msg == "check-storage") {
+          let dbRequest = window.indexedDB.open("TestDatabase");
+          dbRequest.onupgradeneeded = function() {
+            browser.test.fail("Database should exist");
+            browser.test.notifyFail("done");
+          };
+          dbRequest.onsuccess = function(e) {
+            let db = e.target.result;
+            let transaction = db.transaction("TestStore");
+            transaction.onerror = function(e) {
+              browser.test.fail(
+                `Failed with error ${transaction.error.message}`
+              );
+              browser.test.notifyFail("done");
+            };
+            let objectStore = transaction.objectStore("TestStore");
+            let request = objectStore.get("bar");
+            request.onsuccess = function(event) {
+              browser.test.assertEq(
+                request.result,
+                "foo",
+                "Got the expected data"
+              );
+              browser.test.notifyPass("done");
+            };
+            request.onerror = function(e) {
+              browser.test.fail(`Failed with error ${request.error.message}`);
+              browser.test.notifyFail("done");
+            };
+          };
+          dbRequest.onerror = function(e) {
+            browser.test.fail(`Failed with error ${dbRequest.error.message}`);
+            browser.test.notifyFail("done");
+          };
+        }
+      });
+    },
+  });
+
+  await extension.startup();
+  extension.sendMessage("create-storage");
+  await extension.awaitMessage("storage-created");
+
+  await extension.addon.disable();
+
+  Services.prefs.setBoolPref("privacy.firstparty.isolate", false);
+
+  await extension.addon.enable();
+  await extension.awaitStartup();
+
+  extension.sendMessage("check-storage");
+  await extension.awaitFinish("done");
+
+  await extension.unload();
+  Services.prefs.clearUserPref("privacy.firstparty.isolate");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_ipcBlob.js b/toolkit/components/extensions/test/xpcshell/test_ext_ipcBlob.js
new file mode 100644
index 0000000000..dd90d9bbc8
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_ipcBlob.js
@@ -0,0 +1,150 @@
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+add_task(async function test_parent_to_child() {
+  async function background() {
+    const dbName = "broken-blob";
+    const dbStore = "blob-store";
+    const dbVersion = 1;
+    const blobContent = "Hello World!";
+
+    let db = await new Promise((resolve, reject) => {
+      let dbOpen = indexedDB.open(dbName, dbVersion);
+      dbOpen.onerror = event => {
+        browser.test.fail(`Error opening the DB: ${event.target.error}`);
+        browser.test.notifyFail("test-completed");
+        reject();
+      };
+      dbOpen.onsuccess = event => {
+        resolve(event.target.result);
+      };
+      dbOpen.onupgradeneeded = event => {
+        let dbobj = event.target.result;
+        dbobj.onerror = error => {
+          browser.test.fail(`Error updating the DB: ${error.target.error}`);
+          browser.test.notifyFail("test-completed");
+          reject();
+        };
+        dbobj.createObjectStore(dbStore);
+      };
+    });
+
+    async function save(blob) {
+      let txn = db.transaction([dbStore], "readwrite");
+      let store = txn.objectStore(dbStore);
+      let req = store.put(blob, "key");
+
+      return new Promise((resolve, reject) => {
+        req.onsuccess = () => {
+          resolve();
+        };
+        req.onerror = event => {
+          browser.test.fail(
+            `Error saving the blob into the DB: ${event.target.error}`
+          );
+          browser.test.notifyFail("test-completed");
+          reject();
+        };
+      });
+    }
+
+    async function load() {
+      let txn = db.transaction([dbStore], "readonly");
+      let store = txn.objectStore(dbStore);
+      let req = store.getAll();
+
+      return new Promise((resolve, reject) => {
+        req.onsuccess = () => resolve(req.result);
+        req.onerror = () => reject(req.error);
+      })
+        .then(loadDetails => {
+          let blobs = [];
+          loadDetails.forEach(details => {
+            blobs.push(details);
+          });
+          return blobs[0];
+        })
+        .catch(err => {
+          browser.test.fail(
+            `Error loading the blob from the DB: ${err} :: ${err.stack}`
+          );
+          browser.test.notifyFail("test-completed");
+        });
+    }
+
+    browser.test.log("Blob creation");
+    await save(new Blob([blobContent]));
+    let blob = await load();
+
+    db.close();
+
+    browser.runtime.onMessage.addListener(([msg, what]) => {
+      browser.test.log("Message received from content: " + msg);
+      if (msg == "script-ready") {
+        return Promise.resolve({ blob });
+      }
+
+      if (msg == "script-value") {
+        browser.test.assertEq(blobContent, what, "blob content matches");
+        browser.test.notifyPass("test-completed");
+        return;
+      }
+
+      browser.test.fail(`Unexpected test message received: ${msg}`);
+    });
+
+    browser.test.sendMessage("bg-ready");
+  }
+
+  function contentScriptStart() {
+    browser.runtime.sendMessage(["script-ready"], response => {
+      let reader = new FileReader();
+      reader.addEventListener(
+        "load",
+        () => {
+          browser.runtime.sendMessage(["script-value", reader.result]);
+        },
+        { once: true }
+      );
+      reader.readAsText(response.blob);
+    });
+  }
+
+  let extensionData = {
+    background,
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script_start.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+    files: {
+      "content_script_start.js": contentScriptStart,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await extension.awaitMessage("bg-ready");
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  await extension.awaitFinish("test-completed");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_json_parser.js b/toolkit/components/extensions/test/xpcshell/test_ext_json_parser.js
new file mode 100644
index 0000000000..728df04c60
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_json_parser.js
@@ -0,0 +1,39 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_json_parser() {
+  const ID = "json@test.web.extension";
+
+  let xpi = AddonTestUtils.createTempWebExtensionFile({
+    files: {
+      "manifest.json": String.raw`{
+        // This is a manifest.
+        "applications": {"gecko": {"id": "${ID}"}},
+        "name": "This \" is // not a comment",
+        "version": "0.1\\" // , "description": "This is not a description"
+      }`,
+    },
+  });
+
+  let expectedManifest = {
+    applications: { gecko: { id: ID } },
+    name: 'This " is // not a comment',
+    version: "0.1\\",
+  };
+
+  let fileURI = Services.io.newFileURI(xpi);
+  let uri = NetUtil.newURI(`jar:${fileURI.spec}!/`);
+
+  let extension = new ExtensionData(uri);
+
+  await extension.parseManifest();
+
+  Assert.deepEqual(
+    extension.rawManifest,
+    expectedManifest,
+    "Manifest with correctly-filtered comments"
+  );
+
+  Services.obs.notifyObservers(xpi, "flush-cache-entry");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_l10n.js b/toolkit/components/extensions/test/xpcshell/test_ext_l10n.js
new file mode 100644
index 0000000000..b8eb3830fa
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_l10n.js
@@ -0,0 +1,150 @@
+"use strict";
+
+const { L10nRegistry, FileSource } = ChromeUtils.import(
+  "resource://gre/modules/L10nRegistry.jsm"
+);
+const { FileUtils } = ChromeUtils.import(
+  "resource://gre/modules/FileUtils.jsm"
+);
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+
+add_task(async function setup() {
+  // Add a test .ftl file
+  // (Note: other tests do this by patching L10nRegistry.load() but in
+  // this test L10nRegistry is also loaded in the extension process --
+  // just adding a new resource is easier than trying to patch
+  // L10nRegistry in all processes)
+  let dir = FileUtils.getDir("TmpD", ["l10ntest"]);
+  dir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+  await OS.File.writeAtomic(
+    OS.Path.join(dir.path, "test.ftl"),
+    "key = value\n"
+  );
+
+  let target = Services.io.newFileURI(dir);
+  let resProto = Services.io
+    .getProtocolHandler("resource")
+    .QueryInterface(Ci.nsIResProtocolHandler);
+
+  resProto.setSubstitution("l10ntest", target);
+
+  const source = new FileSource(
+    "test",
+    Services.locale.requestedLocales,
+    "resource://l10ntest/"
+  );
+  L10nRegistry.registerSources([source]);
+});
+
+// Test that privileged extensions can use fluent to get strings from
+// language packs (and that unprivileged extensions cannot)
+add_task(async function test_l10n_dom() {
+  const PAGE = `<!DOCTYPE html>
+                <html><head>
+                  <meta charset="utf8">
+                  <link rel="localization" href="test.ftl"/>
+                  <script src="page.js"></script>
+                </head></html>`;
+
+  function SCRIPT() {
+    window.addEventListener(
+      "load",
+      async () => {
+        try {
+          await document.l10n.ready;
+          let result = await document.l10n.formatValue("key");
+          browser.test.sendMessage("result", { success: true, result });
+        } catch (err) {
+          browser.test.sendMessage("result", {
+            success: false,
+            msg: err.message,
+          });
+        }
+      },
+      { once: true }
+    );
+  }
+
+  async function runTest(isPrivileged) {
+    let extension = ExtensionTestUtils.loadExtension({
+      background() {
+        browser.test.sendMessage("ready", browser.runtime.getURL("page.html"));
+      },
+      manifest: {
+        web_accessible_resources: ["page.html"],
+      },
+      isPrivileged,
+      files: {
+        "page.html": PAGE,
+        "page.js": SCRIPT,
+      },
+    });
+
+    await extension.startup();
+    let url = await extension.awaitMessage("ready");
+    let page = await ExtensionTestUtils.loadContentPage(url, { extension });
+    let results = await extension.awaitMessage("result");
+    await page.close();
+    await extension.unload();
+
+    return results;
+  }
+
+  // Everything should work for a privileged extension
+  let results = await runTest(true);
+  equal(results.success, true, "Translation succeeded in privileged extension");
+  equal(results.result, "value", "Translation got the right value");
+
+  // In an unprivleged extension, document.l10n shouldn't show up
+  results = await runTest(false);
+  equal(results.success, false, "Translation failed in unprivileged extension");
+  equal(
+    results.msg.endsWith("document.l10n is undefined"),
+    true,
+    "Translation failed due to missing document.l10n"
+  );
+});
+
+add_task(async function test_l10n_manifest() {
+  // Fluent can't be used to localize properties that the AddonManager
+  // reads (see comment inside ExtensionData.parseManifest for details)
+  // so test by localizing a property that only the extension framework
+  // cares about: page_action.  This means we can only do this test from
+  // browser.
+  if (AppConstants.MOZ_BUILD_APP != "browser") {
+    return;
+  }
+
+  AddonTestUtils.initializeURLPreloader();
+
+  async function runTest(isPrivileged) {
+    let extension = ExtensionTestUtils.loadExtension({
+      isPrivileged,
+      manifest: {
+        l10n_resources: ["test.ftl"],
+        page_action: {
+          default_title: "__MSG_key__",
+        },
+      },
+    });
+
+    await extension.startup();
+    let title = extension.extension.manifest.page_action.default_title;
+    await extension.unload();
+    return title;
+  }
+
+  let title = await runTest(true);
+  equal(
+    title,
+    "value",
+    "Manifest key localized with fluent in privileged extension"
+  );
+  title = await runTest(false);
+  equal(
+    title,
+    "__MSG_key__",
+    "Manifest key not localized in unprivileged extension"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_localStorage.js b/toolkit/components/extensions/test/xpcshell/test_ext_localStorage.js
new file mode 100644
index 0000000000..9ae4a4a873
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_localStorage.js
@@ -0,0 +1,50 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+function backgroundScript() {
+  let hasRun = localStorage.getItem("has-run");
+  let result;
+  if (!hasRun) {
+    localStorage.setItem("has-run", "yup");
+    localStorage.setItem("test-item", "item1");
+    result = "item1";
+  } else {
+    let data = localStorage.getItem("test-item");
+    if (data == "item1") {
+      localStorage.setItem("test-item", "item2");
+      result = "item2";
+    } else if (data == "item2") {
+      localStorage.removeItem("test-item");
+      result = "deleted";
+    } else if (!data) {
+      localStorage.clear();
+      result = "cleared";
+    }
+  }
+  browser.test.sendMessage("result", result);
+  browser.test.notifyPass("localStorage");
+}
+
+const ID = "test-webextension@mozilla.com";
+let extensionData = {
+  manifest: { applications: { gecko: { id: ID } } },
+  background: backgroundScript,
+};
+
+add_task(async function test_localStorage() {
+  const RESULTS = ["item1", "item2", "deleted", "cleared", "item1"];
+
+  for (let expected of RESULTS) {
+    let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+    await extension.startup();
+
+    let actual = await extension.awaitMessage("result");
+
+    await extension.awaitFinish("localStorage");
+    await extension.unload();
+
+    equal(actual, expected, "got expected localStorage data");
+  }
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_management.js b/toolkit/components/extensions/test/xpcshell/test_ext_management.js
new file mode 100644
index 0000000000..c6c73b2249
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_management.js
@@ -0,0 +1,205 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+add_task(async function setup() {
+  Services.prefs.setBoolPref(
+    "extensions.webextOptionalPermissionPrompts",
+    false
+  );
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("extensions.webextOptionalPermissionPrompts");
+  });
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_management_permission() {
+  async function background() {
+    const permObj = { permissions: ["management"] };
+
+    let hasPerm = await browser.permissions.contains(permObj);
+    browser.test.assertTrue(!hasPerm, "does not have management permission");
+    browser.test.assertTrue(
+      !!browser.management,
+      "management namespace exists"
+    );
+    // These require permission
+    let requires_permission = [
+      "getAll",
+      "get",
+      "install",
+      "setEnabled",
+      "onDisabled",
+      "onEnabled",
+      "onInstalled",
+      "onUninstalled",
+    ];
+
+    async function testAvailable() {
+      // These are always available regardless of permission.
+      for (let fn of ["getSelf", "uninstallSelf"]) {
+        browser.test.assertTrue(
+          !!browser.management[fn],
+          `management.${fn} exists`
+        );
+      }
+
+      let hasPerm = await browser.permissions.contains(permObj);
+      for (let fn of requires_permission) {
+        browser.test.assertEq(
+          hasPerm,
+          !!browser.management[fn],
+          `management.${fn} does not exist`
+        );
+      }
+    }
+
+    await testAvailable();
+
+    browser.test.onMessage.addListener(async msg => {
+      browser.test.log("test with permission");
+
+      // get permission
+      await browser.permissions.request(permObj);
+      let hasPerm = await browser.permissions.contains(permObj);
+      browser.test.assertTrue(
+        hasPerm,
+        "management permission.request accepted"
+      );
+      await testAvailable();
+
+      browser.management.onInstalled.addListener(() => {
+        browser.test.fail("onInstalled listener invoked");
+      });
+
+      browser.test.log("test without permission");
+      // remove permission
+      await browser.permissions.remove(permObj);
+      hasPerm = await browser.permissions.contains(permObj);
+      browser.test.assertFalse(
+        hasPerm,
+        "management permission.request removed"
+      );
+      await testAvailable();
+
+      browser.test.sendMessage("done");
+    });
+
+    browser.test.sendMessage("started");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "management@test",
+        },
+      },
+      optional_permissions: ["management"],
+    },
+    background,
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("started");
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request");
+  });
+  await extension.awaitMessage("done");
+
+  // Verify the onInstalled listener does not get used.
+  // The listener will make the test fail if fired.
+  let ext2 = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: {
+          id: "on-installed@test",
+        },
+      },
+      optional_permissions: ["management"],
+    },
+    useAddonManager: "temporary",
+  });
+  await ext2.startup();
+  await ext2.unload();
+
+  await extension.unload();
+});
+
+add_task(async function test_management_getAll() {
+  const id1 = "get_all_test1@tests.mozilla.com";
+  const id2 = "get_all_test2@tests.mozilla.com";
+
+  function getManifest(id) {
+    return {
+      applications: {
+        gecko: {
+          id,
+        },
+      },
+      name: id,
+      version: "1.0",
+      short_name: id,
+      permissions: ["management"],
+    };
+  }
+
+  async function background() {
+    browser.test.onMessage.addListener(async (msg, id) => {
+      let addon = await browser.management.get(id);
+      browser.test.sendMessage("addon", addon);
+    });
+
+    let addons = await browser.management.getAll();
+    browser.test.assertEq(
+      2,
+      addons.length,
+      "management.getAll returned correct number of add-ons."
+    );
+    browser.test.sendMessage("addons", addons);
+  }
+
+  let extension1 = ExtensionTestUtils.loadExtension({
+    manifest: getManifest(id1),
+    useAddonManager: "temporary",
+  });
+
+  let extension2 = ExtensionTestUtils.loadExtension({
+    manifest: getManifest(id2),
+    background,
+    useAddonManager: "temporary",
+  });
+
+  await extension1.startup();
+  await extension2.startup();
+
+  let addons = await extension2.awaitMessage("addons");
+  for (let id of [id1, id2]) {
+    let addon = addons.find(a => {
+      return a.id === id;
+    });
+    equal(
+      addon.name,
+      id,
+      `The extension with id ${id} was returned by getAll.`
+    );
+    equal(addon.shortName, id, "Additional extension metadata was correct");
+  }
+
+  extension2.sendMessage("getAddon", id1);
+  let addon = await extension2.awaitMessage("addon");
+  equal(addon.name, id1, `The extension with id ${id1} was returned by get.`);
+  equal(addon.shortName, id1, "Additional extension metadata was correct");
+
+  extension2.sendMessage("getAddon", id2);
+  addon = await extension2.awaitMessage("addon");
+  equal(addon.name, id2, `The extension with id ${id2} was returned by get.`);
+  equal(addon.shortName, id2, "Additional extension metadata was correct");
+
+  await extension2.unload();
+  await extension1.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_management_uninstall_self.js b/toolkit/components/extensions/test/xpcshell/test_ext_management_uninstall_self.js
new file mode 100644
index 0000000000..caed4f5525
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_management_uninstall_self.js
@@ -0,0 +1,146 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { AddonManager } = ChromeUtils.import(
+  "resource://gre/modules/AddonManager.jsm"
+);
+const { MockRegistrar } = ChromeUtils.import(
+  "resource://testing-common/MockRegistrar.jsm"
+);
+
+const id = "uninstall_self_test@tests.mozilla.com";
+
+const manifest = {
+  applications: {
+    gecko: {
+      id,
+    },
+  },
+  name: "test extension name",
+  version: "1.0",
+};
+
+const waitForUninstalled = () =>
+  new Promise(resolve => {
+    const listener = {
+      onUninstalled: async addon => {
+        equal(addon.id, id, "The expected add-on has been uninstalled");
+        let checkedAddon = await AddonManager.getAddonByID(addon.id);
+        equal(checkedAddon, null, "Add-on no longer exists");
+        AddonManager.removeAddonListener(listener);
+        resolve();
+      },
+    };
+    AddonManager.addAddonListener(listener);
+  });
+
+let promptService = {
+  _response: null,
+  QueryInterface: ChromeUtils.generateQI(["nsIPromptService"]),
+  confirmEx: function(...args) {
+    this._confirmExArgs = args;
+    return this._response;
+  },
+};
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  let fakePromptService = MockRegistrar.register(
+    "@mozilla.org/embedcomp/prompt-service;1",
+    promptService
+  );
+  registerCleanupFunction(() => {
+    MockRegistrar.unregister(fakePromptService);
+  });
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_management_uninstall_no_prompt() {
+  function background() {
+    browser.test.onMessage.addListener(msg => {
+      browser.management.uninstallSelf();
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest,
+    background,
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+  let addon = await AddonManager.getAddonByID(id);
+  notEqual(addon, null, "Add-on is installed");
+  extension.sendMessage("uninstall");
+  await waitForUninstalled();
+  Services.obs.notifyObservers(extension.extension.file, "flush-cache-entry");
+});
+
+add_task(async function test_management_uninstall_prompt_uninstall() {
+  promptService._response = 0;
+
+  function background() {
+    browser.test.onMessage.addListener(msg => {
+      browser.management.uninstallSelf({ showConfirmDialog: true });
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest,
+    background,
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+  let addon = await AddonManager.getAddonByID(id);
+  notEqual(addon, null, "Add-on is installed");
+  extension.sendMessage("uninstall");
+  await waitForUninstalled();
+
+  // Test localization strings
+  equal(promptService._confirmExArgs[1], `Uninstall ${manifest.name}`);
+  equal(
+    promptService._confirmExArgs[2],
+    `The extension “${manifest.name}” is requesting to be uninstalled. What would you like to do?`
+  );
+  equal(promptService._confirmExArgs[4], "Uninstall");
+  equal(promptService._confirmExArgs[5], "Keep Installed");
+  Services.obs.notifyObservers(extension.extension.file, "flush-cache-entry");
+});
+
+add_task(async function test_management_uninstall_prompt_keep() {
+  promptService._response = 1;
+
+  function background() {
+    browser.test.onMessage.addListener(async msg => {
+      await browser.test.assertRejects(
+        browser.management.uninstallSelf({ showConfirmDialog: true }),
+        "User cancelled uninstall of extension",
+        "Expected rejection when user declines uninstall"
+      );
+
+      browser.test.sendMessage("uninstall-rejected");
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest,
+    background,
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+
+  let addon = await AddonManager.getAddonByID(id);
+  notEqual(addon, null, "Add-on is installed");
+
+  extension.sendMessage("uninstall");
+  await extension.awaitMessage("uninstall-rejected");
+
+  addon = await AddonManager.getAddonByID(id);
+  notEqual(addon, null, "Add-on remains installed");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest.js
new file mode 100644
index 0000000000..cf6749f7a8
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest.js
@@ -0,0 +1,95 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+async function testIconPaths(icon, manifest, expectedError) {
+  let normalized = await ExtensionTestUtils.normalizeManifest(manifest);
+
+  if (expectedError) {
+    ok(
+      expectedError.test(normalized.error),
+      `Should have an error for ${JSON.stringify(icon)}`
+    );
+  } else {
+    ok(!normalized.error, `Should not have an error ${JSON.stringify(icon)}`);
+  }
+}
+
+add_task(async function test_manifest() {
+  let badpaths = ["", " ", "\t", "http://foo.com/icon.png"];
+  for (let path of badpaths) {
+    await testIconPaths(
+      path,
+      {
+        icons: path,
+      },
+      /Error processing icons/
+    );
+
+    await testIconPaths(
+      path,
+      {
+        icons: {
+          "16": path,
+        },
+      },
+      /Error processing icons/
+    );
+  }
+
+  let paths = [
+    "icon.png",
+    "/icon.png",
+    "./icon.png",
+    "path to an icon.png",
+    " icon.png",
+  ];
+  for (let path of paths) {
+    // manifest.icons is an object
+    await testIconPaths(
+      path,
+      {
+        icons: path,
+      },
+      /Error processing icons/
+    );
+
+    await testIconPaths(path, {
+      icons: {
+        "16": path,
+      },
+    });
+  }
+});
+
+add_task(async function test_manifest_warnings_on_unexpected_props() {
+  let extension = await ExtensionTestUtils.loadExtension({
+    manifest: {
+      background: {
+        scripts: ["bg.js"],
+        wrong_prop: true,
+      },
+    },
+    files: {
+      "bg.js": "",
+    },
+  });
+
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  await extension.startup();
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+
+  // Retrieve the warning message collected by the Extension class
+  // packagingWarning method.
+  const { warnings } = extension.extension;
+  equal(warnings.length, 1, "Got the expected number of manifest warnings");
+
+  const expectedMessage =
+    "Reading manifest: Warning processing background.wrong_prop";
+  ok(
+    warnings[0].startsWith(expectedMessage),
+    "Got the expected warning message format"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_content_security_policy.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_content_security_policy.js
new file mode 100644
index 0000000000..92dd5ee821
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_content_security_policy.js
@@ -0,0 +1,82 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+Services.prefs.setBoolPref("extensions.manifestV3.enabled", true);
+
+add_task(async function test_manifest_csp() {
+  let normalized = await ExtensionTestUtils.normalizeManifest({
+    content_security_policy: "script-src 'self'; object-src 'none'",
+  });
+
+  equal(normalized.error, undefined, "Should not have an error");
+  equal(normalized.errors.length, 0, "Should not have warnings");
+  equal(
+    normalized.value.content_security_policy,
+    "script-src 'self'; object-src 'none'",
+    "Should have the expected policy string"
+  );
+
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  normalized = await ExtensionTestUtils.normalizeManifest({
+    content_security_policy: "object-src 'none'",
+  });
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+
+  equal(normalized.error, undefined, "Should not have an error");
+
+  Assert.deepEqual(
+    normalized.errors,
+    [
+      "Error processing content_security_policy: Policy is missing a required ‘script-src’ directive",
+    ],
+    "Should have the expected warning"
+  );
+
+  equal(
+    normalized.value.content_security_policy,
+    null,
+    "Invalid policy string should be omitted"
+  );
+});
+
+add_task(async function test_manifest_csp_v3() {
+  let normalized = await ExtensionTestUtils.normalizeManifest({
+    manifest_version: 3,
+    content_security_policy: {
+      extension_pages: "script-src 'self' 'unsafe-eval'; object-src 'none'",
+    },
+  });
+
+  Assert.deepEqual(
+    normalized.errors,
+    [
+      "Error processing content_security_policy.extension_pages: ‘script-src’ directive contains a forbidden 'unsafe-eval' keyword",
+    ],
+    "Should have the expected warning"
+  );
+  equal(
+    normalized.value.content_security_policy.extension_pages,
+    null,
+    "Should have the expected policy string"
+  );
+
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  normalized = await ExtensionTestUtils.normalizeManifest({
+    manifest_version: 3,
+    content_security_policy: {
+      extension_pages: "object-src 'none'",
+    },
+  });
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+
+  equal(normalized.error, undefined, "Should not have an error");
+  equal(normalized.errors.length, 1, "Should have warnings");
+  Assert.deepEqual(
+    normalized.errors,
+    [
+      "Error processing content_security_policy.extension_pages: Policy is missing a required ‘script-src’ directive",
+    ],
+    "Should have the expected warning for extension_pages CSP"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_incognito.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_incognito.js
new file mode 100644
index 0000000000..5aa44c5885
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_incognito.js
@@ -0,0 +1,48 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_manifest_incognito() {
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  let normalized = await ExtensionTestUtils.normalizeManifest({
+    incognito: "spanning",
+  });
+
+  equal(normalized.error, undefined, "Should not have an error");
+  equal(normalized.errors.length, 0, "Should not have warnings");
+  equal(
+    normalized.value.incognito,
+    "spanning",
+    "Should have the expected incognito string"
+  );
+
+  normalized = await ExtensionTestUtils.normalizeManifest({
+    incognito: "not_allowed",
+  });
+
+  equal(normalized.error, undefined, "Should not have an error");
+  equal(normalized.errors.length, 0, "Should not have warnings");
+  equal(
+    normalized.value.incognito,
+    "not_allowed",
+    "Should have the expected incognito string"
+  );
+
+  normalized = await ExtensionTestUtils.normalizeManifest({
+    incognito: "split",
+  });
+
+  equal(
+    normalized.error,
+    'Error processing incognito: Invalid enumeration value "split"',
+    "Should have an error"
+  );
+  Assert.deepEqual(normalized.errors, [], "Should not have a warning");
+  equal(
+    normalized.value,
+    undefined,
+    "Invalid incognito string should be undefined"
+  );
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_minimum_chrome_version.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_minimum_chrome_version.js
new file mode 100644
index 0000000000..39119513fb
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_minimum_chrome_version.js
@@ -0,0 +1,12 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_manifest_minimum_chrome_version() {
+  let normalized = await ExtensionTestUtils.normalizeManifest({
+    minimum_chrome_version: "42",
+  });
+
+  equal(normalized.error, undefined, "Should not have an error");
+  equal(normalized.errors.length, 0, "Should not have warnings");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_minimum_opera_version.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_minimum_opera_version.js
new file mode 100644
index 0000000000..943e8b7270
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_minimum_opera_version.js
@@ -0,0 +1,12 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_manifest_minimum_opera_version() {
+  let normalized = await ExtensionTestUtils.normalizeManifest({
+    minimum_opera_version: "48",
+  });
+
+  equal(normalized.error, undefined, "Should not have an error");
+  equal(normalized.errors.length, 0, "Should not have warnings");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_manifest_themes.js b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_themes.js
new file mode 100644
index 0000000000..8cd44f06dc
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_manifest_themes.js
@@ -0,0 +1,35 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+async function test_theme_property(property) {
+  let normalized = await ExtensionTestUtils.normalizeManifest(
+    {
+      theme: {
+        [property]: {},
+      },
+    },
+    "manifest.ThemeManifest"
+  );
+
+  if (property === "unrecognized_key") {
+    const expectedWarning = `Warning processing theme.${property}`;
+    ok(
+      normalized.errors[0].includes(expectedWarning),
+      `The manifest warning ${JSON.stringify(
+        normalized.errors[0]
+      )} must contain ${JSON.stringify(expectedWarning)}`
+    );
+  } else {
+    equal(normalized.errors.length, 0, "Should have a warning");
+  }
+  equal(normalized.error, undefined, "Should not have an error");
+}
+
+add_task(async function test_manifest_themes() {
+  await test_theme_property("images");
+  await test_theme_property("colors");
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  await test_theme_property("unrecognized_key");
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_messaging_startup.js b/toolkit/components/extensions/test/xpcshell/test_ext_messaging_startup.js
new file mode 100644
index 0000000000..c629c51509
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_messaging_startup.js
@@ -0,0 +1,270 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "43"
+);
+
+let {
+  promiseRestartManager,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  true
+);
+
+const PAGE_HTML = `<!DOCTYPE html><meta charset="utf-8"><script src="script.js"></script>`;
+
+function trackEvents(wrapper) {
+  let events = new Map();
+  for (let event of ["background-page-event", "start-background-page"]) {
+    events.set(event, false);
+    wrapper.extension.once(event, () => events.set(event, true));
+  }
+  return events;
+}
+
+async function test(what, background, script) {
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/*"],
+          js: ["script.js"],
+        },
+      ],
+    },
+
+    files: {
+      "page.html": PAGE_HTML,
+      "script.js": script,
+    },
+
+    background,
+  });
+
+  info(`Set up ${what} listener`);
+  await extension.startup();
+  await extension.awaitMessage("bg-ran");
+
+  info(`Test wakeup for ${what} from an extension page`);
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  function awaitBgEvent() {
+    return new Promise(resolve =>
+      extension.extension.once("background-page-event", resolve)
+    );
+  }
+
+  let events = trackEvents(extension);
+
+  let url = extension.extension.baseURI.resolve("page.html");
+
+  let [, page] = await Promise.all([
+    awaitBgEvent(),
+    ExtensionTestUtils.loadContentPage(url, { extension }),
+  ]);
+
+  equal(
+    events.get("background-page-event"),
+    true,
+    "Should have gotten a background page event"
+  );
+  equal(
+    events.get("start-background-page"),
+    false,
+    "Background page should not be started"
+  );
+
+  equal(extension.messageQueue.size, 0, "Have not yet received bg-ran message");
+
+  let promise = extension.awaitMessage("bg-ran");
+  Services.obs.notifyObservers(null, "browser-delayed-startup-finished");
+  await promise;
+
+  equal(
+    events.get("start-background-page"),
+    true,
+    "Should have gotten start-background-page event"
+  );
+
+  await extension.awaitFinish("messaging-test");
+  ok(true, "Background page loaded and received message from extension page");
+
+  await page.close();
+
+  info(`Test wakeup for ${what} from a content script`);
+  ExtensionParent._resetStartupPromises();
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  events = trackEvents(extension);
+
+  [, page] = await Promise.all([
+    awaitBgEvent(),
+    ExtensionTestUtils.loadContentPage(
+      "http://example.com/data/file_sample.html"
+    ),
+  ]);
+
+  equal(
+    events.get("background-page-event"),
+    true,
+    "Should have gotten a background page event"
+  );
+  equal(
+    events.get("start-background-page"),
+    false,
+    "Background page should not be started"
+  );
+
+  equal(extension.messageQueue.size, 0, "Have not yet received bg-ran message");
+
+  promise = extension.awaitMessage("bg-ran");
+  Services.obs.notifyObservers(null, "browser-delayed-startup-finished");
+  await promise;
+
+  equal(
+    events.get("start-background-page"),
+    true,
+    "Should have gotten start-background-page event"
+  );
+
+  await extension.awaitFinish("messaging-test");
+  ok(true, "Background page loaded and received message from content script");
+
+  await page.close();
+  await extension.unload();
+
+  await promiseShutdownManager();
+  ExtensionParent._resetStartupPromises();
+}
+
+add_task(function test_onMessage() {
+  function script() {
+    browser.runtime.sendMessage("ping").then(reply => {
+      browser.test.assertEq(
+        reply,
+        "pong",
+        "Extension page received pong reply"
+      );
+      browser.test.notifyPass("messaging-test");
+    });
+  }
+
+  async function background() {
+    browser.runtime.onMessage.addListener((msg, sender) => {
+      browser.test.assertEq(
+        msg,
+        "ping",
+        "Background page received ping message"
+      );
+      return Promise.resolve("pong");
+    });
+
+    // addListener() returns right away but make a round trip to the
+    // main process to ensure the persistent onMessage listener is recorded.
+    await browser.runtime.getBrowserInfo();
+    browser.test.sendMessage("bg-ran");
+  }
+
+  return test("onMessage", background, script);
+});
+
+add_task(function test_onConnect() {
+  function script() {
+    let port = browser.runtime.connect();
+    port.onMessage.addListener(msg => {
+      browser.test.assertEq(msg, "pong", "Extension page received pong reply");
+      browser.test.notifyPass("messaging-test");
+    });
+    port.postMessage("ping");
+  }
+
+  async function background() {
+    browser.runtime.onConnect.addListener(port => {
+      port.onMessage.addListener(msg => {
+        browser.test.assertEq(
+          msg,
+          "ping",
+          "Background page received ping message"
+        );
+        port.postMessage("pong");
+      });
+    });
+
+    // addListener() returns right away but make a round trip to the
+    // main process to ensure the persistent onMessage listener is recorded.
+    await browser.runtime.getBrowserInfo();
+    browser.test.sendMessage("bg-ran");
+  }
+
+  return test("onConnect", background, script);
+});
+
+// Test that messaging works if the background page is started before
+// any messages are exchanged.  (See bug 1467136 for an example of how
+// this broke at one point).
+add_task(async function test_other_startup() {
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+
+    async background() {
+      browser.runtime.onMessage.addListener(msg => {
+        browser.test.notifyPass("startup");
+      });
+
+      // addListener() returns right away but make a round trip to the
+      // main process to ensure the persistent onMessage listener is recorded.
+      await browser.runtime.getBrowserInfo();
+      browser.test.sendMessage("bg-ran");
+    },
+
+    files: {
+      "page.html": PAGE_HTML,
+      "script.js"() {
+        browser.runtime.sendMessage("ping");
+      },
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("bg-ran");
+
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  // Start the background page.  No message have been sent at this point.
+  Services.obs.notifyObservers(null, "sessionstore-windows-restored");
+  await extension.awaitMessage("bg-ran");
+
+  // Now that the background page is fully started, load a new page that
+  // sends a message to the background page.
+  let url = extension.extension.baseURI.resolve("page.html");
+  let page = await ExtensionTestUtils.loadContentPage(url, { extension });
+
+  await extension.awaitFinish("startup");
+
+  await page.close();
+  await extension.unload();
+
+  await promiseShutdownManager();
+  ExtensionParent._resetStartupPromises();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging.js b/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging.js
new file mode 100644
index 0000000000..f71001a74d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging.js
@@ -0,0 +1,685 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+/* globals chrome */
+
+const PREF_MAX_READ = "webextensions.native-messaging.max-input-message-bytes";
+const PREF_MAX_WRITE =
+  "webextensions.native-messaging.max-output-message-bytes";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+const ECHO_BODY = String.raw`
+  import struct
+  import sys
+
+  stdin = getattr(sys.stdin, 'buffer', sys.stdin)
+  stdout = getattr(sys.stdout, 'buffer', sys.stdout)
+
+  while True:
+    rawlen = stdin.read(4)
+    if len(rawlen) == 0:
+      sys.exit(0)
+    msglen = struct.unpack('@I', rawlen)[0]
+    msg = stdin.read(msglen)
+
+    stdout.write(struct.pack('@I', msglen))
+    stdout.write(msg)
+`;
+
+const INFO_BODY = String.raw`
+  import json
+  import os
+  import struct
+  import sys
+
+  msg = json.dumps({"args": sys.argv, "cwd": os.getcwd()})
+  if sys.version_info >= (3,):
+    sys.stdout.buffer.write(struct.pack('@I', len(msg)))
+  else:
+    sys.stdout.write(struct.pack('@I', len(msg)))
+  sys.stdout.write(msg)
+  sys.exit(0)
+`;
+
+const STDERR_LINES = ["hello stderr", "this should be a separate line"];
+let STDERR_MSG = STDERR_LINES.join("\\n");
+
+const STDERR_BODY = String.raw`
+  import sys
+  sys.stderr.write("${STDERR_MSG}")
+`;
+
+let SCRIPTS = [
+  {
+    name: "echo",
+    description: "a native app that echoes back messages it receives",
+    script: ECHO_BODY.replace(/^ {2}/gm, ""),
+  },
+  {
+    name: "info",
+    description: "a native app that gives some info about how it was started",
+    script: INFO_BODY.replace(/^ {2}/gm, ""),
+  },
+  {
+    name: "stderr",
+    description: "a native app that writes to stderr and then exits",
+    script: STDERR_BODY.replace(/^ {2}/gm, ""),
+  },
+];
+
+if (AppConstants.platform == "win") {
+  SCRIPTS.push({
+    name: "echocmd",
+    description: "echo but using a .cmd file",
+    scriptExtension: "cmd",
+    script: ECHO_BODY.replace(/^ {2}/gm, ""),
+  });
+}
+
+add_task(async function setup() {
+  await setupHosts(SCRIPTS);
+});
+
+// Test the basic operation of native messaging with a simple
+// script that echoes back whatever message is sent to it.
+add_task(async function test_happy_path() {
+  function background() {
+    let port = browser.runtime.connectNative("echo");
+    port.onMessage.addListener(msg => {
+      browser.test.sendMessage("message", msg);
+    });
+    browser.test.onMessage.addListener((what, payload) => {
+      if (what == "send") {
+        if (payload._json) {
+          let json = payload._json;
+          payload.toJSON = () => json;
+          delete payload._json;
+        }
+        port.postMessage(payload);
+      }
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  const tests = [
+    {
+      data: "this is a string",
+      what: "simple string",
+    },
+    {
+      data: "Это юникода",
+      what: "unicode string",
+    },
+    {
+      data: { test: "hello" },
+      what: "simple object",
+    },
+    {
+      data: {
+        what: "An object with a few properties",
+        number: 123,
+        bool: true,
+        nested: { what: "another object" },
+      },
+      what: "object with several properties",
+    },
+
+    {
+      data: {
+        ignoreme: true,
+        _json: { data: "i have a tojson method" },
+      },
+      expected: { data: "i have a tojson method" },
+      what: "object with toJSON() method",
+    },
+  ];
+  for (let test of tests) {
+    extension.sendMessage("send", test.data);
+    let response = await extension.awaitMessage("message");
+    let expected = test.expected || test.data;
+    deepEqual(response, expected, `Echoed a message of type ${test.what}`);
+  }
+
+  let procCount = await getSubprocessCount();
+  equal(procCount, 1, "subprocess is still running");
+  let exitPromise = waitForSubprocessExit();
+  await extension.unload();
+  await exitPromise;
+});
+
+// Just test that the given app (which should be the echo script above)
+// can be started.  Used to test corner cases in how the native application
+// is located/launched.
+async function simpleTest(app) {
+  function background(appname) {
+    let port = browser.runtime.connectNative(appname);
+    let MSG = "test";
+    port.onMessage.addListener(msg => {
+      browser.test.assertEq(MSG, msg, "Got expected message back");
+      browser.test.sendMessage("done");
+    });
+    port.postMessage(MSG);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${background})(${JSON.stringify(app)});`,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+
+  let procCount = await getSubprocessCount();
+  equal(procCount, 1, "subprocess is still running");
+  let exitPromise = waitForSubprocessExit();
+  await extension.unload();
+  await exitPromise;
+}
+
+if (AppConstants.platform == "win") {
+  // "relative.echo" has a relative path in the host manifest.
+  add_task(function test_relative_path() {
+    return simpleTest("relative.echo");
+  });
+
+  // "echocmd" uses a .cmd file instead of a .bat file
+  add_task(function test_cmd_file() {
+    return simpleTest("echocmd");
+  });
+}
+
+// Test sendNativeMessage()
+add_task(async function test_sendNativeMessage() {
+  async function background() {
+    let MSG = { test: "hello world" };
+
+    // Check error handling
+    await browser.test.assertRejects(
+      browser.runtime.sendNativeMessage("nonexistent", MSG),
+      /Attempt to postMessage on disconnected port/,
+      "sendNativeMessage() to a nonexistent app failed"
+    );
+
+    // Check regular message exchange
+    let reply = await browser.runtime.sendNativeMessage("echo", MSG);
+
+    let expected = JSON.stringify(MSG);
+    let received = JSON.stringify(reply);
+    browser.test.assertEq(expected, received, "Received echoed native message");
+
+    browser.test.sendMessage("finished");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("finished");
+
+  // With sendNativeMessage(), the subprocess should be disconnected
+  // after exchanging a single message.
+  await waitForSubprocessExit();
+
+  await extension.unload();
+});
+
+// Test calling Port.disconnect()
+add_task(async function test_disconnect() {
+  function background() {
+    let port = browser.runtime.connectNative("echo");
+    port.onMessage.addListener((msg, msgPort) => {
+      browser.test.assertEq(
+        port,
+        msgPort,
+        "onMessage handler should receive the port as the second argument"
+      );
+      browser.test.sendMessage("message", msg);
+    });
+    port.onDisconnect.addListener(msgPort => {
+      browser.test.fail("onDisconnect should not be called for disconnect()");
+    });
+    browser.test.onMessage.addListener((what, payload) => {
+      if (what == "send") {
+        if (payload._json) {
+          let json = payload._json;
+          payload.toJSON = () => json;
+          delete payload._json;
+        }
+        port.postMessage(payload);
+      } else if (what == "disconnect") {
+        try {
+          port.disconnect();
+          browser.test.assertThrows(
+            () => port.postMessage("void"),
+            "Attempt to postMessage on disconnected port"
+          );
+          browser.test.sendMessage("disconnect-result", { success: true });
+        } catch (err) {
+          browser.test.sendMessage("disconnect-result", {
+            success: false,
+            errmsg: err.message,
+          });
+        }
+      }
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  extension.sendMessage("send", "test");
+  let response = await extension.awaitMessage("message");
+  equal(response, "test", "Echoed a string");
+
+  let procCount = await getSubprocessCount();
+  equal(procCount, 1, "subprocess is running");
+
+  extension.sendMessage("disconnect");
+  response = await extension.awaitMessage("disconnect-result");
+  equal(response.success, true, "disconnect succeeded");
+
+  info("waiting for subprocess to exit");
+  await waitForSubprocessExit();
+  procCount = await getSubprocessCount();
+  equal(procCount, 0, "subprocess is no longer running");
+
+  extension.sendMessage("disconnect");
+  response = await extension.awaitMessage("disconnect-result");
+  equal(response.success, true, "second call to disconnect silently ignored");
+
+  await extension.unload();
+});
+
+// Test the limit on message size for writing
+add_task(async function test_write_limit() {
+  Services.prefs.setIntPref(PREF_MAX_WRITE, 10);
+  function clearPref() {
+    Services.prefs.clearUserPref(PREF_MAX_WRITE);
+  }
+  registerCleanupFunction(clearPref);
+
+  function background() {
+    const PAYLOAD = "0123456789A";
+    let port = browser.runtime.connectNative("echo");
+    try {
+      port.postMessage(PAYLOAD);
+      browser.test.sendMessage("result", null);
+    } catch (ex) {
+      browser.test.sendMessage("result", ex.message);
+    }
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+
+  let errmsg = await extension.awaitMessage("result");
+  notEqual(
+    errmsg,
+    null,
+    "native postMessage() failed for overly large message"
+  );
+
+  await extension.unload();
+  await waitForSubprocessExit();
+
+  clearPref();
+});
+
+// Test the limit on message size for reading
+add_task(async function test_read_limit() {
+  Services.prefs.setIntPref(PREF_MAX_READ, 10);
+  function clearPref() {
+    Services.prefs.clearUserPref(PREF_MAX_READ);
+  }
+  registerCleanupFunction(clearPref);
+
+  function background() {
+    const PAYLOAD = "0123456789A";
+    let port = browser.runtime.connectNative("echo");
+    port.onDisconnect.addListener(msgPort => {
+      browser.test.assertEq(
+        port,
+        msgPort,
+        "onDisconnect handler should receive the port as the first argument"
+      );
+      browser.test.assertEq(
+        "Native application tried to send a message of 13 bytes, which exceeds the limit of 10 bytes.",
+        port.error && port.error.message
+      );
+      browser.test.sendMessage("result", "disconnected");
+    });
+    port.onMessage.addListener(msg => {
+      browser.test.sendMessage("result", "message");
+    });
+    port.postMessage(PAYLOAD);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+
+  let result = await extension.awaitMessage("result");
+  equal(
+    result,
+    "disconnected",
+    "native port disconnected on receiving large message"
+  );
+
+  await extension.unload();
+  await waitForSubprocessExit();
+
+  clearPref();
+});
+
+// Test that an extension without the nativeMessaging permission cannot
+// use native messaging.
+add_task(async function test_ext_permission() {
+  function background() {
+    browser.test.assertEq(
+      chrome.runtime.connectNative,
+      undefined,
+      "chrome.runtime.connectNative does not exist without nativeMessaging permission"
+    );
+    browser.test.assertEq(
+      browser.runtime.connectNative,
+      undefined,
+      "browser.runtime.connectNative does not exist without nativeMessaging permission"
+    );
+    browser.test.assertEq(
+      chrome.runtime.sendNativeMessage,
+      undefined,
+      "chrome.runtime.sendNativeMessage does not exist without nativeMessaging permission"
+    );
+    browser.test.assertEq(
+      browser.runtime.sendNativeMessage,
+      undefined,
+      "browser.runtime.sendNativeMessage does not exist without nativeMessaging permission"
+    );
+    browser.test.sendMessage("finished");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {},
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("finished");
+  await extension.unload();
+});
+
+// Test that an extension that is not listed in allowed_extensions for
+// a native application cannot use that application.
+add_task(async function test_app_permission() {
+  function background() {
+    let port = browser.runtime.connectNative("echo");
+    port.onDisconnect.addListener(msgPort => {
+      browser.test.assertEq(
+        port,
+        msgPort,
+        "onDisconnect handler should receive the port as the first argument"
+      );
+      browser.test.assertEq(
+        "No such native application echo",
+        port.error && port.error.message
+      );
+      browser.test.sendMessage("result", "disconnected");
+    });
+    port.onMessage.addListener(msg => {
+      browser.test.sendMessage("result", "message");
+    });
+    port.postMessage({ test: "test" });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension(
+    {
+      background,
+      manifest: {
+        permissions: ["nativeMessaging"],
+      },
+    },
+    "somethingelse@tests.mozilla.org"
+  );
+
+  await extension.startup();
+
+  let result = await extension.awaitMessage("result");
+  equal(
+    result,
+    "disconnected",
+    "connectNative() failed without native app permission"
+  );
+
+  await extension.unload();
+
+  let procCount = await getSubprocessCount();
+  equal(procCount, 0, "No child process was started");
+});
+
+// Test that the command-line arguments and working directory for the
+// native application are as expected.
+add_task(async function test_child_process() {
+  function background() {
+    let port = browser.runtime.connectNative("info");
+    port.onMessage.addListener(msg => {
+      browser.test.sendMessage("result", msg);
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+
+  let msg = await extension.awaitMessage("result");
+  equal(msg.args.length, 3, "Received two command line arguments");
+  equal(
+    msg.args[1],
+    getPath("info.json"),
+    "Command line argument is the path to the native host manifest"
+  );
+  equal(
+    msg.args[2],
+    ID,
+    "Second command line argument is the ID of the calling extension"
+  );
+  equal(
+    msg.cwd.replace(/^\/private\//, "/"),
+    OS.Path.join(tmpDir.path, TYPE_SLUG),
+    "Working directory is the directory containing the native appliation"
+  );
+
+  let exitPromise = waitForSubprocessExit();
+  await extension.unload();
+  await exitPromise;
+});
+
+add_task(async function test_stderr() {
+  function background() {
+    let port = browser.runtime.connectNative("stderr");
+    port.onDisconnect.addListener(msgPort => {
+      browser.test.assertEq(
+        port,
+        msgPort,
+        "onDisconnect handler should receive the port as the first argument"
+      );
+      browser.test.assertEq(
+        null,
+        port.error,
+        "Normal application exit is not an error"
+      );
+      browser.test.sendMessage("finished");
+    });
+  }
+
+  let { messages } = await promiseConsoleOutput(async function() {
+    let extension = ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        applications: { gecko: { id: ID } },
+        permissions: ["nativeMessaging"],
+      },
+    });
+
+    await extension.startup();
+    await extension.awaitMessage("finished");
+    await extension.unload();
+
+    await waitForSubprocessExit();
+  });
+
+  let lines = STDERR_LINES.map(line =>
+    messages.findIndex(msg => msg.message.includes(line))
+  );
+  notEqual(lines[0], -1, "Saw first line of stderr output on the console");
+  notEqual(lines[1], -1, "Saw second line of stderr output on the console");
+  notEqual(
+    lines[0],
+    lines[1],
+    "Stderr output lines are separated in the console"
+  );
+});
+
+// Test that calling connectNative() multiple times works
+// (see bug 1313980 for a previous regression in this area)
+add_task(async function test_multiple_connects() {
+  async function background() {
+    function once() {
+      return new Promise(resolve => {
+        let MSG = "hello";
+        let port = browser.runtime.connectNative("echo");
+
+        port.onMessage.addListener(msg => {
+          browser.test.assertEq(MSG, msg, "Got expected message back");
+          port.disconnect();
+          resolve();
+        });
+        port.postMessage(MSG);
+      });
+    }
+
+    await once();
+    await once();
+    browser.test.notifyPass("multiple-connect");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("multiple-connect");
+  await extension.unload();
+});
+
+// Test that native messaging is always rejected on content scripts
+add_task(async function test_connect_native_from_content_script() {
+  async function testScript() {
+    let port = browser.runtime.connectNative("echo");
+    port.onDisconnect.addListener(msgPort => {
+      browser.test.assertEq(
+        port,
+        msgPort,
+        "onDisconnect handler should receive the port as the first argument"
+      );
+      browser.test.assertEq(
+        "An unexpected error occurred",
+        port.error && port.error.message
+      );
+      browser.test.sendMessage("result", "disconnected");
+    });
+    port.onMessage.addListener(msg => {
+      browser.test.sendMessage("result", "message");
+    });
+    port.postMessage({ test: "test" });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          run_at: "document_end",
+          js: ["test.js"],
+          matches: ["http://example.com/dummy"],
+        },
+      ],
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+    files: {
+      "test.js": testScript,
+    },
+  });
+
+  await extension.startup();
+
+  const page = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+
+  let result = await extension.awaitMessage("result");
+  equal(result, "disconnected", "connectNative() failed from content script");
+
+  await page.close();
+  await extension.unload();
+
+  let procCount = await getSubprocessCount();
+  equal(procCount, 0, "No child process was started");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging_perf.js b/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging_perf.js
new file mode 100644
index 0000000000..073c83bfd4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging_perf.js
@@ -0,0 +1,130 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const MAX_ROUND_TRIP_TIME_MS =
+  AppConstants.DEBUG || AppConstants.ASAN ? 60 : 30;
+const MAX_RETRIES = 5;
+
+const ECHO_BODY = String.raw`
+  import struct
+  import sys
+
+  stdin = getattr(sys.stdin, 'buffer', sys.stdin)
+  stdout = getattr(sys.stdout, 'buffer', sys.stdout)
+
+  while True:
+    rawlen = stdin.read(4)
+    if len(rawlen) == 0:
+      sys.exit(0)
+
+    msglen = struct.unpack('@I', rawlen)[0]
+    msg = stdin.read(msglen)
+
+    stdout.write(struct.pack('@I', msglen))
+    stdout.write(msg)
+`;
+
+const SCRIPTS = [
+  {
+    name: "echo",
+    description: "A native app that echoes back messages it receives",
+    script: ECHO_BODY.replace(/^ {2}/gm, ""),
+  },
+];
+
+add_task(async function setup() {
+  await setupHosts(SCRIPTS);
+});
+
+add_task(async function test_round_trip_perf() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.onMessage.addListener(msg => {
+        if (msg != "run-tests") {
+          return;
+        }
+
+        let port = browser.runtime.connectNative("echo");
+
+        function next() {
+          port.postMessage({
+            Lorem: {
+              ipsum: {
+                dolor: [
+                  "sit amet",
+                  "consectetur adipiscing elit",
+                  "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
+                ],
+                "Ut enim": [
+                  "ad minim veniam",
+                  "quis nostrud exercitation ullamco",
+                  "laboris nisi ut aliquip ex ea commodo consequat.",
+                ],
+                Duis: [
+                  "aute irure dolor in reprehenderit in",
+                  "voluptate velit esse cillum dolore eu",
+                  "fugiat nulla pariatur.",
+                ],
+                Excepteur: [
+                  "sint occaecat cupidatat non proident",
+                  "sunt in culpa qui officia deserunt",
+                  "mollit anim id est laborum.",
+                ],
+              },
+            },
+          });
+        }
+
+        const COUNT = 1000;
+        let now;
+        function finish() {
+          let roundTripTime = (Date.now() - now) / COUNT;
+
+          port.disconnect();
+          browser.test.sendMessage("result", roundTripTime);
+        }
+
+        let count = 0;
+        port.onMessage.addListener(() => {
+          if (count == 0) {
+            // Skip the first round, since it includes the time it takes
+            // the app to start up.
+            now = Date.now();
+          }
+
+          if (count++ <= COUNT) {
+            next();
+          } else {
+            finish();
+          }
+        });
+
+        next();
+      });
+    },
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+
+  let roundTripTime = Infinity;
+  for (
+    let i = 0;
+    i < MAX_RETRIES && roundTripTime > MAX_ROUND_TRIP_TIME_MS;
+    i++
+  ) {
+    extension.sendMessage("run-tests");
+    roundTripTime = await extension.awaitMessage("result");
+  }
+
+  await extension.unload();
+
+  ok(
+    roundTripTime <= MAX_ROUND_TRIP_TIME_MS,
+    `Expected round trip time (${roundTripTime}ms) to be less than ${MAX_ROUND_TRIP_TIME_MS}ms`
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging_unresponsive.js b/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging_unresponsive.js
new file mode 100644
index 0000000000..0de24c0c6e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_native_messaging_unresponsive.js
@@ -0,0 +1,85 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const WONTDIE_BODY = String.raw`
+  import signal
+  import struct
+  import sys
+  import time
+
+  signal.signal(signal.SIGTERM, signal.SIG_IGN)
+
+  stdin = getattr(sys.stdin, 'buffer', sys.stdin)
+  stdout = getattr(sys.stdout, 'buffer', sys.stdout)
+
+  def spin():
+    while True:
+      try:
+        signal.pause()
+      except AttributeError:
+        time.sleep(5)
+
+  while True:
+    rawlen = stdin.read(4)
+    if len(rawlen) == 0:
+      spin()
+
+    msglen = struct.unpack('@I', rawlen)[0]
+    msg = stdin.read(msglen)
+
+    stdout.write(struct.pack('@I', msglen))
+    stdout.write(msg)
+`;
+
+const SCRIPTS = [
+  {
+    name: "wontdie",
+    description:
+      "a native app that does not exit when stdin closes or on SIGTERM",
+    script: WONTDIE_BODY.replace(/^ {2}/gm, ""),
+  },
+];
+
+add_task(async function setup() {
+  await setupHosts(SCRIPTS);
+});
+
+// Test that an unresponsive native application still gets killed eventually
+add_task(async function test_unresponsive_native_app() {
+  // XXX expose GRACEFUL_SHUTDOWN_TIME as a pref and reduce it
+  // just for this test?
+
+  function background() {
+    let port = browser.runtime.connectNative("wontdie");
+
+    const MSG = "echo me";
+    // bounce a message to make sure the process actually starts
+    port.onMessage.addListener(msg => {
+      browser.test.assertEq(msg, MSG, "Received echoed message");
+      browser.test.sendMessage("ready");
+    });
+    port.postMessage(MSG);
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: ID } },
+      permissions: ["nativeMessaging"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  let procCount = await getSubprocessCount();
+  equal(procCount, 1, "subprocess is running");
+
+  let exitPromise = waitForSubprocessExit();
+  await extension.unload();
+  await exitPromise;
+
+  procCount = await getSubprocessCount();
+  equal(procCount, 0, "subprocess was successfully killed");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_networkStatus.js b/toolkit/components/extensions/test/xpcshell/test_ext_networkStatus.js
new file mode 100644
index 0000000000..758bf48d0b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_networkStatus.js
@@ -0,0 +1,190 @@
+"use strict";
+
+const Cm = Components.manager;
+
+const uuidGenerator = Cc["@mozilla.org/uuid-generator;1"].getService(
+  Ci.nsIUUIDGenerator
+);
+
+var mockNetworkStatusService = {
+  contractId: "@mozilla.org/network/network-link-service;1",
+
+  _mockClassId: uuidGenerator.generateUUID(),
+
+  _originalClassId: "",
+
+  QueryInterface: ChromeUtils.generateQI(["nsINetworkLinkService"]),
+
+  createInstance(outer, iiD) {
+    if (outer) {
+      throw Components.Exception("", Cr.NS_ERROR_NO_AGGREGATION);
+    }
+    return this.QueryInterface(iiD);
+  },
+
+  register() {
+    let registrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
+    if (!registrar.isCIDRegistered(this._mockClassId)) {
+      this._originalClassId = registrar.contractIDToCID(this.contractId);
+      registrar.registerFactory(
+        this._mockClassId,
+        "Unregister after testing",
+        this.contractId,
+        this
+      );
+    }
+  },
+
+  unregister() {
+    let registrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
+    registrar.unregisterFactory(this._mockClassId, this);
+    registrar.registerFactory(this._originalClassId, "", this.contractId, null);
+  },
+
+  _isLinkUp: true,
+  _linkStatusKnown: false,
+  _linkType: Ci.nsINetworkLinkService.LINK_TYPE_UNKNOWN,
+
+  get isLinkUp() {
+    return this._isLinkUp;
+  },
+
+  get linkStatusKnown() {
+    return this._linkStatusKnown;
+  },
+
+  setLinkStatus(status) {
+    switch (status) {
+      case "up":
+        this._isLinkUp = true;
+        this._linkStatusKnown = true;
+        this._networkID = "foo";
+        break;
+      case "down":
+        this._isLinkUp = false;
+        this._linkStatusKnown = true;
+        this._linkType = Ci.nsINetworkLinkService.LINK_TYPE_UNKNOWN;
+        this._networkID = undefined;
+        break;
+      case "changed":
+        this._linkStatusKnown = true;
+        this._networkID = "foo";
+        break;
+      case "unknown":
+        this._linkStatusKnown = false;
+        this._linkType = Ci.nsINetworkLinkService.LINK_TYPE_UNKNOWN;
+        this._networkID = undefined;
+        break;
+    }
+    Services.obs.notifyObservers(null, "network:link-status-changed", status);
+  },
+
+  get linkType() {
+    return this._linkType;
+  },
+
+  setLinkType(val) {
+    this._linkType = val;
+    this._linkStatusKnown = true;
+    this._isLinkUp = true;
+    this._networkID = "bar";
+    Services.obs.notifyObservers(
+      null,
+      "network:link-type-changed",
+      this._linkType
+    );
+  },
+
+  get networkID() {
+    return this._networkID;
+  },
+};
+
+// nsINetworkLinkService is not directly testable. With the mock service above,
+// we just exercise a couple small things here to validate the api works somewhat.
+add_task(async function test_networkStatus() {
+  mockNetworkStatusService.register();
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "networkstatus@tests.mozilla.org" } },
+      permissions: ["networkStatus"],
+    },
+    isPrivileged: true,
+    async background() {
+      browser.networkStatus.onConnectionChanged.addListener(async details => {
+        browser.test.log(`connection status ${JSON.stringify(details)}`);
+        browser.test.sendMessage("connect-changed", {
+          details,
+          linkInfo: await browser.networkStatus.getLinkInfo(),
+        });
+      });
+      browser.test.sendMessage(
+        "linkdata",
+        await browser.networkStatus.getLinkInfo()
+      );
+    },
+  });
+
+  async function test(expected, change) {
+    if (change.status) {
+      info(`test link change status to ${change.status}`);
+      mockNetworkStatusService.setLinkStatus(change.status);
+    } else if (change.link) {
+      info(`test link change type to ${change.link}`);
+      mockNetworkStatusService.setLinkType(change.link);
+    }
+    let { details, linkInfo } = await extension.awaitMessage("connect-changed");
+    equal(details.type, expected.type, "network type is correct");
+    equal(details.status, expected.status, `network status is correct`);
+    equal(details.id, expected.id, "network id");
+    Assert.deepEqual(
+      linkInfo,
+      details,
+      "getLinkInfo should resolve to the same details received from onConnectionChanged"
+    );
+  }
+
+  await extension.startup();
+
+  let data = await extension.awaitMessage("linkdata");
+  equal(data.type, "unknown", "network type is unknown");
+  equal(data.status, "unknown", `network status is ${data.status}`);
+  equal(data.id, undefined, "network id");
+
+  await test(
+    { type: "unknown", status: "up", id: "foo" },
+    { status: "changed" }
+  );
+
+  await test(
+    { type: "wifi", status: "up", id: "bar" },
+    { link: Ci.nsINetworkLinkService.LINK_TYPE_WIFI }
+  );
+
+  await test({ type: "unknown", status: "down" }, { status: "down" });
+
+  await test({ type: "unknown", status: "unknown" }, { status: "unknown" });
+
+  await extension.unload();
+  mockNetworkStatusService.unregister();
+});
+
+add_task(async function test_networkStatus_permission() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: { id: "networkstatus-permission@tests.mozilla.org" },
+      },
+      permissions: ["networkStatus"],
+    },
+    async background() {
+      browser.test.assertEq(
+        undefined,
+        browser.networkStatus,
+        "networkStatus is privileged"
+      );
+    },
+  });
+  await extension.startup();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_notifications_incognito.js b/toolkit/components/extensions/test/xpcshell/test_ext_notifications_incognito.js
new file mode 100644
index 0000000000..400d60c4a1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_notifications_incognito.js
@@ -0,0 +1,108 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const ALERTS_SERVICE_CONTRACT_ID = "@mozilla.org/alerts-service;1";
+
+const createdAlerts = [];
+
+const mockAlertsService = {
+  showPersistentNotification(persistentData, alert, alertListener) {
+    this.showAlert(alert, alertListener);
+  },
+
+  showAlert(alert, listener) {
+    createdAlerts.push(alert);
+    listener.observe(null, "alertfinished", alert.cookie);
+  },
+
+  showAlertNotification(
+    imageUrl,
+    title,
+    text,
+    textClickable,
+    cookie,
+    alertListener,
+    name,
+    dir,
+    lang,
+    data,
+    principal,
+    privateBrowsing
+  ) {
+    this.showAlert({ cookie, title, text, privateBrowsing }, alertListener);
+  },
+
+  closeAlert(name) {
+    // This mock immediately close the alert on show, so this is empty.
+  },
+
+  QueryInterface: ChromeUtils.generateQI(["nsIAlertsService"]),
+
+  createInstance(outer, iid) {
+    if (outer != null) {
+      throw Components.Exception("", Cr.NS_ERROR_NO_AGGREGATION);
+    }
+    return this.QueryInterface(iid);
+  },
+};
+
+const registrar = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
+registrar.registerFactory(
+  Components.ID("{173a036a-d678-4415-9cff-0baff6bfe554}"),
+  "alerts service",
+  ALERTS_SERVICE_CONTRACT_ID,
+  mockAlertsService
+);
+
+add_task(async function test_notification_privateBrowsing_flag() {
+  let extension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    manifest: {
+      permissions: ["notifications"],
+    },
+    files: {
+      "page.html": `<meta charset="utf-8"><script src="page.js"></script>`,
+      async "page.js"() {
+        let closedPromise = new Promise(resolve => {
+          browser.notifications.onClosed.addListener(resolve);
+        });
+        let createdId = await browser.notifications.create("notifid", {
+          type: "basic",
+          title: "titl",
+          message: "msg",
+        });
+        let closedId = await closedPromise;
+        browser.test.assertEq(createdId, closedId, "ID of closed notification");
+        browser.test.assertEq(
+          "{}",
+          JSON.stringify(await browser.notifications.getAll()),
+          "no notifications left"
+        );
+        browser.test.sendMessage("notification_closed");
+      },
+    },
+  });
+  await extension.startup();
+
+  async function checkPrivateBrowsingFlag(privateBrowsing) {
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      `moz-extension://${extension.uuid}/page.html`,
+      { extension, remote: extension.extension.remote, privateBrowsing }
+    );
+    await extension.awaitMessage("notification_closed");
+    await contentPage.close();
+
+    Assert.equal(createdAlerts.length, 1, "expected one alert");
+    let notification = createdAlerts.shift();
+    Assert.equal(notification.cookie, "notifid", "notification id");
+    Assert.equal(notification.title, "titl", "notification title");
+    Assert.equal(notification.text, "msg", "notification text");
+    Assert.equal(notification.privateBrowsing, privateBrowsing, "pbm flag");
+  }
+
+  await checkPrivateBrowsingFlag(false);
+  await checkPrivateBrowsingFlag(true);
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_notifications_unsupported.js b/toolkit/components/extensions/test/xpcshell/test_ext_notifications_unsupported.js
new file mode 100644
index 0000000000..1213ae4f23
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_notifications_unsupported.js
@@ -0,0 +1,41 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const ALERTS_SERVICE_CONTRACT_ID = "@mozilla.org/alerts-service;1";
+const registrar = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
+registrar.registerFactory(
+  Components.ID("{18f25bb4-ab12-4e24-b3b0-69215056160b}"),
+  "unsupported alerts service",
+  ALERTS_SERVICE_CONTRACT_ID,
+  {} // This object lacks an implementation of nsIAlertsService.
+);
+
+add_task(async function test_notification_unsupported_backend() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["notifications"],
+    },
+    async background() {
+      let closedPromise = new Promise(resolve => {
+        browser.notifications.onClosed.addListener(resolve);
+      });
+      let createdId = await browser.notifications.create("notifid", {
+        type: "basic",
+        title: "titl",
+        message: "msg",
+      });
+      let closedId = await closedPromise;
+      browser.test.assertEq(createdId, closedId, "ID of closed notification");
+      browser.test.assertEq(
+        "{}",
+        JSON.stringify(await browser.notifications.getAll()),
+        "no notifications left"
+      );
+      browser.test.sendMessage("notification_closed");
+    },
+  });
+  await extension.startup();
+  await extension.awaitMessage("notification_closed");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_onmessage_removelistener.js b/toolkit/components/extensions/test/xpcshell/test_ext_onmessage_removelistener.js
new file mode 100644
index 0000000000..7da12b40aa
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_onmessage_removelistener.js
@@ -0,0 +1,30 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+function backgroundScript() {
+  function listener() {
+    browser.test.notifyFail("listener should not be invoked");
+  }
+
+  browser.runtime.onMessage.addListener(listener);
+  browser.runtime.onMessage.removeListener(listener);
+  browser.runtime.sendMessage("hello");
+
+  // Make sure that, if we somehow fail to remove the listener, then we'll run
+  // the listener before the test is marked as passing.
+  setTimeout(function() {
+    browser.test.notifyPass("onmessage_removelistener");
+  }, 0);
+}
+
+let extensionData = {
+  background: backgroundScript,
+};
+
+add_task(async function test_contentscript() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitFinish("onmessage_removelistener");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_performance_counters.js b/toolkit/components/extensions/test/xpcshell/test_ext_performance_counters.js
new file mode 100644
index 0000000000..7e1370d00f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_performance_counters.js
@@ -0,0 +1,86 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { ExtensionParent } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionParent.jsm"
+);
+
+const ENABLE_COUNTER_PREF =
+  "extensions.webextensions.enablePerformanceCounters";
+const TIMING_MAX_AGE = "extensions.webextensions.performanceCountersMaxAge";
+
+let { ParentAPIManager } = ExtensionParent;
+
+function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms)); // eslint-disable-line mozilla/no-arbitrary-setTimeout
+}
+
+async function retrieveSpecificCounter(apiName, expectedCount) {
+  let currentCount = 0;
+  let data;
+  while (currentCount < expectedCount) {
+    data = await ParentAPIManager.retrievePerformanceCounters();
+    for (let [console, counters] of data) {
+      for (let [api, counter] of counters) {
+        if (api == apiName) {
+          currentCount += counter.calls;
+        }
+      }
+    }
+    await sleep(100);
+  }
+  return data;
+}
+
+async function test_counter() {
+  async function background() {
+    // creating a bookmark is done in the parent
+    let folder = await browser.bookmarks.create({ title: "Folder" });
+    await browser.bookmarks.create({
+      title: "Bookmark",
+      url: "http://example.com",
+      parentId: folder.id,
+    });
+
+    // getURL() is done in the child, let do three
+    browser.extension.getURL("beasts/frog.html");
+    browser.extension.getURL("beasts/frog2.html");
+    browser.extension.getURL("beasts/frog3.html");
+    browser.test.sendMessage("done");
+  }
+
+  let extensionData = {
+    background,
+    manifest: {
+      permissions: ["bookmarks"],
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("done");
+
+  let counters = await retrieveSpecificCounter("getURL", 3);
+  await extension.unload();
+
+  // check that the bookmarks.create API was tracked
+  let counter = counters.get(extension.id).get("bookmarks.create");
+  ok(counter.calls > 0);
+  ok(counter.duration > 0);
+
+  // check that the getURL API was tracked
+  counter = counters.get(extension.id).get("getURL");
+  ok(counter.calls > 0);
+  ok(counter.duration > 0);
+}
+
+add_task(function test_performance_counter() {
+  return runWithPrefs(
+    [
+      [ENABLE_COUNTER_PREF, true],
+      [TIMING_MAX_AGE, 1],
+    ],
+    test_counter
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_permission_warnings.js b/toolkit/components/extensions/test/xpcshell/test_ext_permission_warnings.js
new file mode 100644
index 0000000000..cc15e28200
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_permission_warnings.js
@@ -0,0 +1,654 @@
+"use strict";
+
+let { ExtensionTestCommon } = ChromeUtils.import(
+  "resource://testing-common/ExtensionTestCommon.jsm"
+);
+
+let bundle;
+if (AppConstants.MOZ_APP_NAME == "thunderbird") {
+  bundle = Services.strings.createBundle(
+    "chrome://messenger/locale/addons.properties"
+  );
+} else {
+  bundle = Services.strings.createBundle(
+    "chrome://browser/locale/browser.properties"
+  );
+}
+const DUMMY_APP_NAME = "Dummy brandName";
+
+const { createAppInfo } = AddonTestUtils;
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.usePrivilegedSignatures = id => id.startsWith("privileged");
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+async function getManifestPermissions(extensionData) {
+  let extension = ExtensionTestCommon.generate(extensionData);
+  // Some tests contain invalid permissions; ignore the warnings about their invalidity.
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  await extension.loadManifest();
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+  const { manifestPermissions } = extension;
+  await extension.cleanupGeneratedFile();
+  return manifestPermissions;
+}
+
+function getPermissionWarnings(manifestPermissions, options) {
+  let info = {
+    permissions: manifestPermissions,
+    appName: DUMMY_APP_NAME,
+  };
+  let { msgs } = ExtensionData.formatPermissionStrings(info, bundle, options);
+  return msgs;
+}
+
+async function getPermissionWarningsForUpdate(
+  oldExtensionData,
+  newExtensionData
+) {
+  let oldPerms = await getManifestPermissions(oldExtensionData);
+  let newPerms = await getManifestPermissions(newExtensionData);
+  let difference = Extension.comparePermissions(oldPerms, newPerms);
+  return getPermissionWarnings(difference);
+}
+
+// Tests that the expected permission warnings are generated for various
+// combinations of host permissions.
+add_task(async function host_permissions() {
+  let { PluralForm } = ChromeUtils.import(
+    "resource://gre/modules/PluralForm.jsm"
+  );
+
+  let permissionTestCases = [
+    {
+      description: "Empty manifest without permissions",
+      manifest: {},
+      expectedOrigins: [],
+      expectedWarnings: [],
+    },
+    {
+      description: "Invalid match patterns",
+      manifest: {
+        permissions: [
+          "https:///",
+          "https://",
+          "https://*",
+          "about:ugh",
+          "about:*",
+          "about://*/",
+          "resource://*/",
+        ],
+      },
+      expectedOrigins: [],
+      expectedWarnings: [],
+    },
+    {
+      description: "moz-extension: permissions",
+      manifest: {
+        permissions: ["moz-extension://*/*", "moz-extension://uuid/"],
+      },
+      // moz-extension:-origin does not appear in the permission list,
+      // but it is implicitly granted anyway.
+      expectedOrigins: [],
+      expectedWarnings: [],
+    },
+    {
+      description: "*. host permission",
+      manifest: {
+        // This permission is rejected by the manifest and ignored.
+        permissions: ["http://*./"],
+      },
+      expectedOrigins: [],
+      expectedWarnings: [],
+    },
+    {
+      description: "<all_urls> permission",
+      manifest: {
+        permissions: ["<all_urls>"],
+      },
+      expectedOrigins: ["<all_urls>"],
+      expectedWarnings: [
+        bundle.GetStringFromName("webextPerms.hostDescription.allUrls"),
+      ],
+    },
+    {
+      description: "file: permissions",
+      manifest: {
+        permissions: ["file://*/"],
+      },
+      expectedOrigins: ["file://*/"],
+      expectedWarnings: [
+        bundle.GetStringFromName("webextPerms.hostDescription.allUrls"),
+      ],
+    },
+    {
+      description: "http: permission",
+      manifest: {
+        permissions: ["http://*/"],
+      },
+      expectedOrigins: ["http://*/"],
+      expectedWarnings: [
+        bundle.GetStringFromName("webextPerms.hostDescription.allUrls"),
+      ],
+    },
+    {
+      description: "*://*/ permission",
+      manifest: {
+        permissions: ["*://*/"],
+      },
+      expectedOrigins: ["*://*/"],
+      expectedWarnings: [
+        bundle.GetStringFromName("webextPerms.hostDescription.allUrls"),
+      ],
+    },
+    {
+      description: "content_script[*].matches",
+      manifest: {
+        content_scripts: [
+          {
+            // This test uses the manifest file without loading the content script
+            // file, so we can use a non-existing dummy file.
+            js: ["dummy.js"],
+            matches: ["https://*/"],
+          },
+        ],
+      },
+      expectedOrigins: ["https://*/"],
+      expectedWarnings: [
+        bundle.GetStringFromName("webextPerms.hostDescription.allUrls"),
+      ],
+    },
+    {
+      description: "A few host permissions",
+      manifest: {
+        permissions: ["http://a/", "http://*.b/", "http://c/*"],
+      },
+      expectedOrigins: ["http://a/", "http://*.b/", "http://c/*"],
+      expectedWarnings: [
+        // Wildcard hosts take precedence in the permission list.
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "b",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "a",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "c",
+        ]),
+      ],
+    },
+    {
+      description: "many host permission",
+      manifest: {
+        permissions: [
+          "http://a/",
+          "http://b/",
+          "http://c/",
+          "http://d/",
+          "http://e/*",
+          "http://*.1/",
+          "http://*.2/",
+          "http://*.3/",
+          "http://*.4/",
+        ],
+      },
+      expectedOrigins: [
+        "http://a/",
+        "http://b/",
+        "http://c/",
+        "http://d/",
+        "http://e/*",
+        "http://*.1/",
+        "http://*.2/",
+        "http://*.3/",
+        "http://*.4/",
+      ],
+      expectedWarnings: [
+        // Wildcard hosts take precedence in the permission list.
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "1",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "2",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "3",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "4",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "a",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "b",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "c",
+        ]),
+        PluralForm.get(
+          2,
+          bundle.GetStringFromName("webextPerms.hostDescription.tooManySites")
+        ).replace("#1", "2"),
+      ],
+      options: {
+        collapseOrigins: true,
+      },
+    },
+    {
+      description:
+        "many host permissions without item limit in the warning list",
+      manifest: {
+        permissions: [
+          "http://a/",
+          "http://b/",
+          "http://c/",
+          "http://d/",
+          "http://e/*",
+          "http://*.1/",
+          "http://*.2/",
+          "http://*.3/",
+          "http://*.4/",
+          "http://*.5/",
+        ],
+      },
+      expectedOrigins: [
+        "http://a/",
+        "http://b/",
+        "http://c/",
+        "http://d/",
+        "http://e/*",
+        "http://*.1/",
+        "http://*.2/",
+        "http://*.3/",
+        "http://*.4/",
+        "http://*.5/",
+      ],
+      expectedWarnings: [
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "1",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "2",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "3",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "4",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+          "5",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "a",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "b",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "c",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "d",
+        ]),
+        bundle.formatStringFromName("webextPerms.hostDescription.oneSite", [
+          "e",
+        ]),
+      ],
+    },
+  ];
+  for (let {
+    description,
+    manifest,
+    expectedOrigins,
+    expectedWarnings,
+    options,
+  } of permissionTestCases) {
+    let manifestPermissions = await getManifestPermissions({
+      manifest,
+    });
+
+    deepEqual(
+      manifestPermissions.origins,
+      expectedOrigins,
+      `Expected origins (${description})`
+    );
+    deepEqual(
+      manifestPermissions.permissions,
+      [],
+      `Expected no non-host permissions (${description})`
+    );
+
+    let warnings = getPermissionWarnings(manifestPermissions, options);
+    deepEqual(warnings, expectedWarnings, `Expected warnings (${description})`);
+  }
+});
+
+// Tests that the expected permission warnings are generated for a mix of host
+// permissions and API permissions.
+add_task(async function api_permissions() {
+  let manifestPermissions = await getManifestPermissions({
+    manifest: {
+      permissions: [
+        "activeTab",
+        "webNavigation",
+        "tabs",
+        "nativeMessaging",
+        "http://x/",
+        "http://*.x/",
+        "http://*.tld/",
+      ],
+    },
+  });
+  deepEqual(
+    manifestPermissions,
+    {
+      origins: ["http://x/", "http://*.x/", "http://*.tld/"],
+      permissions: ["activeTab", "webNavigation", "tabs", "nativeMessaging"],
+    },
+    "Expected origins and permissions"
+  );
+
+  deepEqual(
+    getPermissionWarnings(manifestPermissions),
+    [
+      // Host permissions first, with wildcards on top.
+      bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+        "x",
+      ]),
+      bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+        "tld",
+      ]),
+      bundle.formatStringFromName("webextPerms.hostDescription.oneSite", ["x"]),
+      // nativeMessaging permission warning first of all permissions.
+      bundle.formatStringFromName("webextPerms.description.nativeMessaging", [
+        DUMMY_APP_NAME,
+      ]),
+      // Other permissions in alphabetical order.
+      // Note: activeTab has no permission warning string.
+      bundle.GetStringFromName("webextPerms.description.tabs"),
+      bundle.GetStringFromName("webextPerms.description.webNavigation"),
+    ],
+    "Expected warnings"
+  );
+});
+
+// Tests that the expected permission warnings are generated for a mix of host
+// permissions and API permissions, for a privileged extension that uses the
+// mozillaAddons permission.
+add_task(async function privileged_with_mozillaAddons() {
+  let manifestPermissions = await getManifestPermissions({
+    isPrivileged: true,
+    manifest: {
+      permissions: [
+        "mozillaAddons",
+        "mozillaAddons",
+        "mozillaAddons",
+        "resource://x/*",
+        "http://a/",
+        "about:reader*",
+      ],
+    },
+  });
+  deepEqual(
+    manifestPermissions,
+    {
+      origins: ["resource://x/*", "http://a/", "about:reader*"],
+      permissions: ["mozillaAddons"],
+    },
+    "Expected origins and permissions for privileged add-on with mozillaAddons"
+  );
+
+  deepEqual(
+    getPermissionWarnings(manifestPermissions),
+    [bundle.GetStringFromName("webextPerms.hostDescription.allUrls")],
+    "Expected warnings for privileged add-on with mozillaAddons permission."
+  );
+});
+
+// Similar to the privileged_with_mozillaAddons test, except the test extension
+// is unprivileged and not allowed to use the mozillaAddons permission.
+add_task(async function unprivileged_with_mozillaAddons() {
+  let manifestPermissions = await getManifestPermissions({
+    manifest: {
+      permissions: [
+        "mozillaAddons",
+        "mozillaAddons",
+        "mozillaAddons",
+        "resource://x/*",
+        "http://a/",
+        "about:reader*",
+      ],
+    },
+  });
+  deepEqual(
+    manifestPermissions,
+    {
+      origins: ["http://a/"],
+      permissions: [],
+    },
+    "Expected origins and permissions for unprivileged add-on with mozillaAddons"
+  );
+
+  deepEqual(
+    getPermissionWarnings(manifestPermissions),
+    [bundle.formatStringFromName("webextPerms.hostDescription.oneSite", ["a"])],
+    "Expected warnings for unprivileged add-on with mozillaAddons permission."
+  );
+});
+
+// Tests that an update with less permissions has no warning.
+add_task(async function update_drop_permission() {
+  let warnings = await getPermissionWarningsForUpdate(
+    {
+      manifest: {
+        permissions: ["<all_urls>", "https://a/", "http://b/"],
+      },
+    },
+    {
+      manifest: {
+        permissions: [
+          "https://a/",
+          "http://b/",
+          "ftp://host_matching_all_urls/",
+        ],
+      },
+    }
+  );
+  deepEqual(
+    warnings,
+    [],
+    "An update with fewer permissions should not have any warnings"
+  );
+});
+
+// Tests that an update that switches from "*://*/*" to "<all_urls>" does not
+// result in additional permission warnings.
+add_task(async function update_all_urls_permission() {
+  let warnings = await getPermissionWarningsForUpdate(
+    {
+      manifest: {
+        permissions: ["*://*/*"],
+      },
+    },
+    {
+      manifest: {
+        permissions: ["<all_urls>"],
+      },
+    }
+  );
+  deepEqual(
+    warnings,
+    [],
+    "An update from a wildcard host to <all_urls> should not have any warnings"
+  );
+});
+
+// Tests that an update where a new permission whose domain overlaps with
+// an existing permission does not result in additional permission warnings.
+add_task(async function update_change_permissions() {
+  let warnings = await getPermissionWarningsForUpdate(
+    {
+      manifest: {
+        permissions: ["https://a/", "http://*.b/", "http://c/", "http://f/"],
+      },
+    },
+    {
+      manifest: {
+        permissions: [
+          // (no new warning) Unchanged permission from old extension.
+          "https://a/",
+          // (no new warning) Different schemes, host should match "*.b" wildcard.
+          "ftp://ftp.b/",
+          "ws://ws.b/",
+          "wss://wss.b",
+          "https://https.b/",
+          "http://http.b/",
+          "*://*.b/",
+          "http://b/",
+
+          // (expect warning) Wildcard was added.
+          "http://*.c/",
+          // (no new warning) file:-scheme, but host "f" is same as "http://f/".
+          "file://f/",
+          // (expect warning) New permission was added.
+          "proxy",
+        ],
+      },
+    }
+  );
+  deepEqual(
+    warnings,
+    [
+      bundle.formatStringFromName("webextPerms.hostDescription.wildcard", [
+        "c",
+      ]),
+      bundle.formatStringFromName("webextPerms.description.proxy", [
+        DUMMY_APP_NAME,
+      ]),
+    ],
+    "Expected permission warnings for new permissions only"
+  );
+});
+
+// Tests that a privileged extension with the mozillaAddons permission can be
+// updated without errors.
+add_task(async function update_privileged_with_mozillaAddons() {
+  let warnings = await getPermissionWarningsForUpdate(
+    {
+      isPrivileged: true,
+      manifest: {
+        permissions: ["mozillaAddons", "resource://a/"],
+      },
+    },
+    {
+      isPrivileged: true,
+      manifest: {
+        permissions: ["mozillaAddons", "resource://a/", "resource://b/"],
+      },
+    }
+  );
+  deepEqual(
+    warnings,
+    [bundle.formatStringFromName("webextPerms.hostDescription.oneSite", ["b"])],
+    "Expected permission warnings for new host only"
+  );
+});
+
+// Tests that an unprivileged extension cannot get privileged permissions
+// through an update.
+add_task(async function update_unprivileged_with_mozillaAddons() {
+  // Unprivileged
+  let warnings = await getPermissionWarningsForUpdate(
+    {
+      manifest: {
+        permissions: ["mozillaAddons", "resource://a/"],
+      },
+    },
+    {
+      manifest: {
+        permissions: ["mozillaAddons", "resource://a/", "resource://b/"],
+      },
+    }
+  );
+  deepEqual(
+    warnings,
+    [],
+    "resource:-scheme is unsupported for unprivileged extensions"
+  );
+});
+
+// Tests that invalid permission warning for privileged permissions requested
+// without the privilged signature are emitted by the Extension class instance
+// but not for the ExtensionData instances (on which the signature is not
+// available and the warning would be emitted even for the ones signed correctly).
+add_task(
+  async function test_invalid_permission_warning_on_privileged_permission() {
+    await AddonTestUtils.promiseStartupManager();
+
+    async function testInvalidPermissionWarning({ isPrivileged }) {
+      let id = isPrivileged
+        ? "privileged-addon@mochi.test"
+        : "nonprivileged-addon@mochi.test";
+
+      let expectedWarnings = isPrivileged
+        ? []
+        : ["Reading manifest: Invalid extension permission: mozillaAddons"];
+
+      const ext = ExtensionTestUtils.loadExtension({
+        useAddonManager: "permanent",
+        manifest: {
+          permissions: ["mozillaAddons"],
+          applications: { gecko: { id } },
+        },
+        background() {},
+      });
+
+      await ext.startup();
+      const { warnings } = ext.extension;
+      Assert.deepEqual(
+        warnings,
+        expectedWarnings,
+        `Got the expected warning for ${id}`
+      );
+      await ext.unload();
+    }
+
+    await testInvalidPermissionWarning({ isPrivileged: false });
+    await testInvalidPermissionWarning({ isPrivileged: true });
+
+    info("Test invalid permission warning on ExtensionData instance");
+    // Generate an extension (just to be able to reuse its rootURI for the
+    // ExtensionData instance created below).
+    let generatedExt = ExtensionTestCommon.generate({
+      manifest: {
+        permissions: ["mozillaAddons"],
+        applications: { gecko: { id: "extension-data@mochi.test" } },
+      },
+    });
+
+    // Verify that XPIInstall.jsm will not collect the warning for the
+    // privileged permission as expected.
+    const extData = new ExtensionData(generatedExt.rootURI);
+    await extData.loadManifest();
+    Assert.deepEqual(
+      extData.warnings,
+      [],
+      "No warnings for mozillaAddons permission collected for the ExtensionData instance"
+    );
+
+    // This assertion is just meant to prevent the test to pass if there were no warnings
+    // because some errors prevented the warnings to be collected).
+    Assert.deepEqual(
+      extData.errors,
+      [],
+      "No errors collected by the ExtensionData instance"
+    );
+    // Cleanup the generated xpi file.
+    await generatedExt.cleanupGeneratedFile();
+
+    await AddonTestUtils.promiseShutdownManager();
+  }
+);
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_permission_xhr.js b/toolkit/components/extensions/test/xpcshell/test_ext_permission_xhr.js
new file mode 100644
index 0000000000..4b9ade044c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_permission_xhr.js
@@ -0,0 +1,235 @@
+"use strict";
+
+const server = createHttpServer({
+  hosts: ["xpcshell.test", "example.com", "example.org"],
+});
+server.registerDirectory("/data/", do_get_file("data"));
+
+server.registerPathHandler("/example.txt", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+server.registerPathHandler("/return_headers.sjs", (request, response) => {
+  response.setHeader("Content-Type", "text/plain", false);
+
+  let headers = {};
+  for (let { data: header } of request.headers) {
+    headers[header.toLowerCase()] = request.getHeader(header);
+  }
+
+  response.write(JSON.stringify(headers));
+});
+
+/* eslint-disable mozilla/balanced-listeners */
+
+add_task(async function test_simple() {
+  async function runTests(cx) {
+    function xhr(XMLHttpRequest) {
+      return url => {
+        return new Promise((resolve, reject) => {
+          let req = new XMLHttpRequest();
+          req.open("GET", url);
+          req.addEventListener("load", resolve);
+          req.addEventListener("error", reject);
+          req.send();
+        });
+      };
+    }
+
+    function run(shouldFail, fetch) {
+      function passListener() {
+        browser.test.succeed(`${cx}.${fetch.name} pass listener`);
+      }
+
+      function failListener() {
+        browser.test.fail(`${cx}.${fetch.name} fail listener`);
+      }
+
+      /* eslint-disable no-else-return */
+      if (shouldFail) {
+        return fetch("http://example.org/example.txt").then(
+          failListener,
+          passListener
+        );
+      } else {
+        return fetch("http://example.com/example.txt").then(
+          passListener,
+          failListener
+        );
+      }
+      /* eslint-enable no-else-return */
+    }
+
+    try {
+      await run(true, xhr(XMLHttpRequest));
+      await run(false, xhr(XMLHttpRequest));
+      await run(true, xhr(window.XMLHttpRequest));
+      await run(false, xhr(window.XMLHttpRequest));
+      await run(true, fetch);
+      await run(false, fetch);
+      await run(true, window.fetch);
+      await run(false, window.fetch);
+    } catch (err) {
+      browser.test.fail(`Error: ${err} :: ${err.stack}`);
+      browser.test.notifyFail("permission_xhr");
+    }
+  }
+
+  async function background(runTestsFn) {
+    await runTestsFn("bg");
+    browser.test.notifyPass("permission_xhr");
+  }
+
+  let extensionData = {
+    background: `(${background})(${runTests})`,
+    manifest: {
+      permissions: ["http://example.com/"],
+      content_scripts: [
+        {
+          matches: ["http://xpcshell.test/data/file_permission_xhr.html"],
+          js: ["content.js"],
+        },
+      ],
+    },
+    files: {
+      "content.js": `(${async runTestsFn => {
+        await runTestsFn("content");
+
+        window.wrappedJSObject.privilegedFetch = fetch;
+        window.wrappedJSObject.privilegedXHR = XMLHttpRequest;
+
+        window.addEventListener("message", function rcv({ data }) {
+          switch (data.msg) {
+            case "test":
+              break;
+
+            case "assertTrue":
+              browser.test.assertTrue(data.condition, data.description);
+              break;
+
+            case "finish":
+              window.removeEventListener("message", rcv);
+              browser.test.sendMessage("content-script-finished");
+              break;
+          }
+        });
+        window.postMessage("test", "*");
+      }})(${runTests})`,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://xpcshell.test/data/file_permission_xhr.html"
+  );
+  await extension.awaitMessage("content-script-finished");
+  await contentPage.close();
+
+  await extension.awaitFinish("permission_xhr");
+  await extension.unload();
+});
+
+// This test case ensures that a WebExtension content script can still use the same
+// XMLHttpRequest and fetch APIs that the webpage can use and be recognized from
+// the target server with the same origin and referer headers of the target webpage
+// (see Bug 1295660 for a rationale).
+add_task(async function test_page_xhr() {
+  async function contentScript() {
+    const content = this.content;
+
+    const { webpageFetchResult, webpageXhrResult } = await new Promise(
+      resolve => {
+        const listenPageMessage = event => {
+          if (!event.data || event.data.type !== "testPageGlobals") {
+            return;
+          }
+
+          window.removeEventListener("message", listenPageMessage);
+
+          browser.test.assertEq(
+            true,
+            !!content.XMLHttpRequest,
+            "The content script should have access to content.XMLHTTPRequest"
+          );
+          browser.test.assertEq(
+            true,
+            !!content.fetch,
+            "The content script should have access to window.pageFetch"
+          );
+
+          resolve(event.data);
+        };
+
+        window.addEventListener("message", listenPageMessage);
+
+        window.postMessage({}, "*");
+      }
+    );
+
+    const url = new URL("/return_headers.sjs", location).href;
+
+    await Promise.all([
+      new Promise((resolve, reject) => {
+        const req = new content.XMLHttpRequest();
+        req.open("GET", url);
+        req.addEventListener("load", () =>
+          resolve(JSON.parse(req.responseText))
+        );
+        req.addEventListener("error", reject);
+        req.send();
+      }),
+      content.fetch(url).then(res => res.json()),
+    ])
+      .then(async ([xhrResult, fetchResult]) => {
+        browser.test.assertEq(
+          webpageFetchResult.referer,
+          fetchResult.referer,
+          "window.pageFetch referrer is the same of a webpage fetch request"
+        );
+        browser.test.assertEq(
+          webpageFetchResult.origin,
+          fetchResult.origin,
+          "window.pageFetch origin is the same of a webpage fetch request"
+        );
+
+        browser.test.assertEq(
+          webpageXhrResult.referer,
+          xhrResult.referer,
+          "content.XMLHttpRequest referrer is the same of a webpage fetch request"
+        );
+      })
+      .catch(error => {
+        browser.test.fail(`Unexpected error: ${error}`);
+      });
+
+    browser.test.notifyPass("content-script-page-xhr");
+  }
+
+  let extensionData = {
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://xpcshell.test/*"],
+          js: ["content.js"],
+        },
+      ],
+    },
+    files: {
+      "content.js": `(${contentScript})()`,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://xpcshell.test/data/file_page_xhr.html"
+  );
+  await extension.awaitFinish("content-script-page-xhr");
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_permissions.js b/toolkit/components/extensions/test/xpcshell/test_ext_permissions.js
new file mode 100644
index 0000000000..385563bab2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_permissions.js
@@ -0,0 +1,845 @@
+"use strict";
+
+const { AddonManager } = ChromeUtils.import(
+  "resource://gre/modules/AddonManager.jsm"
+);
+const { ExtensionPermissions } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionPermissions.jsm"
+);
+
+// ExtensionParent.jsm is being imported lazily because when it is imported Services.appinfo will be
+// retrieved and cached (as a side-effect of Schemas.jsm being imported), and so Services.appinfo
+// will not be returning the version set by AddonTestUtils.createAppInfo and this test will
+// fail on non-nightly builds (because the cached appinfo.version will be undefined and
+// AddonManager startup will fail).
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionParent",
+  "resource://gre/modules/ExtensionParent.jsm"
+);
+
+const BROWSER_PROPERTIES = "chrome://browser/locale/browser.properties";
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  false
+);
+
+let sawPrompt = false;
+let acceptPrompt = false;
+const observer = {
+  observe(subject, topic, data) {
+    if (topic == "webextension-optional-permission-prompt") {
+      sawPrompt = true;
+      let { resolve } = subject.wrappedJSObject;
+      resolve(acceptPrompt);
+    }
+  },
+};
+
+add_task(async function setup() {
+  // Bug 1646182: Force ExtensionPermissions to run in rkv mode, the legacy
+  // storage mode will run in xpcshell-legacy-ep.ini
+  await ExtensionPermissions._uninit();
+
+  Services.prefs.setBoolPref(
+    "extensions.webextOptionalPermissionPrompts",
+    true
+  );
+  Services.obs.addObserver(observer, "webextension-optional-permission-prompt");
+  registerCleanupFunction(() => {
+    Services.obs.removeObserver(
+      observer,
+      "webextension-optional-permission-prompt"
+    );
+    Services.prefs.clearUserPref("extensions.webextOptionalPermissionPrompts");
+  });
+  await AddonTestUtils.promiseStartupManager();
+  AddonTestUtils.usePrivilegedSignatures = false;
+});
+
+add_task(async function test_permissions_on_startup() {
+  let extensionId = "@permissionTest";
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: { id: extensionId },
+      },
+      permissions: ["tabs"],
+    },
+    useAddonManager: "permanent",
+    async background() {
+      let perms = await browser.permissions.getAll();
+      browser.test.sendMessage("permissions", perms);
+    },
+  });
+  let adding = {
+    permissions: ["internal:privateBrowsingAllowed"],
+    origins: [],
+  };
+  await extension.startup();
+  let perms = await extension.awaitMessage("permissions");
+  equal(perms.permissions.length, 1, "one permission");
+  equal(perms.permissions[0], "tabs", "internal permission not present");
+
+  const { StartupCache } = ExtensionParent;
+
+  // StartupCache.permissions will not contain the extension permissions.
+  let manifestData = await StartupCache.permissions.get(extensionId, () => {
+    return { permissions: [], origins: [] };
+  });
+  equal(manifestData.permissions.length, 0, "no permission");
+
+  perms = await ExtensionPermissions.get(extensionId);
+  equal(perms.permissions.length, 0, "no permissions");
+  await ExtensionPermissions.add(extensionId, adding);
+
+  // Restart the extension and re-test the permissions.
+  await ExtensionPermissions._uninit();
+  await AddonTestUtils.promiseRestartManager();
+  let restarted = extension.awaitMessage("permissions");
+  await extension.awaitStartup();
+  perms = await restarted;
+
+  manifestData = await StartupCache.permissions.get(extensionId, () => {
+    return { permissions: [], origins: [] };
+  });
+  deepEqual(
+    manifestData.permissions,
+    adding.permissions,
+    "StartupCache.permissions contains permission"
+  );
+
+  equal(perms.permissions.length, 1, "one permission");
+  equal(perms.permissions[0], "tabs", "internal permission not present");
+  let added = await ExtensionPermissions._get(extensionId);
+  deepEqual(added, adding, "permissions were retained");
+
+  await extension.unload();
+});
+
+add_task(async function test_permissions() {
+  const REQUIRED_PERMISSIONS = ["downloads"];
+  const REQUIRED_ORIGINS = ["*://site.com/", "*://*.domain.com/"];
+  const REQUIRED_ORIGINS_NORMALIZED = ["*://site.com/*", "*://*.domain.com/*"];
+
+  const OPTIONAL_PERMISSIONS = ["idle", "clipboardWrite"];
+  const OPTIONAL_ORIGINS = [
+    "http://optionalsite.com/",
+    "https://*.optionaldomain.com/",
+  ];
+  const OPTIONAL_ORIGINS_NORMALIZED = [
+    "http://optionalsite.com/*",
+    "https://*.optionaldomain.com/*",
+  ];
+
+  function background() {
+    browser.test.onMessage.addListener(async (method, arg) => {
+      if (method == "getAll") {
+        let perms = await browser.permissions.getAll();
+        let url = browser.extension.getURL("*");
+        perms.origins = perms.origins.filter(i => i != url);
+        browser.test.sendMessage("getAll.result", perms);
+      } else if (method == "contains") {
+        let result = await browser.permissions.contains(arg);
+        browser.test.sendMessage("contains.result", result);
+      } else if (method == "request") {
+        try {
+          let result = await browser.permissions.request(arg);
+          browser.test.sendMessage("request.result", {
+            status: "success",
+            result,
+          });
+        } catch (err) {
+          browser.test.sendMessage("request.result", {
+            status: "error",
+            message: err.message,
+          });
+        }
+      } else if (method == "remove") {
+        let result = await browser.permissions.remove(arg);
+        browser.test.sendMessage("remove.result", result);
+      }
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: [...REQUIRED_PERMISSIONS, ...REQUIRED_ORIGINS],
+      optional_permissions: [...OPTIONAL_PERMISSIONS, ...OPTIONAL_ORIGINS],
+    },
+    useAddonManager: "permanent",
+  });
+
+  await extension.startup();
+
+  function call(method, arg) {
+    extension.sendMessage(method, arg);
+    return extension.awaitMessage(`${method}.result`);
+  }
+
+  let result = await call("getAll");
+  deepEqual(result.permissions, REQUIRED_PERMISSIONS);
+  deepEqual(result.origins, REQUIRED_ORIGINS_NORMALIZED);
+
+  for (let perm of REQUIRED_PERMISSIONS) {
+    result = await call("contains", { permissions: [perm] });
+    equal(result, true, `contains() returns true for fixed permission ${perm}`);
+  }
+  for (let origin of REQUIRED_ORIGINS) {
+    result = await call("contains", { origins: [origin] });
+    equal(result, true, `contains() returns true for fixed origin ${origin}`);
+  }
+
+  // None of the optional permissions should be available yet
+  for (let perm of OPTIONAL_PERMISSIONS) {
+    result = await call("contains", { permissions: [perm] });
+    equal(result, false, `contains() returns false for permission ${perm}`);
+  }
+  for (let origin of OPTIONAL_ORIGINS) {
+    result = await call("contains", { origins: [origin] });
+    equal(result, false, `contains() returns false for origin ${origin}`);
+  }
+
+  result = await call("contains", {
+    permissions: [...REQUIRED_PERMISSIONS, ...OPTIONAL_PERMISSIONS],
+  });
+  equal(
+    result,
+    false,
+    "contains() returns false for a mix of available and unavailable permissions"
+  );
+
+  let perm = OPTIONAL_PERMISSIONS[0];
+  result = await call("request", { permissions: [perm] });
+  equal(
+    result.status,
+    "error",
+    "request() fails if not called from an event handler"
+  );
+  ok(
+    /request may only be called from a user input handler/.test(result.message),
+    "error message for calling request() outside an event handler is reasonable"
+  );
+  result = await call("contains", { permissions: [perm] });
+  equal(
+    result,
+    false,
+    "Permission requested outside an event handler was not granted"
+  );
+
+  await withHandlingUserInput(extension, async () => {
+    result = await call("request", { permissions: ["notifications"] });
+    equal(
+      result.status,
+      "error",
+      "request() for permission not in optional_permissions should fail"
+    );
+    ok(
+      /since it was not declared in optional_permissions/.test(result.message),
+      "error message for undeclared optional_permission is reasonable"
+    );
+
+    // Check request() when the prompt is canceled.
+    acceptPrompt = false;
+    result = await call("request", { permissions: [perm] });
+    equal(result.status, "success", "request() returned cleanly");
+    equal(
+      result.result,
+      false,
+      "request() returned false for rejected permission"
+    );
+
+    result = await call("contains", { permissions: [perm] });
+    equal(result, false, "Rejected permission was not granted");
+
+    // Call request() and accept the prompt
+    acceptPrompt = true;
+    let allOptional = {
+      permissions: OPTIONAL_PERMISSIONS,
+      origins: OPTIONAL_ORIGINS,
+    };
+    result = await call("request", allOptional);
+    equal(result.status, "success", "request() returned cleanly");
+    equal(
+      result.result,
+      true,
+      "request() returned true for accepted permissions"
+    );
+
+    // Verify that requesting a permission/origin in the wrong field fails
+    let originsAsPerms = {
+      permissions: OPTIONAL_ORIGINS,
+    };
+    let permsAsOrigins = {
+      origins: OPTIONAL_PERMISSIONS,
+    };
+
+    result = await call("request", originsAsPerms);
+    equal(
+      result.status,
+      "error",
+      "Requesting an origin as a permission should fail"
+    );
+    ok(
+      /Type error for parameter permissions \(Error processing permissions/.test(
+        result.message
+      ),
+      "Error message for origin as permission is reasonable"
+    );
+
+    result = await call("request", permsAsOrigins);
+    equal(
+      result.status,
+      "error",
+      "Requesting a permission as an origin should fail"
+    );
+    ok(
+      /Type error for parameter permissions \(Error processing origins/.test(
+        result.message
+      ),
+      "Error message for permission as origin is reasonable"
+    );
+  });
+
+  let allPermissions = {
+    permissions: [...REQUIRED_PERMISSIONS, ...OPTIONAL_PERMISSIONS],
+    origins: [...REQUIRED_ORIGINS_NORMALIZED, ...OPTIONAL_ORIGINS_NORMALIZED],
+  };
+
+  result = await call("getAll");
+  deepEqual(
+    result,
+    allPermissions,
+    "getAll() returns required and runtime requested permissions"
+  );
+
+  result = await call("contains", allPermissions);
+  equal(
+    result,
+    true,
+    "contains() returns true for runtime requested permissions"
+  );
+
+  // Restart, verify permissions are still present
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+
+  result = await call("getAll");
+  deepEqual(
+    result,
+    allPermissions,
+    "Runtime requested permissions are still present after restart"
+  );
+
+  // Check remove()
+  result = await call("remove", { permissions: OPTIONAL_PERMISSIONS });
+  equal(result, true, "remove() succeeded");
+
+  let perms = {
+    permissions: REQUIRED_PERMISSIONS,
+    origins: [...REQUIRED_ORIGINS_NORMALIZED, ...OPTIONAL_ORIGINS_NORMALIZED],
+  };
+  result = await call("getAll");
+  deepEqual(result, perms, "Expected permissions remain after removing some");
+
+  result = await call("remove", { origins: OPTIONAL_ORIGINS });
+  equal(result, true, "remove() succeeded");
+
+  perms.origins = REQUIRED_ORIGINS_NORMALIZED;
+  result = await call("getAll");
+  deepEqual(result, perms, "Back to default permissions after removing more");
+
+  await extension.unload();
+});
+
+add_task(async function test_startup() {
+  async function background() {
+    browser.test.onMessage.addListener(async perms => {
+      await browser.permissions.request(perms);
+      browser.test.sendMessage("requested");
+    });
+
+    let all = await browser.permissions.getAll();
+    let url = browser.extension.getURL("*");
+    all.origins = all.origins.filter(i => i != url);
+    browser.test.sendMessage("perms", all);
+  }
+
+  const PERMS1 = {
+    permissions: ["clipboardRead", "tabs"],
+  };
+  const PERMS2 = {
+    origins: ["https://site2.com/*"],
+  };
+
+  let extension1 = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      optional_permissions: PERMS1.permissions,
+    },
+    useAddonManager: "permanent",
+  });
+  let extension2 = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      optional_permissions: PERMS2.origins,
+    },
+    useAddonManager: "permanent",
+  });
+
+  await extension1.startup();
+  await extension2.startup();
+
+  let perms = await extension1.awaitMessage("perms");
+  perms = await extension2.awaitMessage("perms");
+
+  await withHandlingUserInput(extension1, async () => {
+    extension1.sendMessage(PERMS1);
+    await extension1.awaitMessage("requested");
+  });
+
+  await withHandlingUserInput(extension2, async () => {
+    extension2.sendMessage(PERMS2);
+    await extension2.awaitMessage("requested");
+  });
+
+  // Restart everything, and force the permissions store to be
+  // re-read on startup
+  await ExtensionPermissions._uninit();
+  await AddonTestUtils.promiseRestartManager();
+  await extension1.awaitStartup();
+  await extension2.awaitStartup();
+
+  async function checkPermissions(extension, permissions) {
+    perms = await extension.awaitMessage("perms");
+    let expect = Object.assign({ permissions: [], origins: [] }, permissions);
+    deepEqual(perms, expect, "Extension got correct permissions on startup");
+  }
+
+  await checkPermissions(extension1, PERMS1);
+  await checkPermissions(extension2, PERMS2);
+
+  await extension1.unload();
+  await extension2.unload();
+});
+
+// Test that we don't prompt for permissions an extension already has.
+add_task(async function test_alreadyGranted() {
+  const REQUIRED_PERMISSIONS = [
+    "geolocation",
+    "*://required-host.com/",
+    "*://*.required-domain.com/",
+  ];
+  const OPTIONAL_PERMISSIONS = [
+    ...REQUIRED_PERMISSIONS,
+    "clipboardRead",
+    "*://optional-host.com/",
+    "*://*.optional-domain.com/",
+  ];
+
+  function pageScript() {
+    browser.test.onMessage.addListener(async (msg, arg) => {
+      if (msg == "request") {
+        let result = await browser.permissions.request(arg);
+        browser.test.sendMessage("request.result", result);
+      } else if (msg == "remove") {
+        let result = await browser.permissions.remove(arg);
+        browser.test.sendMessage("remove.result", result);
+      } else if (msg == "close") {
+        window.close();
+      }
+    });
+
+    browser.test.sendMessage("page-ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.sendMessage("ready", browser.runtime.getURL("page.html"));
+    },
+
+    manifest: {
+      permissions: REQUIRED_PERMISSIONS,
+      optional_permissions: OPTIONAL_PERMISSIONS,
+    },
+
+    files: {
+      "page.html": `<html><head>
+          <script src="page.js"><\/script>
+        </head></html>`,
+
+      "page.js": pageScript,
+    },
+  });
+
+  await extension.startup();
+
+  await withHandlingUserInput(extension, async () => {
+    let url = await extension.awaitMessage("ready");
+    let page = await ExtensionTestUtils.loadContentPage(url, { extension });
+    await extension.awaitMessage("page-ready");
+
+    async function checkRequest(arg, expectPrompt, msg) {
+      sawPrompt = false;
+      extension.sendMessage("request", arg);
+      let result = await extension.awaitMessage("request.result");
+      ok(result, "request() call succeeded");
+      equal(
+        sawPrompt,
+        expectPrompt,
+        `Got ${expectPrompt ? "" : "no "}permission prompt for ${msg}`
+      );
+    }
+
+    await checkRequest(
+      { permissions: ["geolocation"] },
+      false,
+      "required permission from manifest"
+    );
+    await checkRequest(
+      { origins: ["http://required-host.com/"] },
+      false,
+      "origin permission from manifest"
+    );
+    await checkRequest(
+      { origins: ["http://host.required-domain.com/"] },
+      false,
+      "wildcard origin permission from manifest"
+    );
+
+    await checkRequest(
+      { permissions: ["clipboardRead"] },
+      true,
+      "optional permission"
+    );
+    await checkRequest(
+      { permissions: ["clipboardRead"] },
+      false,
+      "already granted optional permission"
+    );
+
+    await checkRequest(
+      { origins: ["http://optional-host.com/"] },
+      true,
+      "optional origin"
+    );
+    await checkRequest(
+      { origins: ["http://optional-host.com/"] },
+      false,
+      "already granted origin permission"
+    );
+
+    await checkRequest(
+      { origins: ["http://*.optional-domain.com/"] },
+      true,
+      "optional wildcard origin"
+    );
+    await checkRequest(
+      { origins: ["http://*.optional-domain.com/"] },
+      false,
+      "already granted optional wildcard origin"
+    );
+    await checkRequest(
+      { origins: ["http://host.optional-domain.com/"] },
+      false,
+      "host matching optional wildcard origin"
+    );
+    await page.close();
+  });
+
+  await extension.unload();
+});
+
+// IMPORTANT: Do not change this list without review from a Web Extensions peer!
+
+const GRANTED_WITHOUT_USER_PROMPT = [
+  "activeTab",
+  "activityLog",
+  "alarms",
+  "captivePortal",
+  "contextMenus",
+  "contextualIdentities",
+  "cookies",
+  "dns",
+  "geckoProfiler",
+  "identity",
+  "idle",
+  "menus",
+  "menus.overrideContext",
+  "mozillaAddons",
+  "networkStatus",
+  "normandyAddonStudy",
+  "search",
+  "storage",
+  "telemetry",
+  "theme",
+  "unlimitedStorage",
+  "urlbar",
+  "webRequest",
+  "webRequestBlocking",
+];
+
+add_task(function test_permissions_have_localization_strings() {
+  let noPromptNames = Schemas.getPermissionNames([
+    "PermissionNoPrompt",
+    "OptionalPermissionNoPrompt",
+  ]);
+  Assert.deepEqual(
+    GRANTED_WITHOUT_USER_PROMPT,
+    noPromptNames,
+    "List of no-prompt permissions is correct."
+  );
+
+  const bundle = Services.strings.createBundle(BROWSER_PROPERTIES);
+
+  for (const perm of Schemas.getPermissionNames()) {
+    try {
+      const str = bundle.GetStringFromName(`webextPerms.description.${perm}`);
+
+      ok(str.length, `Found localization string for '${perm}' permission`);
+    } catch (e) {
+      ok(
+        GRANTED_WITHOUT_USER_PROMPT.includes(perm),
+        `Permission '${perm}' intentionally granted without prompting the user`
+      );
+    }
+  }
+});
+
+// Check <all_urls> used as an optional API permission.
+add_task(async function test_optional_all_urls() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      optional_permissions: ["<all_urls>"],
+    },
+
+    background() {
+      browser.test.onMessage.addListener(async () => {
+        let before = !!browser.tabs.captureVisibleTab;
+        let granted = await browser.permissions.request({
+          origins: ["<all_urls>"],
+        });
+        let after = !!browser.tabs.captureVisibleTab;
+
+        browser.test.sendMessage("results", [before, granted, after]);
+      });
+    },
+  });
+
+  await extension.startup();
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request");
+    let [before, granted, after] = await extension.awaitMessage("results");
+
+    equal(
+      before,
+      false,
+      "captureVisibleTab() unavailable before optional permission request()"
+    );
+    equal(granted, true, "request() for optional permissions granted");
+    equal(
+      after,
+      true,
+      "captureVisibleTab() available after optional permission request()"
+    );
+  });
+
+  await extension.unload();
+});
+
+// Check that optional permissions are not included in update prompts
+add_task(async function test_permissions_prompt() {
+  function background() {
+    browser.test.onMessage.addListener(async (msg, arg) => {
+      if (msg == "request") {
+        let result = await browser.permissions.request(arg);
+        browser.test.sendMessage("result", result);
+      }
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      name: "permissions test",
+      description: "permissions test",
+      manifest_version: 2,
+      version: "1.0",
+
+      permissions: ["tabs", "https://test1.example.com/*"],
+      optional_permissions: ["clipboardWrite", "<all_urls>"],
+
+      content_scripts: [
+        {
+          matches: ["https://test2.example.com/*"],
+          js: [],
+        },
+      ],
+    },
+    useAddonManager: "permanent",
+  });
+
+  await extension.startup();
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request", {
+      permissions: ["clipboardWrite"],
+      origins: ["https://test2.example.com/*"],
+    });
+    let result = await extension.awaitMessage("result");
+    equal(result, true, "request() for optional permissions succeeded");
+  });
+
+  const PERMS = ["history", "tabs"];
+  const ORIGINS = ["https://test1.example.com/*", "https://test3.example.com/"];
+  let xpi = AddonTestUtils.createTempWebExtensionFile({
+    background,
+    manifest: {
+      name: "permissions test",
+      description: "permissions test",
+      manifest_version: 2,
+      version: "2.0",
+
+      applications: { gecko: { id: extension.id } },
+
+      permissions: [...PERMS, ...ORIGINS],
+      optional_permissions: ["clipboardWrite", "<all_urls>"],
+    },
+  });
+
+  let install = await AddonManager.getInstallForFile(xpi);
+
+  Services.prefs.setBoolPref("extensions.webextPermissionPrompts", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("extensions.webextPermissionPrompts");
+  });
+
+  let perminfo;
+  install.promptHandler = info => {
+    perminfo = info;
+    return Promise.resolve();
+  };
+
+  await AddonTestUtils.promiseCompleteInstall(install);
+  await extension.awaitStartup();
+
+  notEqual(perminfo, undefined, "Permission handler was invoked");
+  let perms = perminfo.addon.userPermissions;
+  deepEqual(
+    perms.permissions,
+    PERMS,
+    "Update details includes only manifest api permissions"
+  );
+  deepEqual(
+    perms.origins,
+    ORIGINS,
+    "Update details includes only manifest origin permissions"
+  );
+
+  await extension.unload();
+});
+
+// Check that internal permissions can not be set and are not returned by the API.
+add_task(async function test_internal_permissions() {
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  function background() {
+    browser.test.onMessage.addListener(async (method, arg) => {
+      try {
+        if (method == "getAll") {
+          let perms = await browser.permissions.getAll();
+          browser.test.sendMessage("getAll.result", perms);
+        } else if (method == "contains") {
+          let result = await browser.permissions.contains(arg);
+          browser.test.sendMessage("contains.result", {
+            status: "success",
+            result,
+          });
+        } else if (method == "request") {
+          let result = await browser.permissions.request(arg);
+          browser.test.sendMessage("request.result", {
+            status: "success",
+            result,
+          });
+        } else if (method == "remove") {
+          let result = await browser.permissions.remove(arg);
+          browser.test.sendMessage("remove.result", result);
+        }
+      } catch (err) {
+        browser.test.sendMessage(`${method}.result`, {
+          status: "error",
+          message: err.message,
+        });
+      }
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      name: "permissions test",
+      description: "permissions test",
+      manifest_version: 2,
+      version: "1.0",
+      permissions: [],
+    },
+    useAddonManager: "permanent",
+    incognitoOverride: "spanning",
+  });
+
+  let perm = "internal:privateBrowsingAllowed";
+
+  await extension.startup();
+
+  function call(method, arg) {
+    extension.sendMessage(method, arg);
+    return extension.awaitMessage(`${method}.result`);
+  }
+
+  let result = await call("getAll");
+  ok(!result.permissions.includes(perm), "internal not returned");
+
+  result = await call("contains", { permissions: [perm] });
+  ok(
+    /Type error for parameter permissions \(Error processing permissions/.test(
+      result.message
+    ),
+    `Unable to check for internal permission: ${result.message}`
+  );
+
+  result = await call("remove", { permissions: [perm] });
+  ok(
+    /Type error for parameter permissions \(Error processing permissions/.test(
+      result.message
+    ),
+    `Unable to remove for internal permission ${result.message}`
+  );
+
+  await withHandlingUserInput(extension, async () => {
+    result = await call("request", {
+      permissions: [perm],
+      origins: [],
+    });
+    ok(
+      /Type error for parameter permissions \(Error processing permissions/.test(
+        result.message
+      ),
+      `Unable to request internal permission ${result.message}`
+    );
+  });
+
+  await extension.unload();
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_permissions_api.js b/toolkit/components/extensions/test/xpcshell/test_ext_permissions_api.js
new file mode 100644
index 0000000000..910aef6df7
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_permissions_api.js
@@ -0,0 +1,397 @@
+"use strict";
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  false
+);
+
+const { AddonManager } = ChromeUtils.import(
+  "resource://gre/modules/AddonManager.jsm"
+);
+const { ExtensionPermissions } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionPermissions.jsm"
+);
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionParent",
+  "resource://gre/modules/ExtensionParent.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+let OptionalPermissions;
+
+add_task(async function setup() {
+  // Bug 1646182: Force ExtensionPermissions to run in rkv mode, the legacy
+  // storage mode will run in xpcshell-legacy-ep.ini
+  await ExtensionPermissions._uninit();
+
+  Services.prefs.setBoolPref(
+    "extensions.webextOptionalPermissionPrompts",
+    false
+  );
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("extensions.webextOptionalPermissionPrompts");
+  });
+  await AddonTestUtils.promiseStartupManager();
+  AddonTestUtils.usePrivilegedSignatures = false;
+
+  // We want to get a list of optional permissions prior to loading an extension,
+  // so we'll get ExtensionParent to do that for us.
+  await ExtensionParent.apiManager.lazyInit();
+
+  // These permissions have special behaviors and/or are not mapped directly to an
+  // api namespace.  They will have their own tests for specific behavior.
+  let ignore = [
+    "activeTab",
+    "clipboardRead",
+    "clipboardWrite",
+    "devtools",
+    "downloads.open",
+    "geolocation",
+    "management",
+    "menus.overrideContext",
+    "search",
+    "tabHide",
+    "tabs",
+    "webRequestBlocking",
+  ];
+  OptionalPermissions = Schemas.getPermissionNames([
+    "OptionalPermission",
+    "OptionalPermissionNoPrompt",
+  ]).filter(n => !ignore.includes(n));
+});
+
+add_task(async function test_api_on_permissions_changed() {
+  async function background() {
+    let manifest = browser.runtime.getManifest();
+    let permObj = { permissions: manifest.optional_permissions, origins: [] };
+
+    function verifyPermissions(enabled) {
+      for (let perm of manifest.optional_permissions) {
+        browser.test.assertEq(
+          enabled,
+          !!browser[perm],
+          `${perm} API is ${
+            enabled ? "injected" : "removed"
+          } after permission request`
+        );
+      }
+    }
+
+    browser.permissions.onAdded.addListener(details => {
+      browser.test.assertEq(
+        JSON.stringify(details.permissions),
+        JSON.stringify(manifest.optional_permissions),
+        "expected permissions added"
+      );
+      verifyPermissions(true);
+      browser.test.sendMessage("added");
+    });
+
+    browser.permissions.onRemoved.addListener(details => {
+      browser.test.assertEq(
+        JSON.stringify(details.permissions),
+        JSON.stringify(manifest.optional_permissions),
+        "expected permissions removed"
+      );
+      verifyPermissions(false);
+      browser.test.sendMessage("removed");
+    });
+
+    browser.test.onMessage.addListener((msg, enabled) => {
+      if (msg === "request") {
+        browser.permissions.request(permObj);
+      } else if (msg === "verify_access") {
+        verifyPermissions(enabled);
+        browser.test.sendMessage("verified");
+      } else if (msg === "revoke") {
+        browser.permissions.remove(permObj);
+      }
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      optional_permissions: OptionalPermissions,
+    },
+    useAddonManager: "permanent",
+  });
+  await extension.startup();
+
+  function addPermissions() {
+    extension.sendMessage("request");
+    return extension.awaitMessage("added");
+  }
+
+  function removePermissions() {
+    extension.sendMessage("revoke");
+    return extension.awaitMessage("removed");
+  }
+
+  function verifyPermissions(enabled) {
+    extension.sendMessage("verify_access", enabled);
+    return extension.awaitMessage("verified");
+  }
+
+  await withHandlingUserInput(extension, async () => {
+    await addPermissions();
+    await removePermissions();
+    await addPermissions();
+  });
+
+  // reset handlingUserInput for the restart
+  extensionHandlers.delete(extension);
+
+  // Verify access on restart
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+  await verifyPermissions(true);
+
+  await withHandlingUserInput(extension, async () => {
+    await removePermissions();
+  });
+
+  // Add private browsing to be sure it doesn't come through.
+  let permObj = {
+    permissions: OptionalPermissions.concat("internal:privateBrowsingAllowed"),
+    origins: [],
+  };
+
+  // enable the permissions while the addon is running
+  await ExtensionPermissions.add(extension.id, permObj, extension.extension);
+  await extension.awaitMessage("added");
+  await verifyPermissions(true);
+
+  // disable the permissions while the addon is running
+  await ExtensionPermissions.remove(extension.id, permObj, extension.extension);
+  await extension.awaitMessage("removed");
+  await verifyPermissions(false);
+
+  // Add private browsing to test internal permission.  If it slips through,
+  // we would get an error for an additional added message.
+  await ExtensionPermissions.add(
+    extension.id,
+    { permissions: ["internal:privateBrowsingAllowed"], origins: [] },
+    extension.extension
+  );
+
+  // disable the addon and re-test revoking permissions.
+  await withHandlingUserInput(extension, async () => {
+    await addPermissions();
+  });
+  let addon = await AddonManager.getAddonByID(extension.id);
+  await addon.disable();
+  await ExtensionPermissions.remove(extension.id, permObj);
+  await addon.enable();
+  await extension.awaitStartup();
+
+  await verifyPermissions(false);
+  let perms = await ExtensionPermissions.get(extension.id);
+  equal(perms.permissions.length, 0, "no permissions on startup");
+
+  await extension.unload();
+});
+
+add_task(async function test_geo_permissions() {
+  async function background() {
+    const permObj = { permissions: ["geolocation"] };
+    browser.test.onMessage.addListener(async msg => {
+      if (msg === "request") {
+        await browser.permissions.request(permObj);
+      } else if (msg === "remove") {
+        await browser.permissions.remove(permObj);
+      }
+      let result = await browser.permissions.contains(permObj);
+      browser.test.sendMessage("done", result);
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      applications: { gecko: { id: "geo-test@test" } },
+      optional_permissions: ["geolocation"],
+    },
+    useAddonManager: "permanent",
+  });
+  await extension.startup();
+
+  let policy = WebExtensionPolicy.getByID(extension.id);
+  let principal = policy.extension.principal;
+  equal(
+    Services.perms.testPermissionFromPrincipal(principal, "geo"),
+    Services.perms.UNKNOWN_ACTION,
+    "geolocation not allowed on install"
+  );
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request");
+    ok(await extension.awaitMessage("done"), "permission granted");
+    equal(
+      Services.perms.testPermissionFromPrincipal(principal, "geo"),
+      Services.perms.ALLOW_ACTION,
+      "geolocation allowed after requested"
+    );
+
+    extension.sendMessage("remove");
+    ok(!(await extension.awaitMessage("done")), "permission revoked");
+
+    equal(
+      Services.perms.testPermissionFromPrincipal(principal, "geo"),
+      Services.perms.UNKNOWN_ACTION,
+      "geolocation not allowed after removed"
+    );
+
+    // re-grant to test update removal
+    extension.sendMessage("request");
+    ok(await extension.awaitMessage("done"), "permission granted");
+    equal(
+      Services.perms.testPermissionFromPrincipal(principal, "geo"),
+      Services.perms.ALLOW_ACTION,
+      "geolocation allowed after re-requested"
+    );
+  });
+
+  // We should not have geo permission after this upgrade.
+  await extension.upgrade({
+    manifest: {
+      applications: { gecko: { id: "geo-test@test" } },
+    },
+    useAddonManager: "permanent",
+  });
+
+  equal(
+    Services.perms.testPermissionFromPrincipal(principal, "geo"),
+    Services.perms.UNKNOWN_ACTION,
+    "geolocation not allowed after upgrade"
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_browserSetting_permissions() {
+  async function background() {
+    const permObj = { permissions: ["browserSettings"] };
+    browser.test.onMessage.addListener(async msg => {
+      if (msg === "request") {
+        await browser.permissions.request(permObj);
+        await browser.browserSettings.cacheEnabled.set({ value: false });
+      } else if (msg === "remove") {
+        await browser.permissions.remove(permObj);
+      }
+      browser.test.sendMessage("done");
+    });
+  }
+
+  function cacheIsEnabled() {
+    return (
+      Services.prefs.getBoolPref("browser.cache.disk.enable") &&
+      Services.prefs.getBoolPref("browser.cache.memory.enable")
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      optional_permissions: ["browserSettings"],
+    },
+    useAddonManager: "permanent",
+  });
+  await extension.startup();
+  ok(cacheIsEnabled(), "setting is not set after startup");
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request");
+    await extension.awaitMessage("done");
+    ok(!cacheIsEnabled(), "setting was set after request");
+
+    extension.sendMessage("remove");
+    await extension.awaitMessage("done");
+    ok(cacheIsEnabled(), "setting is reset after remove");
+
+    extension.sendMessage("request");
+    await extension.awaitMessage("done");
+    ok(!cacheIsEnabled(), "setting was set after request");
+  });
+
+  await ExtensionPermissions._uninit();
+  extensionHandlers.delete(extension);
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("remove");
+    await extension.awaitMessage("done");
+    ok(cacheIsEnabled(), "setting is reset after remove");
+  });
+
+  await extension.unload();
+});
+
+add_task(async function test_privacy_permissions() {
+  async function background() {
+    const permObj = { permissions: ["privacy"] };
+    browser.test.onMessage.addListener(async msg => {
+      if (msg === "request") {
+        await browser.permissions.request(permObj);
+        await browser.privacy.websites.trackingProtectionMode.set({
+          value: "always",
+        });
+      } else if (msg === "remove") {
+        await browser.permissions.remove(permObj);
+      }
+      browser.test.sendMessage("done");
+    });
+  }
+
+  function hasSetting() {
+    return Services.prefs.getBoolPref("privacy.trackingprotection.enabled");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      optional_permissions: ["privacy"],
+    },
+    useAddonManager: "permanent",
+  });
+  await extension.startup();
+  ok(!hasSetting(), "setting is not set after startup");
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request");
+    await extension.awaitMessage("done");
+    ok(hasSetting(), "setting was set after request");
+
+    extension.sendMessage("remove");
+    await extension.awaitMessage("done");
+    ok(!hasSetting(), "setting is reset after remove");
+
+    extension.sendMessage("request");
+    await extension.awaitMessage("done");
+    ok(hasSetting(), "setting was set after request");
+  });
+
+  await ExtensionPermissions._uninit();
+  extensionHandlers.delete(extension);
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("remove");
+    await extension.awaitMessage("done");
+    ok(!hasSetting(), "setting is reset after remove");
+  });
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_permissions_migrate.js b/toolkit/components/extensions/test/xpcshell/test_ext_permissions_migrate.js
new file mode 100644
index 0000000000..4b9dccf7b4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_permissions_migrate.js
@@ -0,0 +1,252 @@
+"use strict";
+
+const { ExtensionPermissions } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionPermissions.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+add_task(async function setup() {
+  // Bug 1646182: Force ExtensionPermissions to run in rkv mode, the legacy
+  // storage mode will run in xpcshell-legacy-ep.ini
+  await ExtensionPermissions._uninit();
+
+  Services.prefs.setBoolPref(
+    "extensions.webextOptionalPermissionPrompts",
+    false
+  );
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("extensions.webextOptionalPermissionPrompts");
+  });
+  await AddonTestUtils.promiseStartupManager();
+  AddonTestUtils.usePrivilegedSignatures = false;
+});
+
+add_task(async function test_migrated_permission_to_optional() {
+  let id = "permission-upgrade@test";
+  let extensionData = {
+    manifest: {
+      version: "1.0",
+      applications: { gecko: { id } },
+      permissions: [
+        "webRequest",
+        "tabs",
+        "http://example.net/*",
+        "http://example.com/*",
+      ],
+    },
+    useAddonManager: "permanent",
+  };
+
+  function checkPermissions() {
+    let policy = WebExtensionPolicy.getByID(id);
+    ok(policy.hasPermission("webRequest"), "addon has webRequest permission");
+    ok(policy.hasPermission("tabs"), "addon has tabs permission");
+    ok(
+      policy.canAccessURI(Services.io.newURI("http://example.net/")),
+      "addon has example.net host permission"
+    );
+    ok(
+      policy.canAccessURI(Services.io.newURI("http://example.com/")),
+      "addon has example.com host permission"
+    );
+    ok(
+      !policy.canAccessURI(Services.io.newURI("http://other.com/")),
+      "addon does not have other.com host permission"
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  checkPermissions();
+
+  // Move to using optional permission
+  extensionData.manifest.version = "2.0";
+  extensionData.manifest.permissions = ["tabs", "http://example.net/*"];
+  extensionData.manifest.optional_permissions = [
+    "webRequest",
+    "http://example.com/*",
+    "http://other.com/*",
+  ];
+
+  // Restart the addon manager to flush the AddonInternal instance created
+  // when installing the addon above.  See bug 1622117.
+  await AddonTestUtils.promiseRestartManager();
+  await extension.upgrade(extensionData);
+
+  equal(extension.version, "2.0", "Expected extension version");
+  checkPermissions();
+
+  await extension.unload();
+});
+
+// This tests that settings are removed if a required permission is removed.
+// We use two settings APIs to make sure the one we keep permission to is not
+// removed inadvertantly.
+add_task(async function test_required_permissions_removed() {
+  function cacheIsEnabled() {
+    return (
+      Services.prefs.getBoolPref("browser.cache.disk.enable") &&
+      Services.prefs.getBoolPref("browser.cache.memory.enable")
+    );
+  }
+
+  let extData = {
+    background() {
+      if (browser.browserSettings) {
+        browser.browserSettings.cacheEnabled.set({ value: false });
+      }
+      browser.privacy.services.passwordSavingEnabled.set({ value: false });
+    },
+    manifest: {
+      applications: { gecko: { id: "pref-test@test" } },
+      permissions: ["tabs", "browserSettings", "privacy", "http://test.com/*"],
+    },
+    useAddonManager: "permanent",
+  };
+  let extension = ExtensionTestUtils.loadExtension(extData);
+  ok(
+    Services.prefs.getBoolPref("signon.rememberSignons"),
+    "privacy setting intial value as expected"
+  );
+  await extension.startup();
+  ok(!cacheIsEnabled(), "setting is set after startup");
+
+  extData.manifest.permissions = ["tabs"];
+  extData.manifest.optional_permissions = ["privacy"];
+  await extension.upgrade(extData);
+  ok(cacheIsEnabled(), "setting is reset after upgrade");
+  ok(
+    !Services.prefs.getBoolPref("signon.rememberSignons"),
+    "privacy setting is still set after upgrade"
+  );
+
+  await extension.unload();
+});
+
+// This tests that settings are removed if a granted permission is removed.
+// We use two settings APIs to make sure the one we keep permission to is not
+// removed inadvertantly.
+add_task(async function test_granted_permissions_removed() {
+  function cacheIsEnabled() {
+    return (
+      Services.prefs.getBoolPref("browser.cache.disk.enable") &&
+      Services.prefs.getBoolPref("browser.cache.memory.enable")
+    );
+  }
+
+  let extData = {
+    async background() {
+      browser.test.onMessage.addListener(async msg => {
+        await browser.permissions.request({ permissions: msg.permissions });
+        if (browser.browserSettings) {
+          browser.browserSettings.cacheEnabled.set({ value: false });
+        }
+        browser.privacy.services.passwordSavingEnabled.set({ value: false });
+        browser.test.sendMessage("done");
+      });
+    },
+    // "tabs" is never granted, it is included to exercise the removal code
+    // that called during the upgrade.
+    manifest: {
+      applications: { gecko: { id: "pref-test@test" } },
+      optional_permissions: [
+        "tabs",
+        "browserSettings",
+        "privacy",
+        "http://test.com/*",
+      ],
+    },
+    useAddonManager: "permanent",
+  };
+  let extension = ExtensionTestUtils.loadExtension(extData);
+  ok(
+    Services.prefs.getBoolPref("signon.rememberSignons"),
+    "privacy setting intial value as expected"
+  );
+  await extension.startup();
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage({ permissions: ["browserSettings", "privacy"] });
+    await extension.awaitMessage("done");
+  });
+  ok(!cacheIsEnabled(), "setting is set after startup");
+
+  extData.manifest.permissions = ["privacy"];
+  delete extData.manifest.optional_permissions;
+  await extension.upgrade(extData);
+  ok(cacheIsEnabled(), "setting is reset after upgrade");
+  ok(
+    !Services.prefs.getBoolPref("signon.rememberSignons"),
+    "privacy setting is still set after upgrade"
+  );
+
+  await extension.unload();
+});
+
+// Test an update where an add-on becomes a theme.
+add_task(async function test_addon_to_theme_update() {
+  let id = "theme-test@test";
+  let extData = {
+    manifest: {
+      applications: { gecko: { id } },
+      version: "1.0",
+      optional_permissions: ["tabs"],
+    },
+    async background() {
+      browser.test.onMessage.addListener(async msg => {
+        await browser.permissions.request({ permissions: msg.permissions });
+        browser.test.sendMessage("done");
+      });
+    },
+    useAddonManager: "permanent",
+  };
+  let extension = ExtensionTestUtils.loadExtension(extData);
+  await extension.startup();
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage({ permissions: ["tabs"] });
+    await extension.awaitMessage("done");
+  });
+
+  let policy = WebExtensionPolicy.getByID(id);
+  ok(policy.hasPermission("tabs"), "addon has tabs permission");
+
+  await extension.upgrade({
+    manifest: {
+      applications: { gecko: { id } },
+      version: "2.0",
+      theme: {
+        images: {
+          theme_frame: "image1.png",
+        },
+      },
+    },
+    useAddonManager: "permanent",
+  });
+  // When a theme is installed, it starts off in disabled mode, as seen in
+  //  toolkit/mozapps/extensions/test/xpcshell/test_update_theme.js .
+  // But if we upgrade from an enabled extension, the theme is enabled.
+  equal(extension.addon.userDisabled, false, "Theme is enabled");
+
+  policy = WebExtensionPolicy.getByID(id);
+  ok(!policy.hasPermission("tabs"), "addon tabs permission was removed");
+  let perms = await ExtensionPermissions._get(id);
+  ok(!perms?.permissions?.length, "no retained permissions");
+
+  extData.manifest.version = "3.0";
+  extData.manifest.permissions = ["privacy"];
+  await extension.upgrade(extData);
+
+  policy = WebExtensionPolicy.getByID(id);
+  ok(!policy.hasPermission("tabs"), "addon tabs permission not added");
+  ok(policy.hasPermission("privacy"), "addon privacy permission added");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_permissions_uninstall.js b/toolkit/components/extensions/test/xpcshell/test_ext_permissions_uninstall.js
new file mode 100644
index 0000000000..917a609e32
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_permissions_uninstall.js
@@ -0,0 +1,160 @@
+"use strict";
+
+const { ExtensionPermissions } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionPermissions.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  false
+);
+
+const observer = {
+  observe(subject, topic, data) {
+    if (topic == "webextension-optional-permission-prompt") {
+      let { resolve } = subject.wrappedJSObject;
+      resolve(true);
+    }
+  },
+};
+
+// Look up the cached permissions, if any.
+async function getCachedPermissions(extensionId) {
+  const NotFound = Symbol("extension ID not found in permissions cache");
+  try {
+    return await ExtensionParent.StartupCache.permissions.get(
+      extensionId,
+      () => {
+        // Throw error to prevent the key from being created.
+        throw NotFound;
+      }
+    );
+  } catch (e) {
+    if (e === NotFound) {
+      return null;
+    }
+    throw e;
+  }
+}
+
+// Look up the permissions from the file. Internal methods are used to avoid
+// inadvertently changing the permissions in the cache or the database.
+async function getStoredPermissions(extensionId) {
+  if (await ExtensionPermissions._has(extensionId)) {
+    return ExtensionPermissions._get(extensionId);
+  }
+  return null;
+}
+
+add_task(async function setup() {
+  // Bug 1646182: Force ExtensionPermissions to run in rkv mode, the legacy
+  // storage mode will run in xpcshell-legacy-ep.ini
+  await ExtensionPermissions._uninit();
+
+  Services.prefs.setBoolPref(
+    "extensions.webextOptionalPermissionPrompts",
+    true
+  );
+  Services.obs.addObserver(observer, "webextension-optional-permission-prompt");
+  await AddonTestUtils.promiseStartupManager();
+  registerCleanupFunction(async () => {
+    await AddonTestUtils.promiseShutdownManager();
+    Services.obs.removeObserver(
+      observer,
+      "webextension-optional-permission-prompt"
+    );
+    Services.prefs.clearUserPref("extensions.webextOptionalPermissionPrompts");
+  });
+});
+
+// This test must run before any restart of the addonmanager so the
+// ExtensionAddonObserver works.
+add_task(async function test_permissions_removed() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      optional_permissions: ["idle"],
+    },
+    background() {
+      browser.test.onMessage.addListener(async (msg, arg) => {
+        if (msg == "request") {
+          try {
+            let result = await browser.permissions.request(arg);
+            browser.test.sendMessage("request.result", result);
+          } catch (err) {
+            browser.test.sendMessage("request.result", err.message);
+          }
+        }
+      });
+    },
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request", { permissions: ["idle"], origins: [] });
+    let result = await extension.awaitMessage("request.result");
+    equal(result, true, "request() for optional permissions succeeded");
+  });
+
+  let id = extension.id;
+  let perms = await ExtensionPermissions.get(id);
+  equal(perms.permissions.length, 1, "optional permission added");
+
+  Assert.deepEqual(
+    await getCachedPermissions(id),
+    {
+      permissions: ["idle"],
+      origins: [],
+    },
+    "Optional permission added to cache"
+  );
+  Assert.deepEqual(
+    await getStoredPermissions(id),
+    {
+      permissions: ["idle"],
+      origins: [],
+    },
+    "Optional permission added to persistent file"
+  );
+
+  await extension.unload();
+
+  // Directly read from the internals instead of using ExtensionPermissions.get,
+  // because the latter will lazily cache the extension ID.
+  Assert.deepEqual(
+    await getCachedPermissions(id),
+    null,
+    "Cached permissions removed"
+  );
+  Assert.deepEqual(
+    await getStoredPermissions(id),
+    null,
+    "Stored permissions removed"
+  );
+
+  perms = await ExtensionPermissions.get(id);
+  equal(perms.permissions.length, 0, "no permissions after uninstall");
+  equal(perms.origins.length, 0, "no origin permissions after uninstall");
+
+  // The public ExtensionPermissions.get method should not store (empty)
+  // permissions in the persistent database. Polluting the cache is not ideal,
+  // but acceptable since the cache will eventually be cleared, and non-test
+  // code is not likely to call ExtensionPermissions.get() for non-installed
+  // extensions anyway.
+  Assert.deepEqual(await getCachedPermissions(id), perms, "Permissions cached");
+  Assert.deepEqual(
+    await getStoredPermissions(id),
+    null,
+    "Permissions not saved"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_persistent_events.js b/toolkit/components/extensions/test/xpcshell/test_ext_persistent_events.js
new file mode 100644
index 0000000000..7acb383053
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_persistent_events.js
@@ -0,0 +1,521 @@
+"use strict";
+
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+const { ExtensionAPI } = ExtensionCommon;
+
+const SCHEMA = [
+  {
+    namespace: "eventtest",
+    events: [
+      {
+        name: "onEvent1",
+        type: "function",
+        extraParameters: [{ type: "any" }],
+      },
+      {
+        name: "onEvent2",
+        type: "function",
+        extraParameters: [{ type: "any" }],
+      },
+    ],
+  },
+];
+
+// The code in this class does not actually run in this test scope, it is
+// serialized into a string which is later loaded by the WebExtensions
+// framework in the same context as other extension APIs.  By writing it
+// this way rather than as a big string constant we get lint coverage.
+// But eslint doesn't understand that this code runs in a different context
+// where the EventManager class is available so just tell it here:
+/* global EventManager */
+const API = class extends ExtensionAPI {
+  primeListener(extension, event, fire, params) {
+    Services.obs.notifyObservers(
+      { event, fire, params },
+      "prime-event-listener"
+    );
+
+    const FIRE_TOPIC = `fire-${event}`;
+
+    async function listener(subject, topic, data) {
+      try {
+        if (subject.wrappedJSObject.waitForBackground) {
+          await fire.wakeup();
+        }
+        await fire.async(subject.wrappedJSObject.listenerArgs);
+      } catch (err) {
+        let errSubject = { event, errorMessage: err.toString() };
+        Services.obs.notifyObservers(errSubject, "listener-callback-exception");
+      }
+    }
+    Services.obs.addObserver(listener, FIRE_TOPIC);
+
+    return {
+      unregister() {
+        Services.obs.notifyObservers(
+          { event, params },
+          "unregister-primed-listener"
+        );
+        Services.obs.removeObserver(listener, FIRE_TOPIC);
+      },
+      convert(_fire) {
+        Services.obs.notifyObservers(
+          { event, params },
+          "convert-event-listener"
+        );
+        fire = _fire;
+      },
+    };
+  }
+
+  getAPI(context) {
+    return {
+      eventtest: {
+        onEvent1: new EventManager({
+          context,
+          name: "test.event1",
+          persistent: {
+            module: "eventtest",
+            event: "onEvent1",
+          },
+          register: (fire, ...params) => {
+            let data = { event: "onEvent1", params };
+            Services.obs.notifyObservers(data, "register-event-listener");
+            return () => {
+              Services.obs.notifyObservers(data, "unregister-event-listener");
+            };
+          },
+        }).api(),
+
+        onEvent2: new EventManager({
+          context,
+          name: "test.event1",
+          persistent: {
+            module: "eventtest",
+            event: "onEvent2",
+          },
+          register: (fire, ...params) => {
+            let data = { event: "onEvent2", params };
+            Services.obs.notifyObservers(data, "register-event-listener");
+            return () => {
+              Services.obs.notifyObservers(data, "unregister-event-listener");
+            };
+          },
+        }).api(),
+      },
+    };
+  }
+};
+
+const API_SCRIPT = `this.eventtest = ${API.toString()}`;
+
+const MODULE_INFO = {
+  eventtest: {
+    schema: `data:,${JSON.stringify(SCHEMA)}`,
+    scopes: ["addon_parent"],
+    paths: [["eventtest"]],
+    url: URL.createObjectURL(new Blob([API_SCRIPT])),
+  },
+};
+
+const global = this;
+
+// Wait for the given event (topic) to occur a specific number of times
+// (count).  If fn is not supplied, the Promise returned from this function
+// resolves as soon as that many instances of the event have been observed.
+// If fn is supplied, this function also waits for the Promise that fn()
+// returns to complete and ensures that the given event does not occur more
+// than `count` times before then.  On success, resolves with an array
+// of the subjects from each of the observed events.
+async function promiseObservable(topic, count, fn = null) {
+  let _countResolve;
+  let results = [];
+  function listener(subject, _topic, data) {
+    results.push(subject.wrappedJSObject);
+    if (results.length > count) {
+      ok(false, `Got unexpected ${topic} event`);
+    } else if (results.length == count) {
+      _countResolve();
+    }
+  }
+  Services.obs.addObserver(listener, topic);
+
+  try {
+    await Promise.all([
+      new Promise(resolve => {
+        _countResolve = resolve;
+      }),
+      fn && fn(),
+    ]);
+  } finally {
+    Services.obs.removeObserver(listener, topic);
+  }
+
+  return results;
+}
+
+add_task(async function setup() {
+  Services.prefs.setBoolPref(
+    "extensions.webextensions.background-delayed-startup",
+    true
+  );
+
+  AddonTestUtils.init(global);
+  AddonTestUtils.overrideCertDB();
+  AddonTestUtils.createAppInfo(
+    "xpcshell@tests.mozilla.org",
+    "XPCShell",
+    "1",
+    "43"
+  );
+
+  ExtensionParent.apiManager.registerModules(MODULE_INFO);
+});
+
+add_task(async function test_persistent_events() {
+  await AddonTestUtils.promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background() {
+      let register1 = true,
+        register2 = true;
+      if (localStorage.getItem("skip1")) {
+        register1 = false;
+      }
+      if (localStorage.getItem("skip2")) {
+        register2 = false;
+      }
+
+      let listener1 = arg => browser.test.sendMessage("listener1", arg);
+      let listener2 = arg => browser.test.sendMessage("listener2", arg);
+      let listener3 = arg => browser.test.sendMessage("listener3", arg);
+
+      if (register1) {
+        browser.eventtest.onEvent1.addListener(listener1, "listener1");
+      }
+      if (register2) {
+        browser.eventtest.onEvent1.addListener(listener2, "listener2");
+        browser.eventtest.onEvent2.addListener(listener3, "listener3");
+      }
+
+      browser.test.onMessage.addListener(msg => {
+        if (msg == "unregister2") {
+          browser.eventtest.onEvent2.removeListener(listener3);
+          localStorage.setItem("skip2", true);
+        } else if (msg == "unregister1") {
+          localStorage.setItem("skip1", true);
+          browser.test.sendMessage("unregistered");
+        }
+      });
+
+      browser.test.sendMessage("ready");
+    },
+  });
+
+  function check(
+    info,
+    what,
+    { listener1 = true, listener2 = true, listener3 = true } = {}
+  ) {
+    let count = (listener1 ? 1 : 0) + (listener2 ? 1 : 0) + (listener3 ? 1 : 0);
+    equal(info.length, count, `Got ${count} ${what} events`);
+
+    let i = 0;
+    if (listener1) {
+      equal(info[i].event, "onEvent1", `Got ${what} on event1 for listener 1`);
+      deepEqual(
+        info[i].params,
+        ["listener1"],
+        `Got event1 ${what} args for listener 1`
+      );
+      ++i;
+    }
+
+    if (listener2) {
+      equal(info[i].event, "onEvent1", `Got ${what} on event1 for listener 2`);
+      deepEqual(
+        info[i].params,
+        ["listener2"],
+        `Got event1 ${what} args for listener 2`
+      );
+      ++i;
+    }
+
+    if (listener3) {
+      equal(info[i].event, "onEvent2", `Got ${what} on event2 for listener 3`);
+      deepEqual(
+        info[i].params,
+        ["listener3"],
+        `Got event2 ${what} args for listener 3`
+      );
+      ++i;
+    }
+  }
+
+  // Check that the regular event registration process occurs when
+  // the extension is installed.
+  let [info] = await Promise.all([
+    promiseObservable("register-event-listener", 3),
+    extension.startup(),
+  ]);
+  check(info, "register");
+
+  await extension.awaitMessage("ready");
+
+  // Check that the regular unregister process occurs when
+  // the browser shuts down.
+  [info] = await Promise.all([
+    promiseObservable("unregister-event-listener", 3),
+    new Promise(resolve => extension.extension.once("shutdown", resolve)),
+    AddonTestUtils.promiseShutdownManager(),
+  ]);
+  check(info, "unregister");
+
+  // Check that listeners are primed at the next browser startup.
+  [info] = await Promise.all([
+    promiseObservable("prime-event-listener", 3),
+    AddonTestUtils.promiseStartupManager(),
+  ]);
+  check(info, "prime");
+
+  // Check that primed listeners are converted to regular listeners
+  // when the background page is started after browser startup.
+  let p = promiseObservable("convert-event-listener", 3);
+  Services.obs.notifyObservers(null, "sessionstore-windows-restored");
+  info = await p;
+
+  check(info, "convert");
+
+  await extension.awaitMessage("ready");
+
+  // Check that when the event is triggered, all the plumbing worked
+  // correctly for the primed-then-converted listener.
+  let listenerArgs = { test: "kaboom" };
+  Services.obs.notifyObservers({ listenerArgs }, "fire-onEvent1");
+
+  let details = await extension.awaitMessage("listener1");
+  deepEqual(details, listenerArgs, "Listener 1 fired");
+  details = await extension.awaitMessage("listener2");
+  deepEqual(details, listenerArgs, "Listener 2 fired");
+
+  // Check that the converted listener is properly unregistered at
+  // browser shutdown.
+  [info] = await Promise.all([
+    promiseObservable("unregister-primed-listener", 3),
+    AddonTestUtils.promiseShutdownManager(),
+  ]);
+  check(info, "unregister");
+
+  // Start up again, listener should be primed
+  [info] = await Promise.all([
+    promiseObservable("prime-event-listener", 3),
+    AddonTestUtils.promiseStartupManager(),
+  ]);
+  check(info, "prime");
+
+  // Check that triggering the event before the listener has been converted
+  // causes the background page to be loaded and the listener to be converted,
+  // and the listener is invoked.
+  p = promiseObservable("convert-event-listener", 3);
+  listenerArgs.test = "startup event";
+  Services.obs.notifyObservers({ listenerArgs }, "fire-onEvent2");
+  info = await p;
+
+  check(info, "convert");
+
+  details = await extension.awaitMessage("listener3");
+  deepEqual(details, listenerArgs, "Listener 3 fired for event during startup");
+
+  await extension.awaitMessage("ready");
+
+  // Check that the unregister process works when we manually remove
+  // a listener.
+  p = promiseObservable("unregister-primed-listener", 1);
+  extension.sendMessage("unregister2");
+  info = await p;
+  check(info, "unregister", { listener1: false, listener2: false });
+
+  // Check that we only get unregisters for the remaining events after
+  // one listener has been removed.
+  info = await promiseObservable("unregister-primed-listener", 2, () =>
+    AddonTestUtils.promiseShutdownManager()
+  );
+  check(info, "unregister", { listener3: false });
+
+  // Check that after restart, only listeners that were present at
+  // the end of the last session are primed.
+  info = await promiseObservable("prime-event-listener", 2, () =>
+    AddonTestUtils.promiseStartupManager()
+  );
+  check(info, "prime", { listener3: false });
+
+  // Check that if the background script does not re-register listeners,
+  // the primed listeners are unregistered after the background page
+  // starts up.
+  p = promiseObservable("unregister-primed-listener", 1, () =>
+    extension.awaitMessage("ready")
+  );
+  Services.obs.notifyObservers(null, "sessionstore-windows-restored");
+  info = await p;
+  check(info, "unregister", { listener1: false, listener3: false });
+
+  // Just listener1 should be registered now, fire event1 to confirm.
+  listenerArgs.test = "third time";
+  Services.obs.notifyObservers({ listenerArgs }, "fire-onEvent1");
+  details = await extension.awaitMessage("listener1");
+  deepEqual(details, listenerArgs, "Listener 1 fired");
+
+  // Tell the extension not to re-register listener1 on the next startup
+  extension.sendMessage("unregister1");
+  await extension.awaitMessage("unregistered");
+
+  // Shut down, start up
+  info = await promiseObservable("unregister-primed-listener", 1, () =>
+    AddonTestUtils.promiseShutdownManager()
+  );
+  check(info, "unregister", { listener2: false, listener3: false });
+
+  info = await promiseObservable("prime-event-listener", 1, () =>
+    AddonTestUtils.promiseStartupManager()
+  );
+  check(info, "register", { listener2: false, listener3: false });
+
+  // Check that firing event1 causes the listener fire callback to
+  // reject.
+  p = promiseObservable("listener-callback-exception", 1);
+  Services.obs.notifyObservers(
+    { listenerArgs, waitForBackground: true },
+    "fire-onEvent1"
+  );
+  equal(
+    (await p)[0].errorMessage,
+    "Error: primed listener not re-registered",
+    "Primed listener that was not re-registered received an error when event was triggered during startup"
+  );
+
+  await extension.awaitMessage("ready");
+
+  await extension.unload();
+
+  await AddonTestUtils.promiseShutdownManager();
+});
+
+// This test checks whether primed listeners are correctly unregistered when
+// a background page load is interrupted. In particular, it verifies that the
+// fire.wakeup() and fire.async() promises settle eventually.
+add_task(async function test_shutdown_before_background_loaded() {
+  await AddonTestUtils.promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    background() {
+      let listener = arg => browser.test.sendMessage("triggered", arg);
+      browser.eventtest.onEvent1.addListener(listener, "triggered");
+      browser.test.sendMessage("bg_started");
+    },
+  });
+  await Promise.all([
+    promiseObservable("register-event-listener", 1),
+    extension.startup(),
+  ]);
+  await extension.awaitMessage("bg_started");
+
+  await Promise.all([
+    promiseObservable("unregister-event-listener", 1),
+    new Promise(resolve => extension.extension.once("shutdown", resolve)),
+    AddonTestUtils.promiseShutdownManager(),
+  ]);
+
+  let primeListenerPromise = promiseObservable("prime-event-listener", 1);
+  let fire;
+  let fireWakeupBeforeBgFail;
+  let fireAsyncBeforeBgFail;
+
+  let bgAbortedPromise = new Promise(resolve => {
+    let Management = ExtensionParent.apiManager;
+    Management.once("extension-browser-inserted", (eventName, browser) => {
+      browser.loadURI = async () => {
+        // The fire.wakeup/fire.async promises created while loading the
+        // background page should settle when the page fails to load.
+        fire = (await primeListenerPromise)[0].fire;
+        fireWakeupBeforeBgFail = fire.wakeup();
+        fireAsyncBeforeBgFail = fire.async();
+
+        extension.extension.once("background-page-aborted", resolve);
+        info("Forcing the background load to fail");
+        browser.remove();
+      };
+    });
+  });
+
+  let unregisterPromise = promiseObservable("unregister-primed-listener", 1);
+
+  await Promise.all([
+    primeListenerPromise,
+    AddonTestUtils.promiseStartupManager(),
+  ]);
+  await bgAbortedPromise;
+  info("Loaded extension and aborted load of background page");
+
+  await unregisterPromise;
+  info("Primed listener has been unregistered");
+
+  await fireWakeupBeforeBgFail;
+  info("fire.wakeup() before background load failure should settle");
+
+  await Assert.rejects(
+    fireAsyncBeforeBgFail,
+    /Error: listener not re-registered/,
+    "fire.async before background load failure should be rejected"
+  );
+
+  await fire.wakeup();
+  info("fire.wakeup() after background load failure should settle");
+
+  await Assert.rejects(
+    fire.async(),
+    /Error: primed listener not re-registered/,
+    "fire.async after background load failure should be rejected"
+  );
+
+  await AddonTestUtils.promiseShutdownManager();
+
+  // End of the abnormal shutdown test. Now restart the extension to verify
+  // that the persistent listeners have not been unregistered.
+
+  // Suppress background page start until an explicit notification.
+  ExtensionParent._resetStartupPromises();
+  await Promise.all([
+    promiseObservable("prime-event-listener", 1),
+    AddonTestUtils.promiseStartupManager(),
+  ]);
+  info("Triggering persistent event to force the background page to start");
+  Services.obs.notifyObservers({ listenerArgs: 123 }, "fire-onEvent1");
+  Services.obs.notifyObservers(null, "browser-delayed-startup-finished");
+  await extension.awaitMessage("bg_started");
+  equal(await extension.awaitMessage("triggered"), 123, "triggered event");
+
+  await Promise.all([
+    promiseObservable("unregister-primed-listener", 1),
+    AddonTestUtils.promiseShutdownManager(),
+  ]);
+
+  // And lastly, verify that a primed listener is correctly removed when the
+  // extension unloads normally before the delayed background page can load.
+  ExtensionParent._resetStartupPromises();
+  await Promise.all([
+    promiseObservable("prime-event-listener", 1),
+    AddonTestUtils.promiseStartupManager(),
+  ]);
+
+  info("Unloading extension before background page has loaded");
+  await Promise.all([
+    promiseObservable("unregister-primed-listener", 1),
+    extension.unload(),
+  ]);
+
+  await AddonTestUtils.promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_privacy.js b/toolkit/components/extensions/test/xpcshell/test_ext_privacy.js
new file mode 100644
index 0000000000..14a18b8fac
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_privacy.js
@@ -0,0 +1,964 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionPreferencesManager",
+  "resource://gre/modules/ExtensionPreferencesManager.jsm"
+);
+ChromeUtils.defineModuleGetter(
+  this,
+  "Preferences",
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const {
+  createAppInfo,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+// Currently security.tls.version.min has a different default
+// value in Nightly and Beta as opposed to Release builds.
+const tlsMinPref = Services.prefs.getIntPref("security.tls.version.min");
+if (tlsMinPref != 1 && tlsMinPref != 3) {
+  ok(false, "This test expects security.tls.version.min set to 1 or 3.");
+}
+const tlsMinVer = tlsMinPref === 3 ? "TLSv1.2" : "TLSv1";
+
+add_task(async function test_privacy() {
+  // Create an object to hold the values to which we will initialize the prefs.
+  const SETTINGS = {
+    "network.networkPredictionEnabled": {
+      "network.predictor.enabled": true,
+      "network.prefetch-next": true,
+      // This pref starts with a numerical value and we need to use whatever the
+      // default is or we encounter issues when the pref is reset during the test.
+      "network.http.speculative-parallel-limit": ExtensionPreferencesManager.getDefaultValue(
+        "network.http.speculative-parallel-limit"
+      ),
+      "network.dns.disablePrefetch": false,
+    },
+    "websites.hyperlinkAuditingEnabled": {
+      "browser.send_pings": true,
+    },
+  };
+
+  async function background() {
+    browser.test.onMessage.addListener(async (msg, ...args) => {
+      let data = args[0];
+      // The second argument is the end of the api name,
+      // e.g., "network.networkPredictionEnabled".
+      let apiObj = args[1].split(".").reduce((o, i) => o[i], browser.privacy);
+      let settingData;
+      switch (msg) {
+        case "get":
+          settingData = await apiObj.get(data);
+          browser.test.sendMessage("gotData", settingData);
+          break;
+
+        case "set":
+          await apiObj.set(data);
+          settingData = await apiObj.get({});
+          browser.test.sendMessage("afterSet", settingData);
+          break;
+
+        case "clear":
+          await apiObj.clear(data);
+          settingData = await apiObj.get({});
+          browser.test.sendMessage("afterClear", settingData);
+          break;
+      }
+    });
+  }
+
+  // Set prefs to our initial values.
+  for (let setting in SETTINGS) {
+    for (let pref in SETTINGS[setting]) {
+      Preferences.set(pref, SETTINGS[setting][pref]);
+    }
+  }
+
+  registerCleanupFunction(() => {
+    // Reset the prefs.
+    for (let setting in SETTINGS) {
+      for (let pref in SETTINGS[setting]) {
+        Preferences.reset(pref);
+      }
+    }
+  });
+
+  await promiseStartupManager();
+
+  // Create an array of extensions to install.
+  let testExtensions = [
+    ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        permissions: ["privacy"],
+      },
+      useAddonManager: "temporary",
+    }),
+
+    ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        permissions: ["privacy"],
+      },
+      useAddonManager: "temporary",
+    }),
+  ];
+
+  for (let extension of testExtensions) {
+    await extension.startup();
+  }
+
+  for (let setting in SETTINGS) {
+    testExtensions[0].sendMessage("get", {}, setting);
+    let data = await testExtensions[0].awaitMessage("gotData");
+    ok(data.value, "get returns expected value.");
+    equal(
+      data.levelOfControl,
+      "controllable_by_this_extension",
+      "get returns expected levelOfControl."
+    );
+
+    testExtensions[0].sendMessage("get", { incognito: true }, setting);
+    data = await testExtensions[0].awaitMessage("gotData");
+    ok(data.value, "get returns expected value with incognito.");
+    equal(
+      data.levelOfControl,
+      "not_controllable",
+      "get returns expected levelOfControl with incognito."
+    );
+
+    // Change the value to false.
+    testExtensions[0].sendMessage("set", { value: false }, setting);
+    data = await testExtensions[0].awaitMessage("afterSet");
+    ok(!data.value, "get returns expected value after setting.");
+    equal(
+      data.levelOfControl,
+      "controlled_by_this_extension",
+      "get returns expected levelOfControl after setting."
+    );
+
+    // Verify the prefs have been set to match the "false" setting.
+    for (let pref in SETTINGS[setting]) {
+      let msg = `${pref} set correctly for ${setting}`;
+      if (pref === "network.http.speculative-parallel-limit") {
+        equal(Preferences.get(pref), 0, msg);
+      } else {
+        equal(Preferences.get(pref), !SETTINGS[setting][pref], msg);
+      }
+    }
+
+    // Change the value with a newer extension.
+    testExtensions[1].sendMessage("set", { value: true }, setting);
+    data = await testExtensions[1].awaitMessage("afterSet");
+    ok(
+      data.value,
+      "get returns expected value after setting via newer extension."
+    );
+    equal(
+      data.levelOfControl,
+      "controlled_by_this_extension",
+      "get returns expected levelOfControl after setting."
+    );
+
+    // Verify the prefs have been set to match the "true" setting.
+    for (let pref in SETTINGS[setting]) {
+      let msg = `${pref} set correctly for ${setting}`;
+      if (pref === "network.http.speculative-parallel-limit") {
+        equal(
+          Preferences.get(pref),
+          ExtensionPreferencesManager.getDefaultValue(pref),
+          msg
+        );
+      } else {
+        equal(Preferences.get(pref), SETTINGS[setting][pref], msg);
+      }
+    }
+
+    // Change the value with an older extension.
+    testExtensions[0].sendMessage("set", { value: false }, setting);
+    data = await testExtensions[0].awaitMessage("afterSet");
+    ok(data.value, "Newer extension remains in control.");
+    equal(
+      data.levelOfControl,
+      "controlled_by_other_extensions",
+      "get returns expected levelOfControl when controlled by other."
+    );
+
+    // Clear the value of the newer extension.
+    testExtensions[1].sendMessage("clear", {}, setting);
+    data = await testExtensions[1].awaitMessage("afterClear");
+    ok(!data.value, "Older extension gains control.");
+    equal(
+      data.levelOfControl,
+      "controllable_by_this_extension",
+      "Expected levelOfControl returned after clearing."
+    );
+
+    testExtensions[0].sendMessage("get", {}, setting);
+    data = await testExtensions[0].awaitMessage("gotData");
+    ok(!data.value, "Current, older extension has control.");
+    equal(
+      data.levelOfControl,
+      "controlled_by_this_extension",
+      "Expected levelOfControl returned after clearing."
+    );
+
+    // Set the value again with the newer extension.
+    testExtensions[1].sendMessage("set", { value: true }, setting);
+    data = await testExtensions[1].awaitMessage("afterSet");
+    ok(
+      data.value,
+      "get returns expected value after setting via newer extension."
+    );
+    equal(
+      data.levelOfControl,
+      "controlled_by_this_extension",
+      "get returns expected levelOfControl after setting."
+    );
+
+    // Unload the newer extension. Expect the older extension to regain control.
+    await testExtensions[1].unload();
+    testExtensions[0].sendMessage("get", {}, setting);
+    data = await testExtensions[0].awaitMessage("gotData");
+    ok(!data.value, "Older extension regained control.");
+    equal(
+      data.levelOfControl,
+      "controlled_by_this_extension",
+      "Expected levelOfControl returned after unloading."
+    );
+
+    // Reload the extension for the next iteration of the loop.
+    testExtensions[1] = ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        permissions: ["privacy"],
+      },
+      useAddonManager: "temporary",
+    });
+    await testExtensions[1].startup();
+
+    // Clear the value of the older extension.
+    testExtensions[0].sendMessage("clear", {}, setting);
+    data = await testExtensions[0].awaitMessage("afterClear");
+    ok(data.value, "Setting returns to original value when all are cleared.");
+    equal(
+      data.levelOfControl,
+      "controllable_by_this_extension",
+      "Expected levelOfControl returned after clearing."
+    );
+
+    // Verify that our initial values were restored.
+    for (let pref in SETTINGS[setting]) {
+      equal(
+        Preferences.get(pref),
+        SETTINGS[setting][pref],
+        `${pref} was reset to its initial value.`
+      );
+    }
+  }
+
+  for (let extension of testExtensions) {
+    await extension.unload();
+  }
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_privacy_other_prefs() {
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("security.tls.version.min");
+    Services.prefs.clearUserPref("security.tls.version.max");
+  });
+
+  const cookieSvc = Ci.nsICookieService;
+
+  // Create an object to hold the values to which we will initialize the prefs.
+  const SETTINGS = {
+    "network.webRTCIPHandlingPolicy": {
+      "media.peerconnection.ice.default_address_only": false,
+      "media.peerconnection.ice.no_host": false,
+      "media.peerconnection.ice.proxy_only_if_behind_proxy": false,
+      "media.peerconnection.ice.proxy_only": false,
+    },
+    "network.tlsVersionRestriction": {
+      "security.tls.version.min": tlsMinPref,
+      "security.tls.version.max": 4,
+    },
+    "network.peerConnectionEnabled": {
+      "media.peerconnection.enabled": true,
+    },
+    "services.passwordSavingEnabled": {
+      "signon.rememberSignons": true,
+    },
+    "websites.referrersEnabled": {
+      "network.http.sendRefererHeader": 2,
+    },
+    "websites.resistFingerprinting": {
+      "privacy.resistFingerprinting": true,
+    },
+    "websites.firstPartyIsolate": {
+      "privacy.firstparty.isolate": false,
+    },
+    "websites.cookieConfig": {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_ACCEPT,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+  };
+
+  let defaultPrefs = new Preferences({ defaultBranch: true });
+  let defaultCookieBehavior = defaultPrefs.get("network.cookie.cookieBehavior");
+  let defaultBehavior;
+  switch (defaultCookieBehavior) {
+    case cookieSvc.BEHAVIOR_ACCEPT:
+      defaultBehavior = "allow_all";
+      break;
+    case cookieSvc.BEHAVIOR_REJECT_FOREIGN:
+      defaultBehavior = "reject_third_party";
+      break;
+    case cookieSvc.BEHAVIOR_REJECT:
+      defaultBehavior = "reject_all";
+      break;
+    case cookieSvc.BEHAVIOR_LIMIT_FOREIGN:
+      defaultBehavior = "allow_visited";
+      break;
+    case cookieSvc.BEHAVIOR_REJECT_TRACKER:
+      defaultBehavior = "reject_trackers";
+      break;
+    case cookieSvc.BEHAVIOR_REJECT_TRACKER_AND_PARTITION_FOREIGN:
+      defaultBehavior = "reject_trackers_and_partition_foreign";
+      break;
+    default:
+      ok(
+        false,
+        `Unexpected cookie behavior encountered: ${defaultCookieBehavior}`
+      );
+      break;
+  }
+
+  async function background() {
+    browser.test.onMessage.addListener(async (msg, ...args) => {
+      let data = args[0];
+      // The second argument is the end of the api name,
+      // e.g., "network.webRTCIPHandlingPolicy".
+      let apiObj = args[1].split(".").reduce((o, i) => o[i], browser.privacy);
+      let settingData;
+      switch (msg) {
+        case "set":
+          try {
+            await apiObj.set(data);
+          } catch (e) {
+            browser.test.sendMessage("settingThrowsException", {
+              message: e.message,
+            });
+            break;
+          }
+          settingData = await apiObj.get({});
+          browser.test.sendMessage("settingData", settingData);
+          break;
+        case "get":
+          settingData = await apiObj.get({});
+          browser.test.sendMessage("gettingData", settingData);
+          break;
+      }
+    });
+  }
+
+  // Set prefs to our initial values.
+  for (let setting in SETTINGS) {
+    for (let pref in SETTINGS[setting]) {
+      Preferences.set(pref, SETTINGS[setting][pref]);
+    }
+  }
+
+  registerCleanupFunction(() => {
+    // Reset the prefs.
+    for (let setting in SETTINGS) {
+      for (let pref in SETTINGS[setting]) {
+        Preferences.reset(pref);
+      }
+    }
+  });
+
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["privacy"],
+    },
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+
+  async function testSetting(setting, value, expected, expectedValue = value) {
+    extension.sendMessage("set", { value: value }, setting);
+    let data = await extension.awaitMessage("settingData");
+    deepEqual(
+      data.value,
+      expectedValue,
+      `Got expected result on setting ${setting} to ${uneval(value)}`
+    );
+    for (let pref in expected) {
+      equal(
+        Preferences.get(pref),
+        expected[pref],
+        `${pref} set correctly for ${expected[pref]}`
+      );
+    }
+  }
+
+  async function testSettingException(setting, value, expected) {
+    extension.sendMessage("set", { value: value }, setting);
+    let data = await extension.awaitMessage("settingThrowsException");
+    equal(data.message, expected);
+  }
+
+  async function testGetting(getting, expected, expectedValue) {
+    extension.sendMessage("get", null, getting);
+    let data = await extension.awaitMessage("gettingData");
+    deepEqual(
+      data.value,
+      expectedValue,
+      `Got expected result on getting ${getting}`
+    );
+    for (let pref in expected) {
+      equal(
+        Preferences.get(pref),
+        expected[pref],
+        `${pref} get correctly for ${expected[pref]}`
+      );
+    }
+  }
+
+  await testSetting(
+    "network.webRTCIPHandlingPolicy",
+    "default_public_and_private_interfaces",
+    {
+      "media.peerconnection.ice.default_address_only": true,
+      "media.peerconnection.ice.no_host": false,
+      "media.peerconnection.ice.proxy_only_if_behind_proxy": false,
+      "media.peerconnection.ice.proxy_only": false,
+    }
+  );
+  await testSetting(
+    "network.webRTCIPHandlingPolicy",
+    "default_public_interface_only",
+    {
+      "media.peerconnection.ice.default_address_only": true,
+      "media.peerconnection.ice.no_host": true,
+      "media.peerconnection.ice.proxy_only_if_behind_proxy": false,
+      "media.peerconnection.ice.proxy_only": false,
+    }
+  );
+  await testSetting(
+    "network.webRTCIPHandlingPolicy",
+    "disable_non_proxied_udp",
+    {
+      "media.peerconnection.ice.default_address_only": true,
+      "media.peerconnection.ice.no_host": true,
+      "media.peerconnection.ice.proxy_only_if_behind_proxy": true,
+      "media.peerconnection.ice.proxy_only": false,
+    }
+  );
+  await testSetting("network.webRTCIPHandlingPolicy", "proxy_only", {
+    "media.peerconnection.ice.default_address_only": false,
+    "media.peerconnection.ice.no_host": false,
+    "media.peerconnection.ice.proxy_only_if_behind_proxy": false,
+    "media.peerconnection.ice.proxy_only": true,
+  });
+  await testSetting("network.webRTCIPHandlingPolicy", "default", {
+    "media.peerconnection.ice.default_address_only": false,
+    "media.peerconnection.ice.no_host": false,
+    "media.peerconnection.ice.proxy_only_if_behind_proxy": false,
+    "media.peerconnection.ice.proxy_only": false,
+  });
+
+  await testSetting("network.peerConnectionEnabled", false, {
+    "media.peerconnection.enabled": false,
+  });
+  await testSetting("network.peerConnectionEnabled", true, {
+    "media.peerconnection.enabled": true,
+  });
+
+  await testSetting("websites.referrersEnabled", false, {
+    "network.http.sendRefererHeader": 0,
+  });
+  await testSetting("websites.referrersEnabled", true, {
+    "network.http.sendRefererHeader": 2,
+  });
+
+  await testSetting("websites.resistFingerprinting", false, {
+    "privacy.resistFingerprinting": false,
+  });
+  await testSetting("websites.resistFingerprinting", true, {
+    "privacy.resistFingerprinting": true,
+  });
+
+  await testSetting("websites.trackingProtectionMode", "always", {
+    "privacy.trackingprotection.enabled": true,
+    "privacy.trackingprotection.pbmode.enabled": true,
+  });
+  await testSetting("websites.trackingProtectionMode", "never", {
+    "privacy.trackingprotection.enabled": false,
+    "privacy.trackingprotection.pbmode.enabled": false,
+  });
+  await testSetting("websites.trackingProtectionMode", "private_browsing", {
+    "privacy.trackingprotection.enabled": false,
+    "privacy.trackingprotection.pbmode.enabled": true,
+  });
+
+  await testSetting("services.passwordSavingEnabled", false, {
+    "signon.rememberSignons": false,
+  });
+  await testSetting("services.passwordSavingEnabled", true, {
+    "signon.rememberSignons": true,
+  });
+
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "reject_third_party", nonPersistentCookies: true },
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_REJECT_FOREIGN,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_SESSION,
+    }
+  );
+  // A missing nonPersistentCookies property should default to false.
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "reject_third_party" },
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_REJECT_FOREIGN,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    { behavior: "reject_third_party", nonPersistentCookies: false }
+  );
+  // A missing behavior property should reset the pref.
+  await testSetting(
+    "websites.cookieConfig",
+    { nonPersistentCookies: true },
+    {
+      "network.cookie.cookieBehavior": defaultCookieBehavior,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_SESSION,
+    },
+    { behavior: defaultBehavior, nonPersistentCookies: true }
+  );
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "reject_all" },
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_REJECT,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    { behavior: "reject_all", nonPersistentCookies: false }
+  );
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "allow_visited" },
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_LIMIT_FOREIGN,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    { behavior: "allow_visited", nonPersistentCookies: false }
+  );
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "allow_all" },
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_ACCEPT,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    { behavior: "allow_all", nonPersistentCookies: false }
+  );
+  await testSetting(
+    "websites.cookieConfig",
+    { nonPersistentCookies: true },
+    {
+      "network.cookie.cookieBehavior": defaultCookieBehavior,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_SESSION,
+    },
+    { behavior: defaultBehavior, nonPersistentCookies: true }
+  );
+  await testSetting(
+    "websites.cookieConfig",
+    { nonPersistentCookies: false },
+    {
+      "network.cookie.cookieBehavior": defaultCookieBehavior,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    { behavior: defaultBehavior, nonPersistentCookies: false }
+  );
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "reject_trackers" },
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_REJECT_TRACKER,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    { behavior: "reject_trackers", nonPersistentCookies: false }
+  );
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "reject_trackers_and_partition_foreign" },
+    {
+      "network.cookie.cookieBehavior":
+        cookieSvc.BEHAVIOR_REJECT_TRACKER_AND_PARTITION_FOREIGN,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    {
+      behavior: "reject_trackers_and_partition_foreign",
+      nonPersistentCookies: false,
+    }
+  );
+
+  // 1. Can't enable FPI when cookie behavior is "reject_trackers_and_partition_foreign"
+  await testSettingException(
+    "websites.firstPartyIsolate",
+    true,
+    "Can't enable firstPartyIsolate when cookieBehavior is 'reject_trackers_and_partition_foreign'"
+  );
+
+  // 2. Change cookieConfig to reject_trackers should work normally.
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "reject_trackers" },
+    {
+      "network.cookie.cookieBehavior": cookieSvc.BEHAVIOR_REJECT_TRACKER,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    { behavior: "reject_trackers", nonPersistentCookies: false }
+  );
+
+  // 3. Enable FPI
+  await testSetting("websites.firstPartyIsolate", true, {
+    "privacy.firstparty.isolate": true,
+  });
+
+  // 4. When FPI is enabled, change setting to "reject_trackers_and_partition_foreign" is invalid
+  await testSettingException(
+    "websites.cookieConfig",
+    { behavior: "reject_trackers_and_partition_foreign" },
+    "Invalid cookieConfig 'reject_trackers_and_partition_foreign' when firstPartyIsolate is enabled"
+  );
+
+  // 5. Set conflict settings manually and check prefs.
+  Preferences.set("network.cookie.cookieBehavior", 5);
+  await testGetting(
+    "websites.firstPartyIsolate",
+    { "privacy.firstparty.isolate": true },
+    true
+  );
+  await testGetting(
+    "websites.cookieConfig",
+    {
+      "network.cookie.cookieBehavior":
+        cookieSvc.BEHAVIOR_REJECT_TRACKER_AND_PARTITION_FOREIGN,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    {
+      behavior: "reject_trackers_and_partition_foreign",
+      nonPersistentCookies: false,
+    }
+  );
+
+  // 6. It is okay to set current saved value.
+  await testSetting("websites.firstPartyIsolate", true, {
+    "privacy.firstparty.isolate": true,
+  });
+  await testSetting(
+    "websites.cookieConfig",
+    { behavior: "reject_trackers_and_partition_foreign" },
+    {
+      "network.cookie.cookieBehavior":
+        cookieSvc.BEHAVIOR_REJECT_TRACKER_AND_PARTITION_FOREIGN,
+      "network.cookie.lifetimePolicy": cookieSvc.ACCEPT_NORMALLY,
+    },
+    {
+      behavior: "reject_trackers_and_partition_foreign",
+      nonPersistentCookies: false,
+    }
+  );
+
+  await testSetting("websites.firstPartyIsolate", false, {
+    "privacy.firstparty.isolate": false,
+  });
+
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.2",
+      maximum: "TLSv1.3",
+    },
+    {
+      "security.tls.version.min": 3,
+      "security.tls.version.max": 4,
+    }
+  );
+
+  // Single values
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.3",
+    },
+    {
+      "security.tls.version.min": 4,
+      "security.tls.version.max": 4,
+    },
+    {
+      minimum: "TLSv1.3",
+      maximum: "TLSv1.3",
+    }
+  );
+
+  // Single values
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.3",
+    },
+    {
+      "security.tls.version.min": 4,
+      "security.tls.version.max": 4,
+    },
+    {
+      minimum: "TLSv1.3",
+      maximum: "TLSv1.3",
+    }
+  );
+
+  // Invalid values.
+  await testSettingException(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "invalid",
+      maximum: "invalid",
+    },
+    "Setting TLS version invalid is not allowed for security reasons."
+  );
+
+  // Invalid values.
+  await testSettingException(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "invalid2",
+    },
+    "Setting TLS version invalid2 is not allowed for security reasons."
+  );
+
+  // Invalid values.
+  await testSettingException(
+    "network.tlsVersionRestriction",
+    {
+      maximum: "invalid3",
+    },
+    "Setting TLS version invalid3 is not allowed for security reasons."
+  );
+
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.2",
+    },
+    {
+      "security.tls.version.min": 3,
+      "security.tls.version.max": 4,
+    },
+    {
+      minimum: "TLSv1.2",
+      maximum: "TLSv1.3",
+    }
+  );
+
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {
+      maximum: "TLSv1.2",
+    },
+    {
+      "security.tls.version.min": tlsMinPref,
+      "security.tls.version.max": 3,
+    },
+    {
+      minimum: tlsMinVer,
+      maximum: "TLSv1.2",
+    }
+  );
+
+  // Not supported version.
+  if (tlsMinPref === 3) {
+    await testSettingException(
+      "network.tlsVersionRestriction",
+      {
+        minimum: "TLSv1",
+      },
+      "Setting TLS version TLSv1 is not allowed for security reasons."
+    );
+
+    await testSettingException(
+      "network.tlsVersionRestriction",
+      {
+        minimum: "TLSv1.1",
+      },
+      "Setting TLS version TLSv1.1 is not allowed for security reasons."
+    );
+
+    await testSettingException(
+      "network.tlsVersionRestriction",
+      {
+        maximum: "TLSv1",
+      },
+      "Setting TLS version TLSv1 is not allowed for security reasons."
+    );
+
+    await testSettingException(
+      "network.tlsVersionRestriction",
+      {
+        maximum: "TLSv1.1",
+      },
+      "Setting TLS version TLSv1.1 is not allowed for security reasons."
+    );
+  }
+
+  // Min vs Max
+  await testSettingException(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.3",
+      maximum: "TLSv1.2",
+    },
+    "Setting TLS min version grater than the max version is not allowed."
+  );
+
+  // Min vs Max (with default max)
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.2",
+      maximum: "TLSv1.2",
+    },
+    {
+      "security.tls.version.min": 3,
+      "security.tls.version.max": 3,
+    }
+  );
+  await testSettingException(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.3",
+    },
+    "Setting TLS min version grater than the max version is not allowed."
+  );
+
+  // Max vs Min
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {
+      minimum: "TLSv1.3",
+      maximum: "TLSv1.3",
+    },
+    {
+      "security.tls.version.min": 4,
+      "security.tls.version.max": 4,
+    }
+  );
+  await testSettingException(
+    "network.tlsVersionRestriction",
+    {
+      maximum: "TLSv1.2",
+    },
+    "Setting TLS max version lower than the min version is not allowed."
+  );
+
+  // Empty value.
+  await testSetting(
+    "network.tlsVersionRestriction",
+    {},
+    {
+      "security.tls.version.min": tlsMinPref,
+      "security.tls.version.max": 4,
+    },
+    {
+      minimum: tlsMinVer,
+      maximum: "TLSv1.3",
+    }
+  );
+
+  const HTTPS_ONLY_PREF_NAME = "dom.security.https_only_mode";
+  const HTTPS_ONLY_PBM_PREF_NAME = "dom.security.https_only_mode_pbm";
+
+  Preferences.set(HTTPS_ONLY_PREF_NAME, false);
+  Preferences.set(HTTPS_ONLY_PBM_PREF_NAME, false);
+  await testGetting("network.httpsOnlyMode", {}, "never");
+
+  Preferences.set(HTTPS_ONLY_PREF_NAME, true);
+  Preferences.set(HTTPS_ONLY_PBM_PREF_NAME, false);
+  await testGetting("network.httpsOnlyMode", {}, "always");
+
+  Preferences.set(HTTPS_ONLY_PREF_NAME, false);
+  Preferences.set(HTTPS_ONLY_PBM_PREF_NAME, true);
+  await testGetting("network.httpsOnlyMode", {}, "private_browsing");
+
+  // Please note that if https_only_mode = true, then
+  // https_only_mode_pbm has no effect.
+  Preferences.set(HTTPS_ONLY_PREF_NAME, true);
+  Preferences.set(HTTPS_ONLY_PBM_PREF_NAME, true);
+  await testGetting("network.httpsOnlyMode", {}, "always");
+
+  // trying to "set" should have no effect when readonly!
+  extension.sendMessage("set", { value: "never" }, "network.httpsOnlyMode");
+  let readOnlyData = await extension.awaitMessage("settingData");
+  equal(readOnlyData.value, "always");
+
+  equal(Preferences.get(HTTPS_ONLY_PREF_NAME), true);
+  equal(Preferences.get(HTTPS_ONLY_PBM_PREF_NAME), true);
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_exceptions() {
+  async function background() {
+    await browser.test.assertRejects(
+      browser.privacy.network.networkPredictionEnabled.set({
+        value: true,
+        scope: "regular_only",
+      }),
+      "Firefox does not support the regular_only settings scope.",
+      "Expected rejection calling set with invalid scope."
+    );
+
+    await browser.test.assertRejects(
+      browser.privacy.network.networkPredictionEnabled.clear({
+        scope: "incognito_persistent",
+      }),
+      "Firefox does not support the incognito_persistent settings scope.",
+      "Expected rejection calling clear with invalid scope."
+    );
+
+    browser.test.notifyPass("exceptionTests");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["privacy"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("exceptionTests");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_privacy_disable.js b/toolkit/components/extensions/test/xpcshell/test_ext_privacy_disable.js
new file mode 100644
index 0000000000..ff0d4d9d48
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_privacy_disable.js
@@ -0,0 +1,201 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+XPCOMUtils.defineLazyGetter(this, "Management", () => {
+  // eslint-disable-next-line no-shadow
+  const { Management } = ChromeUtils.import(
+    "resource://gre/modules/Extension.jsm",
+    null
+  );
+  return Management;
+});
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "AddonManager",
+  "resource://gre/modules/AddonManager.jsm"
+);
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionPreferencesManager",
+  "resource://gre/modules/ExtensionPreferencesManager.jsm"
+);
+ChromeUtils.defineModuleGetter(
+  this,
+  "Preferences",
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const {
+  createAppInfo,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+function awaitEvent(eventName) {
+  return new Promise(resolve => {
+    let listener = (_eventName, ...args) => {
+      if (_eventName === eventName) {
+        Management.off(eventName, listener);
+        resolve(...args);
+      }
+    };
+
+    Management.on(eventName, listener);
+  });
+}
+
+function awaitPrefChange(prefName) {
+  return new Promise(resolve => {
+    let listener = args => {
+      Preferences.ignore(prefName, listener);
+      resolve();
+    };
+
+    Preferences.observe(prefName, listener);
+  });
+}
+
+add_task(async function test_disable() {
+  const OLD_ID = "old_id@tests.mozilla.org";
+  const NEW_ID = "new_id@tests.mozilla.org";
+
+  const PREF_TO_WATCH = "network.http.speculative-parallel-limit";
+
+  // Create an object to hold the values to which we will initialize the prefs.
+  const PREFS = {
+    "network.predictor.enabled": true,
+    "network.prefetch-next": true,
+    "network.http.speculative-parallel-limit": 10,
+    "network.dns.disablePrefetch": false,
+  };
+
+  // Set prefs to our initial values.
+  for (let pref in PREFS) {
+    Preferences.set(pref, PREFS[pref]);
+  }
+
+  registerCleanupFunction(() => {
+    // Reset the prefs.
+    for (let pref in PREFS) {
+      Preferences.reset(pref);
+    }
+  });
+
+  function checkPrefs(expected) {
+    for (let pref in PREFS) {
+      let msg = `${pref} set correctly.`;
+      let expectedValue = expected ? PREFS[pref] : !PREFS[pref];
+      if (pref === "network.http.speculative-parallel-limit") {
+        expectedValue = expected
+          ? ExtensionPreferencesManager.getDefaultValue(pref)
+          : 0;
+      }
+      equal(Preferences.get(pref), expectedValue, msg);
+    }
+  }
+
+  async function background() {
+    browser.test.onMessage.addListener(async (msg, data) => {
+      await browser.privacy.network.networkPredictionEnabled.set(data);
+      let settingData = await browser.privacy.network.networkPredictionEnabled.get(
+        {}
+      );
+      browser.test.sendMessage("privacyData", settingData);
+    });
+  }
+
+  await promiseStartupManager();
+
+  let testExtensions = [
+    ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        applications: {
+          gecko: {
+            id: OLD_ID,
+          },
+        },
+        permissions: ["privacy"],
+      },
+      useAddonManager: "temporary",
+    }),
+
+    ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        applications: {
+          gecko: {
+            id: NEW_ID,
+          },
+        },
+        permissions: ["privacy"],
+      },
+      useAddonManager: "temporary",
+    }),
+  ];
+
+  for (let extension of testExtensions) {
+    await extension.startup();
+  }
+
+  // Set the value to true for the older extension.
+  testExtensions[0].sendMessage("set", { value: true });
+  let data = await testExtensions[0].awaitMessage("privacyData");
+  ok(data.value, "Value set to true for the older extension.");
+
+  // Set the value to false for the newest extension.
+  testExtensions[1].sendMessage("set", { value: false });
+  data = await testExtensions[1].awaitMessage("privacyData");
+  ok(!data.value, "Value set to false for the newest extension.");
+
+  // Verify the prefs have been set to match the "false" setting.
+  checkPrefs(false);
+
+  // Disable the newest extension.
+  let disabledPromise = awaitPrefChange(PREF_TO_WATCH);
+  let newAddon = await AddonManager.getAddonByID(NEW_ID);
+  await newAddon.disable();
+  await disabledPromise;
+
+  // Verify the prefs have been set to match the "true" setting.
+  checkPrefs(true);
+
+  // Disable the older extension.
+  disabledPromise = awaitPrefChange(PREF_TO_WATCH);
+  let oldAddon = await AddonManager.getAddonByID(OLD_ID);
+  await oldAddon.disable();
+  await disabledPromise;
+
+  // Verify the prefs have reverted back to their initial values.
+  for (let pref in PREFS) {
+    equal(Preferences.get(pref), PREFS[pref], `${pref} reset correctly.`);
+  }
+
+  // Re-enable the newest extension.
+  let enabledPromise = awaitEvent("ready");
+  await newAddon.enable();
+  await enabledPromise;
+
+  // Verify the prefs have been set to match the "false" setting.
+  checkPrefs(false);
+
+  // Re-enable the older extension.
+  enabledPromise = awaitEvent("ready");
+  await oldAddon.enable();
+  await enabledPromise;
+
+  // Verify the prefs have remained set to match the "false" setting.
+  checkPrefs(false);
+
+  for (let extension of testExtensions) {
+    await extension.unload();
+  }
+
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_privacy_update.js b/toolkit/components/extensions/test/xpcshell/test_ext_privacy_update.js
new file mode 100644
index 0000000000..8b9ae6be9c
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_privacy_update.js
@@ -0,0 +1,167 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "Preferences",
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const {
+  createAppInfo,
+  createTempWebExtensionFile,
+  promiseCompleteAllInstalls,
+  promiseFindAddonUpdates,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+// Allow for unsigned addons.
+AddonTestUtils.overrideCertDB();
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "42", "42");
+
+add_task(async function test_privacy_update() {
+  // Create a object to hold the values to which we will initialize the prefs.
+  const PREFS = {
+    "network.predictor.enabled": true,
+    "network.prefetch-next": true,
+    "network.http.speculative-parallel-limit": 10,
+    "network.dns.disablePrefetch": false,
+  };
+
+  const EXTENSION_ID = "test_privacy_addon_update@tests.mozilla.org";
+  const PREF_EM_CHECK_UPDATE_SECURITY = "extensions.checkUpdateSecurity";
+
+  // Set prefs to our initial values.
+  for (let pref in PREFS) {
+    Preferences.set(pref, PREFS[pref]);
+  }
+
+  registerCleanupFunction(() => {
+    // Reset the prefs.
+    for (let pref in PREFS) {
+      Preferences.reset(pref);
+    }
+  });
+
+  async function background() {
+    browser.test.onMessage.addListener(async (msg, data) => {
+      let settingData;
+      switch (msg) {
+        case "get":
+          settingData = await browser.privacy.network.networkPredictionEnabled.get(
+            {}
+          );
+          browser.test.sendMessage("privacyData", settingData);
+          break;
+
+        case "set":
+          await browser.privacy.network.networkPredictionEnabled.set(data);
+          settingData = await browser.privacy.network.networkPredictionEnabled.get(
+            {}
+          );
+          browser.test.sendMessage("privacyData", settingData);
+          break;
+      }
+    });
+  }
+
+  const testServer = createHttpServer();
+  const port = testServer.identity.primaryPort;
+
+  // The test extension uses an insecure update url.
+  Services.prefs.setBoolPref(PREF_EM_CHECK_UPDATE_SECURITY, false);
+
+  testServer.registerPathHandler("/test_update.json", (request, response) => {
+    response.write(`{
+      "addons": {
+        "${EXTENSION_ID}": {
+          "updates": [
+            {
+              "version": "2.0",
+              "update_link": "http://localhost:${port}/addons/test_privacy-2.0.xpi"
+            }
+          ]
+        }
+      }
+    }`);
+  });
+
+  let webExtensionFile = createTempWebExtensionFile({
+    manifest: {
+      version: "2.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+      permissions: ["privacy"],
+    },
+    background,
+  });
+
+  testServer.registerFile("/addons/test_privacy-2.0.xpi", webExtensionFile);
+
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+          update_url: `http://localhost:${port}/test_update.json`,
+        },
+      },
+      permissions: ["privacy"],
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  // Change the value to false.
+  extension.sendMessage("set", { value: false });
+  let data = await extension.awaitMessage("privacyData");
+  ok(!data.value, "get returns expected value after setting.");
+
+  equal(
+    extension.version,
+    "1.0",
+    "The installed addon has the expected version."
+  );
+
+  let update = await promiseFindAddonUpdates(extension.addon);
+  let install = update.updateAvailable;
+
+  await promiseCompleteAllInstalls([install]);
+
+  await extension.awaitStartup();
+
+  equal(
+    extension.version,
+    "2.0",
+    "The updated addon has the expected version."
+  );
+
+  extension.sendMessage("get");
+  data = await extension.awaitMessage("privacyData");
+  ok(!data.value, "get returns expected value after updating.");
+
+  // Verify the prefs are still set to match the "false" setting.
+  for (let pref in PREFS) {
+    let msg = `${pref} set correctly.`;
+    let expectedValue =
+      pref === "network.http.speculative-parallel-limit" ? 0 : !PREFS[pref];
+    equal(Preferences.get(pref), expectedValue, msg);
+  }
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_proxy_authorization_via_proxyinfo.js b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_authorization_via_proxyinfo.js
new file mode 100644
index 0000000000..27f537b73b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_authorization_via_proxyinfo.js
@@ -0,0 +1,116 @@
+"use strict";
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "authManager",
+  "@mozilla.org/network/http-auth-manager;1",
+  "nsIHttpAuthManager"
+);
+
+const proxy = createHttpServer();
+const proxyToken = "this_is_my_pass";
+
+// accept proxy connections for mozilla.org
+proxy.identity.add("http", "mozilla.org", 80);
+
+proxy.registerPathHandler("/", (request, response) => {
+  if (request.hasHeader("Proxy-Authorization")) {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/plain", false);
+    response.write(request.getHeader("Proxy-Authorization"));
+  } else {
+    response.setStatusLine(
+      request.httpVersion,
+      407,
+      "Proxy authentication required"
+    );
+    response.setHeader("Content-Type", "text/plain", false);
+    response.setHeader("Proxy-Authenticate", "UnknownMeantToFail", false);
+    response.write("auth required");
+  }
+});
+
+function getExtension(background) {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["proxy", "webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background: `(${background})(${proxy.identity.primaryPort}, "${proxyToken}")`,
+  });
+}
+
+add_task(async function test_webRequest_auth_proxy() {
+  function background(port, proxyToken) {
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        browser.test.log(`onCompleted ${JSON.stringify(details)}\n`);
+        browser.test.assertEq(
+          "localhost",
+          details.proxyInfo.host,
+          "proxy host"
+        );
+        browser.test.assertEq(port, details.proxyInfo.port, "proxy port");
+        browser.test.assertEq("http", details.proxyInfo.type, "proxy type");
+        browser.test.assertEq(
+          "",
+          details.proxyInfo.username,
+          "proxy username not set"
+        );
+        browser.test.assertEq(
+          proxyToken,
+          details.proxyInfo.proxyAuthorizationHeader,
+          "proxy authorization header"
+        );
+        browser.test.assertEq(
+          proxyToken,
+          details.proxyInfo.connectionIsolationKey,
+          "proxy connection isolation"
+        );
+
+        browser.test.notifyPass("requestCompleted");
+      },
+      { urls: ["<all_urls>"] }
+    );
+
+    browser.webRequest.onAuthRequired.addListener(
+      details => {
+        // Using proxyAuthorizationHeader should prevent an auth request coming to us in the extension.
+        browser.test.fail("onAuthRequired");
+      },
+      { urls: ["<all_urls>"] },
+      ["blocking"]
+    );
+
+    // Handle the proxy request.
+    browser.proxy.onRequest.addListener(
+      details => {
+        browser.test.log(`onRequest ${JSON.stringify(details)}`);
+        return [
+          {
+            host: "localhost",
+            port,
+            type: "http",
+            proxyAuthorizationHeader: proxyToken,
+            connectionIsolationKey: proxyToken,
+          },
+        ];
+      },
+      { urls: ["<all_urls>"] },
+      ["requestHeaders"]
+    );
+  }
+
+  let extension = getExtension(background);
+
+  await extension.startup();
+
+  authManager.clearAll();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `http://mozilla.org/`
+  );
+
+  await extension.awaitFinish("requestCompleted");
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_proxy_config.js b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_config.js
new file mode 100644
index 0000000000..953bf4bea5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_config.js
@@ -0,0 +1,633 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "Preferences",
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const { ExtensionPermissions } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionPermissions.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  false
+);
+
+add_task(async function setup() {
+  // Bug 1646182: Force ExtensionPermissions to run in rkv mode, the legacy
+  // storage mode will run in xpcshell-legacy-ep.ini
+  await ExtensionPermissions._uninit();
+
+  Services.prefs.setBoolPref(
+    "extensions.webextOptionalPermissionPrompts",
+    false
+  );
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("extensions.webextOptionalPermissionPrompts");
+  });
+
+  await AddonTestUtils.promiseStartupManager();
+});
+
+add_task(async function test_browser_settings() {
+  const proxySvc = Ci.nsIProtocolProxyService;
+
+  // Create an object to hold the values to which we will initialize the prefs.
+  const PREFS = {
+    "network.proxy.type": proxySvc.PROXYCONFIG_SYSTEM,
+    "network.proxy.http": "",
+    "network.proxy.http_port": 0,
+    "network.proxy.share_proxy_settings": false,
+    "network.proxy.ftp": "",
+    "network.proxy.ftp_port": 0,
+    "network.proxy.ssl": "",
+    "network.proxy.ssl_port": 0,
+    "network.proxy.socks": "",
+    "network.proxy.socks_port": 0,
+    "network.proxy.socks_version": 5,
+    "network.proxy.socks_remote_dns": false,
+    "network.proxy.no_proxies_on": "",
+    "network.proxy.autoconfig_url": "",
+    "signon.autologin.proxy": false,
+  };
+
+  async function background() {
+    browser.test.onMessage.addListener(async (msg, value) => {
+      let apiObj = browser.proxy.settings;
+      let result = await apiObj.set({ value });
+      if (msg === "set") {
+        browser.test.assertTrue(result, "set returns true.");
+        browser.test.sendMessage("settingData", await apiObj.get({}));
+      } else {
+        browser.test.assertFalse(result, "set returns false for a no-op.");
+        browser.test.sendMessage("no-op set");
+      }
+    });
+  }
+
+  // Set prefs to our initial values.
+  for (let pref in PREFS) {
+    Preferences.set(pref, PREFS[pref]);
+  }
+
+  registerCleanupFunction(() => {
+    // Reset the prefs.
+    for (let pref in PREFS) {
+      Preferences.reset(pref);
+    }
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["proxy"],
+    },
+    incognitoOverride: "spanning",
+    useAddonManager: "temporary",
+  });
+
+  await extension.startup();
+
+  async function testSetting(value, expected, expectedValue = value) {
+    extension.sendMessage("set", value);
+    let data = await extension.awaitMessage("settingData");
+    deepEqual(data.value, expectedValue, `The setting has the expected value.`);
+    equal(
+      data.levelOfControl,
+      "controlled_by_this_extension",
+      `The setting has the expected levelOfControl.`
+    );
+    for (let pref in expected) {
+      equal(
+        Preferences.get(pref),
+        expected[pref],
+        `${pref} set correctly for ${value}`
+      );
+    }
+  }
+
+  async function testProxy(config, expectedPrefs, expectedConfig = config) {
+    // proxy.settings is not supported on Android.
+    if (AppConstants.platform === "android") {
+      return Promise.resolve();
+    }
+
+    let proxyConfig = {
+      proxyType: "none",
+      autoConfigUrl: "",
+      autoLogin: false,
+      proxyDNS: false,
+      httpProxyAll: false,
+      socksVersion: 5,
+      passthrough: "",
+      http: "",
+      ftp: "",
+      ssl: "",
+      socks: "",
+      respectBeConservative: true,
+    };
+
+    expectedConfig.proxyType = expectedConfig.proxyType || "system";
+
+    return testSetting(
+      config,
+      expectedPrefs,
+      Object.assign(proxyConfig, expectedConfig)
+    );
+  }
+
+  await testProxy(
+    { proxyType: "none" },
+    { "network.proxy.type": proxySvc.PROXYCONFIG_DIRECT }
+  );
+
+  await testProxy(
+    {
+      proxyType: "autoDetect",
+      autoLogin: true,
+      proxyDNS: true,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_WPAD,
+      "signon.autologin.proxy": true,
+      "network.proxy.socks_remote_dns": true,
+    }
+  );
+
+  await testProxy(
+    {
+      proxyType: "system",
+      autoLogin: false,
+      proxyDNS: false,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_SYSTEM,
+      "signon.autologin.proxy": false,
+      "network.proxy.socks_remote_dns": false,
+    }
+  );
+
+  // Verify that proxyType is optional and it defaults to "system".
+  await testProxy(
+    {
+      autoLogin: false,
+      proxyDNS: false,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_SYSTEM,
+      "signon.autologin.proxy": false,
+      "network.proxy.socks_remote_dns": false,
+      "network.http.proxy.respect-be-conservative": true,
+    }
+  );
+
+  await testProxy(
+    {
+      proxyType: "autoConfig",
+      autoConfigUrl: "http://mozilla.org",
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_PAC,
+      "network.proxy.autoconfig_url": "http://mozilla.org",
+      "network.http.proxy.respect-be-conservative": true,
+    }
+  );
+
+  await testProxy(
+    {
+      proxyType: "manual",
+      http: "http://www.mozilla.org",
+      autoConfigUrl: "",
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_MANUAL,
+      "network.proxy.http": "www.mozilla.org",
+      "network.proxy.http_port": 80,
+      "network.proxy.autoconfig_url": "",
+    },
+    {
+      proxyType: "manual",
+      http: "www.mozilla.org:80",
+      autoConfigUrl: "",
+    }
+  );
+
+  // When using proxyAll, we expect all proxies to be set to
+  // be the same as http.
+  await testProxy(
+    {
+      proxyType: "manual",
+      http: "http://www.mozilla.org:8080",
+      ftp: "http://www.mozilla.org:1234",
+      httpProxyAll: true,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_MANUAL,
+      "network.proxy.http": "www.mozilla.org",
+      "network.proxy.http_port": 8080,
+      "network.proxy.ftp": "www.mozilla.org",
+      "network.proxy.ftp_port": 8080,
+      "network.proxy.ssl": "www.mozilla.org",
+      "network.proxy.ssl_port": 8080,
+      "network.proxy.share_proxy_settings": true,
+    },
+    {
+      proxyType: "manual",
+      http: "www.mozilla.org:8080",
+      ftp: "www.mozilla.org:8080",
+      ssl: "www.mozilla.org:8080",
+      socks: "",
+      httpProxyAll: true,
+    }
+  );
+
+  await testProxy(
+    {
+      proxyType: "manual",
+      http: "www.mozilla.org:8080",
+      httpProxyAll: false,
+      ftp: "www.mozilla.org:8081",
+      ssl: "www.mozilla.org:8082",
+      socks: "mozilla.org:8083",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+      respectBeConservative: true,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_MANUAL,
+      "network.proxy.http": "www.mozilla.org",
+      "network.proxy.http_port": 8080,
+      "network.proxy.share_proxy_settings": false,
+      "network.proxy.ftp": "www.mozilla.org",
+      "network.proxy.ftp_port": 8081,
+      "network.proxy.ssl": "www.mozilla.org",
+      "network.proxy.ssl_port": 8082,
+      "network.proxy.socks": "mozilla.org",
+      "network.proxy.socks_port": 8083,
+      "network.proxy.socks_version": 4,
+      "network.proxy.no_proxies_on": ".mozilla.org",
+      "network.http.proxy.respect-be-conservative": true,
+    }
+  );
+
+  await testProxy(
+    {
+      proxyType: "manual",
+      http: "http://www.mozilla.org",
+      ftp: "ftp://www.mozilla.org",
+      ssl: "https://www.mozilla.org",
+      socks: "mozilla.org",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+      respectBeConservative: false,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_MANUAL,
+      "network.proxy.http": "www.mozilla.org",
+      "network.proxy.http_port": 80,
+      "network.proxy.share_proxy_settings": false,
+      "network.proxy.ftp": "www.mozilla.org",
+      "network.proxy.ftp_port": 21,
+      "network.proxy.ssl": "www.mozilla.org",
+      "network.proxy.ssl_port": 443,
+      "network.proxy.socks": "mozilla.org",
+      "network.proxy.socks_port": 1080,
+      "network.proxy.socks_version": 4,
+      "network.proxy.no_proxies_on": ".mozilla.org",
+      "network.http.proxy.respect-be-conservative": false,
+    },
+    {
+      proxyType: "manual",
+      http: "www.mozilla.org:80",
+      httpProxyAll: false,
+      ftp: "www.mozilla.org:21",
+      ssl: "www.mozilla.org:443",
+      socks: "mozilla.org:1080",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+      respectBeConservative: false,
+    }
+  );
+
+  await testProxy(
+    {
+      proxyType: "manual",
+      http: "http://www.mozilla.org:80",
+      ftp: "ftp://www.mozilla.org:21",
+      ssl: "https://www.mozilla.org:443",
+      socks: "mozilla.org:1080",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+      respectBeConservative: true,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_MANUAL,
+      "network.proxy.http": "www.mozilla.org",
+      "network.proxy.http_port": 80,
+      "network.proxy.share_proxy_settings": false,
+      "network.proxy.ftp": "www.mozilla.org",
+      "network.proxy.ftp_port": 21,
+      "network.proxy.ssl": "www.mozilla.org",
+      "network.proxy.ssl_port": 443,
+      "network.proxy.socks": "mozilla.org",
+      "network.proxy.socks_port": 1080,
+      "network.proxy.socks_version": 4,
+      "network.proxy.no_proxies_on": ".mozilla.org",
+      "network.http.proxy.respect-be-conservative": true,
+    },
+    {
+      proxyType: "manual",
+      http: "www.mozilla.org:80",
+      httpProxyAll: false,
+      ftp: "www.mozilla.org:21",
+      ssl: "www.mozilla.org:443",
+      socks: "mozilla.org:1080",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+      respectBeConservative: true,
+    }
+  );
+
+  await testProxy(
+    {
+      proxyType: "manual",
+      http: "http://www.mozilla.org:80",
+      ftp: "ftp://www.mozilla.org:80",
+      ssl: "https://www.mozilla.org:80",
+      socks: "mozilla.org:80",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+      respectBeConservative: false,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_MANUAL,
+      "network.proxy.http": "www.mozilla.org",
+      "network.proxy.http_port": 80,
+      "network.proxy.share_proxy_settings": false,
+      "network.proxy.ftp": "www.mozilla.org",
+      "network.proxy.ftp_port": 80,
+      "network.proxy.ssl": "www.mozilla.org",
+      "network.proxy.ssl_port": 80,
+      "network.proxy.socks": "mozilla.org",
+      "network.proxy.socks_port": 80,
+      "network.proxy.socks_version": 4,
+      "network.proxy.no_proxies_on": ".mozilla.org",
+      "network.http.proxy.respect-be-conservative": false,
+    },
+    {
+      proxyType: "manual",
+      http: "www.mozilla.org:80",
+      httpProxyAll: false,
+      ftp: "www.mozilla.org:80",
+      ssl: "www.mozilla.org:80",
+      socks: "mozilla.org:80",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+      respectBeConservative: false,
+    }
+  );
+
+  // Test resetting values.
+  await testProxy(
+    {
+      proxyType: "none",
+      http: "",
+      ftp: "",
+      ssl: "",
+      socks: "",
+      socksVersion: 5,
+      passthrough: "",
+      respectBeConservative: true,
+    },
+    {
+      "network.proxy.type": proxySvc.PROXYCONFIG_DIRECT,
+      "network.proxy.http": "",
+      "network.proxy.http_port": 0,
+      "network.proxy.ftp": "",
+      "network.proxy.ftp_port": 0,
+      "network.proxy.ssl": "",
+      "network.proxy.ssl_port": 0,
+      "network.proxy.socks": "",
+      "network.proxy.socks_port": 0,
+      "network.proxy.socks_version": 5,
+      "network.proxy.no_proxies_on": "",
+      "network.http.proxy.respect-be-conservative": true,
+    }
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_bad_value_proxy_config() {
+  let background =
+    AppConstants.platform === "android"
+      ? async () => {
+          await browser.test.assertRejects(
+            browser.proxy.settings.set({
+              value: {
+                proxyType: "none",
+              },
+            }),
+            /proxy.settings is not supported on android/,
+            "proxy.settings.set rejects on Android."
+          );
+
+          await browser.test.assertRejects(
+            browser.proxy.settings.get({}),
+            /proxy.settings is not supported on android/,
+            "proxy.settings.get rejects on Android."
+          );
+
+          await browser.test.assertRejects(
+            browser.proxy.settings.clear({}),
+            /proxy.settings is not supported on android/,
+            "proxy.settings.clear rejects on Android."
+          );
+
+          browser.test.sendMessage("done");
+        }
+      : async () => {
+          await browser.test.assertRejects(
+            browser.proxy.settings.set({
+              value: {
+                proxyType: "abc",
+              },
+            }),
+            /abc is not a valid value for proxyType/,
+            "proxy.settings.set rejects with an invalid proxyType value."
+          );
+
+          await browser.test.assertRejects(
+            browser.proxy.settings.set({
+              value: {
+                proxyType: "autoConfig",
+              },
+            }),
+            /undefined is not a valid value for autoConfigUrl/,
+            "proxy.settings.set for type autoConfig rejects with an empty autoConfigUrl value."
+          );
+
+          await browser.test.assertRejects(
+            browser.proxy.settings.set({
+              value: {
+                proxyType: "autoConfig",
+                autoConfigUrl: "abc",
+              },
+            }),
+            /abc is not a valid value for autoConfigUrl/,
+            "proxy.settings.set rejects with an invalid autoConfigUrl value."
+          );
+
+          await browser.test.assertRejects(
+            browser.proxy.settings.set({
+              value: {
+                proxyType: "manual",
+                socksVersion: "abc",
+              },
+            }),
+            /abc is not a valid value for socksVersion/,
+            "proxy.settings.set rejects with an invalid socksVersion value."
+          );
+
+          await browser.test.assertRejects(
+            browser.proxy.settings.set({
+              value: {
+                proxyType: "manual",
+                socksVersion: 3,
+              },
+            }),
+            /3 is not a valid value for socksVersion/,
+            "proxy.settings.set rejects with an invalid socksVersion value."
+          );
+
+          browser.test.sendMessage("done");
+        };
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["proxy"],
+    },
+    incognitoOverride: "spanning",
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+// Verify proxy prefs are unset on permission removal.
+add_task(async function test_proxy_settings_permissions() {
+  async function background() {
+    const permObj = { permissions: ["proxy"] };
+    browser.test.onMessage.addListener(async (msg, value) => {
+      if (msg === "request") {
+        browser.test.log("requesting proxy permission");
+        await browser.permissions.request(permObj);
+        browser.test.log("setting proxy values");
+        await browser.proxy.settings.set({ value });
+        browser.test.sendMessage("set");
+      } else if (msg === "remove") {
+        await browser.permissions.remove(permObj);
+        browser.test.sendMessage("removed");
+      }
+    });
+  }
+
+  let prefNames = [
+    "network.proxy.type",
+    "network.proxy.http",
+    "network.proxy.http_port",
+    "network.proxy.ftp",
+    "network.proxy.ftp_port",
+    "network.proxy.ssl",
+    "network.proxy.ssl_port",
+    "network.proxy.socks",
+    "network.proxy.socks_port",
+    "network.proxy.socks_version",
+    "network.proxy.no_proxies_on",
+  ];
+
+  function checkSettings(msg, expectUserValue = false) {
+    info(msg);
+    for (let pref of prefNames) {
+      equal(
+        expectUserValue,
+        Services.prefs.prefHasUserValue(pref),
+        `${pref} set as expected ${Preferences.get(pref)}`
+      );
+    }
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      optional_permissions: ["proxy"],
+    },
+    incognitoOverride: "spanning",
+    useAddonManager: "permanent",
+  });
+  await extension.startup();
+  checkSettings("setting is not set after startup");
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("request", {
+      proxyType: "manual",
+      http: "www.mozilla.org:8080",
+      httpProxyAll: false,
+      ftp: "www.mozilla.org:8081",
+      ssl: "www.mozilla.org:8082",
+      socks: "mozilla.org:8083",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+    });
+    await extension.awaitMessage("set");
+    checkSettings("setting was set after request", true);
+
+    extension.sendMessage("remove");
+    await extension.awaitMessage("removed");
+    checkSettings("setting is reset after remove");
+
+    // Set again to test after restart
+    extension.sendMessage("request", {
+      proxyType: "manual",
+      http: "www.mozilla.org:8080",
+      httpProxyAll: false,
+      ftp: "www.mozilla.org:8081",
+      ssl: "www.mozilla.org:8082",
+      socks: "mozilla.org:8083",
+      socksVersion: 4,
+      passthrough: ".mozilla.org",
+    });
+    await extension.awaitMessage("set");
+    checkSettings("setting was set after request", true);
+  });
+
+  // force the permissions store to be re-read on startup
+  await ExtensionPermissions._uninit();
+  resetHandlingUserInput();
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("remove");
+    await extension.awaitMessage("removed");
+    checkSettings("setting is reset after remove");
+  });
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_proxy_onauthrequired.js b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_onauthrequired.js
new file mode 100644
index 0000000000..db041d20d0
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_onauthrequired.js
@@ -0,0 +1,302 @@
+"use strict";
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "authManager",
+  "@mozilla.org/network/http-auth-manager;1",
+  "nsIHttpAuthManager"
+);
+
+const proxy = createHttpServer();
+
+// accept proxy connections for mozilla.org
+proxy.identity.add("http", "mozilla.org", 80);
+proxy.identity.add("https", "407.example.com", 443);
+
+proxy.registerPathHandler("CONNECT", (request, response) => {
+  Assert.equal(request.method, "CONNECT");
+  switch (request.host) {
+    case "407.example.com":
+      response.setStatusLine(request.httpVersion, 407, "Authenticate");
+      response.setHeader("Content-Type", "text/plain", false);
+      response.setHeader("Proxy-Authenticate", 'Basic realm="foobar"', false);
+      response.write("auth required");
+      break;
+    default:
+      response.setStatusLine(request.httpVersion, 500, "I am dumb");
+  }
+});
+
+proxy.registerPathHandler("/", (request, response) => {
+  if (request.hasHeader("Proxy-Authorization")) {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/plain", false);
+    response.write("ok, got proxy auth");
+  } else {
+    response.setStatusLine(
+      request.httpVersion,
+      407,
+      "Proxy authentication required"
+    );
+    response.setHeader("Content-Type", "text/plain", false);
+    response.setHeader("Proxy-Authenticate", 'Basic realm="foobar"', false);
+    response.write("auth required");
+  }
+});
+
+function getExtension(background) {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["proxy", "webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background: `(${background})(${proxy.identity.primaryPort})`,
+  });
+}
+
+add_task(async function test_webRequest_auth_proxy() {
+  async function background(port) {
+    let expecting = [
+      "onBeforeSendHeaders",
+      "onSendHeaders",
+      "onAuthRequired",
+      "onBeforeSendHeaders",
+      "onSendHeaders",
+      "onCompleted",
+    ];
+    browser.webRequest.onBeforeSendHeaders.addListener(
+      details => {
+        browser.test.log(`onBeforeSendHeaders ${JSON.stringify(details)}\n`);
+        browser.test.assertEq(
+          "onBeforeSendHeaders",
+          expecting.shift(),
+          "got expected event"
+        );
+        browser.test.assertEq(
+          "localhost",
+          details.proxyInfo.host,
+          "proxy host"
+        );
+        browser.test.assertEq(port, details.proxyInfo.port, "proxy port");
+        browser.test.assertEq("http", details.proxyInfo.type, "proxy type");
+        browser.test.assertEq(
+          "",
+          details.proxyInfo.username,
+          "proxy username not set"
+        );
+      },
+      { urls: ["<all_urls>"] }
+    );
+
+    browser.webRequest.onSendHeaders.addListener(
+      details => {
+        browser.test.log(`onSendHeaders ${JSON.stringify(details)}\n`);
+        browser.test.assertEq(
+          "onSendHeaders",
+          expecting.shift(),
+          "got expected event"
+        );
+      },
+      { urls: ["<all_urls>"] }
+    );
+
+    browser.webRequest.onAuthRequired.addListener(
+      details => {
+        browser.test.log(`onAuthRequired ${JSON.stringify(details)}\n`);
+        browser.test.assertEq(
+          "onAuthRequired",
+          expecting.shift(),
+          "got expected event"
+        );
+        browser.test.assertTrue(details.isProxy, "proxied request");
+        browser.test.assertEq(
+          "localhost",
+          details.proxyInfo.host,
+          "proxy host"
+        );
+        browser.test.assertEq(port, details.proxyInfo.port, "proxy port");
+        browser.test.assertEq("http", details.proxyInfo.type, "proxy type");
+        browser.test.assertEq(
+          "localhost",
+          details.challenger.host,
+          "proxy host"
+        );
+        browser.test.assertEq(port, details.challenger.port, "proxy port");
+        return { authCredentials: { username: "puser", password: "ppass" } };
+      },
+      { urls: ["<all_urls>"] },
+      ["blocking"]
+    );
+
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        browser.test.log(`onCompleted ${JSON.stringify(details)}\n`);
+        browser.test.assertEq(
+          "onCompleted",
+          expecting.shift(),
+          "got expected event"
+        );
+        browser.test.assertEq(
+          "localhost",
+          details.proxyInfo.host,
+          "proxy host"
+        );
+        browser.test.assertEq(port, details.proxyInfo.port, "proxy port");
+        browser.test.assertEq("http", details.proxyInfo.type, "proxy type");
+        browser.test.assertEq(
+          "",
+          details.proxyInfo.username,
+          "proxy username not set by onAuthRequired"
+        );
+        browser.test.assertEq(
+          undefined,
+          details.proxyInfo.password,
+          "no proxy password"
+        );
+        browser.test.assertEq(expecting.length, 0, "got all expected events");
+        browser.test.sendMessage("done");
+      },
+      { urls: ["<all_urls>"] }
+    );
+
+    // Handle the proxy request.
+    browser.proxy.onRequest.addListener(
+      details => {
+        browser.test.log(`onRequest ${JSON.stringify(details)}`);
+        return [{ host: "localhost", port, type: "http" }];
+      },
+      { urls: ["<all_urls>"] },
+      ["requestHeaders"]
+    );
+    browser.test.sendMessage("ready");
+  }
+
+  let handlingExt = getExtension(background);
+
+  await handlingExt.startup();
+  await handlingExt.awaitMessage("ready");
+
+  authManager.clearAll();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `http://mozilla.org/`
+  );
+
+  await handlingExt.awaitMessage("done");
+  await contentPage.close();
+  await handlingExt.unload();
+});
+
+add_task(async function test_webRequest_auth_proxy_https() {
+  async function background(port) {
+    let authReceived = false;
+
+    browser.webRequest.onBeforeSendHeaders.addListener(
+      details => {
+        if (authReceived) {
+          browser.test.sendMessage("done");
+          return { cancel: true };
+        }
+      },
+      { urls: ["<all_urls>"] },
+      ["blocking"]
+    );
+
+    browser.webRequest.onAuthRequired.addListener(
+      details => {
+        authReceived = true;
+        return { authCredentials: { username: "puser", password: "ppass" } };
+      },
+      { urls: ["<all_urls>"] },
+      ["blocking"]
+    );
+
+    // Handle the proxy request.
+    browser.proxy.onRequest.addListener(
+      details => {
+        browser.test.log(`onRequest ${JSON.stringify(details)}`);
+        return [{ host: "localhost", port, type: "http" }];
+      },
+      { urls: ["<all_urls>"] },
+      ["requestHeaders"]
+    );
+    browser.test.sendMessage("ready");
+  }
+
+  let handlingExt = getExtension(background);
+
+  await handlingExt.startup();
+  await handlingExt.awaitMessage("ready");
+
+  authManager.clearAll();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `https://407.example.com/`
+  );
+
+  await handlingExt.awaitMessage("done");
+  await contentPage.close();
+  await handlingExt.unload();
+});
+
+add_task(async function test_webRequest_auth_proxy_system() {
+  async function background(port) {
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.fail("onBeforeRequest");
+      },
+      { urls: ["<all_urls>"] }
+    );
+
+    browser.webRequest.onAuthRequired.addListener(
+      details => {
+        browser.test.sendMessage("onAuthRequired");
+        // cancel is silently ignored, if it were not (e.g someone messes up in
+        // WebRequest.jsm and allows cancel) this test would fail.
+        return {
+          cancel: true,
+          authCredentials: { username: "puser", password: "ppass" },
+        };
+      },
+      { urls: ["<all_urls>"] },
+      ["blocking"]
+    );
+
+    // Handle the proxy request.
+    browser.proxy.onRequest.addListener(
+      details => {
+        browser.test.log(`onRequest ${JSON.stringify(details)}`);
+        return { host: "localhost", port, type: "http" };
+      },
+      { urls: ["<all_urls>"] }
+    );
+    browser.test.sendMessage("ready");
+  }
+
+  let handlingExt = getExtension(background);
+
+  await handlingExt.startup();
+  await handlingExt.awaitMessage("ready");
+
+  authManager.clearAll();
+
+  function fetch(url) {
+    return new Promise((resolve, reject) => {
+      let xhr = new XMLHttpRequest();
+      xhr.mozBackgroundRequest = true;
+      xhr.open("GET", url);
+      xhr.onload = () => {
+        resolve(xhr.responseText);
+      };
+      xhr.onerror = () => {
+        reject(xhr.status);
+      };
+      xhr.send();
+    });
+  }
+
+  await Promise.all([
+    handlingExt.awaitMessage("onAuthRequired"),
+    fetch("http://mozilla.org"),
+  ]);
+  await handlingExt.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_proxy_settings.js b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_settings.js
new file mode 100644
index 0000000000..281804dccb
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_settings.js
@@ -0,0 +1,107 @@
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "HttpServer",
+  "resource://testing-common/httpd.js"
+);
+
+const {
+  createAppInfo,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "42");
+
+// We cannot use createHttpServer because it also messes with proxies.  We want
+// httpChannel to pick up the prefs we set and use those to proxy to our server.
+// If this were to fail, we would get an error about making a request out to
+// the network.
+const proxy = new HttpServer();
+proxy.start(-1);
+proxy.registerPathHandler("/fubar", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+registerCleanupFunction(() => {
+  return new Promise(resolve => {
+    proxy.stop(resolve);
+  });
+});
+
+add_task(async function test_proxy_settings() {
+  async function background(host, port) {
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.assertEq(
+          host,
+          details.proxyInfo.host,
+          "proxy host matched"
+        );
+        browser.test.assertEq(
+          port,
+          details.proxyInfo.port,
+          "proxy port matched"
+        );
+      },
+      { urls: ["http://example.com/*"] }
+    );
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        browser.test.notifyPass("proxytest");
+      },
+      { urls: ["http://example.com/*"] }
+    );
+    browser.webRequest.onErrorOccurred.addListener(
+      details => {
+        browser.test.notifyFail("proxytest");
+      },
+      { urls: ["http://example.com/*"] }
+    );
+
+    // Wait for the settings before testing a request.
+    await browser.proxy.settings.set({
+      value: {
+        proxyType: "manual",
+        http: `${host}:${port}`,
+      },
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "proxy.settings@mochi.test" } },
+      permissions: ["proxy", "webRequest", "<all_urls>"],
+    },
+    incognitoOverride: "spanning",
+    useAddonManager: "temporary",
+    background: `(${background})("${proxy.identity.primaryHost}", ${proxy.identity.primaryPort})`,
+  });
+
+  await promiseStartupManager();
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  equal(
+    Services.prefs.getStringPref("network.proxy.http"),
+    proxy.identity.primaryHost,
+    "proxy address is set"
+  );
+  equal(
+    Services.prefs.getIntPref("network.proxy.http_port"),
+    proxy.identity.primaryPort,
+    "proxy port is set"
+  );
+  let ok = extension.awaitFinish("proxytest");
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/fubar"
+  );
+  await ok;
+
+  await contentPage.close();
+  await extension.unload();
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_proxy_socks.js b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_socks.js
new file mode 100644
index 0000000000..62436737f1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_socks.js
@@ -0,0 +1,557 @@
+"use strict";
+
+/* globals TCPServerSocket */
+
+const CC = Components.Constructor;
+
+const BinaryInputStream = CC(
+  "@mozilla.org/binaryinputstream;1",
+  "nsIBinaryInputStream",
+  "setInputStream"
+);
+
+const currentThread = Cc["@mozilla.org/thread-manager;1"].getService()
+  .currentThread;
+
+// Most of the socks logic here is copied and upgraded to support authentication
+// for socks5. The original test is from netwerk/test/unit/test_socks.js
+
+// Socks 4 support was left in place for future tests.
+
+const STATE_WAIT_GREETING = 1;
+const STATE_WAIT_SOCKS4_REQUEST = 2;
+const STATE_WAIT_SOCKS4_USERNAME = 3;
+const STATE_WAIT_SOCKS4_HOSTNAME = 4;
+const STATE_WAIT_SOCKS5_GREETING = 5;
+const STATE_WAIT_SOCKS5_REQUEST = 6;
+const STATE_WAIT_SOCKS5_AUTH = 7;
+const STATE_WAIT_INPUT = 8;
+const STATE_FINISHED = 9;
+
+/**
+ * A basic socks proxy setup that handles a single http response page.  This
+ * is used for testing socks auth with webrequest.  We don't bother making
+ * sure we buffer ondata, etc., we'll never get anything but tiny chunks here.
+ */
+class SocksClient {
+  constructor(server, socket) {
+    this.server = server;
+    this.type = "";
+    this.username = "";
+    this.dest_name = "";
+    this.dest_addr = [];
+    this.dest_port = [];
+
+    this.inbuf = [];
+    this.state = STATE_WAIT_GREETING;
+    this.socket = socket;
+
+    socket.onclose = event => {
+      this.server.requestCompleted(this);
+    };
+    socket.ondata = event => {
+      let len = event.data.byteLength;
+
+      if (len == 0 && this.state == STATE_FINISHED) {
+        this.close();
+        this.server.requestCompleted(this);
+        return;
+      }
+
+      this.inbuf = new Uint8Array(event.data);
+      Promise.resolve().then(() => {
+        this.callState();
+      });
+    };
+  }
+
+  callState() {
+    switch (this.state) {
+      case STATE_WAIT_GREETING:
+        this.checkSocksGreeting();
+        break;
+      case STATE_WAIT_SOCKS4_REQUEST:
+        this.checkSocks4Request();
+        break;
+      case STATE_WAIT_SOCKS4_USERNAME:
+        this.checkSocks4Username();
+        break;
+      case STATE_WAIT_SOCKS4_HOSTNAME:
+        this.checkSocks4Hostname();
+        break;
+      case STATE_WAIT_SOCKS5_GREETING:
+        this.checkSocks5Greeting();
+        break;
+      case STATE_WAIT_SOCKS5_REQUEST:
+        this.checkSocks5Request();
+        break;
+      case STATE_WAIT_SOCKS5_AUTH:
+        this.checkSocks5Auth();
+        break;
+      case STATE_WAIT_INPUT:
+        this.checkRequest();
+        break;
+      default:
+        do_throw("server: read in invalid state!");
+    }
+  }
+
+  write(buf) {
+    this.socket.send(new Uint8Array(buf).buffer);
+  }
+
+  checkSocksGreeting() {
+    if (!this.inbuf.length) {
+      return;
+    }
+
+    if (this.inbuf[0] == 4) {
+      this.type = "socks4";
+      this.state = STATE_WAIT_SOCKS4_REQUEST;
+      this.checkSocks4Request();
+    } else if (this.inbuf[0] == 5) {
+      this.type = "socks";
+      this.state = STATE_WAIT_SOCKS5_GREETING;
+      this.checkSocks5Greeting();
+    } else {
+      do_throw("Unknown socks protocol!");
+    }
+  }
+
+  checkSocks4Request() {
+    if (this.inbuf.length < 8) {
+      return;
+    }
+
+    this.dest_port = this.inbuf.slice(2, 4);
+    this.dest_addr = this.inbuf.slice(4, 8);
+
+    this.inbuf = this.inbuf.slice(8);
+    this.state = STATE_WAIT_SOCKS4_USERNAME;
+    this.checkSocks4Username();
+  }
+
+  readString() {
+    let i = this.inbuf.indexOf(0);
+    let str = null;
+
+    if (i >= 0) {
+      let decoder = new TextDecoder();
+      str = decoder.decode(this.inbuf.slice(0, i));
+      this.inbuf = this.inbuf.slice(i + 1);
+    }
+
+    return str;
+  }
+
+  checkSocks4Username() {
+    let str = this.readString();
+
+    if (str == null) {
+      return;
+    }
+
+    this.username = str;
+    if (
+      this.dest_addr[0] == 0 &&
+      this.dest_addr[1] == 0 &&
+      this.dest_addr[2] == 0 &&
+      this.dest_addr[3] != 0
+    ) {
+      this.state = STATE_WAIT_SOCKS4_HOSTNAME;
+      this.checkSocks4Hostname();
+    } else {
+      this.sendSocks4Response();
+    }
+  }
+
+  checkSocks4Hostname() {
+    let str = this.readString();
+
+    if (str == null) {
+      return;
+    }
+
+    this.dest_name = str;
+    this.sendSocks4Response();
+  }
+
+  sendSocks4Response() {
+    this.state = STATE_WAIT_INPUT;
+    this.inbuf = [];
+    this.write([0, 0x5a, 0, 0, 0, 0, 0, 0]);
+  }
+
+  /**
+   * checks authentication information.
+   *
+   * buf[0] socks version
+   * buf[1] number of auth methods supported
+   * buf[2+nmethods] value for each auth method
+   *
+   * Response is
+   * byte[0] socks version
+   * byte[1] desired auth method
+   *
+   * For whatever reason, Firefox does not present auth method 0x02 however
+   * responding with that does cause Firefox to send authentication if
+   * the nsIProxyInfo instance has the data.  IUUC Firefox should send
+   * supported methods, but I'm no socks expert.
+   */
+  checkSocks5Greeting() {
+    if (this.inbuf.length < 2) {
+      return;
+    }
+    let nmethods = this.inbuf[1];
+    if (this.inbuf.length < 2 + nmethods) {
+      return;
+    }
+
+    // See comment above, keeping for future update.
+    // let methods = this.inbuf.slice(2, 2 + nmethods);
+
+    this.inbuf = [];
+    if (this.server.password || this.server.username) {
+      this.state = STATE_WAIT_SOCKS5_AUTH;
+      this.write([5, 2]);
+    } else {
+      this.state = STATE_WAIT_SOCKS5_REQUEST;
+      this.write([5, 0]);
+    }
+  }
+
+  checkSocks5Auth() {
+    equal(this.inbuf[0], 0x01, "subnegotiation version");
+    let uname_len = this.inbuf[1];
+    let pass_len = this.inbuf[2 + uname_len];
+    let unnamebuf = this.inbuf.slice(2, 2 + uname_len);
+    let pass_start = 2 + uname_len + 1;
+    let pwordbuf = this.inbuf.slice(pass_start, pass_start + pass_len);
+    let decoder = new TextDecoder();
+    let username = decoder.decode(unnamebuf);
+    let password = decoder.decode(pwordbuf);
+    this.inbuf = [];
+    equal(username, this.server.username, "socks auth username");
+    equal(password, this.server.password, "socks auth password");
+    if (username == this.server.username && password == this.server.password) {
+      this.state = STATE_WAIT_SOCKS5_REQUEST;
+      // x00 is success, any other value closes the connection
+      this.write([1, 0]);
+      return;
+    }
+    this.state = STATE_FINISHED;
+    this.write([1, 1]);
+  }
+
+  checkSocks5Request() {
+    if (this.inbuf.length < 4) {
+      return;
+    }
+
+    let atype = this.inbuf[3];
+    let len;
+    let name = false;
+
+    switch (atype) {
+      case 0x01:
+        len = 4;
+        break;
+      case 0x03:
+        len = this.inbuf[4];
+        name = true;
+        break;
+      case 0x04:
+        len = 16;
+        break;
+      default:
+        do_throw("Unknown address type " + atype);
+    }
+
+    if (name) {
+      if (this.inbuf.length < 4 + len + 1 + 2) {
+        return;
+      }
+
+      let buf = this.inbuf.slice(5, 5 + len);
+      let decoder = new TextDecoder();
+      this.dest_name = decoder.decode(buf);
+      len += 1;
+    } else {
+      if (this.inbuf.length < 4 + len + 2) {
+        return;
+      }
+
+      this.dest_addr = this.inbuf.slice(4, 4 + len);
+    }
+
+    len += 4;
+    this.dest_port = this.inbuf.slice(len, len + 2);
+    this.inbuf = this.inbuf.slice(len + 2);
+    this.sendSocks5Response();
+  }
+
+  sendSocks5Response() {
+    let buf;
+    if (this.dest_addr.length == 16) {
+      // send a successful response with the address, [::1]:80
+      buf = [5, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 80];
+    } else {
+      // send a successful response with the address, 127.0.0.1:80
+      buf = [5, 0, 0, 1, 127, 0, 0, 1, 0, 80];
+    }
+    this.state = STATE_WAIT_INPUT;
+    this.inbuf = [];
+    this.write(buf);
+  }
+
+  checkRequest() {
+    let decoder = new TextDecoder();
+    let request = decoder.decode(this.inbuf);
+
+    if (request == "PING!") {
+      this.state = STATE_FINISHED;
+      this.socket.send("PONG!");
+    } else if (request.startsWith("GET / HTTP/1.1")) {
+      this.socket.send(
+        "HTTP/1.1 200 OK\r\n" +
+          "Content-Length: 2\r\n" +
+          "Content-Type: text/html\r\n" +
+          "\r\nOK"
+      );
+      this.state = STATE_FINISHED;
+    }
+  }
+
+  close() {
+    this.socket.close();
+  }
+}
+
+class SocksTestServer {
+  constructor() {
+    this.client_connections = new Set();
+    this.listener = new TCPServerSocket(-1, { binaryType: "arraybuffer" }, -1);
+    this.listener.onconnect = event => {
+      let client = new SocksClient(this, event.socket);
+      this.client_connections.add(client);
+    };
+  }
+
+  requestCompleted(client) {
+    this.client_connections.delete(client);
+  }
+
+  close() {
+    for (let client of this.client_connections) {
+      client.close();
+    }
+    this.client_connections = new Set();
+    if (this.listener) {
+      this.listener.close();
+      this.listener = null;
+    }
+  }
+
+  setUserPass(username, password) {
+    this.username = username;
+    this.password = password;
+  }
+}
+
+/**
+ * Tests the basic socks logic using a simple socket connection and the
+ * protocol proxy service.  It seems TCPSocket has no way to tie proxy
+ * data to it, so we go old school here.
+ */
+class SocksTestClient {
+  constructor(socks, dest, resolve, reject) {
+    let pps = Cc["@mozilla.org/network/protocol-proxy-service;1"].getService(
+      Ci.nsIProtocolProxyService
+    );
+    let sts = Cc["@mozilla.org/network/socket-transport-service;1"].getService(
+      Ci.nsISocketTransportService
+    );
+
+    let pi_flags = 0;
+    if (socks.dns == "remote") {
+      pi_flags = Ci.nsIProxyInfo.TRANSPARENT_PROXY_RESOLVES_HOST;
+    }
+
+    let pi = pps.newProxyInfoWithAuth(
+      socks.version,
+      socks.host,
+      socks.port,
+      socks.username,
+      socks.password,
+      "",
+      "",
+      pi_flags,
+      -1,
+      null
+    );
+
+    this.trans = sts.createTransport([], dest.host, dest.port, pi);
+    this.input = this.trans.openInputStream(
+      Ci.nsITransport.OPEN_BLOCKING,
+      0,
+      0
+    );
+    this.output = this.trans.openOutputStream(
+      Ci.nsITransport.OPEN_BLOCKING,
+      0,
+      0
+    );
+    this.outbuf = String();
+    this.resolve = resolve;
+    this.reject = reject;
+
+    this.write("PING!");
+    this.input.asyncWait(this, 0, 0, currentThread);
+  }
+
+  onInputStreamReady(stream) {
+    let len = 0;
+    try {
+      len = stream.available();
+    } catch (e) {
+      // This will happen on auth failure.
+      this.reject(e);
+      return;
+    }
+    let bin = new BinaryInputStream(stream);
+    let data = bin.readByteArray(len);
+    let decoder = new TextDecoder();
+    let result = decoder.decode(data);
+    if (result == "PONG!") {
+      this.resolve(result);
+    } else {
+      this.reject();
+    }
+  }
+
+  write(buf) {
+    this.outbuf += buf;
+    this.output.asyncWait(this, 0, 0, currentThread);
+  }
+
+  onOutputStreamReady(stream) {
+    let len = stream.write(this.outbuf, this.outbuf.length);
+    if (len != this.outbuf.length) {
+      this.outbuf = this.outbuf.substring(len);
+      stream.asyncWait(this, 0, 0, currentThread);
+    } else {
+      this.outbuf = String();
+    }
+  }
+
+  close() {
+    this.output.close();
+  }
+}
+
+const socksServer = new SocksTestServer();
+socksServer.setUserPass("foo", "bar");
+registerCleanupFunction(() => {
+  socksServer.close();
+});
+
+// A simple ping/pong to test the socks server.
+add_task(async function test_socks_server() {
+  let socks = {
+    version: "socks",
+    host: "127.0.0.1",
+    port: socksServer.listener.localPort,
+    username: "foo",
+    password: "bar",
+    dns: false,
+  };
+  let dest = {
+    host: "localhost",
+    port: 8888,
+  };
+
+  new Promise((resolve, reject) => {
+    new SocksTestClient(socks, dest, resolve, reject);
+  })
+    .then(result => {
+      equal("PONG!", result, "socks test ok");
+    })
+    .catch(result => {
+      ok(false, `socks test failed ${result}`);
+    });
+});
+
+add_task(async function test_webRequest_socks_proxy() {
+  async function background(port) {
+    function checkProxyData(details) {
+      browser.test.assertEq("127.0.0.1", details.proxyInfo.host, "proxy host");
+      browser.test.assertEq(port, details.proxyInfo.port, "proxy port");
+      browser.test.assertEq("socks", details.proxyInfo.type, "proxy type");
+      browser.test.assertEq(
+        "foo",
+        details.proxyInfo.username,
+        "proxy username not set"
+      );
+      browser.test.assertEq(
+        undefined,
+        details.proxyInfo.password,
+        "no proxy password passed to webrequest"
+      );
+    }
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        checkProxyData(details);
+      },
+      { urls: ["<all_urls>"] }
+    );
+    browser.webRequest.onAuthRequired.addListener(
+      details => {
+        // We should never get onAuthRequired for socks proxy
+        browser.test.fail("onAuthRequired");
+      },
+      { urls: ["<all_urls>"] },
+      ["blocking"]
+    );
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        checkProxyData(details);
+        browser.test.sendMessage("done");
+      },
+      { urls: ["<all_urls>"] }
+    );
+    browser.proxy.onRequest.addListener(
+      () => {
+        return [
+          {
+            type: "socks",
+            host: "127.0.0.1",
+            port,
+            username: "foo",
+            password: "bar",
+          },
+        ];
+      },
+      { urls: ["<all_urls>"] }
+    );
+  }
+
+  let handlingExt = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["proxy", "webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background: `(${background})(${socksServer.listener.localPort})`,
+  });
+
+  // proxy.register is deprecated - bug 1443259.
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  await handlingExt.startup();
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `http://localhost/`
+  );
+
+  await handlingExt.awaitMessage("done");
+  await contentPage.close();
+  await handlingExt.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_proxy_speculative.js b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_speculative.js
new file mode 100644
index 0000000000..01f864cb7a
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_speculative.js
@@ -0,0 +1,52 @@
+"use strict";
+
+const { ExtensionUtils } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionUtils.jsm"
+);
+
+const proxy = createHttpServer();
+
+add_task(async function test_speculative_connect() {
+  function background() {
+    // Handle the proxy request.
+    browser.proxy.onRequest.addListener(
+      details => {
+        browser.test.log(`onRequest ${JSON.stringify(details)}`);
+        browser.test.assertEq(
+          details.type,
+          "speculative",
+          "Should have seen a speculative proxy request."
+        );
+        return [{ type: "direct" }];
+      },
+      { urls: ["<all_urls>"], types: ["speculative"] }
+    );
+  }
+
+  let handlingExt = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["proxy", "<all_urls>"],
+    },
+    background: `(${background})()`,
+  });
+
+  Services.prefs.setBoolPref("network.http.debug-observations", true);
+
+  await handlingExt.startup();
+
+  let notificationPromise = ExtensionUtils.promiseObserved(
+    "speculative-connect-request"
+  );
+
+  let uri = Services.io.newURI(
+    `http://${proxy.identity.primaryHost}:${proxy.identity.primaryPort}`
+  );
+  Services.io.speculativeConnect(
+    uri,
+    Services.scriptSecurityManager.getSystemPrincipal(),
+    null
+  );
+  await notificationPromise;
+
+  await handlingExt.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_proxy_startup.js b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_startup.js
new file mode 100644
index 0000000000..8d0f98f308
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_proxy_startup.js
@@ -0,0 +1,158 @@
+"use strict";
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "43"
+);
+
+let {
+  promiseRestartManager,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+let nonProxiedRequests = 0;
+const nonProxiedServer = createHttpServer({ hosts: ["example.com"] });
+nonProxiedServer.registerPathHandler("/", (request, response) => {
+  nonProxiedRequests++;
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+// No hosts defined to avoid proxy filter setup.
+let proxiedRequests = 0;
+const server = createHttpServer();
+server.identity.add("http", "proxied.example.com", 80);
+server.registerPathHandler("/", (request, response) => {
+  proxiedRequests++;
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  true
+);
+
+function promiseExtensionEvent(wrapper, event) {
+  return new Promise(resolve => {
+    wrapper.extension.once(event, resolve);
+  });
+}
+
+function trackEvents(wrapper) {
+  let events = new Map();
+  for (let event of ["background-page-event", "start-background-page"]) {
+    events.set(event, false);
+    wrapper.extension.once(event, () => events.set(event, true));
+  }
+  return events;
+}
+
+// Test that a proxy listener during startup does not immediately
+// start the background page, but the event is queued until the background
+// page is started.
+add_task(async function test_proxy_startup() {
+  await promiseStartupManager();
+
+  function background(proxyInfo) {
+    browser.proxy.onRequest.addListener(
+      details => {
+        // ignore speculative requests
+        if (details.type == "xmlhttprequest") {
+          browser.test.sendMessage("saw-request");
+        }
+        return proxyInfo;
+      },
+      { urls: ["<all_urls>"] }
+    );
+  }
+
+  let proxyInfo = {
+    host: server.identity.primaryHost,
+    port: server.identity.primaryPort,
+    type: "http",
+  };
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      permissions: ["proxy", "http://proxied.example.com/*"],
+    },
+    background: `(${background})(${JSON.stringify(proxyInfo)})`,
+  });
+
+  await extension.startup();
+
+  // Initial requests to test the proxy and non-proxied servers.
+  await Promise.all([
+    extension.awaitMessage("saw-request"),
+    ExtensionTestUtils.fetch("http://proxied.example.com/?a=0"),
+  ]);
+  equal(1, proxiedRequests, "proxied request ok");
+  equal(0, nonProxiedRequests, "non proxied request ok");
+
+  await ExtensionTestUtils.fetch("http://example.com/?a=0");
+  equal(1, proxiedRequests, "proxied request ok");
+  equal(1, nonProxiedRequests, "non proxied request ok");
+
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  let events = trackEvents(extension);
+
+  // Initiate a non-proxied request to make sure the startup listeners are using
+  // the extensions filters/etc.
+  await ExtensionTestUtils.fetch("http://example.com/?a=1");
+  equal(1, proxiedRequests, "proxied request ok");
+  equal(2, nonProxiedRequests, "non proxied request ok");
+
+  equal(
+    events.get("background-page-event"),
+    false,
+    "Should not have gotten a background page event"
+  );
+
+  // Make a request that the extension will proxy once it is started.
+  let request = Promise.all([
+    extension.awaitMessage("saw-request"),
+    ExtensionTestUtils.fetch("http://proxied.example.com/?a=1"),
+  ]);
+
+  await promiseExtensionEvent(extension, "background-page-event");
+  equal(
+    events.get("background-page-event"),
+    true,
+    "Should have gotten a background page event"
+  );
+
+  // Test the background page startup.
+  equal(
+    events.get("start-background-page"),
+    false,
+    "Should have gotten a background page event"
+  );
+
+  Services.obs.notifyObservers(null, "browser-delayed-startup-finished");
+  await new Promise(executeSoon);
+
+  equal(
+    events.get("start-background-page"),
+    true,
+    "Should have gotten a background page event"
+  );
+
+  // Verify our proxied request finishes properly and that the
+  // request was not handled via our non-proxied server.
+  await request;
+  equal(2, proxiedRequests, "proxied request ok");
+  equal(2, nonProxiedRequests, "non proxied requests ok");
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_redirects.js b/toolkit/components/extensions/test/xpcshell/test_ext_redirects.js
new file mode 100644
index 0000000000..4c8175e0c0
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_redirects.js
@@ -0,0 +1,567 @@
+"use strict";
+
+// Tests whether we can redirect to a moz-extension: url.
+ChromeUtils.defineModuleGetter(
+  this,
+  "TestUtils",
+  "resource://testing-common/TestUtils.jsm"
+);
+
+const server = createHttpServer();
+const gServerUrl = `http://localhost:${server.identity.primaryPort}`;
+
+server.registerPathHandler("/redirect", (request, response) => {
+  let params = new URLSearchParams(request.queryString);
+  response.setStatusLine(request.httpVersion, 302, "Moved Temporarily");
+  response.setHeader("Location", params.get("redirect_uri"));
+  response.write("redirecting");
+});
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+function onStopListener(channel) {
+  return new Promise(resolve => {
+    let orig = channel.QueryInterface(Ci.nsITraceableChannel).setNewListener({
+      QueryInterface: ChromeUtils.generateQI([
+        "nsIRequestObserver",
+        "nsIStreamListener",
+      ]),
+      getFinalURI(request) {
+        let { loadInfo } = request;
+        return (loadInfo && loadInfo.resultPrincipalURI) || request.originalURI;
+      },
+      onDataAvailable(...args) {
+        orig.onDataAvailable(...args);
+      },
+      onStartRequest(request) {
+        orig.onStartRequest(request);
+      },
+      onStopRequest(request, statusCode) {
+        orig.onStopRequest(request, statusCode);
+        let URI = this.getFinalURI(request.QueryInterface(Ci.nsIChannel));
+        resolve(URI && URI.spec);
+      },
+    });
+  });
+}
+
+async function onModifyListener(originUrl, redirectToUrl) {
+  return TestUtils.topicObserved("http-on-modify-request", (subject, data) => {
+    let channel = subject.QueryInterface(Ci.nsIHttpChannel);
+    return channel.URI && channel.URI.spec == originUrl;
+  }).then(([subject, data]) => {
+    let channel = subject.QueryInterface(Ci.nsIHttpChannel);
+    if (redirectToUrl) {
+      channel.redirectTo(Services.io.newURI(redirectToUrl));
+    }
+    return channel;
+  });
+}
+
+function getExtension(
+  accessible = false,
+  background = undefined,
+  blocking = true
+) {
+  let manifest = {
+    permissions: ["webRequest", "<all_urls>"],
+  };
+  if (blocking) {
+    manifest.permissions.push("webRequestBlocking");
+  }
+  if (accessible) {
+    manifest.web_accessible_resources = ["finished.html"];
+  }
+  if (!background) {
+    background = () => {
+      // send the extensions public uri to the test.
+      let exturi = browser.extension.getURL("finished.html");
+      browser.test.sendMessage("redirectURI", exturi);
+    };
+  }
+  return ExtensionTestUtils.loadExtension({
+    manifest,
+    files: {
+      "finished.html": `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+          </head>
+          <body>
+            <h1>redirected!</h1>
+          </body>
+        </html>
+      `.trim(),
+    },
+    background,
+  });
+}
+
+async function redirection_test(url, channelRedirectUrl) {
+  // setup our observer
+  let watcher = onModifyListener(url, channelRedirectUrl).then(channel => {
+    return onStopListener(channel);
+  });
+  let xhr = new XMLHttpRequest();
+  xhr.open("GET", url);
+  xhr.send();
+  return watcher;
+}
+
+// This test verifies failure without web_accessible_resources.
+add_task(async function test_redirect_to_non_accessible_resource() {
+  let extension = getExtension();
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let url = `${gServerUrl}/redirect?redirect_uri=${redirectUrl}`;
+  let result = await redirection_test(url);
+  equal(result, url, `expected no redirect`);
+  await extension.unload();
+});
+
+// This test makes a request against a server that redirects with a 302.
+add_task(async function test_302_redirect_to_extension() {
+  let extension = getExtension(true);
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let url = `${gServerUrl}/redirect?redirect_uri=${redirectUrl}`;
+  let result = await redirection_test(url);
+  equal(result, redirectUrl, "redirect request is finished");
+  await extension.unload();
+});
+
+// This test uses channel.redirectTo during http-on-modify to redirect to the
+// moz-extension url.
+add_task(async function test_channel_redirect_to_extension() {
+  let extension = getExtension(true);
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let url = `${gServerUrl}/dummy?r=${Math.random()}`;
+  let result = await redirection_test(url, redirectUrl);
+  equal(result, redirectUrl, "redirect request is finished");
+  await extension.unload();
+});
+
+// This test verifies failure without web_accessible_resources.
+add_task(async function test_content_redirect_to_non_accessible_resource() {
+  let extension = getExtension();
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let url = `${gServerUrl}/redirect?redirect_uri=${redirectUrl}`;
+  let watcher = onModifyListener(url).then(channel => {
+    return onStopListener(channel);
+  });
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl: "about:blank",
+  });
+  equal(
+    contentPage.browser.documentURI.spec,
+    "about:blank",
+    `expected no redirect`
+  );
+  equal(await watcher, url, "expected no redirect");
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test makes a request against a server that redirects with a 302.
+add_task(async function test_content_302_redirect_to_extension() {
+  let extension = getExtension(true);
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let url = `${gServerUrl}/redirect?redirect_uri=${redirectUrl}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(contentPage.browser.documentURI.spec, redirectUrl, `expected redirect`);
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test uses channel.redirectTo during http-on-modify to redirect to the
+// moz-extension url.
+add_task(async function test_content_channel_redirect_to_extension() {
+  let extension = getExtension(true);
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let url = `${gServerUrl}/dummy?r=${Math.random()}`;
+  onModifyListener(url, redirectUrl);
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(contentPage.browser.documentURI.spec, redirectUrl, `expected redirect`);
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test makes a request against a server and tests redirect to another server page.
+add_task(async function test_extension_302_redirect_web() {
+  function background(serverUrl) {
+    let expectedUrls = ["/redirect", "/dummy"];
+    let expected = [
+      "onBeforeRequest",
+      "onHeadersReceived",
+      "onBeforeRedirect",
+      "onBeforeRequest",
+      "onHeadersReceived",
+      "onResponseStarted",
+      "onCompleted",
+    ];
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.assertTrue(
+          details.url.includes(expectedUrls.shift()),
+          "onBeforeRequest url matches"
+        );
+        browser.test.assertEq(
+          expected.shift(),
+          "onBeforeRequest",
+          "onBeforeRequest matches"
+        );
+      },
+      { urls: [serverUrl] }
+    );
+    browser.webRequest.onHeadersReceived.addListener(
+      details => {
+        browser.test.assertEq(
+          expected.shift(),
+          "onHeadersReceived",
+          "onHeadersReceived matches"
+        );
+      },
+      { urls: [serverUrl] }
+    );
+    browser.webRequest.onResponseStarted.addListener(
+      details => {
+        browser.test.assertEq(
+          expected.shift(),
+          "onResponseStarted",
+          "onResponseStarted matches"
+        );
+      },
+      { urls: [serverUrl] }
+    );
+    browser.webRequest.onBeforeRedirect.addListener(
+      details => {
+        browser.test.assertTrue(
+          details.redirectUrl.includes("/dummy"),
+          "onBeforeRedirect matches redirectUrl"
+        );
+        browser.test.assertEq(
+          expected.shift(),
+          "onBeforeRedirect",
+          "onBeforeRedirect matches"
+        );
+      },
+      { urls: [serverUrl] }
+    );
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        browser.test.assertTrue(
+          details.url.includes("/dummy"),
+          "onCompleted expected url received"
+        );
+        browser.test.assertEq(
+          expected.shift(),
+          "onCompleted",
+          "onCompleted matches"
+        );
+        browser.test.notifyPass("requestCompleted");
+      },
+      { urls: [serverUrl] }
+    );
+    browser.webRequest.onErrorOccurred.addListener(
+      details => {
+        browser.test.log(`onErrorOccurred ${JSON.stringify(details)}`);
+        browser.test.notifyFail("requestCompleted");
+      },
+      { urls: [serverUrl] }
+    );
+  }
+  let extension = getExtension(
+    false,
+    `(${background})("*://${server.identity.primaryHost}/*")`,
+    false
+  );
+  await extension.startup();
+  let redirectUrl = `${gServerUrl}/dummy`;
+  let completed = extension.awaitFinish("requestCompleted");
+  let url = `${gServerUrl}/redirect?r=${Math.random()}&redirect_uri=${redirectUrl}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(
+    contentPage.browser.documentURI.spec,
+    redirectUrl,
+    `expected content redirect`
+  );
+  await completed;
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test makes a request against a server and tests redirect to another server page, without
+// onBeforeRedirect.  Bug 1448599
+add_task(async function test_extension_302_redirect_opening() {
+  let redirectUrl = `${gServerUrl}/dummy`;
+  let expectData = [
+    {
+      event: "onBeforeRequest",
+      url: `${gServerUrl}/redirect`,
+    },
+    {
+      event: "onBeforeRequest",
+      url: redirectUrl,
+    },
+  ];
+  function background(serverUrl, expected) {
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        let expect = expected.shift();
+        browser.test.assertEq(
+          expect.event,
+          "onBeforeRequest",
+          "onBeforeRequest event matches"
+        );
+        browser.test.assertTrue(
+          details.url.startsWith(expect.url),
+          "onBeforeRequest url matches"
+        );
+        if (expected.length === 0) {
+          browser.test.notifyPass("requestCompleted");
+        }
+      },
+      { urls: [serverUrl] }
+    );
+  }
+  let extension = getExtension(
+    false,
+    `(${background})("*://${server.identity.primaryHost}/*", ${JSON.stringify(
+      expectData
+    )})`,
+    false
+  );
+  await extension.startup();
+  let completed = extension.awaitFinish("requestCompleted");
+  let url = `${gServerUrl}/redirect?r=${Math.random()}&redirect_uri=${redirectUrl}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(
+    contentPage.browser.documentURI.spec,
+    redirectUrl,
+    `expected content redirect`
+  );
+  await completed;
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test makes a request against a server and tests redirect to another server page, without
+// onBeforeRedirect.  Bug 1448599
+add_task(async function test_extension_302_redirect_modify() {
+  let redirectUrl = `${gServerUrl}/dummy`;
+  let expectData = [
+    {
+      event: "onHeadersReceived",
+      url: `${gServerUrl}/redirect`,
+    },
+    {
+      event: "onHeadersReceived",
+      url: redirectUrl,
+    },
+  ];
+  function background(serverUrl, expected) {
+    browser.webRequest.onHeadersReceived.addListener(
+      details => {
+        let expect = expected.shift();
+        browser.test.assertEq(
+          expect.event,
+          "onHeadersReceived",
+          "onHeadersReceived event matches"
+        );
+        browser.test.assertTrue(
+          details.url.startsWith(expect.url),
+          "onHeadersReceived url matches"
+        );
+        if (expected.length === 0) {
+          browser.test.notifyPass("requestCompleted");
+        }
+      },
+      { urls: ["<all_urls>"] }
+    );
+  }
+  let extension = getExtension(
+    false,
+    `(${background})("*://${server.identity.primaryHost}/*", ${JSON.stringify(
+      expectData
+    )})`,
+    false
+  );
+  await extension.startup();
+  let completed = extension.awaitFinish("requestCompleted");
+  let url = `${gServerUrl}/redirect?r=${Math.random()}&redirect_uri=${redirectUrl}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(
+    contentPage.browser.documentURI.spec,
+    redirectUrl,
+    `expected content redirect`
+  );
+  await completed;
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test makes a request against a server and tests redirect to another server page, without
+// onBeforeRedirect.  Bug 1448599
+add_task(async function test_extension_302_redirect_tracing() {
+  let redirectUrl = `${gServerUrl}/dummy`;
+  let expectData = [
+    {
+      event: "onCompleted",
+      url: redirectUrl,
+    },
+  ];
+  function background(serverUrl, expected) {
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        let expect = expected.shift();
+        browser.test.assertEq(
+          expect.event,
+          "onCompleted",
+          "onCompleted event matches"
+        );
+        browser.test.assertTrue(
+          details.url.startsWith(expect.url),
+          "onCompleted url matches"
+        );
+        if (expected.length === 0) {
+          browser.test.notifyPass("requestCompleted");
+        }
+      },
+      { urls: [serverUrl] }
+    );
+  }
+  let extension = getExtension(
+    false,
+    `(${background})("*://${server.identity.primaryHost}/*", ${JSON.stringify(
+      expectData
+    )})`,
+    false
+  );
+  await extension.startup();
+  let completed = extension.awaitFinish("requestCompleted");
+  let url = `${gServerUrl}/redirect?r=${Math.random()}&redirect_uri=${redirectUrl}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(
+    contentPage.browser.documentURI.spec,
+    redirectUrl,
+    `expected content redirect`
+  );
+  await completed;
+  await contentPage.close();
+  await extension.unload();
+});
+
+// This test makes a request against a server and tests webrequest.  Currently
+// disabled due to NS_BINDING_ABORTED happening.
+add_task(async function test_extension_302_redirect() {
+  let extension = getExtension(true, () => {
+    let myuri = browser.extension.getURL("*");
+    let exturi = browser.extension.getURL("finished.html");
+    browser.webRequest.onBeforeRedirect.addListener(
+      details => {
+        browser.test.assertEq(details.redirectUrl, exturi, "redirect matches");
+      },
+      { urls: ["<all_urls>", myuri] }
+    );
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        browser.test.assertEq(details.url, exturi, "expected url received");
+        browser.test.notifyPass("requestCompleted");
+      },
+      { urls: ["<all_urls>", myuri] }
+    );
+    browser.webRequest.onErrorOccurred.addListener(
+      details => {
+        browser.test.log(`onErrorOccurred ${JSON.stringify(details)}`);
+        browser.test.notifyFail("requestCompleted");
+      },
+      { urls: ["<all_urls>", myuri] }
+    );
+    // send the extensions public uri to the test.
+    browser.test.sendMessage("redirectURI", exturi);
+  });
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let completed = extension.awaitFinish("requestCompleted");
+  let url = `${gServerUrl}/redirect?r=${Math.random()}&redirect_uri=${redirectUrl}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(
+    contentPage.browser.documentURI.spec,
+    redirectUrl,
+    `expected content redirect`
+  );
+  await completed;
+  await contentPage.close();
+  await extension.unload();
+}).skip();
+
+// This test makes a request and uses onBeforeRequet to redirect to moz-ext.
+// Currently disabled due to NS_BINDING_ABORTED happening.
+add_task(async function test_extension_redirect() {
+  let extension = getExtension(true, () => {
+    let myuri = browser.extension.getURL("*");
+    let exturi = browser.extension.getURL("finished.html");
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        return { redirectUrl: exturi };
+      },
+      { urls: ["<all_urls>", myuri] },
+      ["blocking"]
+    );
+    browser.webRequest.onBeforeRedirect.addListener(
+      details => {
+        browser.test.assertEq(details.redirectUrl, exturi, "redirect matches");
+      },
+      { urls: ["<all_urls>", myuri] }
+    );
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        browser.test.assertEq(details.url, exturi, "expected url received");
+        browser.test.notifyPass("requestCompleted");
+      },
+      { urls: ["<all_urls>", myuri] }
+    );
+    browser.webRequest.onErrorOccurred.addListener(
+      details => {
+        browser.test.log(`onErrorOccurred ${JSON.stringify(details)}`);
+        browser.test.notifyFail("requestCompleted");
+      },
+      { urls: ["<all_urls>", myuri] }
+    );
+    // send the extensions public uri to the test.
+    browser.test.sendMessage("redirectURI", exturi);
+  });
+  await extension.startup();
+  let redirectUrl = await extension.awaitMessage("redirectURI");
+  let completed = extension.awaitFinish("requestCompleted");
+  let url = `${gServerUrl}/dummy?r=${Math.random()}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    redirectUrl,
+  });
+  equal(contentPage.browser.documentURI.spec, redirectUrl, `expected redirect`);
+  await completed;
+  await contentPage.close();
+  await extension.unload();
+}).skip();
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_connect_no_receiver.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_connect_no_receiver.js
new file mode 100644
index 0000000000..e42f45c019
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_connect_no_receiver.js
@@ -0,0 +1,26 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_connect_without_listener() {
+  function background() {
+    let port = browser.runtime.connect();
+    port.onDisconnect.addListener(() => {
+      browser.test.assertEq(
+        "Could not establish connection. Receiving end does not exist.",
+        port.error && port.error.message
+      );
+      browser.test.notifyPass("port.onDisconnect was called");
+    });
+  }
+  let extensionData = {
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await extension.awaitFinish("port.onDisconnect was called");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_getBrowserInfo.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_getBrowserInfo.js
new file mode 100644
index 0000000000..3f3b8f8e95
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_getBrowserInfo.js
@@ -0,0 +1,26 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+add_task(async function setup() {
+  ExtensionTestUtils.mockAppInfo();
+});
+
+add_task(async function test_getBrowserInfo() {
+  async function background() {
+    let info = await browser.runtime.getBrowserInfo();
+
+    browser.test.assertEq(info.name, "XPCShell", "name is valid");
+    browser.test.assertEq(info.vendor, "Mozilla", "vendor is Mozilla");
+    browser.test.assertEq(info.version, "48", "version is correct");
+    browser.test.assertEq(info.buildID, "20160315", "buildID is correct");
+
+    browser.test.notifyPass("runtime.getBrowserInfo");
+  }
+
+  const extension = ExtensionTestUtils.loadExtension({ background });
+  await extension.startup();
+  await extension.awaitFinish("runtime.getBrowserInfo");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_getPlatformInfo.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_getPlatformInfo.js
new file mode 100644
index 0000000000..8f213b0dec
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_getPlatformInfo.js
@@ -0,0 +1,36 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+function backgroundScript() {
+  browser.runtime.getPlatformInfo(info => {
+    let validOSs = ["mac", "win", "android", "cros", "linux", "openbsd"];
+    let validArchs = [
+      "aarch64",
+      "arm",
+      "ppc64",
+      "s390x",
+      "sparc64",
+      "x86-32",
+      "x86-64",
+    ];
+
+    browser.test.assertTrue(validOSs.includes(info.os), "OS is valid");
+    browser.test.assertTrue(
+      validArchs.includes(info.arch),
+      "Architecture is valid"
+    );
+    browser.test.notifyPass("runtime.getPlatformInfo");
+  });
+}
+
+let extensionData = {
+  background: backgroundScript,
+};
+
+add_task(async function() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitFinish("runtime.getPlatformInfo");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_id.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_id.js
new file mode 100644
index 0000000000..6967e81232
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_id.js
@@ -0,0 +1,46 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_runtime_id() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    background() {
+      browser.test.sendMessage("background-id", browser.runtime.id);
+    },
+
+    files: {
+      "content_script.js"() {
+        browser.test.sendMessage("content-id", browser.runtime.id);
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  let backgroundId = await extension.awaitMessage("background-id");
+  equal(
+    backgroundId,
+    extension.id,
+    "runtime.id from background script is correct"
+  );
+
+  let contentId = await extension.awaitMessage("content-id");
+  equal(contentId, extension.id, "runtime.id from content script is correct");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_messaging_self.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_messaging_self.js
new file mode 100644
index 0000000000..6d71758a38
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_messaging_self.js
@@ -0,0 +1,84 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(
+  async function test_messaging_to_self_should_not_trigger_onMessage_onConnect() {
+    async function background() {
+      browser.runtime.onMessage.addListener(msg => {
+        browser.test.assertEq("msg from child", msg);
+        browser.test.sendMessage(
+          "sendMessage did not call same-frame onMessage"
+        );
+      });
+
+      browser.test.onMessage.addListener(msg => {
+        browser.test.assertEq(
+          "sendMessage with a listener in another frame",
+          msg
+        );
+        browser.runtime.sendMessage("should only reach another frame");
+      });
+
+      await browser.test.assertRejects(
+        browser.runtime.sendMessage("should not trigger same-frame onMessage"),
+        "Could not establish connection. Receiving end does not exist."
+      );
+
+      browser.runtime.onConnect.addListener(port => {
+        browser.test.assertEq("from-frame", port.name);
+        browser.runtime.connect({ name: "from-bg-2" });
+      });
+
+      await new Promise(resolve => {
+        let port = browser.runtime.connect({ name: "from-bg-1" });
+        port.onDisconnect.addListener(() => {
+          browser.test.assertEq(
+            "Could not establish connection. Receiving end does not exist.",
+            port.error.message
+          );
+          resolve();
+        });
+      });
+
+      let anotherFrame = document.createElement("iframe");
+      anotherFrame.src = browser.extension.getURL("extensionpage.html");
+      document.body.appendChild(anotherFrame);
+    }
+
+    function lastScript() {
+      browser.runtime.onMessage.addListener(msg => {
+        browser.test.assertEq("should only reach another frame", msg);
+        browser.runtime.sendMessage("msg from child");
+      });
+      browser.test.sendMessage("sendMessage callback called");
+
+      browser.runtime.onConnect.addListener(port => {
+        browser.test.assertEq("from-bg-2", port.name);
+        browser.test.sendMessage("connect did not call same-frame onConnect");
+      });
+      browser.runtime.connect({ name: "from-frame" });
+    }
+
+    let extensionData = {
+      background,
+      files: {
+        "lastScript.js": lastScript,
+        "extensionpage.html": `<!DOCTYPE html><meta charset="utf-8"><script src="lastScript.js"></script>`,
+      },
+    };
+
+    let extension = ExtensionTestUtils.loadExtension(extensionData);
+    await extension.startup();
+
+    await extension.awaitMessage("sendMessage callback called");
+    extension.sendMessage("sendMessage with a listener in another frame");
+
+    await Promise.all([
+      extension.awaitMessage("connect did not call same-frame onConnect"),
+      extension.awaitMessage("sendMessage did not call same-frame onMessage"),
+    ]);
+
+    await extension.unload();
+  }
+);
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_onInstalled_and_onStartup.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_onInstalled_and_onStartup.js
new file mode 100644
index 0000000000..7c54389b39
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_onInstalled_and_onStartup.js
@@ -0,0 +1,401 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { AddonManager } = ChromeUtils.import(
+  "resource://gre/modules/AddonManager.jsm"
+);
+const { Preferences } = ChromeUtils.import(
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const {
+  createAppInfo,
+  createTempWebExtensionFile,
+  promiseAddonEvent,
+  promiseCompleteAllInstalls,
+  promiseFindAddonUpdates,
+  promiseRestartManager,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+// Allow for unsigned addons.
+AddonTestUtils.overrideCertDB();
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "42", "42");
+
+// Ensure that the background page is automatically started after using
+// promiseStartupManager.
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  false
+);
+
+function background() {
+  let onInstalledDetails = null;
+  let onStartupFired = false;
+
+  browser.runtime.onInstalled.addListener(details => {
+    onInstalledDetails = details;
+  });
+
+  browser.runtime.onStartup.addListener(() => {
+    onStartupFired = true;
+  });
+
+  browser.test.onMessage.addListener(message => {
+    if (message === "get-on-installed-details") {
+      onInstalledDetails = onInstalledDetails || { fired: false };
+      browser.test.sendMessage("on-installed-details", onInstalledDetails);
+    } else if (message === "did-on-startup-fire") {
+      browser.test.sendMessage("on-startup-fired", onStartupFired);
+    } else if (message === "reload-extension") {
+      browser.runtime.reload();
+    }
+  });
+
+  browser.runtime.onUpdateAvailable.addListener(details => {
+    browser.test.sendMessage("reloading");
+    browser.runtime.reload();
+  });
+}
+
+async function expectEvents(
+  extension,
+  {
+    onStartupFired,
+    onInstalledFired,
+    onInstalledReason,
+    onInstalledTemporary,
+    onInstalledPrevious,
+  }
+) {
+  extension.sendMessage("get-on-installed-details");
+  let details = await extension.awaitMessage("on-installed-details");
+  if (onInstalledFired) {
+    equal(
+      details.reason,
+      onInstalledReason,
+      "runtime.onInstalled fired with the correct reason"
+    );
+    equal(
+      details.temporary,
+      onInstalledTemporary,
+      "runtime.onInstalled fired with the correct temporary flag"
+    );
+    if (onInstalledPrevious) {
+      equal(
+        details.previousVersion,
+        onInstalledPrevious,
+        "runtime.onInstalled after update with correct previousVersion"
+      );
+    }
+  } else {
+    equal(
+      details.fired,
+      onInstalledFired,
+      "runtime.onInstalled should not have fired"
+    );
+  }
+
+  extension.sendMessage("did-on-startup-fire");
+  let fired = await extension.awaitMessage("on-startup-fired");
+  equal(
+    fired,
+    onStartupFired,
+    `Expected runtime.onStartup to ${onStartupFired ? "" : "not "} fire`
+  );
+}
+
+add_task(async function test_should_fire_on_addon_update() {
+  Preferences.set("extensions.logging.enabled", false);
+
+  await promiseStartupManager();
+
+  const EXTENSION_ID =
+    "test_runtime_on_installed_addon_update@tests.mozilla.org";
+
+  const PREF_EM_CHECK_UPDATE_SECURITY = "extensions.checkUpdateSecurity";
+
+  // The test extension uses an insecure update url.
+  Services.prefs.setBoolPref(PREF_EM_CHECK_UPDATE_SECURITY, false);
+
+  const testServer = createHttpServer();
+  const port = testServer.identity.primaryPort;
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+          update_url: `http://localhost:${port}/test_update.json`,
+        },
+      },
+    },
+    background,
+  });
+
+  testServer.registerPathHandler("/test_update.json", (request, response) => {
+    response.write(`{
+      "addons": {
+        "${EXTENSION_ID}": {
+          "updates": [
+            {
+              "version": "2.0",
+              "update_link": "http://localhost:${port}/addons/test_runtime_on_installed-2.0.xpi"
+            }
+          ]
+        }
+      }
+    }`);
+  });
+
+  let webExtensionFile = createTempWebExtensionFile({
+    manifest: {
+      version: "2.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  testServer.registerFile(
+    "/addons/test_runtime_on_installed-2.0.xpi",
+    webExtensionFile
+  );
+
+  await extension.startup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: true,
+    onInstalledTemporary: false,
+    onInstalledReason: "install",
+  });
+
+  let addon = await AddonManager.getAddonByID(EXTENSION_ID);
+  equal(addon.version, "1.0", "The installed addon has the correct version");
+
+  let update = await promiseFindAddonUpdates(addon);
+  let install = update.updateAvailable;
+
+  let promiseInstalled = promiseAddonEvent("onInstalled");
+  await promiseCompleteAllInstalls([install]);
+
+  await extension.awaitMessage("reloading");
+
+  let [updated_addon] = await promiseInstalled;
+  equal(
+    updated_addon.version,
+    "2.0",
+    "The updated addon has the correct version"
+  );
+
+  await extension.awaitStartup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: true,
+    onInstalledTemporary: false,
+    onInstalledReason: "update",
+    onInstalledPrevious: "1.0",
+  });
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_should_fire_on_browser_update() {
+  const EXTENSION_ID =
+    "test_runtime_on_installed_browser_update@tests.mozilla.org";
+
+  await promiseStartupManager("1");
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: true,
+    onInstalledTemporary: false,
+    onInstalledReason: "install",
+  });
+
+  // Restart the browser.
+  await promiseRestartManager("1");
+  await extension.awaitStartup();
+
+  await expectEvents(extension, {
+    onStartupFired: true,
+    onInstalledFired: false,
+  });
+
+  // Update the browser.
+  await promiseRestartManager("2");
+  await extension.awaitStartup();
+
+  await expectEvents(extension, {
+    onStartupFired: true,
+    onInstalledFired: true,
+    onInstalledTemporary: false,
+    onInstalledReason: "browser_update",
+  });
+
+  // Restart the browser.
+  await promiseRestartManager("2");
+  await extension.awaitStartup();
+
+  await expectEvents(extension, {
+    onStartupFired: true,
+    onInstalledFired: false,
+  });
+
+  // Update the browser again.
+  await promiseRestartManager("3");
+  await extension.awaitStartup();
+
+  await expectEvents(extension, {
+    onStartupFired: true,
+    onInstalledFired: true,
+    onInstalledTemporary: false,
+    onInstalledReason: "browser_update",
+  });
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+});
+
+add_task(async function test_should_not_fire_on_reload() {
+  const EXTENSION_ID = "test_runtime_on_installed_reload@tests.mozilla.org";
+
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: true,
+    onInstalledTemporary: false,
+    onInstalledReason: "install",
+  });
+
+  extension.sendMessage("reload-extension");
+  extension.setRestarting();
+  await extension.awaitStartup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: false,
+  });
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
+
+add_task(async function test_should_not_fire_on_restart() {
+  const EXTENSION_ID = "test_runtime_on_installed_restart@tests.mozilla.org";
+
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: true,
+    onInstalledTemporary: false,
+    onInstalledReason: "install",
+  });
+
+  let addon = await AddonManager.getAddonByID(EXTENSION_ID);
+  await addon.disable();
+  await addon.enable();
+  await extension.awaitStartup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: false,
+  });
+
+  await extension.markUnloaded();
+  await promiseShutdownManager();
+});
+
+add_task(async function test_temporary_installation() {
+  const EXTENSION_ID =
+    "test_runtime_on_installed_addon_temporary@tests.mozilla.org";
+
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await expectEvents(extension, {
+    onStartupFired: false,
+    onInstalledFired: true,
+    onInstalledReason: "install",
+    onInstalledTemporary: true,
+  });
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports.js
new file mode 100644
index 0000000000..7365a13f93
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports.js
@@ -0,0 +1,69 @@
+"use strict";
+
+add_task(async function test_port_disconnected_from_wrong_window() {
+  let extensionData = {
+    background() {
+      let num = 0;
+      let ports = {};
+      let done = false;
+
+      browser.runtime.onConnect.addListener(port => {
+        num++;
+        ports[num] = port;
+
+        port.onMessage.addListener(msg => {
+          browser.test.assertEq(msg, "port-2-response", "Got port 2 response");
+          browser.test.sendMessage(msg + "-received");
+          done = true;
+        });
+
+        port.onDisconnect.addListener(err => {
+          if (port === ports[1]) {
+            browser.test.log("Port 1 disconnected, sending message via port 2");
+            ports[2].postMessage("port-2-msg");
+          } else {
+            browser.test.assertTrue(
+              done,
+              "Port 2 disconnected only after a full roundtrip received"
+            );
+          }
+        });
+
+        browser.test.sendMessage("port-connect-" + num);
+      });
+    },
+    files: {
+      "page.html": `
+        <!DOCTYPE html><meta charset="utf8">
+        <script src="script.js"></script>
+      `,
+      "script.js"() {
+        let port = browser.runtime.connect();
+        port.onMessage.addListener(msg => {
+          browser.test.assertEq(msg, "port-2-msg", "Got message via port 2");
+          port.postMessage("port-2-response");
+        });
+      },
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  let url = `moz-extension://${extension.uuid}/page.html`;
+  await extension.startup();
+
+  let page1 = await ExtensionTestUtils.loadContentPage(url, { extension });
+  await extension.awaitMessage("port-connect-1");
+  info("First page opened port 1");
+
+  let page2 = await ExtensionTestUtils.loadContentPage(url, { extension });
+  await extension.awaitMessage("port-connect-2");
+  info("Second page opened port 2");
+
+  info("Closing the first page should not close port 2");
+  await page1.close();
+  await extension.awaitMessage("port-2-response-received");
+  info("Roundtrip message through port 2 received");
+
+  await page2.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports_gc.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports_gc.js
new file mode 100644
index 0000000000..7b0cf01d08
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_ports_gc.js
@@ -0,0 +1,168 @@
+"use strict";
+
+let gcExperimentAPIs = {
+  gcHelper: {
+    schema: "schema.json",
+    child: {
+      scopes: ["addon_child"],
+      script: "child.js",
+      paths: [["gcHelper"]],
+    },
+  },
+};
+
+let gcExperimentFiles = {
+  "schema.json": JSON.stringify([
+    {
+      namespace: "gcHelper",
+      functions: [
+        {
+          name: "forceGarbageCollect",
+          type: "function",
+          parameters: [],
+          async: true,
+        },
+        {
+          name: "registerWitness",
+          type: "function",
+          parameters: [
+            {
+              name: "obj",
+              // Expected type is "object", but using "any" here to ensure that
+              // the parameter is untouched (not normalized).
+              type: "any",
+            },
+          ],
+          returns: { type: "number" },
+        },
+        {
+          name: "isGarbageCollected",
+          type: "function",
+          parameters: [
+            {
+              name: "witnessId",
+              description: "return value of registerWitness",
+              type: "number",
+            },
+          ],
+          returns: { type: "boolean" },
+        },
+      ],
+    },
+  ]),
+  "child.js": () => {
+    let { setTimeout } = ChromeUtils.import("resource://gre/modules/Timer.jsm");
+    /* globals ExtensionAPI */
+    this.gcHelper = class extends ExtensionAPI {
+      getAPI(context) {
+        let witnesses = new Map();
+        return {
+          gcHelper: {
+            async forceGarbageCollect() {
+              // Logic copied from test_ext_contexts_gc.js
+              for (let i = 0; i < 3; ++i) {
+                Cu.forceShrinkingGC();
+                Cu.forceCC();
+                Cu.forceGC();
+                await new Promise(resolve => setTimeout(resolve, 0));
+              }
+            },
+            registerWitness(obj) {
+              let witnessId = witnesses.size;
+              witnesses.set(witnessId, Cu.getWeakReference(obj));
+              return witnessId;
+            },
+            isGarbageCollected(witnessId) {
+              return witnesses.get(witnessId).get() === null;
+            },
+          },
+        };
+      }
+    };
+  },
+};
+
+// Verify that the experiment is working as intended before using it in tests.
+add_task(async function test_gc_experiment() {
+  let extension = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+    manifest: {
+      experiment_apis: gcExperimentAPIs,
+    },
+    files: gcExperimentFiles,
+    async background() {
+      let obj1 = {};
+      let obj2 = {};
+      let witness1 = browser.gcHelper.registerWitness(obj1);
+      let witness2 = browser.gcHelper.registerWitness(obj2);
+      obj1 = null;
+      await browser.gcHelper.forceGarbageCollect();
+      browser.test.assertTrue(
+        browser.gcHelper.isGarbageCollected(witness1),
+        "obj1 should have been garbage-collected"
+      );
+      browser.test.assertFalse(
+        browser.gcHelper.isGarbageCollected(witness2),
+        "obj2 should not have been garbage-collected"
+      );
+
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
+
+add_task(async function test_port_gc() {
+  let extension = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+    manifest: {
+      experiment_apis: gcExperimentAPIs,
+    },
+    files: gcExperimentFiles,
+    async background() {
+      let witnessPortSender;
+      let witnessPortReceiver;
+
+      browser.runtime.onConnect.addListener(port => {
+        browser.test.assertEq("daName", port.name, "expected port");
+        witnessPortReceiver = browser.gcHelper.registerWitness(port);
+        port.disconnect();
+      });
+
+      // runtime.connect() only triggers onConnect for different contexts,
+      // so create a frame to have a different context.
+      // A blank frame in a moz-extension:-document will have access to the
+      // extension APIs.
+      let frameWindow = await new Promise(resolve => {
+        let f = document.createElement("iframe");
+        f.onload = () => resolve(f.contentWindow);
+        document.body.append(f);
+      });
+      await new Promise(resolve => {
+        let port = frameWindow.browser.runtime.connect({ name: "daName" });
+        witnessPortSender = browser.gcHelper.registerWitness(port);
+        port.onDisconnect.addListener(() => resolve());
+      });
+
+      await browser.gcHelper.forceGarbageCollect();
+
+      browser.test.assertTrue(
+        browser.gcHelper.isGarbageCollected(witnessPortSender),
+        "runtime.connect() port should have been garbage-collected"
+      );
+      browser.test.assertTrue(
+        browser.gcHelper.isGarbageCollected(witnessPortReceiver),
+        "runtime.onConnect port should have been garbage-collected"
+      );
+
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage.js
new file mode 100644
index 0000000000..a7404cf5dd
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage.js
@@ -0,0 +1,452 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function runtimeSendMessageReply() {
+  function background() {
+    browser.runtime.onMessage.addListener((msg, sender, respond) => {
+      if (msg == "respond-now") {
+        respond(msg);
+      } else if (msg == "respond-soon") {
+        setTimeout(() => {
+          respond(msg);
+        }, 0);
+        return true;
+      } else if (msg == "respond-promise") {
+        return Promise.resolve(msg);
+      } else if (msg == "respond-promise-false") {
+        return Promise.resolve(false);
+      } else if (msg == "respond-false") {
+        // return false means that respond() is not expected to be called.
+        setTimeout(() => respond("should be ignored"));
+        return false;
+      } else if (msg == "respond-never") {
+        return undefined;
+      } else if (msg == "respond-error") {
+        return Promise.reject(new Error(msg));
+      } else if (msg == "throw-error") {
+        throw new Error(msg);
+      } else if (msg === "respond-uncloneable") {
+        return Promise.resolve(window);
+      } else if (msg === "reject-uncloneable") {
+        return Promise.reject(window);
+      } else if (msg == "reject-undefined") {
+        return Promise.reject();
+      } else if (msg == "throw-undefined") {
+        throw undefined; // eslint-disable-line no-throw-literal
+      }
+    });
+
+    browser.runtime.onMessage.addListener((msg, sender, respond) => {
+      if (msg == "respond-now") {
+        respond("hello");
+      } else if (msg == "respond-now-2") {
+        respond(msg);
+      }
+    });
+
+    browser.runtime.onMessage.addListener((msg, sender, respond) => {
+      if (msg == "respond-now") {
+        // If a response from another listener is received first, this
+        // exception should be ignored.  Test fails if it is not.
+
+        // All this is of course stupid, but some extensions depend on it.
+        msg.blah.this.throws();
+      }
+    });
+
+    let childFrame = document.createElement("iframe");
+    childFrame.src = "extensionpage.html";
+    document.body.appendChild(childFrame);
+  }
+
+  function senderScript() {
+    Promise.all([
+      browser.runtime.sendMessage("respond-now"),
+      browser.runtime.sendMessage("respond-now-2"),
+      new Promise(resolve =>
+        browser.runtime.sendMessage("respond-soon", resolve)
+      ),
+      browser.runtime.sendMessage("respond-promise"),
+      browser.runtime.sendMessage("respond-promise-false"),
+      browser.runtime.sendMessage("respond-false"),
+      browser.runtime.sendMessage("respond-never"),
+      new Promise(resolve => {
+        browser.runtime.sendMessage("respond-never", response => {
+          resolve(response);
+        });
+      }),
+
+      browser.runtime
+        .sendMessage("respond-error")
+        .catch(error => Promise.resolve({ error })),
+      browser.runtime
+        .sendMessage("throw-error")
+        .catch(error => Promise.resolve({ error })),
+
+      browser.runtime
+        .sendMessage("respond-uncloneable")
+        .catch(error => Promise.resolve({ error })),
+      browser.runtime
+        .sendMessage("reject-uncloneable")
+        .catch(error => Promise.resolve({ error })),
+      browser.runtime
+        .sendMessage("reject-undefined")
+        .catch(error => Promise.resolve({ error })),
+      browser.runtime
+        .sendMessage("throw-undefined")
+        .catch(error => Promise.resolve({ error })),
+    ])
+      .then(
+        ([
+          respondNow,
+          respondNow2,
+          respondSoon,
+          respondPromise,
+          respondPromiseFalse,
+          respondFalse,
+          respondNever,
+          respondNever2,
+          respondError,
+          throwError,
+          respondUncloneable,
+          rejectUncloneable,
+          rejectUndefined,
+          throwUndefined,
+        ]) => {
+          browser.test.assertEq(
+            "respond-now",
+            respondNow,
+            "Got the expected immediate response"
+          );
+          browser.test.assertEq(
+            "respond-now-2",
+            respondNow2,
+            "Got the expected immediate response from the second listener"
+          );
+          browser.test.assertEq(
+            "respond-soon",
+            respondSoon,
+            "Got the expected delayed response"
+          );
+          browser.test.assertEq(
+            "respond-promise",
+            respondPromise,
+            "Got the expected promise response"
+          );
+          browser.test.assertEq(
+            false,
+            respondPromiseFalse,
+            "Got the expected false value as a promise result"
+          );
+          browser.test.assertEq(
+            undefined,
+            respondFalse,
+            "Got the expected no-response when onMessage returns false"
+          );
+          browser.test.assertEq(
+            undefined,
+            respondNever,
+            "Got the expected no-response resolution"
+          );
+          browser.test.assertEq(
+            undefined,
+            respondNever2,
+            "Got the expected no-response resolution"
+          );
+
+          browser.test.assertEq(
+            "respond-error",
+            respondError.error.message,
+            "Got the expected error response"
+          );
+          browser.test.assertEq(
+            "throw-error",
+            throwError.error.message,
+            "Got the expected thrown error response"
+          );
+
+          browser.test.assertEq(
+            "Could not establish connection. Receiving end does not exist.",
+            respondUncloneable.error.message,
+            "An uncloneable response should be ignored"
+          );
+          browser.test.assertEq(
+            "An unexpected error occurred",
+            rejectUncloneable.error.message,
+            "Got the expected error for a rejection with an uncloneable value"
+          );
+          browser.test.assertEq(
+            "An unexpected error occurred",
+            rejectUndefined.error.message,
+            "Got the expected error for a void rejection"
+          );
+          browser.test.assertEq(
+            "An unexpected error occurred",
+            throwUndefined.error.message,
+            "Got the expected error for a void throw"
+          );
+
+          browser.test.notifyPass("sendMessage");
+        }
+      )
+      .catch(e => {
+        browser.test.fail(`Error: ${e} :: ${e.stack}`);
+        browser.test.notifyFail("sendMessage");
+      });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    files: {
+      "senderScript.js": senderScript,
+      "extensionpage.html": `<!DOCTYPE html><meta charset="utf-8"><script src="senderScript.js"></script>`,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("sendMessage");
+  await extension.unload();
+});
+
+add_task(async function runtimeSendMessageBlob() {
+  function background() {
+    browser.runtime.onMessage.addListener(msg => {
+      browser.test.assertTrue(msg.blob instanceof Blob, "Message is a blob");
+      return Promise.resolve(msg);
+    });
+
+    let childFrame = document.createElement("iframe");
+    childFrame.src = "extensionpage.html";
+    document.body.appendChild(childFrame);
+  }
+
+  function senderScript() {
+    browser.runtime
+      .sendMessage({ blob: new Blob(["hello"]) })
+      .then(response => {
+        browser.test.assertTrue(
+          response.blob instanceof Blob,
+          "Response is a blob"
+        );
+        browser.test.notifyPass("sendBlob");
+      });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    files: {
+      "senderScript.js": senderScript,
+      "extensionpage.html": `<!DOCTYPE html><meta charset="utf-8"><script src="senderScript.js"></script>`,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("sendBlob");
+  await extension.unload();
+});
+
+add_task(async function sendMessageResponseGC() {
+  function background() {
+    let savedResolve, savedRespond;
+
+    browser.runtime.onMessage.addListener((msg, _, respond) => {
+      browser.test.log(`Got request: ${msg}`);
+      switch (msg) {
+        case "ping":
+          respond("pong");
+          return;
+
+        case "promise-save":
+          return new Promise(resolve => {
+            savedResolve = resolve;
+          });
+        case "promise-resolve":
+          savedResolve("saved-resolve");
+          return;
+        case "promise-never":
+          return new Promise(r => {});
+
+        case "callback-save":
+          savedRespond = respond;
+          return true;
+        case "callback-call":
+          savedRespond("saved-respond");
+          return;
+        case "callback-never":
+          return true;
+      }
+    });
+
+    const frame = document.createElement("iframe");
+    frame.src = "page.html";
+    document.body.appendChild(frame);
+  }
+
+  function page() {
+    browser.test.onMessage.addListener(msg => {
+      browser.runtime.sendMessage(msg).then(
+        response => {
+          if (response) {
+            browser.test.log(`Got response: ${response}`);
+            browser.test.sendMessage(response);
+          }
+        },
+        error => {
+          browser.test.assertEq(
+            "Promised response from onMessage listener went out of scope",
+            error.message,
+            `Promise rejected with the correct error message`
+          );
+
+          browser.test.assertTrue(
+            /^moz-extension:\/\/[\w-]+\/%7B[\w-]+%7D\.js/.test(error.fileName),
+            `Promise rejected with the correct error filename: ${error.fileName}`
+          );
+
+          browser.test.assertEq(
+            4,
+            error.lineNumber,
+            `Promise rejected with the correct error line number`
+          );
+
+          browser.test.assertTrue(
+            /moz-extension:\/\/[\w-]+\/%7B[\w-]+%7D\.js:4/.test(error.stack),
+            `Promise rejected with the correct error stack: ${error.stack}`
+          );
+          browser.test.sendMessage("rejected");
+        }
+      );
+    });
+    browser.test.sendMessage("ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    files: {
+      "page.html":
+        "<!DOCTYPE html><meta charset=utf-8><script src=page.js></script>",
+      "page.js": page,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  // Setup long-running tasks before GC.
+  extension.sendMessage("promise-save");
+  extension.sendMessage("callback-save");
+
+  // Test returning a Promise that can never resolve.
+  extension.sendMessage("promise-never");
+
+  extension.sendMessage("ping");
+  await extension.awaitMessage("pong");
+
+  Services.ppmm.loadProcessScript("data:,Components.utils.forceGC()", false);
+  await extension.awaitMessage("rejected");
+
+  // Test returning `true` without holding the response handle.
+  extension.sendMessage("callback-never");
+
+  extension.sendMessage("ping");
+  await extension.awaitMessage("pong");
+
+  Services.ppmm.loadProcessScript("data:,Components.utils.forceGC()", false);
+  await extension.awaitMessage("rejected");
+
+  // Test that promises from long-running tasks didn't get GCd.
+  extension.sendMessage("promise-resolve");
+  await extension.awaitMessage("saved-resolve");
+
+  extension.sendMessage("callback-call");
+  await extension.awaitMessage("saved-respond");
+
+  ok("Long running tasks responded");
+  await extension.unload();
+});
+
+add_task(async function sendMessage_async_response_multiple_contexts() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.runtime.onMessage.addListener((msg, _, respond) => {
+        browser.test.log(`Background got request: ${msg}`);
+
+        switch (msg) {
+          case "ask-bg-fast":
+            respond("bg-respond");
+            return true;
+
+          case "ask-bg-slow":
+            return new Promise(r => setTimeout(() => r("bg-promise")), 1000);
+        }
+      });
+      browser.test.sendMessage("bg-ready");
+    },
+
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://localhost/*/file_sample.html"],
+          js: ["cs.js"],
+        },
+      ],
+    },
+
+    files: {
+      "page.html":
+        "<!DOCTYPE html><meta charset=utf-8><script src=page.js></script>",
+      "page.js"() {
+        browser.runtime.onMessage.addListener((msg, _, respond) => {
+          browser.test.log(`Page got request: ${msg}`);
+
+          switch (msg) {
+            case "ask-page-fast":
+              respond("page-respond");
+              return true;
+
+            case "ask-page-slow":
+              return new Promise(r => setTimeout(() => r("page-promise")), 500);
+          }
+        });
+        browser.test.sendMessage("page-ready");
+      },
+
+      "cs.js"() {
+        Promise.all([
+          browser.runtime.sendMessage("ask-bg-fast"),
+          browser.runtime.sendMessage("ask-bg-slow"),
+          browser.runtime.sendMessage("ask-page-fast"),
+          browser.runtime.sendMessage("ask-page-slow"),
+        ]).then(responses => {
+          browser.test.assertEq(
+            responses.join(),
+            ["bg-respond", "bg-promise", "page-respond", "page-promise"].join(),
+            "Got all expected responses from correct contexts"
+          );
+          browser.test.notifyPass("cs-done");
+        });
+      },
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("bg-ready");
+
+  let url = `moz-extension://${extension.uuid}/page.html`;
+  let page = await ExtensionTestUtils.loadContentPage(url, { extension });
+  await extension.awaitMessage("page-ready");
+
+  let content = await ExtensionTestUtils.loadContentPage(
+    BASE_URL + "/file_sample.html"
+  );
+  await extension.awaitFinish("cs-done");
+  await content.close();
+
+  await page.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_args.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_args.js
new file mode 100644
index 0000000000..ecbaba5cfe
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_args.js
@@ -0,0 +1,101 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function() {
+  const ID1 = "sendMessage1@tests.mozilla.org";
+  const ID2 = "sendMessage2@tests.mozilla.org";
+
+  let extension1 = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.onMessage.addListener((...args) => {
+        browser.runtime.sendMessage(...args);
+      });
+
+      let frame = document.createElement("iframe");
+      frame.src = "page.html";
+      document.body.appendChild(frame);
+    },
+    manifest: { applications: { gecko: { id: ID1 } } },
+    files: {
+      "page.js": function() {
+        browser.runtime.onMessage.addListener((msg, sender) => {
+          browser.test.sendMessage("received-page", { msg, sender });
+        });
+        // Let them know we're done loading the page.
+        browser.test.sendMessage("page-ready");
+      },
+      "page.html": `<!DOCTYPE html><meta charset="utf-8"><script src="page.js"></script>`,
+    },
+  });
+
+  let extension2 = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.runtime.onMessageExternal.addListener((msg, sender) => {
+        browser.test.sendMessage("received-external", { msg, sender });
+      });
+    },
+    manifest: { applications: { gecko: { id: ID2 } } },
+  });
+
+  await Promise.all([extension1.startup(), extension2.startup()]);
+  await extension1.awaitMessage("page-ready");
+
+  // Check that a message was sent within extension1.
+  async function checkLocalMessage(msg) {
+    let result = await extension1.awaitMessage("received-page");
+    deepEqual(result.msg, msg, "Received internal message");
+    equal(result.sender.id, ID1, "Received correct sender id");
+  }
+
+  // Check that a message was sent from extension1 to extension2.
+  async function checkRemoteMessage(msg) {
+    let result = await extension2.awaitMessage("received-external");
+    deepEqual(result.msg, msg, "Received cross-extension message");
+    equal(result.sender.id, ID1, "Received correct sender id");
+  }
+
+  // sendMessage() takes 3 arguments:
+  //  optional extensionID
+  //  mandatory message
+  //  optional options
+  // Due to this insane design we parse its arguments manually.  This
+  // test is meant to cover all the combinations.
+
+  // A single null or undefined argument is allowed, and represents the message
+  extension1.sendMessage(null);
+  await checkLocalMessage(null);
+
+  // With one argument, it must be just the message
+  extension1.sendMessage("message");
+  await checkLocalMessage("message");
+
+  // With two arguments, these cases should be treated as (extensionID, message)
+  extension1.sendMessage(ID2, "message");
+  await checkRemoteMessage("message");
+
+  extension1.sendMessage(ID2, { msg: "message" });
+  await checkRemoteMessage({ msg: "message" });
+
+  // And these should be (message, options)
+  extension1.sendMessage("message", {});
+  await checkLocalMessage("message");
+
+  // or (message, non-callback), pick your poison
+  extension1.sendMessage("message", undefined);
+  await checkLocalMessage("message");
+
+  // With three arguments, we send a cross-extension message
+  extension1.sendMessage(ID2, "message", {});
+  await checkRemoteMessage("message");
+
+  // Even when the last one is null or undefined
+  extension1.sendMessage(ID2, "message", undefined);
+  await checkRemoteMessage("message");
+
+  // The four params case is unambigous, so we allow null as a (non-) callback
+  extension1.sendMessage(ID2, "message", {}, null);
+  await checkRemoteMessage("message");
+
+  await Promise.all([extension1.unload(), extension2.unload()]);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_errors.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_errors.js
new file mode 100644
index 0000000000..a56c2fdc79
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_errors.js
@@ -0,0 +1,66 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_sendMessage_error() {
+  async function background() {
+    let circ = {};
+    circ.circ = circ;
+    let testCases = [
+      // [arguments, expected error string],
+      [[], "runtime.sendMessage's message argument is missing"],
+      [
+        [null, null, null, 42],
+        "runtime.sendMessage's last argument is not a function",
+      ],
+      [[null, null, 1], "runtime.sendMessage's options argument is invalid"],
+      [
+        [1, null, null],
+        "runtime.sendMessage's extensionId argument is invalid",
+      ],
+      [
+        [null, null, null, null, null],
+        "runtime.sendMessage received too many arguments",
+      ],
+
+      // Even when the parameters are accepted, we still expect an error
+      // because there is no onMessage listener.
+      [
+        [null, null, null],
+        "Could not establish connection. Receiving end does not exist.",
+      ],
+
+      // Structured cloning doesn't work with DOM objects
+      [[null, location, null], "The object could not be cloned."],
+      [[null, [circ, location], null], "The object could not be cloned."],
+    ];
+
+    // Repeat all tests with the undefined value instead of null.
+    for (let [args, expectedError] of testCases.slice()) {
+      args = args.map(arg => (arg === null ? undefined : arg));
+      testCases.push([args, expectedError]);
+    }
+
+    for (let [args, expectedError] of testCases) {
+      let description = `runtime.sendMessage(${args.map(String).join(", ")})`;
+
+      await browser.test.assertRejects(
+        browser.runtime.sendMessage(...args),
+        expectedError,
+        `expected error message for ${description}`
+      );
+    }
+
+    browser.test.notifyPass("sendMessage parameter validation");
+  }
+  let extensionData = {
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await extension.awaitFinish("sendMessage parameter validation");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_multiple.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_multiple.js
new file mode 100644
index 0000000000..9827a329e3
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_multiple.js
@@ -0,0 +1,67 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+// Regression test for bug 1655624: When there are multiple onMessage receivers
+// that both handle the response asynchronously, destroying the context of one
+// recipient should not prevent the other recipient from sending a reply.
+add_task(async function onMessage_ignores_destroyed_contexts() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.onMessage.addListener(async msg => {
+        if (msg !== "startTest") {
+          return;
+        }
+        try {
+          let res = await browser.runtime.sendMessage("msg_from_bg");
+          browser.test.assertEq(0, res, "Result from onMessage");
+          browser.test.notifyPass("handled_onMessage");
+        } catch (e) {
+          browser.test.fail(`Unexpected error: ${e.message} :: ${e.stack}`);
+          browser.test.notifyFail("handled_onMessage");
+        }
+      });
+    },
+    files: {
+      "tab.html": `
+        <!DOCTYPE html><meta charset="utf-8">
+        <script src="tab.js"></script>
+      `,
+      "tab.js": () => {
+        let where = location.search.slice(1);
+        let resolveOnMessage;
+        browser.runtime.onMessage.addListener(async msg => {
+          browser.test.assertEq("msg_from_bg", msg, `onMessage at ${where}`);
+          browser.test.sendMessage(`received:${where}`);
+          return new Promise(resolve => {
+            resolveOnMessage = resolve;
+          });
+        });
+        browser.test.onMessage.addListener(msg => {
+          if (msg === `resolveOnMessage:${where}`) {
+            resolveOnMessage(0);
+          }
+        });
+      },
+    },
+  });
+  await extension.startup();
+  let tabToCloseEarly = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/tab.html?tabToCloseEarly`,
+    { extension }
+  );
+  let tabToRespond = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/tab.html?tabToRespond`,
+    { extension }
+  );
+  extension.sendMessage("startTest");
+  await Promise.all([
+    extension.awaitMessage("received:tabToCloseEarly"),
+    extension.awaitMessage("received:tabToRespond"),
+  ]);
+  await tabToCloseEarly.close();
+  extension.sendMessage("resolveOnMessage:tabToRespond");
+  await extension.awaitFinish("handled_onMessage");
+  await tabToRespond.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_no_receiver.js b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_no_receiver.js
new file mode 100644
index 0000000000..23d8b05f83
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_runtime_sendMessage_no_receiver.js
@@ -0,0 +1,93 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_sendMessage_without_listener() {
+  async function background() {
+    await browser.test.assertRejects(
+      browser.runtime.sendMessage("msg"),
+      "Could not establish connection. Receiving end does not exist.",
+      "Correct error when there are no receivers from background"
+    );
+
+    browser.test.sendMessage("sendMessage-error-bg");
+  }
+  let extensionData = {
+    background,
+    files: {
+      "page.html": `<!doctype><meta charset=utf-8><script src="page.js"></script>`,
+      async "page.js"() {
+        await browser.test.assertRejects(
+          browser.runtime.sendMessage("msg"),
+          "Could not establish connection. Receiving end does not exist.",
+          "Correct error when there are no receivers from extension page"
+        );
+
+        browser.test.notifyPass("sendMessage-error-page");
+      },
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("sendMessage-error-bg");
+
+  let url = `moz-extension://${extension.uuid}/page.html`;
+  let page = await ExtensionTestUtils.loadContentPage(url, { extension });
+  await extension.awaitFinish("sendMessage-error-page");
+  await page.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_chrome_sendMessage_without_listener() {
+  function background() {
+    /* globals chrome */
+    browser.test.assertEq(
+      null,
+      chrome.runtime.lastError,
+      "no lastError before call"
+    );
+    let retval = chrome.runtime.sendMessage("msg");
+    browser.test.assertEq(
+      null,
+      chrome.runtime.lastError,
+      "no lastError after call"
+    );
+    browser.test.assertEq(
+      undefined,
+      retval,
+      "return value of chrome.runtime.sendMessage without callback"
+    );
+
+    let isAsyncCall = false;
+    retval = chrome.runtime.sendMessage("msg", reply => {
+      browser.test.assertEq(undefined, reply, "no reply");
+      browser.test.assertTrue(
+        isAsyncCall,
+        "chrome.runtime.sendMessage's callback must be called asynchronously"
+      );
+      browser.test.assertEq(
+        undefined,
+        retval,
+        "return value of chrome.runtime.sendMessage with callback"
+      );
+      browser.test.assertEq(
+        "Could not establish connection. Receiving end does not exist.",
+        chrome.runtime.lastError.message
+      );
+      browser.test.notifyPass("finished chrome.runtime.sendMessage");
+    });
+    isAsyncCall = true;
+  }
+  let extensionData = {
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await extension.awaitFinish("finished chrome.runtime.sendMessage");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_same_site_cookies.js b/toolkit/components/extensions/test/xpcshell/test_ext_same_site_cookies.js
new file mode 100644
index 0000000000..80641d7be4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_same_site_cookies.js
@@ -0,0 +1,131 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+const WIN = `<html><body>dummy page setting a same-site cookie</body></html>`;
+
+// Small red image.
+const IMG_BYTES = atob(
+  "iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12" +
+    "P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=="
+);
+
+server.registerPathHandler("/same_site_cookies", (request, response) => {
+  // avoid confusing cache behaviors
+  response.setHeader("Cache-Control", "no-cache", false);
+
+  if (request.queryString === "loadWin") {
+    response.write(WIN);
+    return;
+  }
+
+  // using startsWith and discard the math random
+  if (request.queryString.startsWith("loadImage")) {
+    response.setHeader(
+      "Set-Cookie",
+      "myKey=mySameSiteExtensionCookie; samesite=strict",
+      true
+    );
+    response.setHeader("Content-Type", "image/png");
+    response.write(IMG_BYTES);
+    return;
+  }
+
+  if (request.queryString === "loadXHR") {
+    let cookie = "noCookie";
+    if (request.hasHeader("Cookie")) {
+      cookie = request.getHeader("Cookie");
+    }
+    response.setHeader("Content-Type", "text/plain");
+    response.write(cookie);
+    return;
+  }
+
+  // We should never get here, but just in case return something unexpected.
+  response.write("D'oh");
+});
+
+/* Description of the test:
+ * (1) We load an image from mochi.test which sets a same site cookie
+ * (2) We have the web extension perform an XHR request to mochi.test
+ * (3) We verify the web-extension can access the same-site cookie
+ */
+
+add_task(async function test_webRequest_same_site_cookie_access() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://example.com/*"],
+      content_scripts: [
+        {
+          matches: ["http://example.com/*"],
+          run_at: "document_end",
+          js: ["content_script.js"],
+        },
+      ],
+    },
+
+    background() {
+      browser.test.onMessage.addListener(msg => {
+        if (msg === "verify-same-site-cookie-moz-extension") {
+          let xhr = new XMLHttpRequest();
+          try {
+            xhr.open(
+              "GET",
+              "http://example.com/same_site_cookies?loadXHR",
+              true
+            );
+            xhr.onload = function() {
+              browser.test.assertEq(
+                "myKey=mySameSiteExtensionCookie",
+                xhr.responseText,
+                "cookie should be accessible from moz-extension context"
+              );
+              browser.test.sendMessage("same-site-cookie-test-done");
+            };
+            xhr.onerror = function() {
+              browser.test.fail("xhr onerror");
+              browser.test.sendMessage("same-site-cookie-test-done");
+            };
+          } catch (e) {
+            browser.test.fail("xhr failure: " + e);
+          }
+          xhr.send();
+        }
+      });
+    },
+
+    files: {
+      "content_script.js": function() {
+        let myImage = document.createElement("img");
+        // Set the src via wrappedJSObject so the load is triggered with the
+        // content page's principal rather than ours.
+        myImage.wrappedJSObject.setAttribute(
+          "src",
+          "http://example.com/same_site_cookies?loadImage" + Math.random()
+        );
+        myImage.onload = function() {
+          browser.test.log("image onload");
+          browser.test.sendMessage("image-loaded-and-same-site-cookie-set");
+        };
+        myImage.onerror = function() {
+          browser.test.log("image onerror");
+        };
+        document.body.appendChild(myImage);
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/same_site_cookies?loadWin"
+  );
+
+  await extension.awaitMessage("image-loaded-and-same-site-cookie-set");
+
+  extension.sendMessage("verify-same-site-cookie-moz-extension");
+  await extension.awaitMessage("same-site-cookie-test-done");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_same_site_redirects.js b/toolkit/components/extensions/test/xpcshell/test_ext_same_site_redirects.js
new file mode 100644
index 0000000000..df77f8b0dd
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_same_site_redirects.js
@@ -0,0 +1,233 @@
+"use strict";
+
+/**
+ * This test tests various redirection scenarios, and checks whether sameSite
+ * cookies are sent.
+ *
+ * The file has the following tests:
+ * - verify_firstparty_web_behavior - base case, confirms normal web behavior.
+ * - samesite_is_foreign_without_host_permissions
+ * - wildcard_host_permissions_enable_samesite_cookies
+ * - explicit_host_permissions_enable_samesite_cookies
+ * - some_host_permissions_enable_some_samesite_cookies
+ */
+
+// This simulates a common pattern used for sites that require authentication.
+// After logging in, there may be multiple redirects, HTTP and scripted.
+const SITE_START = "start.example.net";
+// set "start" cookies + 302 redirects to found.
+const SITE_FOUND = "found.example.net";
+// set "found" cookies + uses a HTML redirect to redir.
+const SITE_REDIR = "redir.example.net";
+// set "redir" cookies + 302 redirects to final.
+const SITE_FINAL = "final.example.net";
+
+const SITE = "example.net";
+
+const URL_START = `http://${SITE_START}/start`;
+
+const server = createHttpServer({
+  hosts: [SITE_START, SITE_FOUND, SITE_REDIR, SITE_FINAL],
+});
+
+function getCookies(request) {
+  return request.hasHeader("Cookie") ? request.getHeader("Cookie") : "";
+}
+
+function sendCookies(response, prefix, suffix = "") {
+  const cookies = [
+    prefix + "-none=1; sameSite=none; domain=" + SITE + suffix,
+    prefix + "-lax=1; sameSite=lax; domain=" + SITE + suffix,
+    prefix + "-strict=1; sameSite=strict; domain=" + SITE + suffix,
+  ];
+  for (let cookie of cookies) {
+    response.setHeader("Set-Cookie", cookie, true);
+  }
+}
+
+function deleteCookies(response, prefix) {
+  sendCookies(response, prefix, "; expires=Thu, 01 Jan 1970 00:00:00 GMT");
+}
+
+var receivedCookies = [];
+
+server.registerPathHandler("/start", (request, response) => {
+  Assert.equal(request.host, SITE_START);
+  Assert.equal(getCookies(request), "", "No cookies at start of test");
+
+  response.setStatusLine(request.httpVersion, 302, "Found");
+  sendCookies(response, "start");
+  response.setHeader("Location", `http://${SITE_FOUND}/found`);
+});
+
+server.registerPathHandler("/found", (request, response) => {
+  Assert.equal(request.host, SITE_FOUND);
+  receivedCookies.push(getCookies(request));
+
+  response.setHeader("Content-Type", "text/html; charset=utf-8", false);
+  deleteCookies(response, "start");
+  sendCookies(response, "found");
+  response.write(`<script>location = "http://${SITE_REDIR}/redir";</script>`);
+});
+
+server.registerPathHandler("/redir", (request, response) => {
+  Assert.equal(request.host, SITE_REDIR);
+  receivedCookies.push(getCookies(request));
+
+  response.setStatusLine(request.httpVersion, 302, "Found");
+  deleteCookies(response, "found");
+  sendCookies(response, "redir");
+  response.setHeader("Location", `http://${SITE_FINAL}/final`);
+});
+
+server.registerPathHandler("/final", (request, response) => {
+  Assert.equal(request.host, SITE_FINAL);
+  receivedCookies.push(getCookies(request));
+
+  response.setStatusLine(request.httpVersion, 302, "Found");
+  deleteCookies(response, "redir");
+  // In test some_host_permissions_enable_some_samesite_cookies, the cookies
+  // from the start haven't been cleared due to the lack of host permissions.
+  // Do that here instead.
+  deleteCookies(response, "start");
+  response.setHeader("Location", "/final_and_clean");
+});
+
+// Should be called before any request is made.
+function promiseFinalResponse() {
+  Assert.deepEqual(receivedCookies, [], "Test starts without observed cookies");
+  return new Promise(resolve => {
+    server.registerPathHandler("/final_and_clean", (request, response) => {
+      Assert.equal(request.host, SITE_FINAL);
+      Assert.equal(getCookies(request), "", "Cookies cleaned up");
+      resolve(receivedCookies.splice(0));
+    });
+  });
+}
+
+// Load the page as a child frame of an extension, for the given permissions.
+async function getCookiesForLoadInExtension({ permissions }) {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions,
+    },
+    files: {
+      "embedder.html": `<iframe src="${URL_START}"></iframe>`,
+    },
+  });
+  await extension.startup();
+  let cookiesPromise = promiseFinalResponse();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/embedder.html`,
+    { extension }
+  );
+  let cookies = await cookiesPromise;
+  await contentPage.close();
+  await extension.unload();
+  return cookies;
+}
+
+add_task(async function setup() {
+  Services.prefs.setIntPref("network.cookie.cookieBehavior", 0);
+  Services.prefs.setBoolPref("network.cookie.sameSite.laxByDefault", true);
+
+  // Test server runs on http, so disable Secure requirement of sameSite=none.
+  Services.prefs.setBoolPref(
+    "network.cookie.sameSite.noneRequiresSecure",
+    false
+  );
+});
+
+// First verify that our expectations match with the actual behavior on the web.
+add_task(async function verify_firstparty_web_behavior() {
+  let cookiesPromise = promiseFinalResponse();
+  let contentPage = await ExtensionTestUtils.loadContentPage(URL_START);
+  let cookies = await cookiesPromise;
+  await contentPage.close();
+  Assert.deepEqual(
+    cookies,
+    // Same expectations as in host_permissions_enable_samesite_cookies
+    [
+      "start-none=1; start-lax=1; start-strict=1",
+      "found-none=1; found-lax=1; found-strict=1",
+      "redir-none=1; redir-lax=1; redir-strict=1",
+    ],
+    "Expected cookies from a first-party load on the web"
+  );
+});
+
+// Verify that an extension without permission behaves like a third-party page.
+add_task(async function samesite_is_foreign_without_host_permissions() {
+  let cookies = await getCookiesForLoadInExtension({
+    permissions: [],
+  });
+
+  Assert.deepEqual(
+    cookies,
+    ["start-none=1", "found-none=1", "redir-none=1"],
+    "SameSite cookies excluded without permissions"
+  );
+});
+
+// When an extension has permissions for the site, cookies should be included.
+add_task(async function wildcard_host_permissions_enable_samesite_cookies() {
+  let cookies = await getCookiesForLoadInExtension({
+    permissions: ["*://*.example.net/*"], // = *.SITE
+  });
+
+  Assert.deepEqual(
+    cookies,
+    // Same expectations as in verify_firstparty_web_behavior.
+    [
+      "start-none=1; start-lax=1; start-strict=1",
+      "found-none=1; found-lax=1; found-strict=1",
+      "redir-none=1; redir-lax=1; redir-strict=1",
+    ],
+    "Expected cookies from a load in an extension frame"
+  );
+});
+
+// When an extension has permissions for the site, cookies should be included.
+add_task(async function explicit_host_permissions_enable_samesite_cookies() {
+  let cookies = await getCookiesForLoadInExtension({
+    permissions: [
+      "*://start.example.net/*",
+      "*://found.example.net/*",
+      "*://redir.example.net/*",
+      "*://final.example.net/*",
+    ],
+  });
+
+  Assert.deepEqual(
+    cookies,
+    // Same expectations as in verify_firstparty_web_behavior.
+    [
+      "start-none=1; start-lax=1; start-strict=1",
+      "found-none=1; found-lax=1; found-strict=1",
+      "redir-none=1; redir-lax=1; redir-strict=1",
+    ],
+    "Expected cookies from a load in an extension frame"
+  );
+});
+
+// When an extension does not have host permissions for all sites, but only
+// some, then same-site cookies are only included in requests with the right
+// permissions.
+add_task(async function some_host_permissions_enable_some_samesite_cookies() {
+  let cookies = await getCookiesForLoadInExtension({
+    permissions: ["*://start.example.net/*", "*://final.example.net/*"],
+  });
+
+  Assert.deepEqual(
+    cookies,
+    [
+      // Missing permission for "found.example.net":
+      "start-none=1",
+      // Missing permission for "redir.example.net":
+      "found-none=1",
+      // "final.example.net" can see cookies from "start.example.net":
+      "start-lax=1; start-strict=1; redir-none=1",
+    ],
+    "Expected some cookies from a load in an extension frame"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_sandbox_var.js b/toolkit/components/extensions/test/xpcshell/test_ext_sandbox_var.js
new file mode 100644
index 0000000000..0a8a5acdef
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_sandbox_var.js
@@ -0,0 +1,42 @@
+"use strict";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+function contentScript() {
+  window.x = 12;
+  browser.test.assertEq(window.x, 12, "x is 12");
+  browser.test.notifyPass("background test passed");
+}
+
+let extensionData = {
+  manifest: {
+    content_scripts: [
+      {
+        matches: ["http://localhost/*/file_sample.html"],
+        js: ["content_script.js"],
+        run_at: "document_idle",
+      },
+    ],
+  },
+
+  files: {
+    "content_script.js": contentScript,
+  },
+};
+
+add_task(async function test_contentscript() {
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+
+  await extension.awaitFinish();
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schema.js b/toolkit/components/extensions/test/xpcshell/test_ext_schema.js
new file mode 100644
index 0000000000..90b615d10e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schema.js
@@ -0,0 +1,79 @@
+"use strict";
+
+AddonTestUtils.init(this);
+
+add_task(async function testEmptySchema() {
+  function background() {
+    browser.test.assertEq(
+      undefined,
+      browser.manifest,
+      "browser.manifest is not defined"
+    );
+    browser.test.assertTrue(
+      !!browser.storage,
+      "browser.storage should be defined"
+    );
+    browser.test.assertEq(
+      undefined,
+      browser.contextMenus,
+      "browser.contextMenus should not be defined"
+    );
+    browser.test.notifyPass("schema");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["storage"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("schema");
+  await extension.unload();
+});
+
+add_task(async function test_warnings_as_errors() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: { unrecognized_property_that_should_be_treated_as_a_warning: 1 },
+  });
+
+  // Tests should be run with extensions.webextensions.warnings-as-errors=true
+  // by default, and prevent extensions with manifest warnings from loading.
+  await Assert.rejects(
+    extension.startup(),
+    /unrecognized_property_that_should_be_treated_as_a_warning/,
+    "extension with invalid manifest should not load if warnings-as-errors=true"
+  );
+  // When ExtensionTestUtils.failOnSchemaWarnings(false) is called, startup is
+  // expected to succeed, as shown by the next "testUnknownProperties" test.
+});
+
+add_task(async function testUnknownProperties() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["unknownPermission"],
+
+      unknown_property: {},
+    },
+
+    background() {},
+  });
+
+  let { messages } = await promiseConsoleOutput(async () => {
+    ExtensionTestUtils.failOnSchemaWarnings(false);
+    await extension.startup();
+    ExtensionTestUtils.failOnSchemaWarnings(true);
+  });
+
+  AddonTestUtils.checkMessages(messages, {
+    expected: [
+      { message: /processing permissions\.0: Value "unknownPermission"/ },
+      {
+        message: /processing unknown_property: An unexpected property was found in the WebExtension manifest/,
+      },
+    ],
+  });
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas.js
new file mode 100644
index 0000000000..8eba1b7e83
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas.js
@@ -0,0 +1,2097 @@
+"use strict";
+
+const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+
+let { LocalAPIImplementation, SchemaAPIInterface } = ExtensionCommon;
+
+const global = this;
+
+let json = [
+  {
+    namespace: "testing",
+
+    properties: {
+      PROP1: { value: 20 },
+      prop2: { type: "string" },
+      prop3: {
+        $ref: "submodule",
+      },
+      prop4: {
+        $ref: "submodule",
+        unsupported: true,
+      },
+    },
+
+    types: [
+      {
+        id: "type1",
+        type: "string",
+        enum: ["value1", "value2", "value3"],
+      },
+
+      {
+        id: "type2",
+        type: "object",
+        properties: {
+          prop1: { type: "integer" },
+          prop2: { type: "array", items: { $ref: "type1" } },
+        },
+      },
+
+      {
+        id: "basetype1",
+        type: "object",
+        properties: {
+          prop1: { type: "string" },
+        },
+      },
+
+      {
+        id: "basetype2",
+        choices: [{ type: "integer" }],
+      },
+
+      {
+        $extend: "basetype1",
+        properties: {
+          prop2: { type: "string" },
+        },
+      },
+
+      {
+        $extend: "basetype2",
+        choices: [{ type: "string" }],
+      },
+
+      {
+        id: "basetype3",
+        type: "object",
+        properties: {
+          baseprop: { type: "string" },
+        },
+      },
+
+      {
+        id: "derivedtype1",
+        type: "object",
+        $import: "basetype3",
+        properties: {
+          derivedprop: { type: "string" },
+        },
+      },
+
+      {
+        id: "derivedtype2",
+        type: "object",
+        $import: "basetype3",
+        properties: {
+          derivedprop: { type: "integer" },
+        },
+      },
+
+      {
+        id: "submodule",
+        type: "object",
+        functions: [
+          {
+            name: "sub_foo",
+            type: "function",
+            parameters: [],
+            returns: { type: "integer" },
+          },
+        ],
+      },
+    ],
+
+    functions: [
+      {
+        name: "foo",
+        type: "function",
+        parameters: [
+          { name: "arg1", type: "integer", optional: true, default: 99 },
+          { name: "arg2", type: "boolean", optional: true },
+        ],
+      },
+
+      {
+        name: "bar",
+        type: "function",
+        parameters: [
+          { name: "arg1", type: "integer", optional: true },
+          { name: "arg2", type: "boolean" },
+        ],
+      },
+
+      {
+        name: "baz",
+        type: "function",
+        parameters: [
+          {
+            name: "arg1",
+            type: "object",
+            properties: {
+              prop1: { type: "string" },
+              prop2: { type: "integer", optional: true },
+              prop3: { type: "integer", unsupported: true },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "qux",
+        type: "function",
+        parameters: [{ name: "arg1", $ref: "type1" }],
+      },
+
+      {
+        name: "quack",
+        type: "function",
+        parameters: [{ name: "arg1", $ref: "type2" }],
+      },
+
+      {
+        name: "quora",
+        type: "function",
+        parameters: [{ name: "arg1", type: "function" }],
+      },
+
+      {
+        name: "quileute",
+        type: "function",
+        parameters: [
+          { name: "arg1", type: "integer", optional: true },
+          { name: "arg2", type: "integer" },
+        ],
+      },
+
+      {
+        name: "queets",
+        type: "function",
+        unsupported: true,
+        parameters: [],
+      },
+
+      {
+        name: "quintuplets",
+        type: "function",
+        parameters: [
+          {
+            name: "obj",
+            type: "object",
+            properties: [],
+            additionalProperties: { type: "integer" },
+          },
+        ],
+      },
+
+      {
+        name: "quasar",
+        type: "function",
+        parameters: [
+          {
+            name: "abc",
+            type: "object",
+            properties: {
+              func: {
+                type: "function",
+                parameters: [{ name: "x", type: "integer" }],
+              },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "quosimodo",
+        type: "function",
+        parameters: [
+          {
+            name: "xyz",
+            type: "object",
+            additionalProperties: { type: "any" },
+          },
+        ],
+      },
+
+      {
+        name: "patternprop",
+        type: "function",
+        parameters: [
+          {
+            name: "obj",
+            type: "object",
+            properties: { prop1: { type: "string", pattern: "^\\d+$" } },
+            patternProperties: {
+              "(?i)^prop\\d+$": { type: "string" },
+              "^foo\\d+$": { type: "string" },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "pattern",
+        type: "function",
+        parameters: [
+          { name: "arg", type: "string", pattern: "(?i)^[0-9a-f]+$" },
+        ],
+      },
+
+      {
+        name: "format",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            type: "object",
+            properties: {
+              hostname: { type: "string", format: "hostname", optional: true },
+              url: { type: "string", format: "url", optional: true },
+              relativeUrl: {
+                type: "string",
+                format: "relativeUrl",
+                optional: true,
+              },
+              strictRelativeUrl: {
+                type: "string",
+                format: "strictRelativeUrl",
+                optional: true,
+              },
+              imageDataOrStrictRelativeUrl: {
+                type: "string",
+                format: "imageDataOrStrictRelativeUrl",
+                optional: true,
+              },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "formatDate",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            type: "object",
+            properties: {
+              date: { type: "string", format: "date", optional: true },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "deep",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            type: "object",
+            properties: {
+              foo: {
+                type: "object",
+                properties: {
+                  bar: {
+                    type: "array",
+                    items: {
+                      type: "object",
+                      properties: {
+                        baz: {
+                          type: "object",
+                          properties: {
+                            required: { type: "integer" },
+                            optional: { type: "string", optional: true },
+                          },
+                        },
+                      },
+                    },
+                  },
+                },
+              },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "errors",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            type: "object",
+            properties: {
+              warn: {
+                type: "string",
+                pattern: "^\\d+$",
+                optional: true,
+                onError: "warn",
+              },
+              ignore: {
+                type: "string",
+                pattern: "^\\d+$",
+                optional: true,
+                onError: "ignore",
+              },
+              default: {
+                type: "string",
+                pattern: "^\\d+$",
+                optional: true,
+              },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "localize",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            type: "object",
+            properties: {
+              foo: { type: "string", preprocess: "localize", optional: true },
+              bar: { type: "string", optional: true },
+              url: {
+                type: "string",
+                preprocess: "localize",
+                format: "url",
+                optional: true,
+              },
+            },
+          },
+        ],
+      },
+
+      {
+        name: "extended1",
+        type: "function",
+        parameters: [{ name: "val", $ref: "basetype1" }],
+      },
+
+      {
+        name: "extended2",
+        type: "function",
+        parameters: [{ name: "val", $ref: "basetype2" }],
+      },
+
+      {
+        name: "callderived1",
+        type: "function",
+        parameters: [{ name: "value", $ref: "derivedtype1" }],
+      },
+
+      {
+        name: "callderived2",
+        type: "function",
+        parameters: [{ name: "value", $ref: "derivedtype2" }],
+      },
+    ],
+
+    events: [
+      {
+        name: "onFoo",
+        type: "function",
+      },
+
+      {
+        name: "onBar",
+        type: "function",
+        extraParameters: [
+          {
+            name: "filter",
+            type: "integer",
+            optional: true,
+            default: 1,
+          },
+        ],
+      },
+    ],
+  },
+  {
+    namespace: "foreign",
+    properties: {
+      foreignRef: { $ref: "testing.submodule" },
+    },
+  },
+  {
+    namespace: "inject",
+    properties: {
+      PROP1: { value: "should inject" },
+    },
+  },
+  {
+    namespace: "do-not-inject",
+    properties: {
+      PROP1: { value: "should not inject" },
+    },
+  },
+];
+
+let tallied = null;
+
+function tally(kind, ns, name, args) {
+  tallied = [kind, ns, name, args];
+}
+
+function verify(...args) {
+  Assert.equal(JSON.stringify(tallied), JSON.stringify(args));
+  tallied = null;
+}
+
+let talliedErrors = [];
+
+function checkErrors(errors) {
+  Assert.equal(
+    talliedErrors.length,
+    errors.length,
+    "Got expected number of errors"
+  );
+  for (let [i, error] of errors.entries()) {
+    Assert.ok(
+      i in talliedErrors && String(talliedErrors[i]).includes(error),
+      `${JSON.stringify(error)} is a substring of error ${JSON.stringify(
+        talliedErrors[i]
+      )}`
+    );
+  }
+
+  talliedErrors.length = 0;
+}
+
+let permissions = new Set();
+
+class TallyingAPIImplementation extends SchemaAPIInterface {
+  constructor(namespace, name) {
+    super();
+    this.namespace = namespace;
+    this.name = name;
+  }
+
+  callFunction(args) {
+    tally("call", this.namespace, this.name, args);
+    if (this.name === "sub_foo") {
+      return 13;
+    }
+  }
+
+  callFunctionNoReturn(args) {
+    tally("call", this.namespace, this.name, args);
+  }
+
+  getProperty() {
+    tally("get", this.namespace, this.name);
+  }
+
+  setProperty(value) {
+    tally("set", this.namespace, this.name, value);
+  }
+
+  addListener(listener, args) {
+    tally("addListener", this.namespace, this.name, [listener, args]);
+  }
+
+  removeListener(listener) {
+    tally("removeListener", this.namespace, this.name, [listener]);
+  }
+
+  hasListener(listener) {
+    tally("hasListener", this.namespace, this.name, [listener]);
+  }
+}
+
+let wrapper = {
+  url: "moz-extension://b66e3509-cdb3-44f6-8eb8-c8b39b3a1d27/",
+
+  cloneScope: global,
+
+  checkLoadURL(url) {
+    return !url.startsWith("chrome:");
+  },
+
+  preprocessors: {
+    localize(value, context) {
+      return value.replace(/__MSG_(.*?)__/g, (m0, m1) => `${m1.toUpperCase()}`);
+    },
+  },
+
+  logError(message) {
+    talliedErrors.push(message);
+  },
+
+  hasPermission(permission) {
+    return permissions.has(permission);
+  },
+
+  shouldInject(ns, name) {
+    return name != "do-not-inject";
+  },
+
+  getImplementation(namespace, name) {
+    return new TallyingAPIImplementation(namespace, name);
+  },
+};
+
+add_task(async function() {
+  let url = "data:," + JSON.stringify(json);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let root = {};
+  tallied = null;
+  Schemas.inject(root, wrapper);
+  Assert.equal(tallied, null);
+
+  Assert.equal(root.testing.PROP1, 20, "simple value property");
+  Assert.equal(root.testing.type1.VALUE1, "value1", "enum type");
+  Assert.equal(root.testing.type1.VALUE2, "value2", "enum type");
+
+  Assert.equal("inject" in root, true, "namespace 'inject' should be injected");
+  Assert.equal(
+    root["do-not-inject"],
+    undefined,
+    "namespace 'do-not-inject' should not be injected"
+  );
+
+  root.testing.foo(11, true);
+  verify("call", "testing", "foo", [11, true]);
+
+  root.testing.foo(true);
+  verify("call", "testing", "foo", [99, true]);
+
+  root.testing.foo(null, true);
+  verify("call", "testing", "foo", [99, true]);
+
+  root.testing.foo(undefined, true);
+  verify("call", "testing", "foo", [99, true]);
+
+  root.testing.foo(11);
+  verify("call", "testing", "foo", [11, null]);
+
+  Assert.throws(
+    () => root.testing.bar(11),
+    /Incorrect argument types/,
+    "should throw without required arg"
+  );
+
+  Assert.throws(
+    () => root.testing.bar(11, true, 10),
+    /Incorrect argument types/,
+    "should throw with too many arguments"
+  );
+
+  root.testing.bar(true);
+  verify("call", "testing", "bar", [null, true]);
+
+  root.testing.baz({ prop1: "hello", prop2: 22 });
+  verify("call", "testing", "baz", [{ prop1: "hello", prop2: 22 }]);
+
+  root.testing.baz({ prop1: "hello" });
+  verify("call", "testing", "baz", [{ prop1: "hello", prop2: null }]);
+
+  root.testing.baz({ prop1: "hello", prop2: null });
+  verify("call", "testing", "baz", [{ prop1: "hello", prop2: null }]);
+
+  Assert.throws(
+    () => root.testing.baz({ prop2: 12 }),
+    /Property "prop1" is required/,
+    "should throw without required property"
+  );
+
+  Assert.throws(
+    () => root.testing.baz({ prop1: "hi", prop3: 12 }),
+    /Property "prop3" is unsupported by Firefox/,
+    "should throw with unsupported property"
+  );
+
+  Assert.throws(
+    () => root.testing.baz({ prop1: "hi", prop4: 12 }),
+    /Unexpected property "prop4"/,
+    "should throw with unexpected property"
+  );
+
+  Assert.throws(
+    () => root.testing.baz({ prop1: 12 }),
+    /Expected string instead of 12/,
+    "should throw with wrong type"
+  );
+
+  root.testing.qux("value2");
+  verify("call", "testing", "qux", ["value2"]);
+
+  Assert.throws(
+    () => root.testing.qux("value4"),
+    /Invalid enumeration value "value4"/,
+    "should throw for invalid enum value"
+  );
+
+  root.testing.quack({ prop1: 12, prop2: ["value1", "value3"] });
+  verify("call", "testing", "quack", [
+    { prop1: 12, prop2: ["value1", "value3"] },
+  ]);
+
+  Assert.throws(
+    () =>
+      root.testing.quack({ prop1: 12, prop2: ["value1", "value3", "value4"] }),
+    /Invalid enumeration value "value4"/,
+    "should throw for invalid array type"
+  );
+
+  function f() {}
+  root.testing.quora(f);
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["call", "testing", "quora"])
+  );
+  Assert.equal(tallied[3][0], f);
+  tallied = null;
+
+  let g = () => 0;
+  root.testing.quora(g);
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["call", "testing", "quora"])
+  );
+  Assert.equal(tallied[3][0], g);
+  tallied = null;
+
+  root.testing.quileute(10);
+  verify("call", "testing", "quileute", [null, 10]);
+
+  Assert.throws(
+    () => root.testing.queets(),
+    /queets is not a function/,
+    "should throw for unsupported functions"
+  );
+
+  root.testing.quintuplets({ a: 10, b: 20, c: 30 });
+  verify("call", "testing", "quintuplets", [{ a: 10, b: 20, c: 30 }]);
+
+  Assert.throws(
+    () => root.testing.quintuplets({ a: 10, b: 20, c: 30, d: "hi" }),
+    /Expected integer instead of "hi"/,
+    "should throw for wrong additionalProperties type"
+  );
+
+  root.testing.quasar({ func: f });
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["call", "testing", "quasar"])
+  );
+  Assert.equal(tallied[3][0].func, f);
+  tallied = null;
+
+  root.testing.quosimodo({ a: 10, b: 20, c: 30 });
+  verify("call", "testing", "quosimodo", [{ a: 10, b: 20, c: 30 }]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.quosimodo(10),
+    /Incorrect argument types/,
+    "should throw for wrong type"
+  );
+
+  root.testing.patternprop({
+    prop1: "12",
+    prop2: "42",
+    Prop3: "43",
+    foo1: "x",
+  });
+  verify("call", "testing", "patternprop", [
+    { prop1: "12", prop2: "42", Prop3: "43", foo1: "x" },
+  ]);
+  tallied = null;
+
+  root.testing.patternprop({ prop1: "12" });
+  verify("call", "testing", "patternprop", [{ prop1: "12" }]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.patternprop({ prop1: "12", foo1: null }),
+    /Expected string instead of null/,
+    "should throw for wrong property type"
+  );
+
+  Assert.throws(
+    () => root.testing.patternprop({ prop1: "xx", prop2: "yy" }),
+    /String "xx" must match \/\^\\d\+\$\//,
+    "should throw for wrong property type"
+  );
+
+  Assert.throws(
+    () => root.testing.patternprop({ prop1: "12", prop2: 42 }),
+    /Expected string instead of 42/,
+    "should throw for wrong property type"
+  );
+
+  Assert.throws(
+    () => root.testing.patternprop({ prop1: "12", prop2: null }),
+    /Expected string instead of null/,
+    "should throw for wrong property type"
+  );
+
+  Assert.throws(
+    () => root.testing.patternprop({ prop1: "12", propx: "42" }),
+    /Unexpected property "propx"/,
+    "should throw for unexpected property"
+  );
+
+  Assert.throws(
+    () => root.testing.patternprop({ prop1: "12", Foo1: "x" }),
+    /Unexpected property "Foo1"/,
+    "should throw for unexpected property"
+  );
+
+  root.testing.pattern("DEADbeef");
+  verify("call", "testing", "pattern", ["DEADbeef"]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.pattern("DEADcow"),
+    /String "DEADcow" must match \/\^\[0-9a-f\]\+\$\/i/,
+    "should throw for non-match"
+  );
+
+  root.testing.format({ hostname: "foo" });
+  verify("call", "testing", "format", [
+    {
+      hostname: "foo",
+      imageDataOrStrictRelativeUrl: null,
+      relativeUrl: null,
+      strictRelativeUrl: null,
+      url: null,
+    },
+  ]);
+  tallied = null;
+
+  for (let invalid of ["", " ", "http://foo", "foo/bar", "foo.com/", "foo?"]) {
+    Assert.throws(
+      () => root.testing.format({ hostname: invalid }),
+      /Invalid hostname/,
+      "should throw for invalid hostname"
+    );
+  }
+
+  root.testing.format({ url: "http://foo/bar", relativeUrl: "http://foo/bar" });
+  verify("call", "testing", "format", [
+    {
+      hostname: null,
+      imageDataOrStrictRelativeUrl: null,
+      relativeUrl: "http://foo/bar",
+      strictRelativeUrl: null,
+      url: "http://foo/bar",
+    },
+  ]);
+  tallied = null;
+
+  root.testing.format({
+    relativeUrl: "foo.html",
+    strictRelativeUrl: "foo.html",
+  });
+  verify("call", "testing", "format", [
+    {
+      hostname: null,
+      imageDataOrStrictRelativeUrl: null,
+      relativeUrl: `${wrapper.url}foo.html`,
+      strictRelativeUrl: `${wrapper.url}foo.html`,
+      url: null,
+    },
+  ]);
+  tallied = null;
+
+  root.testing.format({
+    imageDataOrStrictRelativeUrl: "data:image/png;base64,A",
+  });
+  verify("call", "testing", "format", [
+    {
+      hostname: null,
+      imageDataOrStrictRelativeUrl: "data:image/png;base64,A",
+      relativeUrl: null,
+      strictRelativeUrl: null,
+      url: null,
+    },
+  ]);
+  tallied = null;
+
+  root.testing.format({
+    imageDataOrStrictRelativeUrl: "data:image/jpeg;base64,A",
+  });
+  verify("call", "testing", "format", [
+    {
+      hostname: null,
+      imageDataOrStrictRelativeUrl: "data:image/jpeg;base64,A",
+      relativeUrl: null,
+      strictRelativeUrl: null,
+      url: null,
+    },
+  ]);
+  tallied = null;
+
+  root.testing.format({ imageDataOrStrictRelativeUrl: "foo.html" });
+  verify("call", "testing", "format", [
+    {
+      hostname: null,
+      imageDataOrStrictRelativeUrl: `${wrapper.url}foo.html`,
+      relativeUrl: null,
+      strictRelativeUrl: null,
+      url: null,
+    },
+  ]);
+
+  tallied = null;
+
+  for (let format of ["url", "relativeUrl"]) {
+    Assert.throws(
+      () => root.testing.format({ [format]: "chrome://foo/content/" }),
+      /Access denied/,
+      "should throw for access denied"
+    );
+  }
+
+  for (let urlString of ["//foo.html", "http://foo/bar.html"]) {
+    Assert.throws(
+      () => root.testing.format({ strictRelativeUrl: urlString }),
+      /must be a relative URL/,
+      "should throw for non-relative URL"
+    );
+  }
+
+  Assert.throws(
+    () =>
+      root.testing.format({
+        imageDataOrStrictRelativeUrl: "data:image/svg+xml;utf8,A",
+      }),
+    /must be a relative or PNG or JPG data:image URL/,
+    "should throw for non-relative or non PNG/JPG data URL"
+  );
+
+  const dates = [
+    "2016-03-04",
+    "2016-03-04T08:00:00Z",
+    "2016-03-04T08:00:00.000Z",
+    "2016-03-04T08:00:00-08:00",
+    "2016-03-04T08:00:00.000-08:00",
+    "2016-03-04T08:00:00+08:00",
+    "2016-03-04T08:00:00.000+08:00",
+    "2016-03-04T08:00:00+0800",
+    "2016-03-04T08:00:00-0800",
+  ];
+  dates.forEach(str => {
+    root.testing.formatDate({ date: str });
+    verify("call", "testing", "formatDate", [{ date: str }]);
+  });
+
+  // Make sure that a trivial change to a valid date invalidates it.
+  dates.forEach(str => {
+    Assert.throws(
+      () => root.testing.formatDate({ date: "0" + str }),
+      /Invalid date string/,
+      "should throw for invalid iso date string"
+    );
+    Assert.throws(
+      () => root.testing.formatDate({ date: str + "0" }),
+      /Invalid date string/,
+      "should throw for invalid iso date string"
+    );
+  });
+
+  const badDates = [
+    "I do not look anything like a date string",
+    "2016-99-99",
+    "2016-03-04T25:00:00Z",
+  ];
+  badDates.forEach(str => {
+    Assert.throws(
+      () => root.testing.formatDate({ date: str }),
+      /Invalid date string/,
+      "should throw for invalid iso date string"
+    );
+  });
+
+  root.testing.deep({
+    foo: { bar: [{ baz: { required: 12, optional: "42" } }] },
+  });
+  verify("call", "testing", "deep", [
+    { foo: { bar: [{ baz: { optional: "42", required: 12 } }] } },
+  ]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.deep({ foo: { bar: [{ baz: { optional: "42" } }] } }),
+    /Type error for parameter arg \(Error processing foo\.bar\.0\.baz: Property "required" is required\) for testing\.deep/,
+    "should throw with the correct object path"
+  );
+
+  Assert.throws(
+    () =>
+      root.testing.deep({
+        foo: { bar: [{ baz: { optional: 42, required: 12 } }] },
+      }),
+    /Type error for parameter arg \(Error processing foo\.bar\.0\.baz\.optional: Expected string instead of 42\) for testing\.deep/,
+    "should throw with the correct object path"
+  );
+
+  talliedErrors.length = 0;
+
+  root.testing.errors({ default: "0123", ignore: "0123", warn: "0123" });
+  verify("call", "testing", "errors", [
+    { default: "0123", ignore: "0123", warn: "0123" },
+  ]);
+  checkErrors([]);
+
+  root.testing.errors({ default: "0123", ignore: "x123", warn: "0123" });
+  verify("call", "testing", "errors", [
+    { default: "0123", ignore: null, warn: "0123" },
+  ]);
+  checkErrors([]);
+
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  root.testing.errors({ default: "0123", ignore: "0123", warn: "x123" });
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+  verify("call", "testing", "errors", [
+    { default: "0123", ignore: "0123", warn: null },
+  ]);
+  checkErrors(['String "x123" must match /^\\d+$/']);
+
+  root.testing.onFoo.addListener(f);
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["addListener", "testing", "onFoo"])
+  );
+  Assert.equal(tallied[3][0], f);
+  Assert.equal(JSON.stringify(tallied[3][1]), JSON.stringify([]));
+  tallied = null;
+
+  root.testing.onFoo.removeListener(f);
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["removeListener", "testing", "onFoo"])
+  );
+  Assert.equal(tallied[3][0], f);
+  tallied = null;
+
+  root.testing.onFoo.hasListener(f);
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["hasListener", "testing", "onFoo"])
+  );
+  Assert.equal(tallied[3][0], f);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.onFoo.addListener(10),
+    /Invalid listener/,
+    "addListener with non-function should throw"
+  );
+
+  root.testing.onBar.addListener(f, 10);
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["addListener", "testing", "onBar"])
+  );
+  Assert.equal(tallied[3][0], f);
+  Assert.equal(JSON.stringify(tallied[3][1]), JSON.stringify([10]));
+  tallied = null;
+
+  root.testing.onBar.addListener(f);
+  Assert.equal(
+    JSON.stringify(tallied.slice(0, -1)),
+    JSON.stringify(["addListener", "testing", "onBar"])
+  );
+  Assert.equal(tallied[3][0], f);
+  Assert.equal(JSON.stringify(tallied[3][1]), JSON.stringify([1]));
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.onBar.addListener(f, "hi"),
+    /Incorrect argument types/,
+    "addListener with wrong extra parameter should throw"
+  );
+
+  let target = { prop1: 12, prop2: ["value1", "value3"] };
+  let proxy = new Proxy(target, {});
+  Assert.throws(
+    () => root.testing.quack(proxy),
+    /Expected a plain JavaScript object, got a Proxy/,
+    "should throw when passing a Proxy"
+  );
+
+  if (Symbol.toStringTag) {
+    let stringTarget = { prop1: 12, prop2: ["value1", "value3"] };
+    stringTarget[Symbol.toStringTag] = () => "[object Object]";
+    let stringProxy = new Proxy(stringTarget, {});
+    Assert.throws(
+      () => root.testing.quack(stringProxy),
+      /Expected a plain JavaScript object, got a Proxy/,
+      "should throw when passing a Proxy"
+    );
+  }
+
+  root.testing.localize({
+    foo: "__MSG_foo__",
+    bar: "__MSG_foo__",
+    url: "__MSG_http://example.com/__",
+  });
+  verify("call", "testing", "localize", [
+    { bar: "__MSG_foo__", foo: "FOO", url: "http://example.com/" },
+  ]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.localize({ url: "__MSG_/foo/bar__" }),
+    /\/FOO\/BAR is not a valid URL\./,
+    "should throw for invalid URL"
+  );
+
+  root.testing.extended1({ prop1: "foo", prop2: "bar" });
+  verify("call", "testing", "extended1", [{ prop1: "foo", prop2: "bar" }]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.extended1({ prop1: "foo", prop2: 12 }),
+    /Expected string instead of 12/,
+    "should throw for wrong property type"
+  );
+
+  Assert.throws(
+    () => root.testing.extended1({ prop1: "foo" }),
+    /Property "prop2" is required/,
+    "should throw for missing property"
+  );
+
+  Assert.throws(
+    () => root.testing.extended1({ prop1: "foo", prop2: "bar", prop3: "xxx" }),
+    /Unexpected property "prop3"/,
+    "should throw for extra property"
+  );
+
+  root.testing.extended2("foo");
+  verify("call", "testing", "extended2", ["foo"]);
+  tallied = null;
+
+  root.testing.extended2(12);
+  verify("call", "testing", "extended2", [12]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.extended2(true),
+    /Incorrect argument types/,
+    "should throw for wrong argument type"
+  );
+
+  root.testing.prop3.sub_foo();
+  verify("call", "testing.prop3", "sub_foo", []);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.prop4.sub_foo(),
+    /root.testing.prop4 is undefined/,
+    "should throw for unsupported submodule"
+  );
+
+  root.foreign.foreignRef.sub_foo();
+  verify("call", "foreign.foreignRef", "sub_foo", []);
+  tallied = null;
+
+  root.testing.callderived1({ baseprop: "s1", derivedprop: "s2" });
+  verify("call", "testing", "callderived1", [
+    { baseprop: "s1", derivedprop: "s2" },
+  ]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.callderived1({ baseprop: "s1", derivedprop: 42 }),
+    /Error processing derivedprop: Expected string/,
+    "Two different objects may $import the same base object"
+  );
+  Assert.throws(
+    () => root.testing.callderived1({ baseprop: "s1" }),
+    /Property "derivedprop" is required/,
+    "Object using $import has its local properites"
+  );
+  Assert.throws(
+    () => root.testing.callderived1({ derivedprop: "s2" }),
+    /Property "baseprop" is required/,
+    "Object using $import has imported properites"
+  );
+
+  root.testing.callderived2({ baseprop: "s1", derivedprop: 42 });
+  verify("call", "testing", "callderived2", [
+    { baseprop: "s1", derivedprop: 42 },
+  ]);
+  tallied = null;
+
+  Assert.throws(
+    () => root.testing.callderived2({ baseprop: "s1", derivedprop: "s2" }),
+    /Error processing derivedprop: Expected integer/,
+    "Two different objects may $import the same base object"
+  );
+  Assert.throws(
+    () => root.testing.callderived2({ baseprop: "s1" }),
+    /Property "derivedprop" is required/,
+    "Object using $import has its local properites"
+  );
+  Assert.throws(
+    () => root.testing.callderived2({ derivedprop: 42 }),
+    /Property "baseprop" is required/,
+    "Object using $import has imported properites"
+  );
+});
+
+let deprecatedJson = [
+  {
+    namespace: "deprecated",
+
+    properties: {
+      accessor: {
+        type: "string",
+        writable: true,
+        deprecated: "This is not the property you are looking for",
+      },
+    },
+
+    types: [
+      {
+        id: "Type",
+        type: "string",
+      },
+    ],
+
+    functions: [
+      {
+        name: "property",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            type: "object",
+            properties: {
+              foo: {
+                type: "string",
+              },
+            },
+            additionalProperties: {
+              type: "any",
+              deprecated: "Unknown property",
+            },
+          },
+        ],
+      },
+
+      {
+        name: "value",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            choices: [
+              {
+                type: "integer",
+              },
+              {
+                type: "string",
+                deprecated: "Please use an integer, not ${value}",
+              },
+            ],
+          },
+        ],
+      },
+
+      {
+        name: "choices",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            deprecated: "You have no choices",
+            choices: [
+              {
+                type: "integer",
+              },
+            ],
+          },
+        ],
+      },
+
+      {
+        name: "ref",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            choices: [
+              {
+                $ref: "Type",
+                deprecated: "Deprecated alias",
+              },
+            ],
+          },
+        ],
+      },
+
+      {
+        name: "method",
+        type: "function",
+        deprecated: "Do not call this method",
+        parameters: [],
+      },
+    ],
+
+    events: [
+      {
+        name: "onDeprecated",
+        type: "function",
+        deprecated: "This event does not work",
+      },
+    ],
+  },
+];
+
+add_task(async function testDeprecation() {
+  // This whole test expects deprecation warnings.
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+
+  let url = "data:," + JSON.stringify(deprecatedJson);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let root = {};
+  Schemas.inject(root, wrapper);
+
+  talliedErrors.length = 0;
+
+  root.deprecated.property({ foo: "bar", xxx: "any", yyy: "property" });
+  verify("call", "deprecated", "property", [
+    { foo: "bar", xxx: "any", yyy: "property" },
+  ]);
+  checkErrors([
+    "Warning processing xxx: Unknown property",
+    "Warning processing yyy: Unknown property",
+  ]);
+
+  root.deprecated.value(12);
+  verify("call", "deprecated", "value", [12]);
+  checkErrors([]);
+
+  root.deprecated.value("12");
+  verify("call", "deprecated", "value", ["12"]);
+  checkErrors(['Please use an integer, not "12"']);
+
+  root.deprecated.choices(12);
+  verify("call", "deprecated", "choices", [12]);
+  checkErrors(["You have no choices"]);
+
+  root.deprecated.ref("12");
+  verify("call", "deprecated", "ref", ["12"]);
+  checkErrors(["Deprecated alias"]);
+
+  root.deprecated.method();
+  verify("call", "deprecated", "method", []);
+  checkErrors(["Do not call this method"]);
+
+  void root.deprecated.accessor;
+  verify("get", "deprecated", "accessor", null);
+  checkErrors(["This is not the property you are looking for"]);
+
+  root.deprecated.accessor = "x";
+  verify("set", "deprecated", "accessor", "x");
+  checkErrors(["This is not the property you are looking for"]);
+
+  root.deprecated.onDeprecated.addListener(() => {});
+  checkErrors(["This event does not work"]);
+
+  root.deprecated.onDeprecated.removeListener(() => {});
+  checkErrors(["This event does not work"]);
+
+  root.deprecated.onDeprecated.hasListener(() => {});
+  checkErrors(["This event does not work"]);
+
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+
+  Assert.throws(
+    () => root.deprecated.onDeprecated.hasListener(() => {}),
+    /This event does not work/,
+    "Deprecation warning with extensions.webextensions.warnings-as-errors=true"
+  );
+});
+
+let choicesJson = [
+  {
+    namespace: "choices",
+
+    types: [],
+
+    functions: [
+      {
+        name: "meh",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            choices: [
+              {
+                type: "string",
+                enum: ["foo", "bar", "baz"],
+              },
+              {
+                type: "string",
+                pattern: "florg.*meh",
+              },
+              {
+                type: "integer",
+                minimum: 12,
+                maximum: 42,
+              },
+            ],
+          },
+        ],
+      },
+
+      {
+        name: "foo",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            choices: [
+              {
+                type: "object",
+                properties: {
+                  blurg: {
+                    type: "string",
+                    unsupported: true,
+                    optional: true,
+                  },
+                },
+                additionalProperties: {
+                  type: "string",
+                },
+              },
+              {
+                type: "string",
+              },
+              {
+                type: "array",
+                minItems: 2,
+                maxItems: 3,
+                items: {
+                  type: "integer",
+                },
+              },
+            ],
+          },
+        ],
+      },
+
+      {
+        name: "bar",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            choices: [
+              {
+                type: "object",
+                properties: {
+                  baz: {
+                    type: "string",
+                  },
+                },
+              },
+              {
+                type: "array",
+                items: {
+                  type: "integer",
+                },
+              },
+            ],
+          },
+        ],
+      },
+    ],
+  },
+];
+
+add_task(async function testChoices() {
+  let url = "data:," + JSON.stringify(choicesJson);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let root = {};
+  Schemas.inject(root, wrapper);
+
+  talliedErrors.length = 0;
+
+  Assert.throws(
+    () => root.choices.meh("frog"),
+    /Value "frog" must either: be one of \["foo", "bar", "baz"\], match the pattern \/florg\.\*meh\/, or be an integer value/
+  );
+
+  Assert.throws(
+    () => root.choices.meh(4),
+    /be a string value, or be at least 12/
+  );
+
+  Assert.throws(
+    () => root.choices.meh(43),
+    /be a string value, or be no greater than 42/
+  );
+
+  Assert.throws(
+    () => root.choices.foo([]),
+    /be an object value, be a string value, or have at least 2 items/
+  );
+
+  Assert.throws(
+    () => root.choices.foo([1, 2, 3, 4]),
+    /be an object value, be a string value, or have at most 3 items/
+  );
+
+  Assert.throws(
+    () => root.choices.foo({ foo: 12 }),
+    /.foo must be a string value, be a string value, or be an array value/
+  );
+
+  Assert.throws(
+    () => root.choices.foo({ blurg: "foo" }),
+    /not contain an unsupported "blurg" property, be a string value, or be an array value/
+  );
+
+  Assert.throws(
+    () => root.choices.bar({}),
+    /contain the required "baz" property, or be an array value/
+  );
+
+  Assert.throws(
+    () => root.choices.bar({ baz: "x", quux: "y" }),
+    /not contain an unexpected "quux" property, or be an array value/
+  );
+
+  Assert.throws(
+    () => root.choices.bar({ baz: "x", quux: "y", foo: "z" }),
+    /not contain the unexpected properties \[foo, quux\], or be an array value/
+  );
+});
+
+let permissionsJson = [
+  {
+    namespace: "noPerms",
+
+    types: [],
+
+    functions: [
+      {
+        name: "noPerms",
+        type: "function",
+        parameters: [],
+      },
+
+      {
+        name: "fooPerm",
+        type: "function",
+        permissions: ["foo"],
+        parameters: [],
+      },
+    ],
+  },
+
+  {
+    namespace: "fooPerm",
+
+    permissions: ["foo"],
+
+    types: [],
+
+    functions: [
+      {
+        name: "noPerms",
+        type: "function",
+        parameters: [],
+      },
+
+      {
+        name: "fooBarPerm",
+        type: "function",
+        permissions: ["foo.bar"],
+        parameters: [],
+      },
+    ],
+  },
+];
+
+add_task(async function testPermissions() {
+  let url = "data:," + JSON.stringify(permissionsJson);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let root = {};
+  Schemas.inject(root, wrapper);
+
+  equal(typeof root.noPerms, "object", "noPerms namespace should exist");
+  equal(
+    typeof root.noPerms.noPerms,
+    "function",
+    "noPerms.noPerms method should exist"
+  );
+
+  equal(
+    root.noPerms.fooPerm,
+    undefined,
+    "noPerms.fooPerm should not method exist"
+  );
+
+  equal(root.fooPerm, undefined, "fooPerm namespace should not exist");
+
+  info('Add "foo" permission');
+  permissions.add("foo");
+
+  root = {};
+  Schemas.inject(root, wrapper);
+
+  equal(typeof root.noPerms, "object", "noPerms namespace should exist");
+  equal(
+    typeof root.noPerms.noPerms,
+    "function",
+    "noPerms.noPerms method should exist"
+  );
+  equal(
+    typeof root.noPerms.fooPerm,
+    "function",
+    "noPerms.fooPerm method should exist"
+  );
+
+  equal(typeof root.fooPerm, "object", "fooPerm namespace should exist");
+  equal(
+    typeof root.fooPerm.noPerms,
+    "function",
+    "noPerms.noPerms method should exist"
+  );
+
+  equal(
+    root.fooPerm.fooBarPerm,
+    undefined,
+    "fooPerm.fooBarPerm method should not exist"
+  );
+
+  info('Add "foo.bar" permission');
+  permissions.add("foo.bar");
+
+  root = {};
+  Schemas.inject(root, wrapper);
+
+  equal(typeof root.noPerms, "object", "noPerms namespace should exist");
+  equal(
+    typeof root.noPerms.noPerms,
+    "function",
+    "noPerms.noPerms method should exist"
+  );
+  equal(
+    typeof root.noPerms.fooPerm,
+    "function",
+    "noPerms.fooPerm method should exist"
+  );
+
+  equal(typeof root.fooPerm, "object", "fooPerm namespace should exist");
+  equal(
+    typeof root.fooPerm.noPerms,
+    "function",
+    "noPerms.noPerms method should exist"
+  );
+  equal(
+    typeof root.fooPerm.fooBarPerm,
+    "function",
+    "noPerms.fooBarPerm method should exist"
+  );
+});
+
+let nestedNamespaceJson = [
+  {
+    namespace: "nested.namespace",
+    types: [
+      {
+        id: "CustomType",
+        type: "object",
+        events: [
+          {
+            name: "onEvent",
+            type: "function",
+          },
+        ],
+        properties: {
+          url: {
+            type: "string",
+          },
+        },
+        functions: [
+          {
+            name: "functionOnCustomType",
+            type: "function",
+            parameters: [
+              {
+                name: "title",
+                type: "string",
+              },
+            ],
+          },
+        ],
+      },
+    ],
+    properties: {
+      instanceOfCustomType: {
+        $ref: "CustomType",
+      },
+    },
+    functions: [
+      {
+        name: "create",
+        type: "function",
+        parameters: [
+          {
+            name: "title",
+            type: "string",
+          },
+        ],
+      },
+    ],
+  },
+];
+
+add_task(async function testNestedNamespace() {
+  let url = "data:," + JSON.stringify(nestedNamespaceJson);
+
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let root = {};
+  Schemas.inject(root, wrapper);
+
+  talliedErrors.length = 0;
+
+  ok(root.nested, "The root object contains the first namespace level");
+  ok(
+    root.nested.namespace,
+    "The first level object contains the second namespace level"
+  );
+
+  ok(
+    root.nested.namespace.create,
+    "Got the expected function in the nested namespace"
+  );
+  equal(
+    typeof root.nested.namespace.create,
+    "function",
+    "The property is a function as expected"
+  );
+
+  let { instanceOfCustomType } = root.nested.namespace;
+
+  ok(
+    instanceOfCustomType,
+    "Got the expected instance of the CustomType defined in the schema"
+  );
+  ok(
+    instanceOfCustomType.functionOnCustomType,
+    "Got the expected method in the CustomType instance"
+  );
+  ok(
+    instanceOfCustomType.onEvent &&
+      instanceOfCustomType.onEvent.addListener &&
+      typeof instanceOfCustomType.onEvent.addListener == "function",
+    "Got the expected event defined in the CustomType instance"
+  );
+
+  instanceOfCustomType.functionOnCustomType("param_value");
+  verify(
+    "call",
+    "nested.namespace.instanceOfCustomType",
+    "functionOnCustomType",
+    ["param_value"]
+  );
+
+  let fakeListener = () => {};
+  instanceOfCustomType.onEvent.addListener(fakeListener);
+  verify("addListener", "nested.namespace.instanceOfCustomType", "onEvent", [
+    fakeListener,
+    [],
+  ]);
+  instanceOfCustomType.onEvent.removeListener(fakeListener);
+  verify("removeListener", "nested.namespace.instanceOfCustomType", "onEvent", [
+    fakeListener,
+  ]);
+
+  // TODO: test support properties in a SubModuleType defined in the schema,
+  // once implemented, e.g.:
+  // ok("url" in instanceOfCustomType,
+  //   "Got the expected property defined in the CustomType instance");
+});
+
+let $importJson = [
+  {
+    namespace: "from_the",
+    $import: "future",
+  },
+  {
+    namespace: "future",
+    properties: {
+      PROP1: { value: "original value" },
+      PROP2: { value: "second original" },
+    },
+    types: [
+      {
+        id: "Colour",
+        type: "string",
+        enum: ["red", "white", "blue"],
+      },
+    ],
+    functions: [
+      {
+        name: "dye",
+        type: "function",
+        parameters: [{ name: "arg", $ref: "Colour" }],
+      },
+    ],
+  },
+  {
+    namespace: "embrace",
+    $import: "future",
+    properties: {
+      PROP2: { value: "overridden value" },
+    },
+    types: [
+      {
+        id: "Colour",
+        type: "string",
+        enum: ["blue", "orange"],
+      },
+    ],
+  },
+];
+
+add_task(async function test_$import() {
+  let url = "data:," + JSON.stringify($importJson);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let root = {};
+  tallied = null;
+  Schemas.inject(root, wrapper);
+  equal(tallied, null);
+
+  equal(root.from_the.PROP1, "original value", "imported property");
+  equal(root.from_the.PROP2, "second original", "second imported property");
+  equal(root.from_the.Colour.RED, "red", "imported enum type");
+  equal(typeof root.from_the.dye, "function", "imported function");
+
+  root.from_the.dye("white");
+  verify("call", "from_the", "dye", ["white"]);
+
+  Assert.throws(
+    () => root.from_the.dye("orange"),
+    /Invalid enumeration value/,
+    "original imported argument type Colour doesn't include 'orange'"
+  );
+
+  equal(root.embrace.PROP1, "original value", "imported property");
+  equal(root.embrace.PROP2, "overridden value", "overridden property");
+  equal(root.embrace.Colour.ORANGE, "orange", "overridden enum type");
+  equal(typeof root.embrace.dye, "function", "imported function");
+
+  root.embrace.dye("orange");
+  verify("call", "embrace", "dye", ["orange"]);
+
+  Assert.throws(
+    () => root.embrace.dye("white"),
+    /Invalid enumeration value/,
+    "overridden argument type Colour doesn't include 'white'"
+  );
+});
+
+add_task(async function testLocalAPIImplementation() {
+  let countGet2 = 0;
+  let countProp3 = 0;
+  let countProp3SubFoo = 0;
+
+  let testingApiObj = {
+    get PROP1() {
+      // PROP1 is a schema-defined constant.
+      throw new Error("Unexpected get PROP1");
+    },
+    get prop2() {
+      ++countGet2;
+      return "prop2 val";
+    },
+    get prop3() {
+      throw new Error("Unexpected get prop3");
+    },
+    set prop3(v) {
+      // prop3 is a submodule, defined as a function, so the API should not pass
+      // through assignment to prop3.
+      throw new Error("Unexpected set prop3");
+    },
+  };
+  let submoduleApiObj = {
+    get sub_foo() {
+      ++countProp3;
+      return () => {
+        return ++countProp3SubFoo;
+      };
+    },
+  };
+
+  let localWrapper = {
+    cloneScope: global,
+    shouldInject(ns, name) {
+      return name == "testing" || ns == "testing" || ns == "testing.prop3";
+    },
+    getImplementation(ns, name) {
+      Assert.ok(ns == "testing" || ns == "testing.prop3");
+      if (ns == "testing.prop3" && name == "sub_foo") {
+        // It is fine to use `null` here because we don't call async functions.
+        return new LocalAPIImplementation(submoduleApiObj, name, null);
+      }
+      // It is fine to use `null` here because we don't call async functions.
+      return new LocalAPIImplementation(testingApiObj, name, null);
+    },
+  };
+
+  let root = {};
+  Schemas.inject(root, localWrapper);
+  Assert.equal(countGet2, 0);
+  Assert.equal(countProp3, 0);
+  Assert.equal(countProp3SubFoo, 0);
+
+  Assert.equal(root.testing.PROP1, 20);
+
+  Assert.equal(root.testing.prop2, "prop2 val");
+  Assert.equal(countGet2, 1);
+
+  Assert.equal(root.testing.prop2, "prop2 val");
+  Assert.equal(countGet2, 2);
+
+  info(JSON.stringify(root.testing));
+  Assert.equal(root.testing.prop3.sub_foo(), 1);
+  Assert.equal(countProp3, 1);
+  Assert.equal(countProp3SubFoo, 1);
+
+  Assert.equal(root.testing.prop3.sub_foo(), 2);
+  Assert.equal(countProp3, 2);
+  Assert.equal(countProp3SubFoo, 2);
+
+  root.testing.prop3.sub_foo = () => {
+    return "overwritten";
+  };
+  Assert.equal(root.testing.prop3.sub_foo(), "overwritten");
+
+  root.testing.prop3 = {
+    sub_foo() {
+      return "overwritten again";
+    },
+  };
+  Assert.equal(root.testing.prop3.sub_foo(), "overwritten again");
+  Assert.equal(countProp3SubFoo, 2);
+});
+
+let defaultsJson = [
+  {
+    namespace: "defaultsJson",
+
+    types: [],
+
+    functions: [
+      {
+        name: "defaultFoo",
+        type: "function",
+        parameters: [
+          {
+            name: "arg",
+            type: "object",
+            optional: true,
+            properties: {
+              prop1: { type: "integer", optional: true },
+            },
+            default: { prop1: 1 },
+          },
+        ],
+        returns: {
+          type: "object",
+          additionalProperties: true,
+        },
+      },
+    ],
+  },
+];
+
+add_task(async function testDefaults() {
+  let url = "data:," + JSON.stringify(defaultsJson);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let testingApiObj = {
+    defaultFoo: function(arg) {
+      if (Object.keys(arg) != "prop1") {
+        throw new Error(
+          `Received the expected default object, default: ${JSON.stringify(
+            arg
+          )}`
+        );
+      }
+      arg.newProp = 1;
+      return arg;
+    },
+  };
+
+  let localWrapper = {
+    cloneScope: global,
+    shouldInject(ns) {
+      return true;
+    },
+    getImplementation(ns, name) {
+      return new LocalAPIImplementation(testingApiObj, name, null);
+    },
+  };
+
+  let root = {};
+  Schemas.inject(root, localWrapper);
+
+  deepEqual(root.defaultsJson.defaultFoo(), { prop1: 1, newProp: 1 });
+  deepEqual(root.defaultsJson.defaultFoo({ prop1: 2 }), {
+    prop1: 2,
+    newProp: 1,
+  });
+  deepEqual(root.defaultsJson.defaultFoo(), { prop1: 1, newProp: 1 });
+});
+
+let returnsJson = [
+  {
+    namespace: "returns",
+    types: [
+      {
+        id: "Widget",
+        type: "object",
+        properties: {
+          size: { type: "integer" },
+          colour: { type: "string", optional: true },
+        },
+      },
+    ],
+    functions: [
+      {
+        name: "complete",
+        type: "function",
+        returns: { $ref: "Widget" },
+        parameters: [],
+      },
+      {
+        name: "optional",
+        type: "function",
+        returns: { $ref: "Widget" },
+        parameters: [],
+      },
+      {
+        name: "invalid",
+        type: "function",
+        returns: { $ref: "Widget" },
+        parameters: [],
+      },
+    ],
+  },
+];
+
+add_task(async function testReturns() {
+  const url = "data:," + JSON.stringify(returnsJson);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  const apiObject = {
+    complete() {
+      return { size: 3, colour: "orange" };
+    },
+    optional() {
+      return { size: 4 };
+    },
+    invalid() {
+      return {};
+    },
+  };
+
+  const localWrapper = {
+    cloneScope: global,
+    shouldInject(ns) {
+      return true;
+    },
+    getImplementation(ns, name) {
+      return new LocalAPIImplementation(apiObject, name, null);
+    },
+  };
+
+  const root = {};
+  Schemas.inject(root, localWrapper);
+
+  deepEqual(root.returns.complete(), { size: 3, colour: "orange" });
+  deepEqual(
+    root.returns.optional(),
+    { size: 4 },
+    "Missing optional properties is allowed"
+  );
+
+  if (AppConstants.DEBUG) {
+    Assert.throws(
+      () => root.returns.invalid(),
+      /Type error for result value \(Property "size" is required\)/,
+      "Should throw for invalid result in DEBUG builds"
+    );
+  } else {
+    deepEqual(
+      root.returns.invalid(),
+      {},
+      "Doesn't throw for invalid result value in release builds"
+    );
+  }
+});
+
+let booleanEnumJson = [
+  {
+    namespace: "booleanEnum",
+
+    types: [
+      {
+        id: "enumTrue",
+        type: "boolean",
+        enum: [true],
+      },
+    ],
+    functions: [
+      {
+        name: "paramMustBeTrue",
+        type: "function",
+        parameters: [{ name: "arg", $ref: "enumTrue" }],
+      },
+    ],
+  },
+];
+
+add_task(async function testBooleanEnum() {
+  let url = "data:," + JSON.stringify(booleanEnumJson);
+  Schemas._rootSchema = null;
+  await Schemas.load(url);
+
+  let root = {};
+  tallied = null;
+  Schemas.inject(root, wrapper);
+  Assert.equal(tallied, null);
+
+  ok(root.booleanEnum, "namespace exists");
+  root.booleanEnum.paramMustBeTrue(true);
+  verify("call", "booleanEnum", "paramMustBeTrue", [true]);
+  Assert.throws(
+    () => root.booleanEnum.paramMustBeTrue(false),
+    /Type error for parameter arg \(Invalid value false\) for booleanEnum\.paramMustBeTrue\./,
+    "should throw because enum of the type restricts parameter to true"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas_allowed_contexts.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_allowed_contexts.js
new file mode 100644
index 0000000000..0c90cda51e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_allowed_contexts.js
@@ -0,0 +1,157 @@
+"use strict";
+
+const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+
+const global = this;
+
+let schemaJson = [
+  {
+    namespace: "noAllowedContexts",
+    properties: {
+      prop1: { type: "object" },
+      prop2: { type: "object", allowedContexts: ["test_zero", "test_one"] },
+      prop3: { type: "number", value: 1 },
+      prop4: { type: "number", value: 1, allowedContexts: ["numeric_one"] },
+    },
+  },
+  {
+    namespace: "defaultContexts",
+    defaultContexts: ["test_two"],
+    properties: {
+      prop1: { type: "object" },
+      prop2: { type: "object", allowedContexts: ["test_three"] },
+      prop3: { type: "number", value: 1 },
+      prop4: { type: "number", value: 1, allowedContexts: ["numeric_two"] },
+    },
+  },
+  {
+    namespace: "withAllowedContexts",
+    allowedContexts: ["test_four"],
+    properties: {
+      prop1: { type: "object" },
+      prop2: { type: "object", allowedContexts: ["test_five"] },
+      prop3: { type: "number", value: 1 },
+      prop4: { type: "number", value: 1, allowedContexts: ["numeric_three"] },
+    },
+  },
+  {
+    namespace: "withAllowedContextsAndDefault",
+    allowedContexts: ["test_six"],
+    defaultContexts: ["test_seven"],
+    properties: {
+      prop1: { type: "object" },
+      prop2: { type: "object", allowedContexts: ["test_eight"] },
+      prop3: { type: "number", value: 1 },
+      prop4: { type: "number", value: 1, allowedContexts: ["numeric_four"] },
+    },
+  },
+  {
+    namespace: "with_submodule",
+    defaultContexts: ["test_nine"],
+    types: [
+      {
+        id: "subtype",
+        type: "object",
+        functions: [
+          {
+            name: "noAllowedContexts",
+            type: "function",
+            parameters: [],
+          },
+          {
+            name: "allowedContexts",
+            allowedContexts: ["test_ten"],
+            type: "function",
+            parameters: [],
+          },
+        ],
+      },
+    ],
+    properties: {
+      prop1: { $ref: "subtype" },
+      prop2: { $ref: "subtype", allowedContexts: ["test_eleven"] },
+    },
+  },
+];
+
+add_task(async function testRestrictions() {
+  let url = "data:," + JSON.stringify(schemaJson);
+  await Schemas.load(url);
+  let results = {};
+  let localWrapper = {
+    cloneScope: global,
+    shouldInject(ns, name, allowedContexts) {
+      name = ns ? ns + "." + name : name;
+      results[name] = allowedContexts.join(",");
+      return true;
+    },
+    getImplementation() {
+      // The actual implementation is not significant for this test.
+      // Let's take this opportunity to see if schema generation is free of
+      // exceptions even when somehow getImplementation does not return an
+      // implementation.
+    },
+  };
+
+  let root = {};
+  Schemas.inject(root, localWrapper);
+
+  function verify(path, expected) {
+    let obj = root;
+    for (let thing of path.split(".")) {
+      try {
+        obj = obj[thing];
+      } catch (e) {
+        // Blech.
+      }
+    }
+
+    let result = results[path];
+    equal(result, expected, path);
+  }
+
+  verify("noAllowedContexts", "");
+  verify("noAllowedContexts.prop1", "");
+  verify("noAllowedContexts.prop2", "test_zero,test_one");
+  verify("noAllowedContexts.prop3", "");
+  verify("noAllowedContexts.prop4", "numeric_one");
+
+  verify("defaultContexts", "");
+  verify("defaultContexts.prop1", "test_two");
+  verify("defaultContexts.prop2", "test_three");
+  verify("defaultContexts.prop3", "test_two");
+  verify("defaultContexts.prop4", "numeric_two");
+
+  verify("withAllowedContexts", "test_four");
+  verify("withAllowedContexts.prop1", "");
+  verify("withAllowedContexts.prop2", "test_five");
+  verify("withAllowedContexts.prop3", "");
+  verify("withAllowedContexts.prop4", "numeric_three");
+
+  verify("withAllowedContextsAndDefault", "test_six");
+  verify("withAllowedContextsAndDefault.prop1", "test_seven");
+  verify("withAllowedContextsAndDefault.prop2", "test_eight");
+  verify("withAllowedContextsAndDefault.prop3", "test_seven");
+  verify("withAllowedContextsAndDefault.prop4", "numeric_four");
+
+  verify("with_submodule", "");
+  verify("with_submodule.prop1", "test_nine");
+  verify("with_submodule.prop1.noAllowedContexts", "test_nine");
+  verify("with_submodule.prop1.allowedContexts", "test_ten");
+  verify("with_submodule.prop2", "test_eleven");
+  // Note: test_nine inherits allowed contexts from the namespace, not from
+  // submodule. There is no "defaultContexts" for submodule types to not
+  // complicate things.
+  verify("with_submodule.prop1.noAllowedContexts", "test_nine");
+  verify("with_submodule.prop1.allowedContexts", "test_ten");
+
+  // This is a constant, so it does not matter that getImplementation does not
+  // return an implementation since the API injector should take care of it.
+  equal(root.noAllowedContexts.prop3, 1);
+
+  Assert.throws(
+    () => root.noAllowedContexts.prop1,
+    /undefined/,
+    "Should throw when the implementation is absent."
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas_async.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_async.js
new file mode 100644
index 0000000000..0ef7b81eaf
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_async.js
@@ -0,0 +1,352 @@
+"use strict";
+
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+
+let { BaseContext, LocalAPIImplementation } = ExtensionCommon;
+
+let schemaJson = [
+  {
+    namespace: "testnamespace",
+    types: [
+      {
+        id: "Widget",
+        type: "object",
+        properties: {
+          size: { type: "integer" },
+          colour: { type: "string", optional: true },
+        },
+      },
+    ],
+    functions: [
+      {
+        name: "one_required",
+        type: "function",
+        parameters: [
+          {
+            name: "first",
+            type: "function",
+            parameters: [],
+          },
+        ],
+      },
+      {
+        name: "one_optional",
+        type: "function",
+        parameters: [
+          {
+            name: "first",
+            type: "function",
+            parameters: [],
+            optional: true,
+          },
+        ],
+      },
+      {
+        name: "async_required",
+        type: "function",
+        async: "first",
+        parameters: [
+          {
+            name: "first",
+            type: "function",
+            parameters: [],
+          },
+        ],
+      },
+      {
+        name: "async_optional",
+        type: "function",
+        async: "first",
+        parameters: [
+          {
+            name: "first",
+            type: "function",
+            parameters: [],
+            optional: true,
+          },
+        ],
+      },
+      {
+        name: "async_result",
+        type: "function",
+        async: "callback",
+        parameters: [
+          {
+            name: "callback",
+            type: "function",
+            parameters: [
+              {
+                name: "widget",
+                $ref: "Widget",
+              },
+            ],
+          },
+        ],
+      },
+    ],
+  },
+];
+
+const global = this;
+class StubContext extends BaseContext {
+  constructor() {
+    let fakeExtension = { id: "test@web.extension" };
+    super("testEnv", fakeExtension);
+    this.sandbox = Cu.Sandbox(global);
+  }
+
+  get cloneScope() {
+    return this.sandbox;
+  }
+
+  get principal() {
+    return Cu.getObjectPrincipal(this.sandbox);
+  }
+}
+
+let context;
+
+function generateAPIs(extraWrapper, apiObj) {
+  context = new StubContext();
+  let localWrapper = {
+    cloneScope: global,
+    shouldInject() {
+      return true;
+    },
+    getImplementation(namespace, name) {
+      return new LocalAPIImplementation(apiObj, name, context);
+    },
+  };
+  Object.assign(localWrapper, extraWrapper);
+
+  let root = {};
+  Schemas.inject(root, localWrapper);
+  return root.testnamespace;
+}
+
+add_task(async function testParameterValidation() {
+  await Schemas.load("data:," + JSON.stringify(schemaJson));
+
+  let testnamespace;
+  function assertThrows(name, ...args) {
+    Assert.throws(
+      () => testnamespace[name](...args),
+      /Incorrect argument types/,
+      `Expected testnamespace.${name}(${args.map(String).join(", ")}) to throw.`
+    );
+  }
+  function assertNoThrows(name, ...args) {
+    try {
+      testnamespace[name](...args);
+    } catch (e) {
+      info(
+        `testnamespace.${name}(${args
+          .map(String)
+          .join(", ")}) unexpectedly threw.`
+      );
+      throw new Error(e);
+    }
+  }
+  let cb = () => {};
+
+  for (let isChromeCompat of [true, false]) {
+    info(`Testing API validation with isChromeCompat=${isChromeCompat}`);
+    testnamespace = generateAPIs(
+      {
+        isChromeCompat,
+      },
+      {
+        one_required() {},
+        one_optional() {},
+        async_required() {},
+        async_optional() {},
+      }
+    );
+
+    assertThrows("one_required");
+    assertThrows("one_required", null);
+    assertNoThrows("one_required", cb);
+    assertThrows("one_required", cb, null);
+    assertThrows("one_required", cb, cb);
+
+    assertNoThrows("one_optional");
+    assertNoThrows("one_optional", null);
+    assertNoThrows("one_optional", cb);
+    assertThrows("one_optional", cb, null);
+    assertThrows("one_optional", cb, cb);
+
+    // Schema-based validation happens before an async method is called, so
+    // errors should be thrown synchronously.
+
+    // The parameter was declared as required, but there was also an "async"
+    // attribute with the same value as the parameter name, so the callback
+    // parameter is actually optional.
+    assertNoThrows("async_required");
+    assertNoThrows("async_required", null);
+    assertNoThrows("async_required", cb);
+    assertThrows("async_required", cb, null);
+    assertThrows("async_required", cb, cb);
+
+    assertNoThrows("async_optional");
+    assertNoThrows("async_optional", null);
+    assertNoThrows("async_optional", cb);
+    assertThrows("async_optional", cb, null);
+    assertThrows("async_optional", cb, cb);
+  }
+});
+
+add_task(async function testCheckAsyncResults() {
+  await Schemas.load("data:," + JSON.stringify(schemaJson));
+
+  const complete = generateAPIs(
+    {},
+    {
+      async_result: async () => ({ size: 5, colour: "green" }),
+    }
+  );
+
+  const optional = generateAPIs(
+    {},
+    {
+      async_result: async () => ({ size: 6 }),
+    }
+  );
+
+  const invalid = generateAPIs(
+    {},
+    {
+      async_result: async () => ({}),
+    }
+  );
+
+  deepEqual(await complete.async_result(), { size: 5, colour: "green" });
+
+  deepEqual(
+    await optional.async_result(),
+    { size: 6 },
+    "Missing optional properties is allowed"
+  );
+
+  if (AppConstants.DEBUG) {
+    await Assert.rejects(
+      invalid.async_result(),
+      /Type error for widget value \(Property "size" is required\)/,
+      "Should throw for invalid callback argument in DEBUG builds"
+    );
+  } else {
+    deepEqual(
+      await invalid.async_result(),
+      {},
+      "Invalid callback argument doesn't throw in release builds"
+    );
+  }
+});
+
+add_task(async function testAsyncResults() {
+  await Schemas.load("data:," + JSON.stringify(schemaJson));
+  function runWithCallback(func) {
+    info(`Calling testnamespace.${func.name}, expecting callback with result`);
+    return new Promise(resolve => {
+      let result = "uninitialized value";
+      let returnValue = func(reply => {
+        result = reply;
+        resolve(result);
+      });
+      // When a callback is given, the return value must be missing.
+      Assert.equal(returnValue, undefined);
+      // Callback must be called asynchronously.
+      Assert.equal(result, "uninitialized value");
+    });
+  }
+
+  function runFailCallback(func) {
+    info(`Calling testnamespace.${func.name}, expecting callback with error`);
+    return new Promise(resolve => {
+      func(reply => {
+        Assert.equal(reply, undefined);
+        resolve(context.lastError.message); // eslint-disable-line no-undef
+      });
+    });
+  }
+
+  for (let isChromeCompat of [true, false]) {
+    info(`Testing API invocation with isChromeCompat=${isChromeCompat}`);
+    let testnamespace = generateAPIs(
+      {
+        isChromeCompat,
+      },
+      {
+        async_required(cb) {
+          Assert.equal(cb, undefined);
+          return Promise.resolve(1);
+        },
+        async_optional(cb) {
+          Assert.equal(cb, undefined);
+          return Promise.resolve(2);
+        },
+      }
+    );
+    if (!isChromeCompat) {
+      // No promises for chrome.
+      info("testnamespace.async_required should be a Promise");
+      let promise = testnamespace.async_required();
+      Assert.ok(promise instanceof context.cloneScope.Promise);
+      Assert.equal(await promise, 1);
+
+      info("testnamespace.async_optional should be a Promise");
+      promise = testnamespace.async_optional();
+      Assert.ok(promise instanceof context.cloneScope.Promise);
+      Assert.equal(await promise, 2);
+    }
+
+    Assert.equal(await runWithCallback(testnamespace.async_required), 1);
+    Assert.equal(await runWithCallback(testnamespace.async_optional), 2);
+
+    let otherSandbox = Cu.Sandbox(null, {});
+    let errorFactories = [
+      msg => {
+        throw new context.cloneScope.Error(msg);
+      },
+      msg => context.cloneScope.Promise.reject({ message: msg }),
+      msg => Cu.evalInSandbox(`throw new Error("${msg}")`, otherSandbox),
+      msg =>
+        Cu.evalInSandbox(`Promise.reject({message: "${msg}"})`, otherSandbox),
+    ];
+    for (let makeError of errorFactories) {
+      info(`Testing callback/promise with error caused by: ${makeError}`);
+      testnamespace = generateAPIs(
+        {
+          isChromeCompat,
+        },
+        {
+          async_required() {
+            return makeError("ONE");
+          },
+          async_optional() {
+            return makeError("TWO");
+          },
+        }
+      );
+
+      if (!isChromeCompat) {
+        // No promises for chrome.
+        await Assert.rejects(
+          testnamespace.async_required(),
+          /ONE/,
+          "should reject testnamespace.async_required()"
+        );
+        await Assert.rejects(
+          testnamespace.async_optional(),
+          /TWO/,
+          "should reject testnamespace.async_optional()"
+        );
+      }
+
+      Assert.equal(await runFailCallback(testnamespace.async_required), "ONE");
+      Assert.equal(await runFailCallback(testnamespace.async_optional), "TWO");
+    }
+  }
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas_interactive.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_interactive.js
new file mode 100644
index 0000000000..66de5c8aba
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_interactive.js
@@ -0,0 +1,174 @@
+"use strict";
+
+const { ExtensionManager } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionChild.jsm",
+  null
+);
+
+let experimentAPIs = {
+  userinputtest: {
+    schema: "schema.json",
+    parent: {
+      scopes: ["addon_parent"],
+      script: "parent.js",
+      paths: [["userinputtest"]],
+    },
+    child: {
+      scopes: ["addon_child"],
+      script: "child.js",
+      paths: [["userinputtest", "child"]],
+    },
+  },
+};
+
+let experimentFiles = {
+  "schema.json": JSON.stringify([
+    {
+      namespace: "userinputtest",
+      functions: [
+        {
+          name: "test",
+          type: "function",
+          async: true,
+          requireUserInput: true,
+          parameters: [],
+        },
+        {
+          name: "child",
+          type: "function",
+          async: true,
+          requireUserInput: true,
+          parameters: [],
+        },
+      ],
+    },
+  ]),
+
+  /* globals ExtensionAPI */
+  "parent.js": () => {
+    this.userinputtest = class extends ExtensionAPI {
+      getAPI(context) {
+        return {
+          userinputtest: {
+            test() {},
+          },
+        };
+      }
+    };
+  },
+
+  "child.js": () => {
+    this.userinputtest = class extends ExtensionAPI {
+      getAPI(context) {
+        return {
+          userinputtest: {
+            child() {},
+          },
+        };
+      }
+    };
+  },
+};
+
+// Set the "handlingUserInput" flag for the given extension's background page.
+// Returns an RAIIHelper that should be destruct()ed eventually.
+function setHandlingUserInput(extension) {
+  let extensionChild = ExtensionManager.extensions.get(extension.extension.id);
+  let bgwin = null;
+  for (let view of extensionChild.views) {
+    if (view.viewType == "background") {
+      bgwin = view.contentWindow;
+      break;
+    }
+  }
+  notEqual(bgwin, null, "Found background window for the test extension");
+  let winutils = bgwin.windowUtils;
+  return winutils.setHandlingUserInput(true);
+}
+
+// Test that the schema requireUserInput flag works correctly for
+// proxied api implementations.
+add_task(async function test_proxy() {
+  let extension = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+    background() {
+      browser.test.onMessage.addListener(async () => {
+        try {
+          await browser.userinputtest.test();
+          browser.test.sendMessage("result", null);
+        } catch (err) {
+          browser.test.sendMessage("result", err.message);
+        }
+      });
+    },
+    manifest: {
+      permissions: ["experiments.userinputtest"],
+      experiment_apis: experimentAPIs,
+    },
+    files: experimentFiles,
+  });
+
+  await extension.startup();
+
+  extension.sendMessage("test");
+  let result = await extension.awaitMessage("result");
+  ok(
+    /test may only be called from a user input handler/.test(result),
+    `function failed when not called from a user input handler: ${result}`
+  );
+
+  let handle = setHandlingUserInput(extension);
+  extension.sendMessage("test");
+  result = await extension.awaitMessage("result");
+  equal(
+    result,
+    null,
+    "function succeeded when called from a user input handler"
+  );
+  handle.destruct();
+
+  await extension.unload();
+});
+
+// Test that the schema requireUserInput flag works correctly for
+// non-proxied api implementations.
+add_task(async function test_local() {
+  let extension = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+    background() {
+      browser.test.onMessage.addListener(async () => {
+        try {
+          await browser.userinputtest.child();
+          browser.test.sendMessage("result", null);
+        } catch (err) {
+          browser.test.sendMessage("result", err.message);
+        }
+      });
+    },
+    manifest: {
+      experiment_apis: experimentAPIs,
+    },
+    files: experimentFiles,
+  });
+
+  await extension.startup();
+
+  extension.sendMessage("test");
+  let result = await extension.awaitMessage("result");
+  ok(
+    /child may only be called from a user input handler/.test(result),
+    `function failed when not called from a user input handler: ${result}`
+  );
+
+  let handle = setHandlingUserInput(extension);
+  extension.sendMessage("test");
+  result = await extension.awaitMessage("result");
+  equal(
+    result,
+    null,
+    "function succeeded when called from a user input handler"
+  );
+  handle.destruct();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas_manifest_permissions.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_manifest_permissions.js
new file mode 100644
index 0000000000..86ce07a5da
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_manifest_permissions.js
@@ -0,0 +1,174 @@
+"use strict";
+
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+const { ExtensionAPI } = ExtensionCommon;
+
+add_task(async function() {
+  const schema = [
+    {
+      namespace: "manifest",
+      types: [
+        {
+          $extend: "WebExtensionManifest",
+          properties: {
+            a_manifest_property: {
+              type: "object",
+              optional: true,
+              properties: {
+                nested: {
+                  optional: true,
+                  type: "any",
+                },
+              },
+              additionalProperties: { $ref: "UnrecognizedProperty" },
+            },
+          },
+        },
+      ],
+    },
+    {
+      namespace: "testManifestPermission",
+      permissions: ["manifest:a_manifest_property"],
+      functions: [
+        {
+          name: "testMethod",
+          type: "function",
+          async: true,
+          parameters: [],
+          permissions: ["manifest:a_manifest_property.nested"],
+        },
+      ],
+    },
+  ];
+
+  class FakeAPI extends ExtensionAPI {
+    getAPI(context) {
+      return {
+        testManifestPermission: {
+          get testProperty() {
+            return "value";
+          },
+          testMethod() {
+            return Promise.resolve("value");
+          },
+        },
+      };
+    }
+  }
+
+  const modules = {
+    testNamespace: {
+      url: URL.createObjectURL(new Blob([FakeAPI.toString()])),
+      schema: `data:,${JSON.stringify(schema)}`,
+      scopes: ["addon_parent", "addon_child"],
+      paths: [["testManifestPermission"]],
+    },
+  };
+
+  Services.catMan.addCategoryEntry(
+    "webextension-modules",
+    "test-manifest-permission",
+    `data:,${JSON.stringify(modules)}`,
+    false,
+    false
+  );
+
+  async function testExtension(extensionDef, assertFn) {
+    let extension = ExtensionTestUtils.loadExtension(extensionDef);
+
+    await extension.startup();
+    await assertFn(extension);
+    await extension.unload();
+  }
+
+  await testExtension(
+    {
+      manifest: {
+        a_manifest_property: {},
+      },
+      background() {
+        // Test hasPermission method implemented in ExtensionChild.jsm.
+        browser.test.assertTrue(
+          "testManifestPermission" in browser,
+          "The API namespace is defined as expected"
+        );
+        browser.test.assertEq(
+          undefined,
+          browser.testManifestPermission &&
+            browser.testManifestPermission.testMethod,
+          "The property with nested manifest property permission should not be available "
+        );
+        browser.test.notifyPass("test-extension-manifest-without-nested-prop");
+      },
+    },
+    async extension => {
+      await extension.awaitFinish(
+        "test-extension-manifest-without-nested-prop"
+      );
+
+      // Test hasPermission method implemented in Extension.jsm.
+      equal(
+        extension.extension.hasPermission("manifest:a_manifest_property"),
+        true,
+        "Got the expected Extension's hasPermission result on existing property"
+      );
+      equal(
+        extension.extension.hasPermission(
+          "manifest:a_manifest_property.nested"
+        ),
+        false,
+        "Got the expected Extension's hasPermission result on existing subproperty"
+      );
+    }
+  );
+
+  await testExtension(
+    {
+      manifest: {
+        a_manifest_property: {
+          nested: {},
+        },
+      },
+      background() {
+        // Test hasPermission method implemented in ExtensionChild.jsm.
+        browser.test.assertTrue(
+          "testManifestPermission" in browser,
+          "The API namespace is defined as expected"
+        );
+        browser.test.assertEq(
+          "function",
+          browser.testManifestPermission &&
+            typeof browser.testManifestPermission.testMethod,
+          "The property with nested manifest property permission should be available "
+        );
+        browser.test.notifyPass("test-extension-manifest-with-nested-prop");
+      },
+    },
+    async extension => {
+      await extension.awaitFinish("test-extension-manifest-with-nested-prop");
+
+      // Test hasPermission method implemented in Extension.jsm.
+      equal(
+        extension.extension.hasPermission("manifest:a_manifest_property"),
+        true,
+        "Got the expected Extension's hasPermission result on existing property"
+      );
+      equal(
+        extension.extension.hasPermission(
+          "manifest:a_manifest_property.nested"
+        ),
+        true,
+        "Got the expected Extension's hasPermission result on existing subproperty"
+      );
+      equal(
+        extension.extension.hasPermission(
+          "manifest:a_manifest_property.unexisting"
+        ),
+        false,
+        "Got the expected Extension's hasPermission result on non existing subproperty"
+      );
+    }
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas_privileged.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_privileged.js
new file mode 100644
index 0000000000..ece69a4106
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_privileged.js
@@ -0,0 +1,103 @@
+"use strict";
+
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+const { ExtensionAPI } = ExtensionCommon;
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+add_task(async function() {
+  const schema = [
+    {
+      namespace: "privileged",
+      permissions: ["mozillaAddons"],
+      properties: {
+        test: {
+          type: "any",
+        },
+      },
+    },
+  ];
+
+  class API extends ExtensionAPI {
+    getAPI(context) {
+      return {
+        privileged: {
+          test: "hello",
+        },
+      };
+    }
+  }
+
+  const modules = {
+    privileged: {
+      url: URL.createObjectURL(new Blob([API.toString()])),
+      schema: `data:,${JSON.stringify(schema)}`,
+      scopes: ["addon_parent"],
+      paths: [["privileged"]],
+    },
+  };
+
+  Services.catMan.addCategoryEntry(
+    "webextension-modules",
+    "test-privileged",
+    `data:,${JSON.stringify(modules)}`,
+    false,
+    false
+  );
+
+  AddonTestUtils.createAppInfo(
+    "xpcshell@tests.mozilla.org",
+    "XPCShell",
+    "1",
+    "42"
+  );
+  await AddonTestUtils.promiseStartupManager();
+
+  // Try accessing the privileged namespace.
+  async function testOnce() {
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        applications: { gecko: { id: "privilegedapi@tests.mozilla.org" } },
+        permissions: ["mozillaAddons"],
+      },
+      background() {
+        browser.test.sendMessage(
+          "result",
+          browser.privileged instanceof Object
+        );
+      },
+      useAddonManager: "permanent",
+    });
+
+    await extension.startup();
+    let result = await extension.awaitMessage("result");
+    await extension.unload();
+    return result;
+  }
+
+  AddonTestUtils.usePrivilegedSignatures = false;
+  let result = await testOnce();
+  equal(
+    result,
+    false,
+    "Privileged namespace should not be accessible to a regular webextension"
+  );
+
+  AddonTestUtils.usePrivilegedSignatures = true;
+  result = await testOnce();
+  equal(
+    result,
+    true,
+    "Privileged namespace should be accessible to a webextension signed with Mozilla Extensions"
+  );
+
+  await AddonTestUtils.promiseShutdownManager();
+  Services.catMan.deleteCategoryEntry(
+    "webextension-modules",
+    "test-privileged",
+    false
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas_revoke.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_revoke.js
new file mode 100644
index 0000000000..d215338dc9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_revoke.js
@@ -0,0 +1,507 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+
+let { SchemaAPIInterface } = ExtensionCommon;
+
+const global = this;
+
+let json = [
+  {
+    namespace: "revokableNs",
+
+    permissions: ["revokableNs"],
+
+    properties: {
+      stringProp: {
+        type: "string",
+        writable: true,
+      },
+
+      revokableStringProp: {
+        type: "string",
+        permissions: ["revokableProp"],
+        writable: true,
+      },
+
+      submoduleProp: {
+        $ref: "submodule",
+      },
+
+      revokableSubmoduleProp: {
+        $ref: "submodule",
+        permissions: ["revokableProp"],
+      },
+    },
+
+    types: [
+      {
+        id: "submodule",
+        type: "object",
+        functions: [
+          {
+            name: "sub_foo",
+            type: "function",
+            parameters: [],
+            returns: { type: "integer" },
+          },
+        ],
+      },
+    ],
+
+    functions: [
+      {
+        name: "func",
+        type: "function",
+        parameters: [],
+      },
+
+      {
+        name: "revokableFunc",
+        type: "function",
+        parameters: [],
+        permissions: ["revokableFunc"],
+      },
+    ],
+
+    events: [
+      {
+        name: "onEvent",
+        type: "function",
+      },
+
+      {
+        name: "onRevokableEvent",
+        type: "function",
+        permissions: ["revokableEvent"],
+      },
+    ],
+  },
+];
+
+let recorded = [];
+
+function record(...args) {
+  recorded.push(args);
+}
+
+function verify(expected) {
+  for (let [i, rec] of expected.entries()) {
+    Assert.deepEqual(recorded[i], rec, `Record ${i} matches`);
+  }
+
+  equal(recorded.length, expected.length, "Got expected number of records");
+
+  recorded.length = 0;
+}
+
+registerCleanupFunction(() => {
+  equal(recorded.length, 0, "No unchecked recorded events at shutdown");
+});
+
+let permissions = new Set();
+
+class APIImplementation extends SchemaAPIInterface {
+  constructor(namespace, name) {
+    super();
+    this.namespace = namespace;
+    this.name = name;
+  }
+
+  record(method, args) {
+    record(method, this.namespace, this.name, args);
+  }
+
+  revoke(...args) {
+    this.record("revoke", args);
+  }
+
+  callFunction(...args) {
+    this.record("callFunction", args);
+    if (this.name === "sub_foo") {
+      return 13;
+    }
+  }
+
+  callFunctionNoReturn(...args) {
+    this.record("callFunctionNoReturn", args);
+  }
+
+  getProperty(...args) {
+    this.record("getProperty", args);
+  }
+
+  setProperty(...args) {
+    this.record("setProperty", args);
+  }
+
+  addListener(...args) {
+    this.record("addListener", args);
+  }
+
+  removeListener(...args) {
+    this.record("removeListener", args);
+  }
+
+  hasListener(...args) {
+    this.record("hasListener", args);
+  }
+}
+
+let context = {
+  cloneScope: global,
+
+  permissionsChanged: null,
+
+  setPermissionsChangedCallback(callback) {
+    this.permissionsChanged = callback;
+  },
+
+  hasPermission(permission) {
+    return permissions.has(permission);
+  },
+
+  isPermissionRevokable(permission) {
+    return permission.startsWith("revokable");
+  },
+
+  getImplementation(namespace, name) {
+    return new APIImplementation(namespace, name);
+  },
+
+  shouldInject() {
+    return true;
+  },
+};
+
+function ignoreError(fn) {
+  try {
+    fn();
+  } catch (e) {
+    // Meh.
+  }
+}
+
+add_task(async function() {
+  let url = "data:," + JSON.stringify(json);
+  await Schemas.load(url);
+
+  let root = {};
+  Schemas.inject(root, context);
+  equal(recorded.length, 0, "No recorded events");
+
+  let listener = () => {};
+  let captured = {};
+
+  function checkRecorded() {
+    let possible = [
+      ["revokableNs", ["getProperty", "revokableNs", "stringProp", []]],
+      [
+        "revokableProp",
+        ["getProperty", "revokableNs", "revokableStringProp", []],
+      ],
+
+      [
+        "revokableNs",
+        ["setProperty", "revokableNs", "stringProp", ["stringProp"]],
+      ],
+      [
+        "revokableProp",
+        [
+          "setProperty",
+          "revokableNs",
+          "revokableStringProp",
+          ["revokableStringProp"],
+        ],
+      ],
+
+      ["revokableNs", ["callFunctionNoReturn", "revokableNs", "func", [[]]]],
+      [
+        "revokableFunc",
+        ["callFunctionNoReturn", "revokableNs", "revokableFunc", [[]]],
+      ],
+
+      [
+        "revokableNs",
+        ["callFunction", "revokableNs.submoduleProp", "sub_foo", [[]]],
+      ],
+      [
+        "revokableProp",
+        ["callFunction", "revokableNs.revokableSubmoduleProp", "sub_foo", [[]]],
+      ],
+
+      [
+        "revokableNs",
+        ["addListener", "revokableNs", "onEvent", [listener, []]],
+      ],
+      ["revokableNs", ["removeListener", "revokableNs", "onEvent", [listener]]],
+      ["revokableNs", ["hasListener", "revokableNs", "onEvent", [listener]]],
+
+      [
+        "revokableEvent",
+        ["addListener", "revokableNs", "onRevokableEvent", [listener, []]],
+      ],
+      [
+        "revokableEvent",
+        ["removeListener", "revokableNs", "onRevokableEvent", [listener]],
+      ],
+      [
+        "revokableEvent",
+        ["hasListener", "revokableNs", "onRevokableEvent", [listener]],
+      ],
+    ];
+
+    let expected = [];
+    if (permissions.has("revokableNs")) {
+      for (let [perm, recording] of possible) {
+        if (!perm || permissions.has(perm)) {
+          expected.push(recording);
+        }
+      }
+    }
+
+    verify(expected);
+  }
+
+  function check() {
+    info(`Check normal access (permissions: [${Array.from(permissions)}])`);
+
+    let ns = root.revokableNs;
+
+    void ns.stringProp;
+    void ns.revokableStringProp;
+
+    ns.stringProp = "stringProp";
+    ns.revokableStringProp = "revokableStringProp";
+
+    ns.func();
+
+    if (ns.revokableFunc) {
+      ns.revokableFunc();
+    }
+
+    ns.submoduleProp.sub_foo();
+    if (ns.revokableSubmoduleProp) {
+      ns.revokableSubmoduleProp.sub_foo();
+    }
+
+    ns.onEvent.addListener(listener);
+    ns.onEvent.removeListener(listener);
+    ns.onEvent.hasListener(listener);
+
+    if (ns.onRevokableEvent) {
+      ns.onRevokableEvent.addListener(listener);
+      ns.onRevokableEvent.removeListener(listener);
+      ns.onRevokableEvent.hasListener(listener);
+    }
+
+    checkRecorded();
+  }
+
+  function capture() {
+    info("Capture values");
+
+    let ns = root.revokableNs;
+
+    captured = { ns };
+    captured.revokableStringProp = Object.getOwnPropertyDescriptor(
+      ns,
+      "revokableStringProp"
+    );
+
+    captured.revokableSubmoduleProp = ns.revokableSubmoduleProp;
+    if (ns.revokableSubmoduleProp) {
+      captured.sub_foo = ns.revokableSubmoduleProp.sub_foo;
+    }
+
+    captured.revokableFunc = ns.revokableFunc;
+
+    captured.onRevokableEvent = ns.onRevokableEvent;
+    if (ns.onRevokableEvent) {
+      captured.addListener = ns.onRevokableEvent.addListener;
+      captured.removeListener = ns.onRevokableEvent.removeListener;
+      captured.hasListener = ns.onRevokableEvent.hasListener;
+    }
+  }
+
+  function checkCaptured() {
+    info(
+      `Check captured value access (permissions: [${Array.from(permissions)}])`
+    );
+
+    let { ns } = captured;
+
+    void ns.stringProp;
+    ignoreError(() => captured.revokableStringProp.get());
+    if (!permissions.has("revokableProp")) {
+      void ns.revokableStringProp;
+    }
+
+    ns.stringProp = "stringProp";
+    ignoreError(() => captured.revokableStringProp.set("revokableStringProp"));
+    if (!permissions.has("revokableProp")) {
+      ns.revokableStringProp = "revokableStringProp";
+    }
+
+    ignoreError(() => ns.func());
+    ignoreError(() => captured.revokableFunc());
+    if (!permissions.has("revokableFunc")) {
+      ignoreError(() => ns.revokableFunc());
+    }
+
+    ignoreError(() => ns.submoduleProp.sub_foo());
+
+    ignoreError(() => captured.sub_foo());
+    if (!permissions.has("revokableProp")) {
+      ignoreError(() => captured.revokableSubmoduleProp.sub_foo());
+      ignoreError(() => ns.revokableSubmoduleProp.sub_foo());
+    }
+
+    ignoreError(() => ns.onEvent.addListener(listener));
+    ignoreError(() => ns.onEvent.removeListener(listener));
+    ignoreError(() => ns.onEvent.hasListener(listener));
+
+    ignoreError(() => captured.addListener(listener));
+    ignoreError(() => captured.removeListener(listener));
+    ignoreError(() => captured.hasListener(listener));
+    if (!permissions.has("revokableEvent")) {
+      ignoreError(() => captured.onRevokableEvent.addListener(listener));
+      ignoreError(() => captured.onRevokableEvent.removeListener(listener));
+      ignoreError(() => captured.onRevokableEvent.hasListener(listener));
+
+      ignoreError(() => ns.onRevokableEvent.addListener(listener));
+      ignoreError(() => ns.onRevokableEvent.removeListener(listener));
+      ignoreError(() => ns.onRevokableEvent.hasListener(listener));
+    }
+
+    checkRecorded();
+  }
+
+  permissions.add("revokableNs");
+  permissions.add("revokableProp");
+  permissions.add("revokableFunc");
+  permissions.add("revokableEvent");
+
+  check();
+  capture();
+  checkCaptured();
+
+  permissions.delete("revokableProp");
+  context.permissionsChanged();
+  verify([
+    ["revoke", "revokableNs", "revokableStringProp", []],
+    ["revoke", "revokableNs.revokableSubmoduleProp", "sub_foo", []],
+  ]);
+
+  check();
+  checkCaptured();
+
+  permissions.delete("revokableFunc");
+  context.permissionsChanged();
+  verify([["revoke", "revokableNs", "revokableFunc", []]]);
+
+  check();
+  checkCaptured();
+
+  permissions.delete("revokableEvent");
+  context.permissionsChanged();
+
+  verify([["revoke", "revokableNs", "onRevokableEvent", []]]);
+
+  check();
+  checkCaptured();
+
+  permissions.delete("revokableNs");
+  context.permissionsChanged();
+  verify([
+    ["revoke", "revokableNs", "stringProp", []],
+    ["revoke", "revokableNs", "func", []],
+    ["revoke", "revokableNs.submoduleProp", "sub_foo", []],
+    ["revoke", "revokableNs", "onEvent", []],
+  ]);
+
+  checkCaptured();
+
+  permissions.add("revokableNs");
+  permissions.add("revokableProp");
+  permissions.add("revokableFunc");
+  permissions.add("revokableEvent");
+  context.permissionsChanged();
+
+  check();
+  capture();
+  checkCaptured();
+
+  permissions.delete("revokableProp");
+  permissions.delete("revokableFunc");
+  permissions.delete("revokableEvent");
+  context.permissionsChanged();
+  verify([
+    ["revoke", "revokableNs", "revokableStringProp", []],
+    ["revoke", "revokableNs", "revokableFunc", []],
+    ["revoke", "revokableNs.revokableSubmoduleProp", "sub_foo", []],
+    ["revoke", "revokableNs", "onRevokableEvent", []],
+  ]);
+
+  check();
+  checkCaptured();
+
+  permissions.add("revokableProp");
+  permissions.add("revokableFunc");
+  permissions.add("revokableEvent");
+  context.permissionsChanged();
+
+  check();
+  capture();
+  checkCaptured();
+
+  permissions.delete("revokableNs");
+  context.permissionsChanged();
+  verify([
+    ["revoke", "revokableNs", "stringProp", []],
+    ["revoke", "revokableNs", "revokableStringProp", []],
+    ["revoke", "revokableNs", "func", []],
+    ["revoke", "revokableNs", "revokableFunc", []],
+    ["revoke", "revokableNs.submoduleProp", "sub_foo", []],
+    ["revoke", "revokableNs.revokableSubmoduleProp", "sub_foo", []],
+    ["revoke", "revokableNs", "onEvent", []],
+    ["revoke", "revokableNs", "onRevokableEvent", []],
+  ]);
+
+  equal(root.revokableNs, undefined, "Namespace is not defined");
+  checkCaptured();
+});
+
+add_task(async function test_neuter() {
+  context.permissionsChanged = null;
+
+  let root = {};
+  Schemas.inject(root, context);
+  equal(recorded.length, 0, "No recorded events");
+
+  permissions.add("revokableNs");
+  permissions.add("revokableProp");
+  permissions.add("revokableFunc");
+  permissions.add("revokableEvent");
+
+  let ns = root.revokableNs;
+  let { submoduleProp } = ns;
+
+  let lazyGetter = Object.getOwnPropertyDescriptor(submoduleProp, "sub_foo");
+
+  permissions.delete("revokableNs");
+  context.permissionsChanged();
+  verify([]);
+
+  equal(root.revokableNs, undefined, "Should have no revokableNs");
+  equal(ns.submoduleProp, undefined, "Should have no ns.submoduleProp");
+
+  equal(submoduleProp.sub_foo, undefined, "No sub_foo");
+  lazyGetter.get.call(submoduleProp);
+  equal(submoduleProp.sub_foo, undefined, "No sub_foo");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_schemas_roots.js b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_roots.js
new file mode 100644
index 0000000000..ebc881a804
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_schemas_roots.js
@@ -0,0 +1,242 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { SchemaRoot } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+
+let { SchemaAPIInterface } = ExtensionCommon;
+
+const global = this;
+
+let baseSchemaJSON = [
+  {
+    namespace: "base",
+
+    properties: {
+      PROP1: { value: 42 },
+    },
+
+    types: [
+      {
+        id: "type1",
+        type: "string",
+        enum: ["value1", "value2", "value3"],
+      },
+    ],
+
+    functions: [
+      {
+        name: "foo",
+        type: "function",
+        parameters: [{ name: "arg1", $ref: "type1" }],
+      },
+    ],
+  },
+];
+
+let experimentFooJSON = [
+  {
+    namespace: "experiments.foo",
+    types: [
+      {
+        id: "typeFoo",
+        type: "string",
+        enum: ["foo1", "foo2", "foo3"],
+      },
+    ],
+
+    functions: [
+      {
+        name: "foo",
+        type: "function",
+        parameters: [
+          { name: "arg1", $ref: "typeFoo" },
+          { name: "arg2", $ref: "base.type1" },
+        ],
+      },
+    ],
+  },
+];
+
+let experimentBarJSON = [
+  {
+    namespace: "experiments.bar",
+    types: [
+      {
+        id: "typeBar",
+        type: "string",
+        enum: ["bar1", "bar2", "bar3"],
+      },
+    ],
+
+    functions: [
+      {
+        name: "bar",
+        type: "function",
+        parameters: [
+          { name: "arg1", $ref: "typeBar" },
+          { name: "arg2", $ref: "base.type1" },
+        ],
+      },
+    ],
+  },
+];
+
+let tallied = null;
+
+function tally(kind, ns, name, args) {
+  tallied = [kind, ns, name, args];
+}
+
+function verify(...args) {
+  equal(JSON.stringify(tallied), JSON.stringify(args));
+  tallied = null;
+}
+
+let talliedErrors = [];
+
+let permissions = new Set();
+
+class TallyingAPIImplementation extends SchemaAPIInterface {
+  constructor(namespace, name) {
+    super();
+    this.namespace = namespace;
+    this.name = name;
+  }
+
+  callFunction(args) {
+    tally("call", this.namespace, this.name, args);
+    if (this.name === "sub_foo") {
+      return 13;
+    }
+  }
+
+  callFunctionNoReturn(args) {
+    tally("call", this.namespace, this.name, args);
+  }
+
+  getProperty() {
+    tally("get", this.namespace, this.name);
+  }
+
+  setProperty(value) {
+    tally("set", this.namespace, this.name, value);
+  }
+
+  addListener(listener, args) {
+    tally("addListener", this.namespace, this.name, [listener, args]);
+  }
+
+  removeListener(listener) {
+    tally("removeListener", this.namespace, this.name, [listener]);
+  }
+
+  hasListener(listener) {
+    tally("hasListener", this.namespace, this.name, [listener]);
+  }
+}
+
+let wrapper = {
+  url: "moz-extension://b66e3509-cdb3-44f6-8eb8-c8b39b3a1d27/",
+
+  cloneScope: global,
+
+  checkLoadURL(url) {
+    return !url.startsWith("chrome:");
+  },
+
+  preprocessors: {
+    localize(value, context) {
+      return value.replace(/__MSG_(.*?)__/g, (m0, m1) => `${m1.toUpperCase()}`);
+    },
+  },
+
+  logError(message) {
+    talliedErrors.push(message);
+  },
+
+  hasPermission(permission) {
+    return permissions.has(permission);
+  },
+
+  shouldInject(ns, name) {
+    return name != "do-not-inject";
+  },
+
+  getImplementation(namespace, name) {
+    return new TallyingAPIImplementation(namespace, name);
+  },
+};
+
+add_task(async function() {
+  let baseSchemas = new Map([["resource://schemas/base.json", baseSchemaJSON]]);
+  let experimentSchemas = new Map([
+    ["resource://experiment-foo/schema.json", experimentFooJSON],
+    ["resource://experiment-bar/schema.json", experimentBarJSON],
+  ]);
+
+  let baseSchema = new SchemaRoot(null, baseSchemas);
+  let schema = new SchemaRoot(baseSchema, experimentSchemas);
+
+  baseSchema.parseSchemas();
+  schema.parseSchemas();
+
+  let root = {};
+  let base = {};
+
+  tallied = null;
+
+  baseSchema.inject(base, wrapper);
+  schema.inject(root, wrapper);
+
+  equal(typeof base.base, "object", "base.base exists");
+  equal(typeof root.base, "object", "root.base exists");
+  equal(typeof base.experiments, "undefined", "base.experiments exists not");
+  equal(typeof root.experiments, "object", "root.experiments exists");
+  equal(typeof root.experiments.foo, "object", "root.experiments.foo exists");
+  equal(typeof root.experiments.bar, "object", "root.experiments.bar exists");
+
+  equal(tallied, null);
+
+  equal(root.base.PROP1, 42, "root.base.PROP1");
+  equal(base.base.PROP1, 42, "root.base.PROP1");
+
+  root.base.foo("value2");
+  verify("call", "base", "foo", ["value2"]);
+
+  base.base.foo("value3");
+  verify("call", "base", "foo", ["value3"]);
+
+  root.experiments.foo.foo("foo2", "value1");
+  verify("call", "experiments.foo", "foo", ["foo2", "value1"]);
+
+  root.experiments.bar.bar("bar2", "value1");
+  verify("call", "experiments.bar", "bar", ["bar2", "value1"]);
+
+  Assert.throws(
+    () => root.base.foo("Meh."),
+    /Type error for parameter arg1/,
+    "root.base.foo()"
+  );
+
+  Assert.throws(
+    () => base.base.foo("Meh."),
+    /Type error for parameter arg1/,
+    "base.base.foo()"
+  );
+
+  Assert.throws(
+    () => root.experiments.foo.foo("Meh."),
+    /Incorrect argument types/,
+    "root.experiments.foo.foo()"
+  );
+
+  Assert.throws(
+    () => root.experiments.bar.bar("Meh."),
+    /Incorrect argument types/,
+    "root.experiments.bar.bar()"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_shadowdom.js b/toolkit/components/extensions/test/xpcshell/test_ext_shadowdom.js
new file mode 100644
index 0000000000..626d8de22d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_shadowdom.js
@@ -0,0 +1,59 @@
+"use strict";
+
+// ExtensionContent.jsm needs to know when it's running from xpcshell,
+// to use the right timeout for content scripts executed at document_idle.
+ExtensionTestUtils.mockAppInfo();
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function test_contentscript_shadowDOM() {
+  function backgroundScript() {
+    browser.test.assertTrue(
+      "openOrClosedShadowRoot" in document.documentElement,
+      "Should have openOrClosedShadowRoot in Element in background script."
+    );
+  }
+
+  function contentScript() {
+    let host = document.getElementById("host");
+    browser.test.assertTrue(
+      "openOrClosedShadowRoot" in host,
+      "Should have openOrClosedShadowRoot in Element."
+    );
+    let shadowRoot = host.openOrClosedShadowRoot;
+    browser.test.assertEq(
+      shadowRoot.mode,
+      "closed",
+      "Should have closed ShadowRoot."
+    );
+    browser.test.sendMessage("contentScript");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_shadowdom.html"],
+          js: ["content_script.js"],
+        },
+      ],
+    },
+    background: backgroundScript,
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_shadowdom.html`
+  );
+  await extension.awaitMessage("contentScript");
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_shared_workers.js b/toolkit/components/extensions/test/xpcshell/test_ext_shared_workers.js
new file mode 100644
index 0000000000..3952cefb07
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_shared_workers.js
@@ -0,0 +1,40 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// This test attemps to verify that:
+// - SharedWorkers can be created and successfully spawned by web extensions
+//   when web-extensions run in their own child process.
+add_task(async function test_spawn_shared_worker() {
+  if (!WebExtensionPolicy.useRemoteWebExtensions) {
+    // Ensure RemoteWorkerService has been initialized in the main
+    // process.
+    Services.obs.notifyObservers(null, "profile-after-change");
+  }
+
+  const background = async function() {
+    const worker = new SharedWorker("worker.js");
+    await new Promise(resolve => {
+      worker.port.onmessage = resolve;
+      worker.port.postMessage("bgpage->worker");
+    });
+    browser.test.sendMessage("test-shared-worker:done");
+  };
+
+  const extension = ExtensionTestUtils.loadExtension({
+    background,
+    files: {
+      "worker.js": function() {
+        self.onconnect = evt => {
+          const port = evt.ports[0];
+          port.onmessage = () => port.postMessage("worker-reply");
+        };
+      },
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("test-shared-worker:done");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_shutdown_cleanup.js b/toolkit/components/extensions/test/xpcshell/test_ext_shutdown_cleanup.js
new file mode 100644
index 0000000000..8221219a38
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_shutdown_cleanup.js
@@ -0,0 +1,42 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+
+"use strict";
+
+const { GlobalManager } = ChromeUtils.import(
+  "resource://gre/modules/Extension.jsm",
+  null
+);
+
+add_task(async function test_global_manager_shutdown_cleanup() {
+  equal(
+    GlobalManager.initialized,
+    false,
+    "GlobalManager start as not initialized"
+  );
+
+  function background() {
+    browser.test.notifyPass("background page loaded");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("background page loaded");
+
+  equal(
+    GlobalManager.initialized,
+    true,
+    "GlobalManager has been initialized once an extension is started"
+  );
+
+  await extension.unload();
+
+  equal(
+    GlobalManager.initialized,
+    false,
+    "GlobalManager has been uninitialized once all the webextensions have been stopped"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_simple.js b/toolkit/components/extensions/test/xpcshell/test_ext_simple.js
new file mode 100644
index 0000000000..7fd75eb088
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_simple.js
@@ -0,0 +1,111 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_simple() {
+  let extensionData = {
+    manifest: {
+      name: "Simple extension test",
+      version: "1.0",
+      manifest_version: 2,
+      description: "",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.unload();
+});
+
+add_task(async function test_manifest_V3_disabled() {
+  Services.prefs.setBoolPref("extensions.manifestV3.enabled", false);
+  let extensionData = {
+    manifest: {
+      manifest_version: 3,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await Assert.rejects(
+    extension.startup(),
+    /Unsupported manifest version: 3/,
+    "manifest V3 cannot be loaded"
+  );
+  Services.prefs.clearUserPref("extensions.manifestV3.enabled");
+});
+
+add_task(async function test_manifest_V3_enabled() {
+  Services.prefs.setBoolPref("extensions.manifestV3.enabled", true);
+  let extensionData = {
+    manifest: {
+      manifest_version: 3,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  equal(extension.extension.manifest.manifest_version, 3, "manifest V3 loads");
+  await extension.unload();
+  Services.prefs.clearUserPref("extensions.manifestV3.enabled");
+});
+
+add_task(async function test_background() {
+  function background() {
+    browser.test.log("running background script");
+
+    browser.test.onMessage.addListener((x, y) => {
+      browser.test.assertEq(x, 10, "x is 10");
+      browser.test.assertEq(y, 20, "y is 20");
+
+      browser.test.notifyPass("background test passed");
+    });
+
+    browser.test.sendMessage("running", 1);
+  }
+
+  let extensionData = {
+    background,
+    manifest: {
+      name: "Simple extension test",
+      version: "1.0",
+      manifest_version: 2,
+      description: "",
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  let [, x] = await Promise.all([
+    extension.startup(),
+    extension.awaitMessage("running"),
+  ]);
+  equal(x, 1, "got correct value from extension");
+
+  extension.sendMessage(10, 20);
+  await extension.awaitFinish();
+  await extension.unload();
+});
+
+add_task(async function test_extensionTypes() {
+  let extensionData = {
+    background: function() {
+      browser.test.assertEq(
+        typeof browser.extensionTypes,
+        "object",
+        "browser.extensionTypes exists"
+      );
+      browser.test.assertEq(
+        typeof browser.extensionTypes.RunAt,
+        "object",
+        "browser.extensionTypes.RunAt exists"
+      );
+      browser.test.notifyPass("extentionTypes test passed");
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+  await extension.awaitFinish();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_startupData.js b/toolkit/components/extensions/test/xpcshell/test_ext_startupData.js
new file mode 100644
index 0000000000..df51fa9abf
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_startupData.js
@@ -0,0 +1,55 @@
+"use strict";
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "1"
+);
+
+// Tests that startupData is persisted and is available at startup
+add_task(async function test_startupData() {
+  await AddonTestUtils.promiseStartupManager();
+
+  let wrapper = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+  });
+  await wrapper.startup();
+
+  let { extension } = wrapper;
+
+  deepEqual(
+    extension.startupData,
+    {},
+    "startupData for a new extension defaults to empty object"
+  );
+
+  const DATA = { test: "i am some startup data" };
+  extension.startupData = DATA;
+  extension.saveStartupData();
+
+  await AddonTestUtils.promiseRestartManager();
+  await wrapper.startupPromise;
+
+  ({ extension } = wrapper);
+  deepEqual(extension.startupData, DATA, "startupData is present on restart");
+
+  const DATA2 = { other: "this is different data" };
+  extension.startupData = DATA2;
+  extension.saveStartupData();
+
+  await AddonTestUtils.promiseRestartManager();
+  await wrapper.startupPromise;
+
+  ({ extension } = wrapper);
+  deepEqual(
+    extension.startupData,
+    DATA2,
+    "updated startupData is present on restart"
+  );
+
+  await wrapper.unload();
+  await AddonTestUtils.promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_startup_cache.js b/toolkit/components/extensions/test/xpcshell/test_ext_startup_cache.js
new file mode 100644
index 0000000000..c21458e5a1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_startup_cache.js
@@ -0,0 +1,172 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { AddonManager } = ChromeUtils.import(
+  "resource://gre/modules/AddonManager.jsm"
+);
+const { Preferences } = ChromeUtils.import(
+  "resource://gre/modules/Preferences.jsm"
+);
+
+const { TestUtils } = ChromeUtils.import(
+  "resource://testing-common/TestUtils.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "42",
+  "42"
+);
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  false
+);
+
+const ADDON_ID = "test-startup-cache@xpcshell.mozilla.org";
+
+function makeExtension(opts) {
+  return {
+    useAddonManager: "permanent",
+
+    manifest: {
+      version: opts.version,
+      applications: { gecko: { id: ADDON_ID } },
+
+      name: "__MSG_name__",
+
+      default_locale: "en_US",
+    },
+
+    files: {
+      "_locales/en_US/messages.json": {
+        name: {
+          message: `en-US ${opts.version}`,
+          description: "Name.",
+        },
+      },
+      "_locales/fr/messages.json": {
+        name: {
+          message: `fr ${opts.version}`,
+          description: "Name.",
+        },
+      },
+    },
+
+    background() {
+      browser.test.onMessage.addListener(msg => {
+        if (msg === "get-manifest") {
+          browser.test.sendMessage("manifest", browser.runtime.getManifest());
+        }
+      });
+    },
+  };
+}
+
+add_task(async function() {
+  Preferences.set("extensions.logging.enabled", false);
+  await AddonTestUtils.promiseStartupManager();
+
+  // Install langpacks to get proper locale startup.
+  let langpack = {
+    "manifest.json": {
+      name: "test Language Pack",
+      version: "1.0",
+      manifest_version: 2,
+      applications: {
+        gecko: {
+          id: "@test-langpack",
+          strict_min_version: "42.0",
+          strict_max_version: "42.0",
+        },
+      },
+      langpack_id: "fr",
+      languages: {
+        fr: {
+          chrome_resources: {
+            global: "chrome/fr/locale/fr/global/",
+          },
+          version: "20171001190118",
+        },
+      },
+      sources: {
+        browser: {
+          base_path: "browser/",
+        },
+      },
+    },
+  };
+
+  let [, { addon }] = await Promise.all([
+    TestUtils.topicObserved("webextension-langpack-startup"),
+    AddonTestUtils.promiseInstallXPI(langpack),
+  ]);
+
+  let extension = ExtensionTestUtils.loadExtension(
+    makeExtension({ version: "1.0" })
+  );
+
+  function getManifest() {
+    extension.sendMessage("get-manifest");
+    return extension.awaitMessage("manifest");
+  }
+
+  // At the moment extension language negotiation is tied to Firefox language
+  // negotiation result. That means that to test an extension in `fr`, we need
+  // to mock `fr` being available in Firefox and then request it.
+  //
+  // In the future, we should provide some way for tests to decouple their
+  // language selection from that of Firefox.
+  ok(Services.locale.availableLocales.includes("fr"), "fr locale is avialable");
+
+  await extension.startup();
+
+  equal(extension.version, "1.0", "Expected extension version");
+  let manifest = await getManifest();
+  equal(manifest.name, "en-US 1.0", "Got expected manifest name");
+
+  info("Restart and re-check");
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+
+  equal(extension.version, "1.0", "Expected extension version");
+  manifest = await getManifest();
+  equal(manifest.name, "en-US 1.0", "Got expected manifest name");
+
+  info("Change locale to 'fr' and restart");
+  Services.locale.requestedLocales = ["fr"];
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+
+  equal(extension.version, "1.0", "Expected extension version");
+  manifest = await getManifest();
+  equal(manifest.name, "fr 1.0", "Got expected manifest name");
+
+  info("Update to version 1.1");
+  await extension.upgrade(makeExtension({ version: "1.1" }));
+
+  equal(extension.version, "1.1", "Expected extension version");
+  manifest = await getManifest();
+  equal(manifest.name, "fr 1.1", "Got expected manifest name");
+
+  info("Change locale to 'en-US' and restart");
+  Services.locale.requestedLocales = ["en-US"];
+  await AddonTestUtils.promiseRestartManager();
+  await extension.awaitStartup();
+
+  equal(extension.version, "1.1", "Expected extension version");
+  manifest = await getManifest();
+  equal(manifest.name, "en-US 1.1", "Got expected manifest name");
+
+  info("uninstall locale 'fr'");
+  addon = await AddonManager.getAddonByID("@test-langpack");
+  await addon.uninstall();
+  ok(!Services.locale.availableLocales.includes("fr"), "fr locale is removed");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js b/toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js
new file mode 100644
index 0000000000..691232479d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js
@@ -0,0 +1,73 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const STARTUP_APIS = ["backgroundPage"];
+
+const STARTUP_MODULES = [
+  "resource://gre/modules/Extension.jsm",
+  "resource://gre/modules/ExtensionCommon.jsm",
+  "resource://gre/modules/ExtensionParent.jsm",
+  // FIXME: This is only loaded at startup for new extension installs.
+  // Otherwise the data comes from the startup cache. We should test for
+  // this.
+  "resource://gre/modules/ExtensionPermissions.jsm",
+  "resource://gre/modules/ExtensionProcessScript.jsm",
+  "resource://gre/modules/ExtensionUtils.jsm",
+  "resource://gre/modules/ExtensionTelemetry.jsm",
+];
+
+if (!Services.prefs.getBoolPref("extensions.webextensions.remote")) {
+  STARTUP_MODULES.push(
+    "resource://gre/modules/ExtensionChild.jsm",
+    "resource://gre/modules/ExtensionPageChild.jsm"
+  );
+}
+
+if (AppConstants.MOZ_APP_NAME == "thunderbird") {
+  STARTUP_MODULES.push(
+    "resource://gre/modules/ExtensionChild.jsm",
+    "resource://gre/modules/ExtensionContent.jsm",
+    "resource://gre/modules/ExtensionPageChild.jsm"
+  );
+}
+
+AddonTestUtils.init(this);
+
+// Tests that only the minimal set of API scripts and modules are loaded at
+// startup for a simple extension.
+add_task(async function test_loaded_scripts() {
+  await ExtensionTestUtils.startAddonManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    background() {},
+    manifest: {},
+  });
+
+  await extension.startup();
+
+  const { apiManager } = ExtensionParent;
+
+  const loadedAPIs = Array.from(apiManager.modules.values())
+    .filter(m => m.loaded || m.asyncLoaded)
+    .map(m => m.namespaceName);
+
+  deepEqual(
+    loadedAPIs.sort(),
+    STARTUP_APIS,
+    "No extra APIs should be loaded at startup for a simple extension"
+  );
+
+  let loadedModules = Cu.loadedModules.filter(url =>
+    url.startsWith("resource://gre/modules/Extension")
+  );
+
+  deepEqual(
+    loadedModules.sort(),
+    STARTUP_MODULES.sort(),
+    "No extra extension modules should be loaded at startup for a simple extension"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_startup_request_handler.js b/toolkit/components/extensions/test/xpcshell/test_ext_startup_request_handler.js
new file mode 100644
index 0000000000..5ebe4c5230
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_startup_request_handler.js
@@ -0,0 +1,64 @@
+"use strict";
+
+function delay(time) {
+  return new Promise(resolve => {
+    // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+    setTimeout(resolve, time);
+  });
+}
+
+const { Extension } = ChromeUtils.import(
+  "resource://gre/modules/Extension.jsm"
+);
+
+add_task(async function test_startup_request_handler() {
+  const ID = "request-startup@xpcshell.mozilla.org";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: ID } },
+    },
+
+    files: {
+      "meh.txt": "Meh.",
+    },
+  });
+
+  let ready = false;
+  let resolvePromise;
+  let promise = new Promise(resolve => {
+    resolvePromise = resolve;
+  });
+  promise.then(() => {
+    ready = true;
+  });
+
+  let origInitLocale = Extension.prototype.initLocale;
+  Extension.prototype.initLocale = async function initLocale() {
+    await promise;
+    return origInitLocale.call(this);
+  };
+
+  let startupPromise = extension.startup();
+
+  await delay(0);
+  let policy = WebExtensionPolicy.getByID(ID);
+  let url = policy.getURL("meh.txt");
+
+  let resp = ExtensionTestUtils.fetch(url, url);
+  resp.then(() => {
+    ok(ready, "Shouldn't get response before extension is ready");
+  });
+
+  await delay(2000);
+
+  resolvePromise();
+  await startupPromise;
+
+  let body = await resp;
+  equal(body, "Meh.", "Got the correct response");
+
+  await extension.unload();
+
+  Extension.prototype.initLocale = origInitLocale;
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_local.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_local.js
new file mode 100644
index 0000000000..b677110a47
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_local.js
@@ -0,0 +1,39 @@
+"use strict";
+
+const { ExtensionStorageIDB } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageIDB.jsm"
+);
+
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /WebExtension context not found/
+);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+// The storage API in content scripts should behave identical to the storage API
+// in background pages.
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_contentscript_storage_local_file_backend() {
+  return runWithPrefs([[ExtensionStorageIDB.BACKEND_ENABLED_PREF, false]], () =>
+    test_contentscript_storage("local")
+  );
+});
+
+add_task(async function test_contentscript_storage_local_idb_backend() {
+  return runWithPrefs([[ExtensionStorageIDB.BACKEND_ENABLED_PREF, true]], () =>
+    test_contentscript_storage("local")
+  );
+});
+
+add_task(async function test_contentscript_storage_local_idb_no_bytes_in_use() {
+  return runWithPrefs([[ExtensionStorageIDB.BACKEND_ENABLED_PREF, true]], () =>
+    test_contentscript_storage_area_no_bytes_in_use("local")
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync.js
new file mode 100644
index 0000000000..6b1695417d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync.js
@@ -0,0 +1,31 @@
+"use strict";
+
+Services.prefs.setBoolPref("webextensions.storage.sync.kinto", false);
+
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /WebExtension context not found/
+);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+// The storage API in content scripts should behave identical to the storage API
+// in background pages.
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_contentscript_storage_sync() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_contentscript_storage("sync")
+  );
+});
+
+add_task(async function test_contentscript_bytes_in_use_sync() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_contentscript_storage_area_with_bytes_in_use("sync", true)
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync_kinto.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync_kinto.js
new file mode 100644
index 0000000000..92ec405520
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_content_sync_kinto.js
@@ -0,0 +1,31 @@
+"use strict";
+
+Services.prefs.setBoolPref("webextensions.storage.sync.kinto", true);
+
+PromiseTestUtils.allowMatchingRejectionsGlobally(
+  /WebExtension context not found/
+);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+// The storage API in content scripts should behave identical to the storage API
+// in background pages.
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_contentscript_storage_sync() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_contentscript_storage("sync")
+  );
+});
+
+add_task(async function test_contentscript_storage_no_bytes_in_use() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_contentscript_storage_area_with_bytes_in_use("sync", false)
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_idb_data_migration.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_idb_data_migration.js
new file mode 100644
index 0000000000..90d4740bf9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_idb_data_migration.js
@@ -0,0 +1,787 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+// This test file verifies various scenarios related to the data migration
+// from the JSONFile backend to the IDB backend.
+
+AddonTestUtils.init(this);
+
+// Create appInfo before importing any other jsm file, to prevent
+// Services.appinfo to be cached before an appInfo.version is
+// actually defined (which prevent failures to be triggered when
+// the test run in a non nightly build).
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+const { getTrimmedString } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionTelemetry.jsm"
+);
+const { ExtensionStorage } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorage.jsm"
+);
+const { ExtensionStorageIDB } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageIDB.jsm"
+);
+const { TelemetryController } = ChromeUtils.import(
+  "resource://gre/modules/TelemetryController.jsm"
+);
+const { TelemetryTestUtils } = ChromeUtils.import(
+  "resource://testing-common/TelemetryTestUtils.jsm"
+);
+
+XPCOMUtils.defineLazyModuleGetters(this, {
+  OS: "resource://gre/modules/osfile.jsm",
+});
+
+const { promiseShutdownManager, promiseStartupManager } = AddonTestUtils;
+
+const {
+  IDB_MIGRATED_PREF_BRANCH,
+  IDB_MIGRATE_RESULT_HISTOGRAM,
+} = ExtensionStorageIDB;
+const CATEGORIES = ["success", "failure"];
+const EVENT_CATEGORY = "extensions.data";
+const EVENT_OBJECT = "storageLocal";
+const EVENT_METHOD = "migrateResult";
+const LEAVE_STORAGE_PREF = "extensions.webextensions.keepStorageOnUninstall";
+const LEAVE_UUID_PREF = "extensions.webextensions.keepUuidOnUninstall";
+const TELEMETRY_EVENTS_FILTER = {
+  category: "extensions.data",
+  method: "migrateResult",
+  object: "storageLocal",
+};
+
+async function createExtensionJSONFileWithData(extensionId, data) {
+  await ExtensionStorage.set(extensionId, data);
+  const jsonFile = await ExtensionStorage.getFile(extensionId);
+  await jsonFile._save();
+  const oldStorageFilename = ExtensionStorage.getStorageFile(extensionId);
+  equal(
+    await OS.File.exists(oldStorageFilename),
+    true,
+    "The old json file has been created"
+  );
+
+  return { jsonFile, oldStorageFilename };
+}
+
+function clearMigrationHistogram() {
+  const histogram = Services.telemetry.getHistogramById(
+    IDB_MIGRATE_RESULT_HISTOGRAM
+  );
+  histogram.clear();
+  equal(
+    histogram.snapshot().sum,
+    0,
+    `No data recorded for histogram ${IDB_MIGRATE_RESULT_HISTOGRAM}`
+  );
+}
+
+function assertMigrationHistogramCount(category, expectedCount) {
+  const histogram = Services.telemetry.getHistogramById(
+    IDB_MIGRATE_RESULT_HISTOGRAM
+  );
+
+  equal(
+    histogram.snapshot().values[CATEGORIES.indexOf(category)],
+    expectedCount,
+    `Got the expected count on category "${category}" for histogram ${IDB_MIGRATE_RESULT_HISTOGRAM}`
+  );
+}
+
+function assertTelemetryEvents(expectedEvents) {
+  TelemetryTestUtils.assertEvents(expectedEvents, {
+    category: EVENT_CATEGORY,
+    method: EVENT_METHOD,
+    object: EVENT_OBJECT,
+  });
+}
+
+add_task(async function setup() {
+  Services.prefs.setBoolPref(ExtensionStorageIDB.BACKEND_ENABLED_PREF, true);
+
+  await promiseStartupManager();
+
+  // Telemetry test setup needed to ensure that the builtin events are defined
+  // and they can be collected and verified.
+  await TelemetryController.testSetup();
+
+  // This is actually only needed on Android, because it does not properly support unified telemetry
+  // and so, if not enabled explicitly here, it would make these tests to fail when running on a
+  // non-Nightly build.
+  const oldCanRecordBase = Services.telemetry.canRecordBase;
+  Services.telemetry.canRecordBase = true;
+  registerCleanupFunction(() => {
+    Services.telemetry.canRecordBase = oldCanRecordBase;
+  });
+
+  // Clear any telemetry events collected so far.
+  Services.telemetry.clearEvents();
+});
+
+// Test that for newly installed extension the IDB backend is enabled without
+// any data migration.
+add_task(async function test_no_migration_for_newly_installed_extensions() {
+  const EXTENSION_ID = "test-no-data-migration@mochi.test";
+
+  await createExtensionJSONFileWithData(EXTENSION_ID, {
+    test_old_data: "test_old_value",
+  });
+
+  const extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: EXTENSION_ID } },
+    },
+    async background() {
+      const data = await browser.storage.local.get();
+      browser.test.assertEq(
+        Object.keys(data).length,
+        0,
+        "Expect the storage.local store to be empty"
+      );
+      browser.test.sendMessage("test-stored-data:done");
+    },
+  });
+
+  await extension.startup();
+  equal(
+    ExtensionStorageIDB.isMigratedExtension(extension),
+    true,
+    "The newly installed test extension is marked as migrated"
+  );
+  await extension.awaitMessage("test-stored-data:done");
+  await extension.unload();
+
+  // Verify that no data migration have been needed on the newly installed
+  // extension, by asserting that no telemetry events has been collected.
+  await TelemetryTestUtils.assertEvents([], TELEMETRY_EVENTS_FILTER);
+});
+
+// Test that the data migration is still running for a newly installed extension
+// if keepStorageOnUninstall is true.
+add_task(async function test_data_migration_on_keep_storage_on_uninstall() {
+  Services.prefs.setBoolPref(LEAVE_STORAGE_PREF, true);
+
+  // Store some fake data in the storage.local file backend before starting the extension.
+  const EXTENSION_ID = "new-extension-on-keep-storage-on-uninstall@mochi.test";
+  await createExtensionJSONFileWithData(EXTENSION_ID, {
+    test_key_string: "test_value",
+  });
+
+  const extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: EXTENSION_ID } },
+    },
+    async background() {
+      const storedData = await browser.storage.local.get();
+      browser.test.assertEq(
+        "test_value",
+        storedData.test_key_string,
+        "Got the expected data after the storage.local data migration"
+      );
+      browser.test.sendMessage("storage-local-data-migrated");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("storage-local-data-migrated");
+  equal(
+    ExtensionStorageIDB.isMigratedExtension(extension),
+    true,
+    "The newly installed test extension is marked as migrated"
+  );
+  await extension.unload();
+
+  // Verify that the expected telemetry has been recorded.
+  await TelemetryTestUtils.assertEvents(
+    [
+      {
+        method: "migrateResult",
+        value: EXTENSION_ID,
+        extra: {
+          backend: "IndexedDB",
+          data_migrated: "y",
+          has_jsonfile: "y",
+          has_olddata: "y",
+        },
+      },
+    ],
+    TELEMETRY_EVENTS_FILTER
+  );
+
+  Services.prefs.clearUserPref(LEAVE_STORAGE_PREF);
+});
+
+// Test that the old data is migrated successfully to the new storage backend
+// and that the original JSONFile has been renamed.
+add_task(async function test_storage_local_data_migration() {
+  const EXTENSION_ID = "extension-to-be-migrated@mozilla.org";
+
+  // Keep the extension storage and the uuid on uninstall, to verify that no telemetry events
+  // are being sent for an already migrated extension.
+  Services.prefs.setBoolPref(LEAVE_STORAGE_PREF, true);
+  Services.prefs.setBoolPref(LEAVE_UUID_PREF, true);
+
+  const data = {
+    test_key_string: "test_value1",
+    test_key_number: 1000,
+    test_nested_data: {
+      nested_key: true,
+    },
+  };
+
+  // Store some fake data in the storage.local file backend before starting the extension.
+  const { oldStorageFilename } = await createExtensionJSONFileWithData(
+    EXTENSION_ID,
+    data
+  );
+
+  async function background() {
+    const storedData = await browser.storage.local.get();
+
+    browser.test.assertEq(
+      "test_value1",
+      storedData.test_key_string,
+      "Got the expected data after the storage.local data migration"
+    );
+    browser.test.assertEq(
+      1000,
+      storedData.test_key_number,
+      "Got the expected data after the storage.local data migration"
+    );
+    browser.test.assertEq(
+      true,
+      storedData.test_nested_data.nested_key,
+      "Got the expected data after the storage.local data migration"
+    );
+
+    browser.test.sendMessage("storage-local-data-migrated");
+  }
+
+  clearMigrationHistogram();
+
+  let extensionDefinition = {
+    useAddonManager: "temporary",
+    manifest: {
+      permissions: ["storage"],
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionDefinition);
+
+  // Install the extension while the storage.local IDB backend is disabled.
+  Services.prefs.setBoolPref(ExtensionStorageIDB.BACKEND_ENABLED_PREF, false);
+  await extension.startup();
+
+  ok(
+    !ExtensionStorageIDB.isMigratedExtension(extension),
+    "The test extension should be using the JSONFile backend"
+  );
+
+  // Enabled the storage.local IDB backend and upgrade the extension.
+  Services.prefs.setBoolPref(ExtensionStorageIDB.BACKEND_ENABLED_PREF, true);
+  await extension.upgrade({
+    ...extensionDefinition,
+    background,
+  });
+
+  await extension.awaitMessage("storage-local-data-migrated");
+
+  ok(
+    ExtensionStorageIDB.isMigratedExtension(extension),
+    "The test extension should be using the IndexedDB backend"
+  );
+
+  const storagePrincipal = ExtensionStorageIDB.getStoragePrincipal(
+    extension.extension
+  );
+
+  const idbConn = await ExtensionStorageIDB.open(storagePrincipal);
+
+  equal(
+    await idbConn.isEmpty(extension.extension),
+    false,
+    "Data stored in the ExtensionStorageIDB backend as expected"
+  );
+
+  equal(
+    await OS.File.exists(oldStorageFilename),
+    false,
+    "The old json storage file name should not exist anymore"
+  );
+
+  equal(
+    await OS.File.exists(`${oldStorageFilename}.migrated`),
+    true,
+    "The old json storage file name should have been renamed as .migrated"
+  );
+
+  equal(
+    Services.prefs.getBoolPref(
+      `${IDB_MIGRATED_PREF_BRANCH}.${EXTENSION_ID}`,
+      false
+    ),
+    true,
+    `Got the ${IDB_MIGRATED_PREF_BRANCH} preference set to true as expected`
+  );
+
+  assertMigrationHistogramCount("success", 1);
+  assertMigrationHistogramCount("failure", 0);
+
+  assertTelemetryEvents([
+    {
+      method: "migrateResult",
+      value: EXTENSION_ID,
+      extra: {
+        backend: "IndexedDB",
+        data_migrated: "y",
+        has_jsonfile: "y",
+        has_olddata: "y",
+      },
+    },
+  ]);
+
+  equal(
+    Services.prefs.getBoolPref(
+      `${IDB_MIGRATED_PREF_BRANCH}.${EXTENSION_ID}`,
+      false
+    ),
+    true,
+    `${IDB_MIGRATED_PREF_BRANCH} should still be true on keepStorageOnUninstall=true`
+  );
+
+  // Upgrade the extension and check that no telemetry events are being sent
+  // for an already migrated extension.
+  await extension.upgrade({
+    ...extensionDefinition,
+    background,
+  });
+
+  await extension.awaitMessage("storage-local-data-migrated");
+
+  // The histogram values are unmodified.
+  assertMigrationHistogramCount("success", 1);
+  assertMigrationHistogramCount("failure", 0);
+
+  // No new telemetry events recorded for the extension.
+  const snapshot = Services.telemetry.snapshotEvents(
+    Ci.nsITelemetry.DATASET_PRERELEASE_CHANNELS,
+    true
+  );
+  const filterByCategory = ([timestamp, category]) =>
+    category === EVENT_CATEGORY;
+
+  ok(
+    !snapshot.parent || snapshot.parent.filter(filterByCategory).length === 0,
+    "No telemetry events should be recorded for an already migrated extension"
+  );
+
+  Services.prefs.setBoolPref(LEAVE_STORAGE_PREF, false);
+  Services.prefs.setBoolPref(LEAVE_UUID_PREF, false);
+
+  await extension.unload();
+
+  equal(
+    Services.prefs.getPrefType(`${IDB_MIGRATED_PREF_BRANCH}.${EXTENSION_ID}`),
+    Services.prefs.PREF_INVALID,
+    `Got the ${IDB_MIGRATED_PREF_BRANCH} preference has been cleared on addon uninstall`
+  );
+});
+
+// Test that the extensionId included in the telemetry event is being trimmed down to 80 chars
+// as expected.
+add_task(async function test_extensionId_trimmed_in_telemetry_event() {
+  // Generated extensionId in email-like format, longer than 80 chars.
+  const EXTENSION_ID = `long.extension.id@${Array(80)
+    .fill("a")
+    .join("")}`;
+
+  const data = { test_key_string: "test_value" };
+
+  // Store some fake data in the storage.local file backend before starting the extension.
+  await createExtensionJSONFileWithData(EXTENSION_ID, data);
+
+  async function background() {
+    const storedData = await browser.storage.local.get("test_key_string");
+
+    browser.test.assertEq(
+      "test_value",
+      storedData.test_key_string,
+      "Got the expected data after the storage.local data migration"
+    );
+
+    browser.test.sendMessage("storage-local-data-migrated");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("storage-local-data-migrated");
+
+  const expectedTrimmedExtensionId = getTrimmedString(EXTENSION_ID);
+
+  equal(
+    expectedTrimmedExtensionId.length,
+    80,
+    "The trimmed version of the extensionId should be 80 chars long"
+  );
+
+  assertTelemetryEvents([
+    {
+      method: "migrateResult",
+      value: expectedTrimmedExtensionId,
+      extra: {
+        backend: "IndexedDB",
+        data_migrated: "y",
+        has_jsonfile: "y",
+        has_olddata: "y",
+      },
+    },
+  ]);
+
+  await extension.unload();
+});
+
+// Test that if the old JSONFile data file is corrupted and the old data
+// can't be successfully migrated to the new storage backend, then:
+// - the new storage backend for that extension is still initialized and enabled
+// - any new data is being stored in the new backend
+// - the old file is being renamed (with the `.corrupted` suffix that JSONFile.jsm
+//   adds when it fails to load the data file) and still available on disk.
+add_task(async function test_storage_local_corrupted_data_migration() {
+  const EXTENSION_ID = "extension-corrupted-data-migration@mozilla.org";
+
+  const invalidData = `{"test_key_string": "test_value1"`;
+  const oldStorageFilename = ExtensionStorage.getStorageFile(EXTENSION_ID);
+
+  const profileDir = OS.Constants.Path.profileDir;
+  await OS.File.makeDir(
+    OS.Path.join(profileDir, "browser-extension-data", EXTENSION_ID),
+    { from: profileDir, ignoreExisting: true }
+  );
+
+  // Write the json file with some invalid data.
+  await OS.File.writeAtomic(oldStorageFilename, invalidData, { flush: true });
+  equal(
+    await OS.File.read(oldStorageFilename, { encoding: "utf-8" }),
+    invalidData,
+    "The old json file has been overwritten with invalid data"
+  );
+
+  async function background() {
+    const storedData = await browser.storage.local.get();
+
+    browser.test.assertEq(
+      Object.keys(storedData).length,
+      0,
+      "No data should be found on invalid data migration"
+    );
+
+    await browser.storage.local.set({
+      test_key_string_on_IDBBackend: "expected-value",
+    });
+
+    browser.test.sendMessage("storage-local-data-migrated-and-set");
+  }
+
+  clearMigrationHistogram();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("storage-local-data-migrated-and-set");
+
+  const storagePrincipal = ExtensionStorageIDB.getStoragePrincipal(
+    extension.extension
+  );
+
+  const idbConn = await ExtensionStorageIDB.open(storagePrincipal);
+
+  equal(
+    await idbConn.isEmpty(extension.extension),
+    false,
+    "Data stored in the ExtensionStorageIDB backend as expected"
+  );
+
+  equal(
+    await OS.File.exists(`${oldStorageFilename}.corrupt`),
+    true,
+    "The old json storage should still be available if failed to be read"
+  );
+
+  // The extension is still migrated successfully to the new backend if the file from the
+  // original json file was corrupted.
+
+  equal(
+    Services.prefs.getBoolPref(
+      `${IDB_MIGRATED_PREF_BRANCH}.${EXTENSION_ID}`,
+      false
+    ),
+    true,
+    `Got the ${IDB_MIGRATED_PREF_BRANCH} preference set to true as expected`
+  );
+
+  assertMigrationHistogramCount("success", 1);
+  assertMigrationHistogramCount("failure", 0);
+
+  assertTelemetryEvents([
+    {
+      method: "migrateResult",
+      value: EXTENSION_ID,
+      extra: {
+        backend: "IndexedDB",
+        data_migrated: "y",
+        has_jsonfile: "y",
+        has_olddata: "n",
+      },
+    },
+  ]);
+
+  await extension.unload();
+});
+
+// Test that if the data migration fails to store the old data into the IndexedDB backend
+// then the expected telemetry histogram is being updated.
+add_task(async function test_storage_local_data_migration_failure() {
+  const EXTENSION_ID = "extension-data-migration-failure@mozilla.org";
+
+  // Create the file under the expected directory tree.
+  const {
+    jsonFile,
+    oldStorageFilename,
+  } = await createExtensionJSONFileWithData(EXTENSION_ID, {});
+
+  // Store a fake invalid value which is going to fail to be saved into IndexedDB
+  // (because it can't be cloned and it is going to raise a DataCloneError), which
+  // will trigger a data migration failure that we expect to increment the related
+  // telemetry histogram.
+  jsonFile.data.set("fake_invalid_key", new Error());
+
+  async function background() {
+    await browser.storage.local.set({
+      test_key_string_on_JSONFileBackend: "expected-value",
+    });
+    browser.test.sendMessage("storage-local-data-migrated-and-set");
+  }
+
+  clearMigrationHistogram();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("storage-local-data-migrated-and-set");
+
+  const storagePrincipal = ExtensionStorageIDB.getStoragePrincipal(
+    extension.extension
+  );
+
+  const idbConn = await ExtensionStorageIDB.open(storagePrincipal);
+  equal(
+    await idbConn.isEmpty(extension.extension),
+    true,
+    "No data stored in the ExtensionStorageIDB backend as expected"
+  );
+  equal(
+    await OS.File.exists(oldStorageFilename),
+    true,
+    "The old json storage should still be available if failed to be read"
+  );
+
+  await extension.unload();
+
+  assertTelemetryEvents([
+    {
+      method: "migrateResult",
+      value: EXTENSION_ID,
+      extra: {
+        backend: "JSONFile",
+        data_migrated: "n",
+        error_name: "DataCloneError",
+        has_jsonfile: "y",
+        has_olddata: "y",
+      },
+    },
+  ]);
+
+  assertMigrationHistogramCount("success", 0);
+  assertMigrationHistogramCount("failure", 1);
+});
+
+add_task(async function test_migration_aborted_on_shutdown() {
+  const EXTENSION_ID = "test-migration-aborted-on-shutdown@mochi.test";
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+      applications: {
+        gecko: {
+          id: EXTENSION_ID,
+        },
+      },
+    },
+  });
+
+  await extension.startup();
+
+  equal(
+    extension.extension.hasShutdown,
+    false,
+    "The extension is still running"
+  );
+
+  await extension.unload();
+  equal(extension.extension.hasShutdown, true, "The extension has shutdown");
+
+  // Trigger a data migration after the extension has been unloaded.
+  const result = await ExtensionStorageIDB.selectBackend({
+    extension: extension.extension,
+  });
+  Assert.deepEqual(
+    result,
+    { backendEnabled: false },
+    "Expect migration to have been aborted"
+  );
+  TelemetryTestUtils.assertEvents(
+    [
+      {
+        value: EXTENSION_ID,
+        extra: {
+          backend: "JSONFile",
+          error_name: "DataMigrationAbortedError",
+        },
+      },
+    ],
+    TELEMETRY_EVENTS_FILTER
+  );
+});
+
+add_task(async function test_storage_local_data_migration_clear_pref() {
+  Services.prefs.clearUserPref(LEAVE_STORAGE_PREF);
+  Services.prefs.clearUserPref(LEAVE_UUID_PREF);
+  Services.prefs.clearUserPref(ExtensionStorageIDB.BACKEND_ENABLED_PREF);
+  await promiseShutdownManager();
+  await TelemetryController.testShutdown();
+});
+
+add_task(async function setup_quota_manager_testing_prefs() {
+  Services.prefs.setBoolPref("dom.quotaManager.testing", true);
+  Services.prefs.setIntPref(
+    "dom.quotaManager.temporaryStorage.fixedLimit",
+    100
+  );
+  await promiseQuotaManagerServiceReset();
+});
+
+add_task(
+  // TODO: temporarily disabled because it currently perma-fails on
+  // android builds (Bug 1564871)
+  { skip_if: () => AppConstants.platform === "android" },
+  // eslint-disable-next-line no-use-before-define
+  test_quota_exceeded_while_migrating_data
+);
+async function test_quota_exceeded_while_migrating_data() {
+  const EXT_ID = "test-data-migration-stuck@mochi.test";
+  const dataSize = 1000 * 1024;
+
+  await createExtensionJSONFileWithData(EXT_ID, {
+    data: new Array(dataSize).fill("x").join(""),
+  });
+
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: EXT_ID } },
+    },
+    background() {
+      browser.test.onMessage.addListener(async (msg, dataSize) => {
+        if (msg !== "verify-stored-data") {
+          return;
+        }
+        const res = await browser.storage.local.get();
+        browser.test.assertEq(
+          res.data && res.data.length,
+          dataSize,
+          "Got the expected data"
+        );
+        browser.test.sendMessage("verify-stored-data:done");
+      });
+
+      browser.test.sendMessage("bg-page:ready");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("bg-page:ready");
+
+  extension.sendMessage("verify-stored-data", dataSize);
+  await extension.awaitMessage("verify-stored-data:done");
+
+  await ok(
+    !ExtensionStorageIDB.isMigratedExtension(extension),
+    "The extension falls back to the JSONFile backend because of the migration failure"
+  );
+  await extension.unload();
+
+  TelemetryTestUtils.assertEvents(
+    [
+      {
+        value: EXT_ID,
+        extra: {
+          backend: "JSONFile",
+          error_name: "QuotaExceededError",
+        },
+      },
+    ],
+    TELEMETRY_EVENTS_FILTER
+  );
+
+  Services.prefs.clearUserPref("dom.quotaManager.temporaryStorage.fixedLimit");
+  await promiseQuotaManagerServiceClear();
+  Services.prefs.clearUserPref("dom.quotaManager.testing");
+}
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_local.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_local.js
new file mode 100644
index 0000000000..a74528db7d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_local.js
@@ -0,0 +1,73 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionStorageIDB",
+  "resource://gre/modules/ExtensionStorageIDB.jsm"
+);
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_local_cache_invalidation() {
+  function background(checkGet) {
+    browser.test.onMessage.addListener(async msg => {
+      if (msg === "set-initial") {
+        await browser.storage.local.set({
+          "test-prop1": "value1",
+          "test-prop2": "value2",
+        });
+        browser.test.sendMessage("set-initial-done");
+      } else if (msg === "check") {
+        await checkGet("local", "test-prop1", "value1");
+        await checkGet("local", "test-prop2", "value2");
+        browser.test.sendMessage("check-done");
+      }
+    });
+
+    browser.test.sendMessage("ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+    },
+    background: `(${background})(${checkGetImpl})`,
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  extension.sendMessage("set-initial");
+  await extension.awaitMessage("set-initial-done");
+
+  Services.obs.notifyObservers(null, "extension-invalidate-storage-cache");
+
+  extension.sendMessage("check");
+  await extension.awaitMessage("check-done");
+
+  await extension.unload();
+});
+
+add_task(function test_storage_local_file_backend() {
+  return runWithPrefs([[ExtensionStorageIDB.BACKEND_ENABLED_PREF, false]], () =>
+    test_background_page_storage("local")
+  );
+});
+
+add_task(function test_storage_local_idb_backend() {
+  return runWithPrefs([[ExtensionStorageIDB.BACKEND_ENABLED_PREF, true]], () =>
+    test_background_page_storage("local")
+  );
+});
+
+add_task(function test_storage_local_idb_bytes_in_use() {
+  return runWithPrefs([[ExtensionStorageIDB.BACKEND_ENABLED_PREF, true]], () =>
+    test_background_storage_area_no_bytes_in_use("local")
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_managed.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_managed.js
new file mode 100644
index 0000000000..b35e4240c4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_managed.js
@@ -0,0 +1,170 @@
+"use strict";
+
+XPCOMUtils.defineLazyModuleGetters(this, {
+  MockRegistry: "resource://testing-common/MockRegistry.jsm",
+  OS: "resource://gre/modules/osfile.jsm",
+});
+
+const MANIFEST = {
+  name: "test-storage-managed@mozilla.com",
+  description: "",
+  type: "storage",
+  data: {
+    null: null,
+    str: "hello",
+    obj: {
+      a: [2, 3],
+      b: true,
+    },
+  },
+};
+
+AddonTestUtils.init(this);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function setup() {
+  await ExtensionTestUtils.startAddonManager();
+
+  let tmpDir = FileUtils.getDir("TmpD", ["native-manifests"]);
+  tmpDir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+  let dirProvider = {
+    getFile(property) {
+      if (property.endsWith("NativeManifests")) {
+        return tmpDir.clone();
+      }
+    },
+  };
+  Services.dirsvc.registerProvider(dirProvider);
+
+  let typeSlug =
+    AppConstants.platform === "linux" ? "managed-storage" : "ManagedStorage";
+  OS.File.makeDir(OS.Path.join(tmpDir.path, typeSlug));
+
+  let path = OS.Path.join(tmpDir.path, typeSlug, `${MANIFEST.name}.json`);
+  await OS.File.writeAtomic(path, JSON.stringify(MANIFEST));
+
+  let registry;
+  if (AppConstants.platform === "win") {
+    registry = new MockRegistry();
+    registry.setValue(
+      Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+      `Software\\\Mozilla\\\ManagedStorage\\${MANIFEST.name}`,
+      "",
+      path
+    );
+  }
+
+  registerCleanupFunction(() => {
+    Services.dirsvc.unregisterProvider(dirProvider);
+    tmpDir.remove(true);
+    if (registry) {
+      registry.shutdown();
+    }
+  });
+});
+
+add_task(async function test_storage_managed() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: MANIFEST.name } },
+      permissions: ["storage"],
+    },
+
+    async background() {
+      await browser.test.assertRejects(
+        browser.storage.managed.set({ a: 1 }),
+        /storage.managed is read-only/,
+        "browser.storage.managed.set() rejects because it's read only"
+      );
+
+      await browser.test.assertRejects(
+        browser.storage.managed.remove("str"),
+        /storage.managed is read-only/,
+        "browser.storage.managed.remove() rejects because it's read only"
+      );
+
+      await browser.test.assertRejects(
+        browser.storage.managed.clear(),
+        /storage.managed is read-only/,
+        "browser.storage.managed.clear() rejects because it's read only"
+      );
+
+      browser.test.sendMessage(
+        "results",
+        await Promise.all([
+          browser.storage.managed.get(),
+          browser.storage.managed.get("str"),
+          browser.storage.managed.get(["null", "obj"]),
+          browser.storage.managed.get({ str: "a", num: 2 }),
+        ])
+      );
+    },
+  });
+
+  await extension.startup();
+  deepEqual(await extension.awaitMessage("results"), [
+    MANIFEST.data,
+    { str: "hello" },
+    { null: null, obj: MANIFEST.data.obj },
+    { str: "hello", num: 2 },
+  ]);
+  await extension.unload();
+});
+
+add_task(async function test_storage_managed_from_content_script() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: MANIFEST.name } },
+      permissions: ["storage"],
+      content_scripts: [
+        {
+          js: ["contentscript.js"],
+          matches: ["*://*/*"],
+          run_at: "document_end",
+        },
+      ],
+    },
+
+    files: {
+      "contentscript.js": async function() {
+        browser.test.sendMessage(
+          "results",
+          await browser.storage.managed.get()
+        );
+      },
+    },
+  });
+
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+  deepEqual(await extension.awaitMessage("results"), MANIFEST.data);
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_manifest_not_found() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+    },
+
+    async background() {
+      await browser.test.assertRejects(
+        browser.storage.managed.get({ a: 1 }),
+        /Managed storage manifest not found/,
+        "browser.storage.managed.get() rejects when without manifest"
+      );
+
+      browser.test.notifyPass();
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_managed_policy.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_managed_policy.js
new file mode 100644
index 0000000000..d99956671d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_managed_policy.js
@@ -0,0 +1,55 @@
+"use strict";
+
+const PREF_DISABLE_SECURITY =
+  "security.turn_off_all_security_so_that_" +
+  "viruses_can_take_over_this_computer";
+
+const { EnterprisePolicyTesting } = ChromeUtils.import(
+  "resource://testing-common/EnterprisePolicyTesting.jsm"
+);
+
+// Setting PREF_DISABLE_SECURITY tells the policy engine that we are in testing
+// mode and enables restarting the policy engine without restarting the browser.
+Services.prefs.setBoolPref(PREF_DISABLE_SECURITY, true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref(PREF_DISABLE_SECURITY);
+});
+
+// Load policy engine
+Services.policies; // eslint-disable-line no-unused-expressions
+
+AddonTestUtils.init(this);
+
+add_task(async function test_storage_managed_policy() {
+  await ExtensionTestUtils.startAddonManager();
+
+  await EnterprisePolicyTesting.setupPolicyEngineWithJson({
+    policies: {
+      "3rdparty": {
+        Extensions: {
+          "test-storage-managed-policy@mozilla.com": {
+            string: "value",
+          },
+        },
+      },
+    },
+  });
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: { id: "test-storage-managed-policy@mozilla.com" },
+      },
+      permissions: ["storage"],
+    },
+
+    async background() {
+      let str = await browser.storage.managed.get("string");
+      browser.test.sendMessage("results", str);
+    },
+  });
+
+  await extension.startup();
+  deepEqual(await extension.awaitMessage("results"), { string: "value" });
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_quota_exceeded_errors.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_quota_exceeded_errors.js
new file mode 100644
index 0000000000..b9dc8a0212
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_quota_exceeded_errors.js
@@ -0,0 +1,82 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionStorageIDB",
+  "resource://gre/modules/ExtensionStorageIDB.jsm"
+);
+
+const LEAVE_STORAGE_PREF = "extensions.webextensions.keepStorageOnUninstall";
+const LEAVE_UUID_PREF = "extensions.webextensions.keepUuidOnUninstall";
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  // Ensure that the IDB backend is enabled.
+  Services.prefs.setBoolPref("ExtensionStorageIDB.BACKEND_ENABLED_PREF", true);
+
+  Services.prefs.setBoolPref("dom.quotaManager.testing", true);
+  Services.prefs.setIntPref(
+    "dom.quotaManager.temporaryStorage.fixedLimit",
+    100
+  );
+  await promiseQuotaManagerServiceReset();
+
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_storage_local_set_quota_exceeded_error() {
+  const EXT_ID = "test-quota-exceeded@mochi.test";
+
+  const extensionDef = {
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: EXT_ID } },
+    },
+    async background() {
+      const data = new Array(1000 * 1024).fill("x").join("");
+      await browser.test.assertRejects(
+        browser.storage.local.set({ data }),
+        /QuotaExceededError/,
+        "Got a rejection with the expected error message"
+      );
+      browser.test.sendMessage("data-stored");
+    },
+  };
+
+  Services.prefs.setBoolPref(LEAVE_STORAGE_PREF, true);
+  Services.prefs.setBoolPref(LEAVE_UUID_PREF, true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref(LEAVE_STORAGE_PREF);
+    Services.prefs.clearUserPref(LEAVE_UUID_PREF);
+  });
+
+  const extension = ExtensionTestUtils.loadExtension(extensionDef);
+
+  // Run test on a test extension being migrated to the IDB backend.
+  await extension.startup();
+  await extension.awaitMessage("data-stored");
+
+  ok(
+    ExtensionStorageIDB.isMigratedExtension(extension),
+    "The extension has been successfully migrated to the IDB backend"
+  );
+  await extension.unload();
+
+  // Run again on a test extension already already migrated to the IDB backend.
+  const extensionUpdated = ExtensionTestUtils.loadExtension(extensionDef);
+  await extensionUpdated.startup();
+  ok(
+    ExtensionStorageIDB.isMigratedExtension(extension),
+    "The extension has been successfully migrated to the IDB backend"
+  );
+  await extensionUpdated.awaitMessage("data-stored");
+
+  await extensionUpdated.unload();
+
+  Services.prefs.clearUserPref("dom.quotaManager.temporaryStorage.fixedLimit");
+  await promiseQuotaManagerServiceClear();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_sanitizer.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sanitizer.js
new file mode 100644
index 0000000000..38d1de29fa
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sanitizer.js
@@ -0,0 +1,106 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "Sanitizer",
+  "resource:///modules/Sanitizer.jsm"
+);
+
+async function test_sanitize_offlineApps(storageHelpersScript) {
+  const extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["storage"],
+      background: {
+        scripts: ["storageHelpers.js", "background.js"],
+      },
+    },
+    files: {
+      "storageHelpers.js": storageHelpersScript,
+      "background.js": function() {
+        browser.test.onMessage.addListener(async (msg, args) => {
+          let result = {};
+          switch (msg) {
+            case "set-storage-data":
+              await window.testWriteKey(...args);
+              break;
+            case "get-storage-data":
+              const value = await window.testReadKey(args[0]);
+              browser.test.assertEq(args[1], value, "Got the expected value");
+              break;
+            default:
+              browser.test.fail(`Unexpected test message received: ${msg}`);
+          }
+
+          browser.test.sendMessage(`${msg}:done`, result);
+        });
+      },
+    },
+  });
+
+  await extension.startup();
+
+  extension.sendMessage("set-storage-data", ["aKey", "aValue"]);
+  await extension.awaitMessage("set-storage-data:done");
+
+  await extension.sendMessage("get-storage-data", ["aKey", "aValue"]);
+  await extension.awaitMessage("get-storage-data:done");
+
+  info("Verify the extension data not cleared by offlineApps Sanitizer");
+  await Sanitizer.sanitize(["offlineApps"]);
+  await extension.sendMessage("get-storage-data", ["aKey", "aValue"]);
+  await extension.awaitMessage("get-storage-data:done");
+
+  await extension.unload();
+}
+
+add_task(async function test_sanitize_offlineApps_extension_indexedDB() {
+  await test_sanitize_offlineApps(function indexedDBStorageHelpers() {
+    const getIDBStore = () =>
+      new Promise(resolve => {
+        let dbreq = window.indexedDB.open("TestDB");
+        dbreq.onupgradeneeded = () =>
+          dbreq.result.createObjectStore("TestStore");
+        dbreq.onsuccess = () => resolve(dbreq.result);
+      });
+
+    // Export writeKey and readKey storage test helpers.
+    window.testWriteKey = (k, v) =>
+      getIDBStore().then(db => {
+        const tx = db.transaction("TestStore", "readwrite");
+        const store = tx.objectStore("TestStore");
+        return new Promise((resolve, reject) => {
+          tx.oncomplete = evt => resolve(evt.target.result);
+          tx.onerror = evt => reject(evt.target.error);
+          store.add(v, k);
+        });
+      });
+    window.testReadKey = k =>
+      getIDBStore().then(db => {
+        const tx = db.transaction("TestStore");
+        const store = tx.objectStore("TestStore");
+        return new Promise((resolve, reject) => {
+          const req = store.get(k);
+          tx.oncomplete = evt => resolve(req.result);
+          tx.onerror = evt => reject(evt.target.error);
+        });
+      });
+  });
+});
+
+add_task(
+  {
+    // Skip this test if LSNG is not enabled (because this test is only
+    // going to pass when nextgen local storage is being used).
+    skip_if: () => !Services.prefs.getBoolPref("dom.storage.next_gen"),
+  },
+  async function test_sanitize_offlineApps_extension_localStorage() {
+    await test_sanitize_offlineApps(function indexedDBStorageHelpers() {
+      // Export writeKey and readKey storage test helpers.
+      window.testWriteKey = (k, v) => window.localStorage.setItem(k, v);
+      window.testReadKey = k => window.localStorage.getItem(k);
+    });
+  }
+);
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync.js
new file mode 100644
index 0000000000..ad821c5a07
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync.js
@@ -0,0 +1,29 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+Services.prefs.setBoolPref("webextensions.storage.sync.kinto", false);
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(test_config_flag_needed);
+
+add_task(test_sync_reloading_extensions_works);
+
+add_task(function test_storage_sync() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_background_page_storage("sync")
+  );
+});
+
+add_task(test_storage_sync_requires_real_id);
+
+add_task(function test_bytes_in_use() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_background_storage_area_with_bytes_in_use("sync", true)
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto.js
new file mode 100644
index 0000000000..db7091db8d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto.js
@@ -0,0 +1,2290 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// This is a kinto-specific test...
+Services.prefs.setBoolPref("webextensions.storage.sync.kinto", true);
+
+do_get_profile(); // so we can use FxAccounts
+
+const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
+const { CommonUtils } = ChromeUtils.import(
+  "resource://services-common/utils.js"
+);
+const {
+  cleanUpForContext,
+  CollectionKeyEncryptionRemoteTransformer,
+  CryptoCollection,
+  ExtensionStorageSync,
+  idToKey,
+  keyToId,
+  KeyRingEncryptionRemoteTransformer,
+} = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageSyncKinto.jsm",
+  null
+);
+const { BulkKeyBundle } = ChromeUtils.import(
+  "resource://services-sync/keys.js"
+);
+const { FxAccountsKeys } = ChromeUtils.import(
+  "resource://gre/modules/FxAccountsKeys.jsm"
+);
+const { Utils } = ChromeUtils.import("resource://services-sync/util.js");
+
+const { createAppInfo, promiseStartupManager } = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "69");
+
+function handleCannedResponse(cannedResponse, request, response) {
+  response.setStatusLine(
+    null,
+    cannedResponse.status.status,
+    cannedResponse.status.statusText
+  );
+  // send the headers
+  for (let headerLine of cannedResponse.sampleHeaders) {
+    let headerElements = headerLine.split(":");
+    response.setHeader(headerElements[0], headerElements[1].trimLeft());
+  }
+  response.setHeader("Date", new Date().toUTCString());
+
+  response.write(cannedResponse.responseBody);
+}
+
+function collectionPath(collectionId) {
+  return `/buckets/default/collections/${collectionId}`;
+}
+
+function collectionRecordsPath(collectionId) {
+  return `/buckets/default/collections/${collectionId}/records`;
+}
+
+class KintoServer {
+  constructor() {
+    // Set up an HTTP Server
+    this.httpServer = new HttpServer();
+    this.httpServer.start(-1);
+
+    // Set<Object> corresponding to records that might be served.
+    // The format of these objects is defined in the documentation for #addRecord.
+    this.records = [];
+
+    // Collections that we have set up access to (see `installCollection`).
+    this.collections = new Set();
+
+    // ETag to serve with responses
+    this.etag = 1;
+
+    this.port = this.httpServer.identity.primaryPort;
+
+    // POST requests we receive from the client go here
+    this.posts = [];
+    // DELETEd buckets will go here.
+    this.deletedBuckets = [];
+    // Anything in here will force the next POST to generate a conflict
+    this.conflicts = [];
+    // If this is true, reject the next request with a 401
+    this.rejectNextAuthResponse = false;
+    this.failedAuths = [];
+
+    this.installConfigPath();
+    this.installBatchPath();
+    this.installCatchAll();
+  }
+
+  clearPosts() {
+    this.posts = [];
+  }
+
+  getPosts() {
+    return this.posts;
+  }
+
+  getDeletedBuckets() {
+    return this.deletedBuckets;
+  }
+
+  rejectNextAuthWith(response) {
+    this.rejectNextAuthResponse = response;
+  }
+
+  checkAuth(request, response) {
+    equal(request.getHeader("Authorization"), "Bearer some-access-token");
+
+    if (this.rejectNextAuthResponse) {
+      response.setStatusLine(null, 401, "Unauthorized");
+      response.write(this.rejectNextAuthResponse);
+      this.rejectNextAuthResponse = false;
+      this.failedAuths.push(request);
+      return true;
+    }
+    return false;
+  }
+
+  installConfigPath() {
+    const configPath = "/v1/";
+    const responseBody = JSON.stringify({
+      settings: { batch_max_requests: 25 },
+      url: `http://localhost:${this.port}/v1/`,
+      documentation: "https://kinto.readthedocs.org/",
+      version: "1.5.1",
+      commit: "cbc6f58",
+      hello: "kinto",
+    });
+    const configResponse = {
+      sampleHeaders: [
+        "Access-Control-Allow-Origin: *",
+        "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+        "Content-Type: application/json; charset=UTF-8",
+        "Server: waitress",
+      ],
+      status: { status: 200, statusText: "OK" },
+      responseBody: responseBody,
+    };
+
+    function handleGetConfig(request, response) {
+      if (request.method != "GET") {
+        dump(`ARGH, got ${request.method}\n`);
+      }
+      return handleCannedResponse(configResponse, request, response);
+    }
+
+    this.httpServer.registerPathHandler(configPath, handleGetConfig);
+  }
+
+  installBatchPath() {
+    const batchPath = "/v1/batch";
+
+    function handlePost(request, response) {
+      if (this.checkAuth(request, response)) {
+        return;
+      }
+
+      let bodyStr = CommonUtils.readBytesFromInputStream(
+        request.bodyInputStream
+      );
+      let body = JSON.parse(bodyStr);
+      let defaults = body.defaults;
+      for (let req of body.requests) {
+        let headers = Object.assign(
+          {},
+          (defaults && defaults.headers) || {},
+          req.headers
+        );
+        this.posts.push(Object.assign({}, req, { headers }));
+      }
+
+      response.setStatusLine(null, 200, "OK");
+      response.setHeader("Content-Type", "application/json; charset=UTF-8");
+      response.setHeader("Date", new Date().toUTCString());
+
+      let postResponse = {
+        responses: body.requests.map(req => {
+          let oneBody;
+          if (req.method == "DELETE") {
+            let id = req.path.match(
+              /^\/buckets\/default\/collections\/.+\/records\/(.+)$/
+            )[1];
+            oneBody = {
+              data: {
+                deleted: true,
+                id: id,
+                last_modified: this.etag,
+              },
+            };
+          } else {
+            oneBody = {
+              data: Object.assign({}, req.body.data, {
+                last_modified: this.etag,
+              }),
+              permissions: [],
+            };
+          }
+
+          return {
+            path: req.path,
+            status: 201, // FIXME -- only for new posts??
+            headers: { ETag: 3000 }, // FIXME???
+            body: oneBody,
+          };
+        }),
+      };
+
+      if (this.conflicts.length) {
+        const nextConflict = this.conflicts.shift();
+        if (!nextConflict.transient) {
+          this.records.push(nextConflict);
+        }
+        const { data } = nextConflict;
+        postResponse = {
+          responses: body.requests.map(req => {
+            return {
+              path: req.path,
+              status: 412,
+              headers: { ETag: this.etag }, // is this correct??
+              body: {
+                details: {
+                  existing: data,
+                },
+              },
+            };
+          }),
+        };
+      }
+
+      response.write(JSON.stringify(postResponse));
+
+      //   "sampleHeaders": [
+      //     "Access-Control-Allow-Origin: *",
+      //     "Access-Control-Expose-Headers: Retry-After, Content-Length, Alert, Backoff",
+      //     "Server: waitress",
+      //     "Etag: \"4000\""
+      //   ],
+    }
+
+    this.httpServer.registerPathHandler(batchPath, handlePost.bind(this));
+  }
+
+  installCatchAll() {
+    this.httpServer.registerPathHandler("/", (request, response) => {
+      dump(
+        `got request: ${request.method}:${request.path}?${request.queryString}\n`
+      );
+      dump(
+        `${CommonUtils.readBytesFromInputStream(request.bodyInputStream)}\n`
+      );
+    });
+  }
+
+  /**
+   * Add a record to those that can be served by this server.
+   *
+   * @param {Object} properties  An object describing the record that
+   *   should be served. The properties of this object are:
+   * - collectionId {string} This record should only be served if a
+   *   request is for this collection.
+   * - predicate {Function} If present, this record should only be served if the
+   *   predicate returns true. The predicate will be called with
+   *   {request: Request, response: Response, since: number, server: KintoServer}.
+   * - data {string} The record to serve.
+   * - conflict {boolean} If present and true, this record is added to
+   *   "conflicts" and won't be served, but will cause a conflict on
+   *   the next push.
+   */
+  addRecord(properties) {
+    if (!properties.conflict) {
+      this.records.push(properties);
+    } else {
+      this.conflicts.push(properties);
+    }
+
+    this.installCollection(properties.collectionId);
+  }
+
+  /**
+   * Tell the server to set up a route for this collection.
+   *
+   * This will automatically be called for any collection to which you `addRecord`.
+   *
+   * @param {string} collectionId   the collection whose route we
+   *    should set up.
+   */
+  installCollection(collectionId) {
+    if (this.collections.has(collectionId)) {
+      return;
+    }
+    this.collections.add(collectionId);
+    const remoteCollectionPath =
+      "/v1" + collectionPath(encodeURIComponent(collectionId));
+    this.httpServer.registerPathHandler(
+      remoteCollectionPath,
+      this.handleGetCollection.bind(this, collectionId)
+    );
+    const remoteRecordsPath =
+      "/v1" + collectionRecordsPath(encodeURIComponent(collectionId));
+    this.httpServer.registerPathHandler(
+      remoteRecordsPath,
+      this.handleGetRecords.bind(this, collectionId)
+    );
+  }
+
+  handleGetCollection(collectionId, request, response) {
+    if (this.checkAuth(request, response)) {
+      return;
+    }
+
+    response.setStatusLine(null, 200, "OK");
+    response.setHeader("Content-Type", "application/json; charset=UTF-8");
+    response.setHeader("Date", new Date().toUTCString());
+    response.write(
+      JSON.stringify({
+        data: {
+          id: collectionId,
+        },
+      })
+    );
+  }
+
+  handleGetRecords(collectionId, request, response) {
+    if (this.checkAuth(request, response)) {
+      return;
+    }
+
+    if (request.method != "GET") {
+      do_throw(`only GET is supported on ${request.path}`);
+    }
+
+    let sinceMatch = request.queryString.match(/(^|&)_since=(\d+)/);
+    let since = sinceMatch && parseInt(sinceMatch[2], 10);
+
+    response.setStatusLine(null, 200, "OK");
+    response.setHeader("Content-Type", "application/json; charset=UTF-8");
+    response.setHeader("Date", new Date().toUTCString());
+    response.setHeader("ETag", this.etag.toString());
+
+    const records = this.records
+      .filter(properties => {
+        if (properties.collectionId != collectionId) {
+          return false;
+        }
+
+        if (properties.predicate) {
+          const predAllowed = properties.predicate({
+            request: request,
+            response: response,
+            since: since,
+            server: this,
+          });
+          if (!predAllowed) {
+            return false;
+          }
+        }
+
+        return true;
+      })
+      .map(properties => properties.data);
+
+    const body = JSON.stringify({
+      data: records,
+    });
+    response.write(body);
+  }
+
+  installDeleteBucket() {
+    this.httpServer.registerPrefixHandler(
+      "/v1/buckets/",
+      (request, response) => {
+        if (request.method != "DELETE") {
+          dump(
+            `got a non-delete action on bucket: ${request.method} ${request.path}\n`
+          );
+          return;
+        }
+
+        const noPrefix = request.path.slice("/v1/buckets/".length);
+        const [bucket, afterBucket] = noPrefix.split("/", 1);
+        if (afterBucket && afterBucket != "") {
+          dump(
+            `got a delete for a non-bucket: ${request.method} ${request.path}\n`
+          );
+        }
+
+        this.deletedBuckets.push(bucket);
+        // Fake like this actually deletes the records.
+        this.records = [];
+
+        response.write(
+          JSON.stringify({
+            data: {
+              deleted: true,
+              last_modified: 1475161309026,
+              id: "b09f1618-d789-302d-696e-74ec53ee18a8", // FIXME
+            },
+          })
+        );
+      }
+    );
+  }
+
+  // Utility function to install a keyring at the start of a test.
+  async installKeyRing(fxaService, keysData, salts, etag, properties) {
+    const keysRecord = {
+      id: "keys",
+      keys: keysData,
+      salts: salts,
+      last_modified: etag,
+    };
+    this.etag = etag;
+    const transformer = new KeyRingEncryptionRemoteTransformer(fxaService);
+    return this.encryptAndAddRecord(
+      transformer,
+      Object.assign({}, properties, {
+        collectionId: "storage-sync-crypto",
+        data: keysRecord,
+      })
+    );
+  }
+
+  encryptAndAddRecord(transformer, properties) {
+    return transformer.encode(properties.data).then(encrypted => {
+      this.addRecord(Object.assign({}, properties, { data: encrypted }));
+    });
+  }
+
+  stop() {
+    this.httpServer.stop(() => {});
+  }
+}
+
+/**
+ * Predicate that represents a record appearing at some time.
+ * Requests with "_since" before this time should see this record,
+ * unless the server itself isn't at this time yet (etag is before
+ * this time).
+ *
+ * Requests with _since after this time shouldn't see this record any
+ * more, since it hasn't changed after this time.
+ *
+ * @param {int} startTime  the etag at which time this record should
+ *    start being available (and thus, the predicate should start
+ *    returning true)
+ * @returns {Function}
+ */
+function appearsAt(startTime) {
+  return function({ since, server }) {
+    return since < startTime && startTime < server.etag;
+  };
+}
+
+// Run a block of code with access to a KintoServer.
+async function withServer(f) {
+  let server = new KintoServer();
+  // Point the sync.storage client to use the test server we've just started.
+  Services.prefs.setCharPref(
+    "webextensions.storage.sync.serverURL",
+    `http://localhost:${server.port}/v1`
+  );
+  try {
+    await f(server);
+  } finally {
+    server.stop();
+  }
+}
+
+// Run a block of code with access to both a sync context and a
+// KintoServer. This is meant as a workaround for eslint's refusal to
+// let me have 5 nested callbacks.
+async function withContextAndServer(f) {
+  await withSyncContext(async function(context) {
+    await withServer(async function(server) {
+      await f(context, server);
+    });
+  });
+}
+
+// Run a block of code with fxa mocked out to return a specific user.
+// Calls the given function with an ExtensionStorageSync instance that
+// was constructed using a mocked FxAccounts instance.
+async function withSignedInUser(user, f) {
+  let fxaServiceMock = {
+    getSignedInUser() {
+      return Promise.resolve({ uid: user.uid });
+    },
+    getOAuthToken() {
+      return Promise.resolve("some-access-token");
+    },
+    checkAccountStatus() {
+      return Promise.resolve(true);
+    },
+    removeCachedOAuthToken() {
+      return Promise.resolve();
+    },
+    keys: {
+      getKeyForScope(scope) {
+        return Promise.resolve({ ...user.scopedKeys[scope] });
+      },
+      kidAsHex(jwk) {
+        return new FxAccountsKeys({}).kidAsHex(jwk);
+      },
+    },
+  };
+
+  let telemetryMock = {
+    _calls: [],
+    _histograms: {},
+    scalarSet(name, value) {
+      this._calls.push({ method: "scalarSet", name, value });
+    },
+    keyedScalarSet(name, key, value) {
+      this._calls.push({ method: "keyedScalarSet", name, key, value });
+    },
+    getKeyedHistogramById(name) {
+      let self = this;
+      return {
+        add(key, value) {
+          if (!self._histograms[name]) {
+            self._histograms[name] = [];
+          }
+          self._histograms[name].push(value);
+        },
+      };
+    },
+  };
+  let extensionStorageSync = new ExtensionStorageSync(
+    fxaServiceMock,
+    telemetryMock
+  );
+  await f(extensionStorageSync, fxaServiceMock);
+}
+
+// Some assertions that make it easier to write tests about what was
+// posted and when.
+
+// Assert that a post in a batch was made with the correct access token.
+// This should be true of all requests, so this is usually called from
+// another assertion.
+function assertAuthenticatedPost(post) {
+  equal(post.headers.Authorization, "Bearer some-access-token");
+}
+
+// Assert that this post was made with the correct request headers to
+// create a new resource while protecting against someone else
+// creating it at the same time (in other words, "If-None-Match: *").
+// Also calls assertAuthenticatedPost(post).
+function assertPostedNewRecord(post) {
+  assertAuthenticatedPost(post);
+  equal(post.headers["If-None-Match"], "*");
+}
+
+// Assert that this post was made with the correct request headers to
+// update an existing resource while protecting against concurrent
+// modification (in other words, `If-Match: "${etag}"`).
+// Also calls assertAuthenticatedPost(post).
+function assertPostedUpdatedRecord(post, since) {
+  assertAuthenticatedPost(post);
+  equal(post.headers["If-Match"], `"${since}"`);
+}
+
+// Assert that this post was an encrypted keyring, and produce the
+// decrypted body. Sanity check the body while we're here.
+const assertPostedEncryptedKeys = async function(fxaService, post) {
+  equal(post.path, collectionRecordsPath("storage-sync-crypto") + "/keys");
+
+  let body = await new KeyRingEncryptionRemoteTransformer(fxaService).decode(
+    post.body.data
+  );
+  ok(body.keys, `keys object should be present in decoded body`);
+  ok(body.keys.default, `keys object should have a default key`);
+  ok(body.salts, `salts object should be present in decoded body`);
+  return body;
+};
+
+// assertEqual, but for keyring[extensionId] == key.
+function assertKeyRingKey(keyRing, extensionId, expectedKey, message) {
+  if (!message) {
+    message = `expected keyring's key for ${extensionId} to match ${expectedKey.keyPairB64}`;
+  }
+  ok(
+    keyRing.hasKeysFor([extensionId]),
+    `expected keyring to have a key for ${extensionId}\n`
+  );
+  deepEqual(
+    keyRing.keyForCollection(extensionId).keyPairB64,
+    expectedKey.keyPairB64,
+    message
+  );
+}
+
+// Assert that this post was posted for a given extension.
+const assertExtensionRecord = async function(fxaService, post, extension, key) {
+  const extensionId = extension.id;
+  const cryptoCollection = new CryptoCollection(fxaService);
+  const hashedId =
+    "id-" +
+    (await cryptoCollection.hashWithExtensionSalt(keyToId(key), extensionId));
+  const collectionId = await cryptoCollection.extensionIdToCollectionId(
+    extensionId
+  );
+  const transformer = new CollectionKeyEncryptionRemoteTransformer(
+    cryptoCollection,
+    await cryptoCollection.getKeyRing(),
+    extensionId
+  );
+  equal(
+    post.path,
+    `${collectionRecordsPath(collectionId)}/${hashedId}`,
+    "decrypted data should be posted to path corresponding to its key"
+  );
+  let decoded = await transformer.decode(post.body.data);
+  equal(
+    decoded.key,
+    key,
+    "decrypted data should have a key attribute corresponding to the extension data key"
+  );
+  return decoded;
+};
+
+// Tests using this ID will share keys in local storage, so be careful.
+const defaultExtensionId = "{13bdde76-4dc7-11e6-9bdc-54ee758d6342}";
+const defaultExtension = { id: defaultExtensionId };
+
+const loggedInUser = {
+  uid: "0123456789abcdef0123456789abcdef",
+  scopedKeys: {
+    "sync:addon_storage": {
+      kid: "1234567890123-I1DLqPztWi-647HxgLr4YPePZUK-975wn9qWzT49yAA",
+      k:
+        "Y_kFdXfAS7u58MP9hbXUAytg4T7cH43TCb9DBdZvLMMS3eFs5GAhpJb3E5UNCmxWbOGBUhpEcm576Xz1d7MbMQ",
+      kty: "oct",
+    },
+  },
+  oauthTokens: {
+    "sync:addon_storage": {
+      token: "some-access-token",
+    },
+  },
+};
+
+function uuid() {
+  const uuidgen = Cc["@mozilla.org/uuid-generator;1"].getService(
+    Ci.nsIUUIDGenerator
+  );
+  return uuidgen.generateUUID().toString();
+}
+
+add_task(async function test_setup() {
+  await promiseStartupManager();
+});
+
+add_task(async function test_single_initialization() {
+  // Grab access to this via the backstage pass to check if we're calling openConnection too often.
+  const { FirefoxAdapter } = ChromeUtils.import(
+    "resource://gre/modules/ExtensionStorageSyncKinto.jsm",
+    null
+  );
+  const origOpenConnection = FirefoxAdapter.openConnection;
+  let callCount = 0;
+  FirefoxAdapter.openConnection = function(...args) {
+    ++callCount;
+    return origOpenConnection.apply(this, args);
+  };
+  function background() {
+    let promises = ["foo", "bar", "baz", "quux"].map(key =>
+      browser.storage.sync.get(key)
+    );
+    Promise.all(promises).then(() =>
+      browser.test.notifyPass("initialize once")
+    );
+  }
+  try {
+    let extension = ExtensionTestUtils.loadExtension({
+      manifest: {
+        permissions: ["storage"],
+      },
+      background: `(${background})()`,
+    });
+
+    await extension.startup();
+    await extension.awaitFinish("initialize once");
+    await extension.unload();
+    equal(
+      callCount,
+      1,
+      "Initialized FirefoxAdapter connection and Kinto exactly once"
+    );
+  } finally {
+    FirefoxAdapter.openConnection = origOpenConnection;
+  }
+});
+
+add_task(async function test_key_to_id() {
+  equal(keyToId("foo"), "key-foo");
+  equal(keyToId("my-new-key"), "key-my_2D_new_2D_key");
+  equal(keyToId(""), "key-");
+  equal(keyToId("™"), "key-_2122_");
+  equal(keyToId("\b"), "key-_8_");
+  equal(keyToId("abc\ndef"), "key-abc_A_def");
+  equal(keyToId("Kinto's fancy_string"), "key-Kinto_27_s_20_fancy_5F_string");
+
+  const KEYS = ["foo", "my-new-key", "", "Kinto's fancy_string", "™", "\b"];
+  for (let key of KEYS) {
+    equal(idToKey(keyToId(key)), key);
+  }
+
+  equal(idToKey("hi"), null);
+  equal(idToKey("-key-hi"), null);
+  equal(idToKey("key--abcd"), null);
+  equal(idToKey("key-%"), null);
+  equal(idToKey("key-_HI"), null);
+  equal(idToKey("key-_HI_"), null);
+  equal(idToKey("key-"), "");
+  equal(idToKey("key-1"), "1");
+  equal(idToKey("key-_2D_"), "-");
+});
+
+add_task(async function test_extension_id_to_collection_id() {
+  const extensionId = "{9419cce6-5435-11e6-84bf-54ee758d6342}";
+  // FIXME: this doesn't actually require the signed in user, but the
+  // extensionIdToCollectionId method exists on CryptoCollection,
+  // which needs an fxaService to be instantiated.
+  await withSignedInUser(loggedInUser, async function(
+    extensionStorageSync,
+    fxaService
+  ) {
+    // Fake a static keyring since the server doesn't exist.
+    const salt = "Scgx8RJ8Y0rxMGFYArUiKeawlW+0zJyFmtTDvro9qPo=";
+    const cryptoCollection = new CryptoCollection(fxaService);
+    await cryptoCollection._setSalt(extensionId, salt);
+
+    equal(
+      await cryptoCollection.extensionIdToCollectionId(extensionId),
+      "ext-0_QHA1P93_yJoj7ONisrR0lW6uN4PZ3Ii-rT-QOjtvo"
+    );
+  });
+});
+
+add_task(async function ensureCanSync_clearAll() {
+  // A test extension that will not have any active context around
+  // but it is returned from a call to AddonManager.getExtensionsByType.
+  const extensionId = "test-wipe-on-enabled-and-synced@mochi.test";
+  const testExtension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: extensionId } },
+    },
+  });
+
+  await testExtension.startup();
+
+  // Retrieve the Extension class instance from the test extension.
+  const { extension } = testExtension;
+
+  // Another test extension that will have an active extension context.
+  const extensionId2 = "test-wipe-on-active-context@mochi.test";
+  const extension2 = { id: extensionId2 };
+
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      async function assertSetAndGetData(extension, data) {
+        await extensionStorageSync.set(extension, data, context);
+        let storedData = await extensionStorageSync.get(
+          extension,
+          Object.keys(data),
+          context
+        );
+        const extId = extensionId;
+        deepEqual(storedData, data, `${extId} should get back the data we set`);
+      }
+
+      async function assertDataCleared(extension, keys) {
+        const storedData = await extensionStorageSync.get(
+          extension,
+          keys,
+          context
+        );
+        deepEqual(storedData, {}, `${extension.id} should have lost the data`);
+      }
+
+      server.installCollection("storage-sync-crypto");
+      server.etag = 1000;
+
+      let newKeys = await extensionStorageSync.ensureCanSync([
+        extensionId,
+        extensionId2,
+      ]);
+      ok(
+        newKeys.hasKeysFor([extensionId]),
+        `key isn't present for ${extensionId}`
+      );
+      ok(
+        newKeys.hasKeysFor([extensionId2]),
+        `key isn't present for ${extensionId2}`
+      );
+
+      let posts = server.getPosts();
+      equal(posts.length, 1);
+      assertPostedNewRecord(posts[0]);
+
+      await assertSetAndGetData(extension, { "my-key": 1 });
+      await assertSetAndGetData(extension2, { "my-key": 2 });
+
+      // Call cleanup for the first extension, to double check it has
+      // been wiped out even without an active extension context.
+      cleanUpForContext(extension, context);
+
+      // clear everything.
+      await extensionStorageSync.clearAll();
+
+      // Assert that the data is gone for both the extensions.
+      await assertDataCleared(extension, ["my-key"]);
+      await assertDataCleared(extension2, ["my-key"]);
+
+      // should have been no posts caused by the clear.
+      posts = server.getPosts();
+      equal(posts.length, 1);
+    });
+  });
+
+  await testExtension.unload();
+});
+
+add_task(async function ensureCanSync_posts_new_keys() {
+  const extensionId = uuid();
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      server.installCollection("storage-sync-crypto");
+      server.etag = 1000;
+
+      let newKeys = await extensionStorageSync.ensureCanSync([extensionId]);
+      ok(
+        newKeys.hasKeysFor([extensionId]),
+        `key isn't present for ${extensionId}`
+      );
+
+      let posts = server.getPosts();
+      equal(posts.length, 1);
+      const post = posts[0];
+      assertPostedNewRecord(post);
+      const body = await assertPostedEncryptedKeys(fxaService, post);
+      const oldSalt = body.salts[extensionId];
+      ok(
+        body.keys.collections[extensionId],
+        `keys object should have a key for ${extensionId}`
+      );
+      ok(oldSalt, `salts object should have a salt for ${extensionId}`);
+
+      // Try adding another key to make sure that the first post was
+      // OK, even on a new profile.
+      await extensionStorageSync.cryptoCollection._clear();
+      server.clearPosts();
+      // Restore the first posted keyring, but add a last_modified date
+      const firstPostedKeyring = Object.assign({}, post.body.data, {
+        last_modified: server.etag,
+      });
+      server.addRecord({
+        data: firstPostedKeyring,
+        collectionId: "storage-sync-crypto",
+        predicate: appearsAt(250),
+      });
+      const extensionId2 = uuid();
+      newKeys = await extensionStorageSync.ensureCanSync([extensionId2]);
+      ok(
+        newKeys.hasKeysFor([extensionId]),
+        `didn't forget key for ${extensionId}`
+      );
+      ok(
+        newKeys.hasKeysFor([extensionId2]),
+        `new key generated for ${extensionId2}`
+      );
+
+      posts = server.getPosts();
+      equal(posts.length, 1);
+      const newPost = posts[posts.length - 1];
+      const newBody = await assertPostedEncryptedKeys(fxaService, newPost);
+      ok(
+        newBody.keys.collections[extensionId],
+        `keys object should have a key for ${extensionId}`
+      );
+      ok(
+        newBody.keys.collections[extensionId2],
+        `keys object should have a key for ${extensionId2}`
+      );
+      ok(
+        newBody.salts[extensionId],
+        `salts object should have a key for ${extensionId}`
+      );
+      ok(
+        newBody.salts[extensionId2],
+        `salts object should have a key for ${extensionId2}`
+      );
+      equal(
+        oldSalt,
+        newBody.salts[extensionId],
+        `old salt should be preserved in post`
+      );
+    });
+  });
+});
+
+add_task(async function ensureCanSync_pulls_key() {
+  // ensureCanSync is implemented by adding a key to our local record
+  // and doing a sync. This means that if the same key exists
+  // remotely, we get a "conflict". Ensure that we handle this
+  // correctly -- we keep the server key (since presumably it's
+  // already been used to encrypt records) and we don't wipe out other
+  // collections' keys.
+  const extensionId = uuid();
+  const extensionId2 = uuid();
+  const extensionOnlyKey = uuid();
+  const extensionOnlySalt = uuid();
+  const DEFAULT_KEY = new BulkKeyBundle("[default]");
+  await DEFAULT_KEY.generateRandom();
+  const RANDOM_KEY = new BulkKeyBundle(extensionId);
+  await RANDOM_KEY.generateRandom();
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      // FIXME: generating a random salt probably shouldn't require a CryptoCollection?
+      const cryptoCollection = new CryptoCollection(fxaService);
+      const RANDOM_SALT = cryptoCollection.getNewSalt();
+      await extensionStorageSync.cryptoCollection._clear();
+      const keysData = {
+        default: DEFAULT_KEY.keyPairB64,
+        collections: {
+          [extensionId]: RANDOM_KEY.keyPairB64,
+        },
+      };
+      const saltData = {
+        [extensionId]: RANDOM_SALT,
+      };
+      await server.installKeyRing(fxaService, keysData, saltData, 950, {
+        predicate: appearsAt(900),
+      });
+
+      let collectionKeys = await extensionStorageSync.ensureCanSync([
+        extensionId,
+      ]);
+      assertKeyRingKey(collectionKeys, extensionId, RANDOM_KEY);
+
+      let posts = server.getPosts();
+      equal(
+        posts.length,
+        0,
+        "ensureCanSync shouldn't push when the server keyring has the right key"
+      );
+
+      // Another client generates a key for extensionId2
+      const newKey = new BulkKeyBundle(extensionId2);
+      await newKey.generateRandom();
+      keysData.collections[extensionId2] = newKey.keyPairB64;
+      saltData[extensionId2] = cryptoCollection.getNewSalt();
+      await server.installKeyRing(fxaService, keysData, saltData, 1050, {
+        predicate: appearsAt(1000),
+      });
+
+      let newCollectionKeys = await extensionStorageSync.ensureCanSync([
+        extensionId,
+        extensionId2,
+      ]);
+      assertKeyRingKey(newCollectionKeys, extensionId2, newKey);
+      assertKeyRingKey(
+        newCollectionKeys,
+        extensionId,
+        RANDOM_KEY,
+        `ensureCanSync shouldn't lose the old key for ${extensionId}`
+      );
+
+      posts = server.getPosts();
+      equal(posts.length, 0, "ensureCanSync shouldn't push when updating keys");
+
+      // Another client generates a key, but not a salt, for extensionOnlyKey
+      const onlyKey = new BulkKeyBundle(extensionOnlyKey);
+      await onlyKey.generateRandom();
+      keysData.collections[extensionOnlyKey] = onlyKey.keyPairB64;
+      await server.installKeyRing(fxaService, keysData, saltData, 1150, {
+        predicate: appearsAt(1100),
+      });
+
+      let withNewKey = await extensionStorageSync.ensureCanSync([
+        extensionId,
+        extensionOnlyKey,
+      ]);
+      dump(`got ${JSON.stringify(withNewKey.asWBO().cleartext)}\n`);
+      assertKeyRingKey(withNewKey, extensionOnlyKey, onlyKey);
+      assertKeyRingKey(
+        withNewKey,
+        extensionId,
+        RANDOM_KEY,
+        `ensureCanSync shouldn't lose the old key for ${extensionId}`
+      );
+
+      posts = server.getPosts();
+      equal(
+        posts.length,
+        1,
+        "ensureCanSync should push when generating a new salt"
+      );
+      const withNewKeyRecord = await assertPostedEncryptedKeys(
+        fxaService,
+        posts[0]
+      );
+      // We don't a priori know what the new salt is
+      dump(`${JSON.stringify(withNewKeyRecord)}\n`);
+      ok(
+        withNewKeyRecord.salts[extensionOnlyKey],
+        `ensureCanSync should generate a salt for an extension that only had a key`
+      );
+
+      // Another client generates a key, but not a salt, for extensionOnlyKey
+      const newSalt = cryptoCollection.getNewSalt();
+      saltData[extensionOnlySalt] = newSalt;
+      await server.installKeyRing(fxaService, keysData, saltData, 1250, {
+        predicate: appearsAt(1200),
+      });
+
+      let withOnlySaltKey = await extensionStorageSync.ensureCanSync([
+        extensionId,
+        extensionOnlySalt,
+      ]);
+      assertKeyRingKey(
+        withOnlySaltKey,
+        extensionId,
+        RANDOM_KEY,
+        `ensureCanSync shouldn't lose the old key for ${extensionId}`
+      );
+      // We don't a priori know what the new key is
+      ok(
+        withOnlySaltKey.hasKeysFor([extensionOnlySalt]),
+        `ensureCanSync generated a key for an extension that only had a salt`
+      );
+
+      posts = server.getPosts();
+      equal(
+        posts.length,
+        2,
+        "ensureCanSync should push when generating a new key"
+      );
+      const withNewSaltRecord = await assertPostedEncryptedKeys(
+        fxaService,
+        posts[1]
+      );
+      equal(
+        withNewSaltRecord.salts[extensionOnlySalt],
+        newSalt,
+        "ensureCanSync should keep the existing salt when generating only a key"
+      );
+    });
+  });
+});
+
+add_task(async function ensureCanSync_handles_conflicts() {
+  // Syncing is done through a pull followed by a push of any merged
+  // changes. Accordingly, the only way to have a "true" conflict --
+  // i.e. with the server rejecting a change -- is if
+  // someone pushes changes between our pull and our push. Ensure that
+  // if this happens, we still behave sensibly (keep the remote key).
+  const extensionId = uuid();
+  const DEFAULT_KEY = new BulkKeyBundle("[default]");
+  await DEFAULT_KEY.generateRandom();
+  const RANDOM_KEY = new BulkKeyBundle(extensionId);
+  await RANDOM_KEY.generateRandom();
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      // FIXME: generating salts probably shouldn't rely on a CryptoCollection
+      const cryptoCollection = new CryptoCollection(fxaService);
+      const RANDOM_SALT = cryptoCollection.getNewSalt();
+      const keysData = {
+        default: DEFAULT_KEY.keyPairB64,
+        collections: {
+          [extensionId]: RANDOM_KEY.keyPairB64,
+        },
+      };
+      const saltData = {
+        [extensionId]: RANDOM_SALT,
+      };
+      await server.installKeyRing(fxaService, keysData, saltData, 765, {
+        conflict: true,
+      });
+
+      await extensionStorageSync.cryptoCollection._clear();
+
+      let collectionKeys = await extensionStorageSync.ensureCanSync([
+        extensionId,
+      ]);
+      assertKeyRingKey(
+        collectionKeys,
+        extensionId,
+        RANDOM_KEY,
+        `syncing keyring should keep the server key for ${extensionId}`
+      );
+
+      let posts = server.getPosts();
+      equal(
+        posts.length,
+        1,
+        "syncing keyring should have tried to post a keyring"
+      );
+      const failedPost = posts[0];
+      assertPostedNewRecord(failedPost);
+      let body = await assertPostedEncryptedKeys(fxaService, failedPost);
+      // This key will be the one the client generated locally, so
+      // we don't know what its value will be
+      ok(
+        body.keys.collections[extensionId],
+        `decrypted failed post should have a key for ${extensionId}`
+      );
+      notEqual(
+        body.keys.collections[extensionId],
+        RANDOM_KEY.keyPairB64,
+        `decrypted failed post should have a randomly-generated key for ${extensionId}`
+      );
+    });
+  });
+});
+
+add_task(async function ensureCanSync_handles_deleted_conflicts() {
+  // A keyring can be deleted, and this changes the format of the 412
+  // Conflict response from the Kinto server. Make sure we handle it correctly.
+  const extensionId = uuid();
+  const extensionId2 = uuid();
+  await withContextAndServer(async function(context, server) {
+    server.installCollection("storage-sync-crypto");
+    server.installDeleteBucket();
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      server.etag = 700;
+      await extensionStorageSync.cryptoCollection._clear();
+
+      // Generate keys that we can check for later.
+      let collectionKeys = await extensionStorageSync.ensureCanSync([
+        extensionId,
+      ]);
+      const extensionKey = collectionKeys.keyForCollection(extensionId);
+      server.clearPosts();
+
+      // This is the response that the Kinto server return when the
+      // keyring has been deleted.
+      server.addRecord({
+        collectionId: "storage-sync-crypto",
+        conflict: true,
+        transient: true,
+        data: null,
+        etag: 765,
+      });
+
+      // Try to add a new extension to trigger a sync of the keyring.
+      let collectionKeys2 = await extensionStorageSync.ensureCanSync([
+        extensionId2,
+      ]);
+
+      assertKeyRingKey(
+        collectionKeys2,
+        extensionId,
+        extensionKey,
+        `syncing keyring should keep our local key for ${extensionId}`
+      );
+
+      deepEqual(
+        server.getDeletedBuckets(),
+        ["default"],
+        "Kinto server should have been wiped when keyring was thrown away"
+      );
+
+      let posts = server.getPosts();
+      equal(
+        posts.length,
+        2,
+        "syncing keyring should have tried to post a keyring twice"
+      );
+      // The first post got a conflict.
+      const failedPost = posts[0];
+      assertPostedUpdatedRecord(failedPost, 700);
+      let body = await assertPostedEncryptedKeys(fxaService, failedPost);
+
+      deepEqual(
+        body.keys.collections[extensionId],
+        extensionKey.keyPairB64,
+        `decrypted failed post should have the key for ${extensionId}`
+      );
+
+      // The second post was after the wipe, and succeeded.
+      const afterWipePost = posts[1];
+      assertPostedNewRecord(afterWipePost);
+      let afterWipeBody = await assertPostedEncryptedKeys(
+        fxaService,
+        afterWipePost
+      );
+
+      deepEqual(
+        afterWipeBody.keys.collections[extensionId],
+        extensionKey.keyPairB64,
+        `decrypted new post should have preserved the key for ${extensionId}`
+      );
+    });
+  });
+});
+
+add_task(async function ensureCanSync_handles_flushes() {
+  // See Bug 1359879 and Bug 1350088. One of the ways that 1359879 presents is
+  // as 1350088. This seems to be the symptom that results when the user had
+  // two devices, one of which was not syncing at the time the keyring was
+  // lost. Ensure we can recover for these users as well.
+  const extensionId = uuid();
+  const extensionId2 = uuid();
+  await withContextAndServer(async function(context, server) {
+    server.installCollection("storage-sync-crypto");
+    server.installDeleteBucket();
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      server.etag = 700;
+      // Generate keys that we can check for later.
+      let collectionKeys = await extensionStorageSync.ensureCanSync([
+        extensionId,
+      ]);
+      const extensionKey = collectionKeys.keyForCollection(extensionId);
+      server.clearPosts();
+
+      // last_modified is new, but there is no data.
+      server.etag = 800;
+
+      // Try to add a new extension to trigger a sync of the keyring.
+      let collectionKeys2 = await extensionStorageSync.ensureCanSync([
+        extensionId2,
+      ]);
+
+      assertKeyRingKey(
+        collectionKeys2,
+        extensionId,
+        extensionKey,
+        `syncing keyring should keep our local key for ${extensionId}`
+      );
+
+      deepEqual(
+        server.getDeletedBuckets(),
+        ["default"],
+        "Kinto server should have been wiped when keyring was thrown away"
+      );
+
+      let posts = server.getPosts();
+      equal(
+        posts.length,
+        1,
+        "syncing keyring should have tried to post a keyring once"
+      );
+
+      const post = posts[0];
+      assertPostedNewRecord(post);
+      let postBody = await assertPostedEncryptedKeys(fxaService, post);
+
+      deepEqual(
+        postBody.keys.collections[extensionId],
+        extensionKey.keyPairB64,
+        `decrypted new post should have preserved the key for ${extensionId}`
+      );
+    });
+  });
+});
+
+add_task(async function checkSyncKeyRing_reuploads_keys() {
+  // Verify that when keys are present, they are reuploaded with the
+  // new kbHash when we call touchKeys().
+  const extensionId = uuid();
+  let extensionKey, extensionSalt;
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      server.installCollection("storage-sync-crypto");
+      server.etag = 765;
+
+      await extensionStorageSync.cryptoCollection._clear();
+
+      // Do an `ensureCanSync` to generate some keys.
+      let collectionKeys = await extensionStorageSync.ensureCanSync([
+        extensionId,
+      ]);
+      ok(
+        collectionKeys.hasKeysFor([extensionId]),
+        `ensureCanSync should return a keyring that has a key for ${extensionId}`
+      );
+      extensionKey = collectionKeys.keyForCollection(extensionId).keyPairB64;
+      equal(
+        server.getPosts().length,
+        1,
+        "generating a key that doesn't exist on the server should post it"
+      );
+      const body = await assertPostedEncryptedKeys(
+        fxaService,
+        server.getPosts()[0]
+      );
+      extensionSalt = body.salts[extensionId];
+    });
+
+    // The user changes their password. This is their new kbHash, with
+    // the last character changed.
+    const newUser = Object.assign({}, loggedInUser, {
+      scopedKeys: {
+        "sync:addon_storage": {
+          kid: "1234567890123-I1DLqPztWi-647HxgLr4YPePZUK-975wn9qWzT49yAE",
+          k:
+            "Y_kFdXfAS7u58MP9hbXUAytg4T7cH43TCb9DBdZvLMMS3eFs5GAhpJb3E5UNCmxWbOGBUhpEcm576Xz1d7MbMA",
+          kty: "oct",
+        },
+      },
+    });
+    let postedKeys;
+    await withSignedInUser(newUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      await extensionStorageSync.checkSyncKeyRing();
+
+      let posts = server.getPosts();
+      equal(
+        posts.length,
+        2,
+        "when kBHash changes, checkSyncKeyRing should post the keyring reencrypted with the new kBHash"
+      );
+      postedKeys = posts[1];
+      assertPostedUpdatedRecord(postedKeys, 765);
+
+      let body = await assertPostedEncryptedKeys(fxaService, postedKeys);
+      deepEqual(
+        body.keys.collections[extensionId],
+        extensionKey,
+        `the posted keyring should have the same key for ${extensionId} as the old one`
+      );
+      deepEqual(
+        body.salts[extensionId],
+        extensionSalt,
+        `the posted keyring should have the same salt for ${extensionId} as the old one`
+      );
+    });
+
+    // Verify that with the old kBHash, we can't decrypt the record.
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      let error;
+      try {
+        await new KeyRingEncryptionRemoteTransformer(fxaService).decode(
+          postedKeys.body.data
+        );
+      } catch (e) {
+        error = e;
+      }
+      ok(error, "decrypting the keyring with the old kBHash should fail");
+      ok(
+        Utils.isHMACMismatch(error) ||
+          KeyRingEncryptionRemoteTransformer.isOutdatedKB(error),
+        "decrypting the keyring with the old kBHash should throw an HMAC mismatch"
+      );
+    });
+  });
+});
+
+add_task(async function checkSyncKeyRing_overwrites_on_conflict() {
+  // If there is already a record on the server that was encrypted
+  // with a different kbHash, we wipe the server, clear sync state, and
+  // overwrite it with our keys.
+  const extensionId = uuid();
+  let extensionKey;
+  await withSyncContext(async function(context) {
+    await withServer(async function(server) {
+      // The old device has this kbHash, which is very similar to the
+      // current kbHash but with the last character changed.
+      const oldUser = Object.assign({}, loggedInUser, {
+        scopedKeys: {
+          "sync:addon_storage": {
+            kid: "1234567890123-I1DLqPztWi-647HxgLr4YPePZUK-975wn9qWzT49yAE",
+            k:
+              "Y_kFdXfAS7u58MP9hbXUAytg4T7cH43TCb9DBdZvLMMS3eFs5GAhpJb3E5UNCmxWbOGBUhpEcm576Xz1d7MbMA",
+            kty: "oct",
+          },
+        },
+      });
+      server.installDeleteBucket();
+      await withSignedInUser(oldUser, async function(
+        extensionStorageSync,
+        fxaService
+      ) {
+        await server.installKeyRing(fxaService, {}, {}, 765);
+      });
+
+      // Now we have this new user with a different kbHash.
+      await withSignedInUser(loggedInUser, async function(
+        extensionStorageSync,
+        fxaService
+      ) {
+        await extensionStorageSync.cryptoCollection._clear();
+
+        // Do an `ensureCanSync` to generate some keys.
+        // This will try to sync, notice that the record is
+        // undecryptable, and clear the server.
+        let collectionKeys = await extensionStorageSync.ensureCanSync([
+          extensionId,
+        ]);
+        ok(
+          collectionKeys.hasKeysFor([extensionId]),
+          `ensureCanSync should always return a keyring with a key for ${extensionId}`
+        );
+        extensionKey = collectionKeys.keyForCollection(extensionId).keyPairB64;
+
+        deepEqual(
+          server.getDeletedBuckets(),
+          ["default"],
+          "Kinto server should have been wiped when keyring was thrown away"
+        );
+
+        let posts = server.getPosts();
+        equal(posts.length, 1, "new keyring should have been uploaded");
+        const postedKeys = posts[0];
+        // The POST was to an empty server, so etag shouldn't be respected
+        equal(
+          postedKeys.headers.Authorization,
+          "Bearer some-access-token",
+          "keyring upload should be authorized"
+        );
+        equal(
+          postedKeys.headers["If-None-Match"],
+          "*",
+          "keyring upload should be to empty Kinto server"
+        );
+        equal(
+          postedKeys.path,
+          collectionRecordsPath("storage-sync-crypto") + "/keys",
+          "keyring upload should be to keyring path"
+        );
+
+        let body = await new KeyRingEncryptionRemoteTransformer(
+          fxaService
+        ).decode(postedKeys.body.data);
+        ok(body.uuid, "new keyring should have a UUID");
+        equal(typeof body.uuid, "string", "keyring UUIDs should be strings");
+        notEqual(
+          body.uuid,
+          "abcd",
+          "new keyring should not have the same UUID as previous keyring"
+        );
+        ok(body.keys, "new keyring should have a keys attribute");
+        ok(body.keys.default, "new keyring should have a default key");
+        // We should keep the extension key that was in our uploaded version.
+        deepEqual(
+          extensionKey,
+          body.keys.collections[extensionId],
+          "ensureCanSync should have returned keyring with the same key that was uploaded"
+        );
+
+        // This should be a no-op; the keys were uploaded as part of ensurekeysfor
+        await extensionStorageSync.checkSyncKeyRing();
+        equal(
+          server.getPosts().length,
+          1,
+          "checkSyncKeyRing should not need to post keys after they were reuploaded"
+        );
+      });
+    });
+  });
+});
+
+add_task(async function checkSyncKeyRing_flushes_on_uuid_change() {
+  // If we can decrypt the record, but the UUID has changed, that
+  // means another client has wiped the server and reuploaded a
+  // keyring, so reset sync state and reupload everything.
+  const extensionId = uuid();
+  const extension = { id: extensionId };
+  await withSyncContext(async function(context) {
+    await withServer(async function(server) {
+      server.installCollection("storage-sync-crypto");
+      server.installDeleteBucket();
+      await withSignedInUser(loggedInUser, async function(
+        extensionStorageSync,
+        fxaService
+      ) {
+        const cryptoCollection = new CryptoCollection(fxaService);
+        const transformer = new KeyRingEncryptionRemoteTransformer(fxaService);
+        await extensionStorageSync.cryptoCollection._clear();
+
+        // Do an `ensureCanSync` to get access to keys and salt.
+        let collectionKeys = await extensionStorageSync.ensureCanSync([
+          extensionId,
+        ]);
+        const collectionId = await cryptoCollection.extensionIdToCollectionId(
+          extensionId
+        );
+        server.installCollection(collectionId);
+
+        ok(
+          collectionKeys.hasKeysFor([extensionId]),
+          `ensureCanSync should always return a keyring that has a key for ${extensionId}`
+        );
+        const extensionKey = collectionKeys.keyForCollection(extensionId)
+          .keyPairB64;
+
+        // Set something to make sure that it gets re-uploaded when
+        // uuid changes.
+        await extensionStorageSync.set(extension, { "my-key": 5 }, context);
+        await extensionStorageSync.syncAll();
+
+        let posts = server.getPosts();
+        equal(
+          posts.length,
+          2,
+          "should have posted a new keyring and an extension datum"
+        );
+        const postedKeys = posts[0];
+        equal(
+          postedKeys.path,
+          collectionRecordsPath("storage-sync-crypto") + "/keys",
+          "should have posted keyring to /keys"
+        );
+
+        let body = await transformer.decode(postedKeys.body.data);
+        ok(body.uuid, "keyring should have a UUID");
+        ok(body.keys, "keyring should have a keys attribute");
+        ok(body.keys.default, "keyring should have a default key");
+        ok(
+          body.salts[extensionId],
+          `keyring should have a salt for ${extensionId}`
+        );
+        const extensionSalt = body.salts[extensionId];
+        deepEqual(
+          extensionKey,
+          body.keys.collections[extensionId],
+          "new keyring should have the same key that we uploaded"
+        );
+
+        // Another client comes along and replaces the UUID.
+        // In real life, this would mean changing the keys too, but
+        // this test verifies that just changing the UUID is enough.
+        const newKeyRingData = Object.assign({}, body, {
+          uuid: "abcd",
+          // Technically, last_modified should be served outside the
+          // object, but the transformer will pass it through in
+          // either direction, so this is OK.
+          last_modified: 765,
+        });
+        server.etag = 1000;
+        await server.encryptAndAddRecord(transformer, {
+          collectionId: "storage-sync-crypto",
+          data: newKeyRingData,
+          predicate: appearsAt(800),
+        });
+
+        // Fake adding another extension just so that the keyring will
+        // really get synced.
+        const newExtension = uuid();
+        const newKeyRing = await extensionStorageSync.ensureCanSync([
+          newExtension,
+        ]);
+
+        // This should have detected the UUID change and flushed everything.
+        // The keyring should, however, be the same, since we just
+        // changed the UUID of the previously POSTed one.
+        deepEqual(
+          newKeyRing.keyForCollection(extensionId).keyPairB64,
+          extensionKey,
+          "ensureCanSync should have pulled down a new keyring with the same keys"
+        );
+
+        // Syncing should reupload the data for the extension.
+        await extensionStorageSync.syncAll();
+        posts = server.getPosts();
+        equal(
+          posts.length,
+          4,
+          "should have posted keyring for new extension and reuploaded extension data"
+        );
+
+        const finalKeyRingPost = posts[2];
+        const reuploadedPost = posts[3];
+
+        equal(
+          finalKeyRingPost.path,
+          collectionRecordsPath("storage-sync-crypto") + "/keys",
+          "keyring for new extension should have been posted to /keys"
+        );
+        let finalKeyRing = await transformer.decode(finalKeyRingPost.body.data);
+        equal(
+          finalKeyRing.uuid,
+          "abcd",
+          "newly uploaded keyring should preserve UUID from replacement keyring"
+        );
+        deepEqual(
+          finalKeyRing.salts[extensionId],
+          extensionSalt,
+          "newly uploaded keyring should preserve salts from existing salts"
+        );
+
+        // Confirm that the data got reuploaded
+        let reuploadedData = await assertExtensionRecord(
+          fxaService,
+          reuploadedPost,
+          extension,
+          "my-key"
+        );
+        equal(
+          reuploadedData.data,
+          5,
+          "extension data should have a data attribute corresponding to the extension data value"
+        );
+      });
+    });
+  });
+});
+
+add_task(async function test_storage_sync_pulls_changes() {
+  const extensionId = defaultExtensionId;
+  const extension = defaultExtension;
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      const cryptoCollection = new CryptoCollection(fxaService);
+      server.installCollection("storage-sync-crypto");
+
+      let calls = [];
+      await extensionStorageSync.addOnChangedListener(
+        extension,
+        function() {
+          calls.push(arguments);
+        },
+        context
+      );
+
+      await extensionStorageSync.ensureCanSync([extensionId]);
+      const collectionId = await cryptoCollection.extensionIdToCollectionId(
+        extensionId
+      );
+      let transformer = new CollectionKeyEncryptionRemoteTransformer(
+        cryptoCollection,
+        await cryptoCollection.getKeyRing(),
+        extensionId
+      );
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-remote_2D_key",
+          key: "remote-key",
+          data: 6,
+        },
+        predicate: appearsAt(850),
+      });
+      server.etag = 900;
+
+      await extensionStorageSync.syncAll();
+      const remoteValue = (
+        await extensionStorageSync.get(extension, "remote-key", context)
+      )["remote-key"];
+      equal(
+        remoteValue,
+        6,
+        "ExtensionStorageSync.get() returns value retrieved from sync"
+      );
+
+      equal(calls.length, 1, "syncing calls on-changed listener");
+      deepEqual(calls[0][0], { "remote-key": { newValue: 6 } });
+      calls = [];
+
+      // Syncing again doesn't do anything
+      await extensionStorageSync.syncAll();
+
+      equal(
+        calls.length,
+        0,
+        "syncing again shouldn't call on-changed listener"
+      );
+
+      // Updating the server causes us to pull down the new value
+      server.etag = 1000;
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-remote_2D_key",
+          key: "remote-key",
+          data: 7,
+        },
+        predicate: appearsAt(950),
+      });
+
+      await extensionStorageSync.syncAll();
+      const remoteValue2 = (
+        await extensionStorageSync.get(extension, "remote-key", context)
+      )["remote-key"];
+      equal(
+        remoteValue2,
+        7,
+        "ExtensionStorageSync.get() returns value updated from sync"
+      );
+
+      equal(calls.length, 1, "syncing calls on-changed listener on update");
+      deepEqual(calls[0][0], { "remote-key": { oldValue: 6, newValue: 7 } });
+    });
+  });
+});
+
+// Tests that an enabled extension which have been synced before it is going
+// to be synced on ExtensionStorageSync.syncAll even if there is no active
+// context that is currently using the API.
+add_task(async function test_storage_sync_on_no_active_context() {
+  const extensionId = "sync@mochi.test";
+  const extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id: extensionId } },
+    },
+    files: {
+      "ext-page.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <script src="ext-page.js"></script>
+          </head>
+        </html>
+      `,
+      "ext-page.js": function() {
+        const { browser } = this;
+        browser.test.onMessage.addListener(async msg => {
+          if (msg === "get-sync-data") {
+            browser.test.sendMessage(
+              "get-sync-data:done",
+              await browser.storage.sync.get(["remote-key"])
+            );
+          }
+        });
+      },
+    },
+  });
+
+  await extension.startup();
+
+  await withServer(async server => {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      const cryptoCollection = new CryptoCollection(fxaService);
+      server.installCollection("storage-sync-crypto");
+
+      await extensionStorageSync.ensureCanSync([extensionId]);
+      const collectionId = await cryptoCollection.extensionIdToCollectionId(
+        extensionId
+      );
+      let transformer = new CollectionKeyEncryptionRemoteTransformer(
+        cryptoCollection,
+        await cryptoCollection.getKeyRing(),
+        extensionId
+      );
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-remote_2D_key",
+          key: "remote-key",
+          data: 6,
+        },
+        predicate: appearsAt(850),
+      });
+
+      server.etag = 1000;
+      await extensionStorageSync.syncAll();
+    });
+  });
+
+  const extPage = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/ext-page.html`,
+    { extension }
+  );
+
+  await extension.sendMessage("get-sync-data");
+  const res = await extension.awaitMessage("get-sync-data:done");
+  Assert.deepEqual(res, { "remote-key": 6 }, "Got the expected sync data");
+
+  await extPage.close();
+
+  await extension.unload();
+});
+
+add_task(async function test_storage_sync_pushes_changes() {
+  // FIXME: This test relies on the fact that previous tests pushed
+  // keys and salts for the default extension ID
+  const extension = defaultExtension;
+  const extensionId = defaultExtensionId;
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      const cryptoCollection = new CryptoCollection(fxaService);
+      const collectionId = await cryptoCollection.extensionIdToCollectionId(
+        extensionId
+      );
+      server.installCollection(collectionId);
+      server.installCollection("storage-sync-crypto");
+      server.etag = 1000;
+
+      await extensionStorageSync.set(extension, { "my-key": 5 }, context);
+
+      // install this AFTER we set the key to 5...
+      let calls = [];
+      extensionStorageSync.addOnChangedListener(
+        extension,
+        function() {
+          calls.push(arguments);
+        },
+        context
+      );
+
+      await extensionStorageSync.syncAll();
+      const localValue = (
+        await extensionStorageSync.get(extension, "my-key", context)
+      )["my-key"];
+      equal(
+        localValue,
+        5,
+        "pushing an ExtensionStorageSync value shouldn't change local value"
+      );
+      const hashedId =
+        "id-" +
+        (await cryptoCollection.hashWithExtensionSalt(
+          "key-my_2D_key",
+          extensionId
+        ));
+
+      let posts = server.getPosts();
+      // FIXME: Keys were pushed in a previous test
+      equal(
+        posts.length,
+        1,
+        "pushing a value should cause a post to the server"
+      );
+      const post = posts[0];
+      assertPostedNewRecord(post);
+      equal(
+        post.path,
+        `${collectionRecordsPath(collectionId)}/${hashedId}`,
+        "pushing a value should have a path corresponding to its id"
+      );
+
+      const encrypted = post.body.data;
+      ok(
+        encrypted.ciphertext,
+        "pushing a value should post an encrypted record"
+      );
+      ok(!encrypted.data, "pushing a value should not have any plaintext data");
+      equal(
+        encrypted.id,
+        hashedId,
+        "pushing a value should use a kinto-friendly record ID"
+      );
+
+      const record = await assertExtensionRecord(
+        fxaService,
+        post,
+        extension,
+        "my-key"
+      );
+      equal(
+        record.data,
+        5,
+        "when decrypted, a pushed value should have a data field corresponding to its storage.sync value"
+      );
+      equal(
+        record.id,
+        "key-my_2D_key",
+        "when decrypted, a pushed value should have an id field corresponding to its record ID"
+      );
+
+      equal(
+        calls.length,
+        0,
+        "pushing a value shouldn't call the on-changed listener"
+      );
+
+      await extensionStorageSync.set(extension, { "my-key": 6 }, context);
+      await extensionStorageSync.syncAll();
+
+      // Doesn't push keys because keys were pushed by a previous test.
+      posts = server.getPosts();
+      equal(posts.length, 2, "updating a value should trigger another push");
+      const updatePost = posts[1];
+      assertPostedUpdatedRecord(updatePost, 1000);
+      equal(
+        updatePost.path,
+        `${collectionRecordsPath(collectionId)}/${hashedId}`,
+        "pushing an updated value should go to the same path"
+      );
+
+      const updateEncrypted = updatePost.body.data;
+      ok(
+        updateEncrypted.ciphertext,
+        "pushing an updated value should still be encrypted"
+      );
+      ok(
+        !updateEncrypted.data,
+        "pushing an updated value should not have any plaintext visible"
+      );
+      equal(
+        updateEncrypted.id,
+        hashedId,
+        "pushing an updated value should maintain the same ID"
+      );
+    });
+  });
+});
+
+add_task(async function test_storage_sync_retries_failed_auth() {
+  const extensionId = uuid();
+  const extension = { id: extensionId };
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      const cryptoCollection = new CryptoCollection(fxaService);
+      server.installCollection("storage-sync-crypto");
+
+      await extensionStorageSync.ensureCanSync([extensionId]);
+      await extensionStorageSync.set(extension, { "my-key": 5 }, context);
+      const collectionId = await cryptoCollection.extensionIdToCollectionId(
+        extensionId
+      );
+      let transformer = new CollectionKeyEncryptionRemoteTransformer(
+        cryptoCollection,
+        await cryptoCollection.getKeyRing(),
+        extensionId
+      );
+      // Put a remote record just to verify that eventually we succeeded
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-remote_2D_key",
+          key: "remote-key",
+          data: 6,
+        },
+        predicate: appearsAt(850),
+      });
+      server.etag = 900;
+
+      // This is a typical response from a production stack if your
+      // bearer token is bad.
+      server.rejectNextAuthWith(
+        '{"code": 401, "errno": 104, "error": "Unauthorized", "message": "Please authenticate yourself to use this endpoint"}'
+      );
+      await extensionStorageSync.syncAll();
+
+      equal(server.failedAuths.length, 1, "an auth was failed");
+
+      const remoteValue = (
+        await extensionStorageSync.get(extension, "remote-key", context)
+      )["remote-key"];
+      equal(
+        remoteValue,
+        6,
+        "ExtensionStorageSync.get() returns value retrieved from sync"
+      );
+
+      // Try again with an emptier JSON body to make sure this still
+      // works with a less-cooperative server.
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-remote_2D_key",
+          key: "remote-key",
+          data: 7,
+        },
+        predicate: appearsAt(950),
+      });
+      server.etag = 1000;
+      // Need to write a JSON response.
+      // kinto.js 9.0.2 doesn't throw unless there's json.
+      // See https://github.com/Kinto/kinto-http.js/issues/192.
+      server.rejectNextAuthWith("{}");
+
+      await extensionStorageSync.syncAll();
+
+      equal(server.failedAuths.length, 2, "an auth was failed");
+
+      const newRemoteValue = (
+        await extensionStorageSync.get(extension, "remote-key", context)
+      )["remote-key"];
+      equal(
+        newRemoteValue,
+        7,
+        "ExtensionStorageSync.get() returns value retrieved from sync"
+      );
+    });
+  });
+});
+
+add_task(async function test_storage_sync_pulls_conflicts() {
+  const extensionId = uuid();
+  const extension = { id: extensionId };
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      const cryptoCollection = new CryptoCollection(fxaService);
+      server.installCollection("storage-sync-crypto");
+
+      await extensionStorageSync.ensureCanSync([extensionId]);
+      const collectionId = await cryptoCollection.extensionIdToCollectionId(
+        extensionId
+      );
+      let transformer = new CollectionKeyEncryptionRemoteTransformer(
+        cryptoCollection,
+        await cryptoCollection.getKeyRing(),
+        extensionId
+      );
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-remote_2D_key",
+          key: "remote-key",
+          data: 6,
+        },
+        predicate: appearsAt(850),
+      });
+      server.etag = 900;
+
+      await extensionStorageSync.set(extension, { "remote-key": 8 }, context);
+
+      let calls = [];
+      await extensionStorageSync.addOnChangedListener(
+        extension,
+        function() {
+          calls.push(arguments);
+        },
+        context
+      );
+
+      await extensionStorageSync.syncAll();
+      const remoteValue = (
+        await extensionStorageSync.get(extension, "remote-key", context)
+      )["remote-key"];
+      equal(remoteValue, 8, "locally set value overrides remote value");
+
+      equal(calls.length, 1, "conflicts manifest in on-changed listener");
+      deepEqual(calls[0][0], { "remote-key": { newValue: 8 } });
+      calls = [];
+
+      // Syncing again doesn't do anything
+      await extensionStorageSync.syncAll();
+
+      equal(
+        calls.length,
+        0,
+        "syncing again shouldn't call on-changed listener"
+      );
+
+      // Updating the server causes us to pull down the new value
+      server.etag = 1000;
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-remote_2D_key",
+          key: "remote-key",
+          data: 7,
+        },
+        predicate: appearsAt(950),
+      });
+
+      await extensionStorageSync.syncAll();
+      const remoteValue2 = (
+        await extensionStorageSync.get(extension, "remote-key", context)
+      )["remote-key"];
+      equal(
+        remoteValue2,
+        7,
+        "conflicts do not prevent retrieval of new values"
+      );
+
+      equal(calls.length, 1, "syncing calls on-changed listener on update");
+      deepEqual(calls[0][0], { "remote-key": { oldValue: 8, newValue: 7 } });
+    });
+  });
+});
+
+add_task(async function test_storage_sync_pulls_deletes() {
+  const extension = defaultExtension;
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      const cryptoCollection = new CryptoCollection(fxaService);
+      const collectionId = await cryptoCollection.extensionIdToCollectionId(
+        defaultExtensionId
+      );
+      server.installCollection(collectionId);
+      server.installCollection("storage-sync-crypto");
+
+      await extensionStorageSync.set(extension, { "my-key": 5 }, context);
+      await extensionStorageSync.syncAll();
+      server.clearPosts();
+
+      let calls = [];
+      await extensionStorageSync.addOnChangedListener(
+        extension,
+        function() {
+          calls.push(arguments);
+        },
+        context
+      );
+
+      const transformer = new CollectionKeyEncryptionRemoteTransformer(
+        new CryptoCollection(fxaService),
+        await cryptoCollection.getKeyRing(),
+        extension.id
+      );
+      await server.encryptAndAddRecord(transformer, {
+        collectionId,
+        data: {
+          id: "key-my_2D_key",
+          data: 6,
+          _status: "deleted",
+        },
+      });
+
+      await extensionStorageSync.syncAll();
+      const remoteValues = await extensionStorageSync.get(
+        extension,
+        "my-key",
+        context
+      );
+      ok(
+        !remoteValues["my-key"],
+        "ExtensionStorageSync.get() shows value was deleted by sync"
+      );
+
+      equal(
+        server.getPosts().length,
+        0,
+        "pulling the delete shouldn't cause posts"
+      );
+
+      equal(calls.length, 1, "syncing calls on-changed listener");
+      deepEqual(calls[0][0], { "my-key": { oldValue: 5 } });
+      calls = [];
+
+      // Syncing again doesn't do anything
+      await extensionStorageSync.syncAll();
+
+      equal(
+        calls.length,
+        0,
+        "syncing again shouldn't call on-changed listener"
+      );
+    });
+  });
+});
+
+add_task(async function test_storage_sync_pushes_deletes() {
+  const extensionId = uuid();
+  const extension = { id: extensionId };
+  await withContextAndServer(async function(context, server) {
+    await withSignedInUser(loggedInUser, async function(
+      extensionStorageSync,
+      fxaService
+    ) {
+      const cryptoCollection = new CryptoCollection(fxaService);
+      await cryptoCollection._clear();
+      await cryptoCollection._setSalt(
+        extensionId,
+        cryptoCollection.getNewSalt()
+      );
+      const collectionId = await cryptoCollection.extensionIdToCollectionId(
+        extensionId
+      );
+
+      server.installCollection(collectionId);
+      server.installCollection("storage-sync-crypto");
+      server.etag = 1000;
+
+      await extensionStorageSync.set(extension, { "my-key": 5 }, context);
+
+      let calls = [];
+      extensionStorageSync.addOnChangedListener(
+        extension,
+        function() {
+          calls.push(arguments);
+        },
+        context
+      );
+
+      await extensionStorageSync.syncAll();
+      let posts = server.getPosts();
+      equal(
+        posts.length,
+        2,
+        "pushing a non-deleted value should post keys and post the value to the server"
+      );
+
+      await extensionStorageSync.remove(extension, ["my-key"], context);
+      equal(
+        calls.length,
+        1,
+        "deleting a value should call the on-changed listener"
+      );
+
+      await extensionStorageSync.syncAll();
+      equal(
+        calls.length,
+        1,
+        "pushing a deleted value shouldn't call the on-changed listener"
+      );
+
+      // Doesn't push keys because keys were pushed by a previous test.
+      const hashedId =
+        "id-" +
+        (await cryptoCollection.hashWithExtensionSalt(
+          "key-my_2D_key",
+          extensionId
+        ));
+      posts = server.getPosts();
+      equal(posts.length, 3, "deleting a value should trigger another push");
+      const post = posts[2];
+      assertPostedUpdatedRecord(post, 1000);
+      equal(
+        post.path,
+        `${collectionRecordsPath(collectionId)}/${hashedId}`,
+        "pushing a deleted value should go to the same path"
+      );
+      ok(post.method, "PUT");
+      ok(
+        post.body.data.ciphertext,
+        "deleting a value should have an encrypted body"
+      );
+      const decoded = await new CollectionKeyEncryptionRemoteTransformer(
+        cryptoCollection,
+        await cryptoCollection.getKeyRing(),
+        extensionId
+      ).decode(post.body.data);
+      equal(decoded._status, "deleted");
+      // Ideally, we'd check that decoded.deleted is not true, because
+      // the encrypted record shouldn't have it, but the decoder will
+      // add it when it sees _status == deleted
+    });
+  });
+});
+
+// Some sync tests shared between implementations.
+add_task(test_config_flag_needed);
+
+add_task(test_sync_reloading_extensions_works);
+
+add_task(function test_storage_sync() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_background_page_storage("sync")
+  );
+});
+
+add_task(test_storage_sync_requires_real_id);
+
+add_task(function test_storage_sync_with_bytes_in_use() {
+  return runWithPrefs([[STORAGE_SYNC_PREF, true]], () =>
+    test_background_storage_area_with_bytes_in_use("sync", false)
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto_crypto.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto_crypto.js
new file mode 100644
index 0000000000..8c4137b078
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_sync_kinto_crypto.js
@@ -0,0 +1,122 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// This is a kinto-specific test...
+Services.prefs.setBoolPref("webextensions.storage.sync.kinto", true);
+
+const { EncryptionRemoteTransformer } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageSyncKinto.jsm",
+  null
+);
+const { CryptoUtils } = ChromeUtils.import(
+  "resource://services-crypto/utils.js"
+);
+const { Utils } = ChromeUtils.import("resource://services-sync/util.js");
+
+/**
+ * Like Assert.throws, but for generators.
+ *
+ * @param {string | Object | function} constraint
+ *        What to use to check the exception.
+ * @param {function} f
+ *        The function to call.
+ */
+async function throwsGen(constraint, f) {
+  let threw = false;
+  let exception;
+  try {
+    await f();
+  } catch (e) {
+    threw = true;
+    exception = e;
+  }
+
+  ok(threw, "did not throw an exception");
+
+  const debuggingMessage = `got ${exception}, expected ${constraint}`;
+
+  if (typeof constraint === "function") {
+    ok(constraint(exception), debuggingMessage);
+  } else {
+    let message = exception;
+    if (typeof exception === "object") {
+      message = exception.message;
+    }
+    ok(constraint === message, debuggingMessage);
+  }
+}
+
+/**
+ * An EncryptionRemoteTransformer that uses a fixed key bundle,
+ * suitable for testing.
+ */
+class StaticKeyEncryptionRemoteTransformer extends EncryptionRemoteTransformer {
+  constructor(keyBundle) {
+    super();
+    this.keyBundle = keyBundle;
+  }
+
+  getKeys() {
+    return Promise.resolve(this.keyBundle);
+  }
+}
+const BORING_KB =
+  "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+let transformer;
+add_task(async function setup() {
+  const STRETCHED_KEY = await CryptoUtils.hkdfLegacy(
+    BORING_KB,
+    undefined,
+    `testing storage.sync encryption`,
+    2 * 32
+  );
+  const KEY_BUNDLE = {
+    sha256HMACHasher: Utils.makeHMACHasher(
+      Ci.nsICryptoHMAC.SHA256,
+      Utils.makeHMACKey(STRETCHED_KEY.slice(0, 32))
+    ),
+    encryptionKeyB64: btoa(STRETCHED_KEY.slice(32, 64)),
+  };
+  transformer = new StaticKeyEncryptionRemoteTransformer(KEY_BUNDLE);
+});
+
+add_task(async function test_encryption_transformer_roundtrip() {
+  const POSSIBLE_DATAS = [
+    "string",
+    2, // number
+    [1, 2, 3], // array
+    { key: "value" }, // object
+  ];
+
+  for (let data of POSSIBLE_DATAS) {
+    const record = { data, id: "key-some_2D_key", key: "some-key" };
+
+    deepEqual(
+      record,
+      await transformer.decode(await transformer.encode(record))
+    );
+  }
+});
+
+add_task(async function test_refuses_to_decrypt_tampered() {
+  const encryptedRecord = await transformer.encode({
+    data: [1, 2, 3],
+    id: "key-some_2D_key",
+    key: "some-key",
+  });
+  const tamperedHMAC = Object.assign({}, encryptedRecord, {
+    hmac: "0000000000000000000000000000000000000000000000000000000000000001",
+  });
+  await throwsGen(Utils.isHMACMismatch, async function() {
+    await transformer.decode(tamperedHMAC);
+  });
+
+  const tamperedIV = Object.assign({}, encryptedRecord, {
+    IV: "aaaaaaaaaaaaaaaaaaaaaa==",
+  });
+  await throwsGen(Utils.isHMACMismatch, async function() {
+    await transformer.decode(tamperedIV);
+  });
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_tab.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_tab.js
new file mode 100644
index 0000000000..7d7f70ee14
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_tab.js
@@ -0,0 +1,245 @@
+"use strict";
+
+const { ExtensionStorageIDB } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageIDB.jsm"
+);
+
+async function test_multiple_pages() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      function awaitMessage(expectedMsg, api = "test") {
+        return new Promise(resolve => {
+          browser[api].onMessage.addListener(function listener(msg) {
+            if (msg === expectedMsg) {
+              browser[api].onMessage.removeListener(listener);
+              resolve();
+            }
+          });
+        });
+      }
+
+      let tabReady = awaitMessage("tab-ready", "runtime");
+
+      try {
+        let storage = browser.storage.local;
+
+        browser.test.sendMessage(
+          "load-page",
+          browser.runtime.getURL("tab.html")
+        );
+        await awaitMessage("page-loaded");
+        await tabReady;
+
+        let result = await storage.get("key");
+        browser.test.assertEq(undefined, result.key, "Key should be undefined");
+
+        await browser.runtime.sendMessage("tab-set-key");
+
+        result = await storage.get("key");
+        browser.test.assertEq(
+          JSON.stringify({ foo: { bar: "baz" } }),
+          JSON.stringify(result.key),
+          "Key should be set to the value from the tab"
+        );
+
+        browser.test.sendMessage("remove-page");
+        await awaitMessage("page-removed");
+
+        result = await storage.get("key");
+        browser.test.assertEq(
+          JSON.stringify({ foo: { bar: "baz" } }),
+          JSON.stringify(result.key),
+          "Key should still be set to the value from the tab"
+        );
+
+        browser.test.notifyPass("storage-multiple");
+      } catch (e) {
+        browser.test.fail(`Error: ${e} :: ${e.stack}`);
+        browser.test.notifyFail("storage-multiple");
+      }
+    },
+
+    files: {
+      "tab.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="tab.js"></script>
+          </head>
+        </html>`,
+
+      "tab.js"() {
+        browser.test.log("tab");
+        browser.runtime.onMessage.addListener(msg => {
+          if (msg == "tab-set-key") {
+            return browser.storage.local.set({ key: { foo: { bar: "baz" } } });
+          }
+        });
+
+        browser.runtime.sendMessage("tab-ready");
+      },
+    },
+
+    manifest: {
+      permissions: ["storage"],
+    },
+  });
+
+  let contentPage;
+  extension.onMessage("load-page", async url => {
+    contentPage = await ExtensionTestUtils.loadContentPage(url, { extension });
+    extension.sendMessage("page-loaded");
+  });
+  extension.onMessage("remove-page", async url => {
+    await contentPage.close();
+    extension.sendMessage("page-removed");
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("storage-multiple");
+  await extension.unload();
+}
+
+add_task(async function test_storage_local_file_backend_from_tab() {
+  return runWithPrefs(
+    [[ExtensionStorageIDB.BACKEND_ENABLED_PREF, false]],
+    test_multiple_pages
+  );
+});
+
+add_task(async function test_storage_local_idb_backend_from_tab() {
+  return runWithPrefs(
+    [[ExtensionStorageIDB.BACKEND_ENABLED_PREF, true]],
+    test_multiple_pages
+  );
+});
+
+async function test_storage_local_call_from_destroying_context() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      let numberOfChanges = 0;
+      browser.storage.onChanged.addListener((changes, areaName) => {
+        if (areaName !== "local") {
+          browser.test.fail(
+            `Received unexpected storage changes for "${areaName}"`
+          );
+        }
+
+        numberOfChanges++;
+      });
+
+      browser.test.onMessage.addListener(async ({ msg, values }) => {
+        switch (msg) {
+          case "storage-set": {
+            await browser.storage.local.set(values);
+            browser.test.sendMessage("storage-set:done");
+            break;
+          }
+          case "storage-get": {
+            const res = await browser.storage.local.get();
+            browser.test.sendMessage("storage-get:done", res);
+            break;
+          }
+          case "storage-changes": {
+            browser.test.sendMessage("storage-changes-count", numberOfChanges);
+            break;
+          }
+          default:
+            browser.test.fail(`Received unexpected message: ${msg}`);
+        }
+      });
+
+      browser.test.sendMessage(
+        "ext-page-url",
+        browser.runtime.getURL("tab.html")
+      );
+    },
+    files: {
+      "tab.html": `<!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="tab.js"></script>
+          </head>
+        </html>`,
+
+      "tab.js"() {
+        browser.test.log("Extension tab - calling storage.local API method");
+        // Call the storage.local API from a tab that is going to be quickly closed.
+        browser.storage.local.set({
+          "test-key-from-destroying-context": "testvalue2",
+        });
+        // Navigate away from the extension page, so that the storage.local API call will be unable
+        // to send the call to the caller context (because it has been destroyed in the meantime).
+        window.location = "about:blank";
+      },
+    },
+    manifest: {
+      permissions: ["storage"],
+    },
+  });
+
+  await extension.startup();
+  const url = await extension.awaitMessage("ext-page-url");
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(url, {
+    extension,
+  });
+  let expectedBackgroundPageData = {
+    "test-key-from-background-page": "test-value",
+  };
+  let expectedTabData = { "test-key-from-destroying-context": "testvalue2" };
+
+  info(
+    "Call storage.local.set from the background page and wait it to be completed"
+  );
+  extension.sendMessage({
+    msg: "storage-set",
+    values: expectedBackgroundPageData,
+  });
+  await extension.awaitMessage("storage-set:done");
+
+  info(
+    "Call storage.local.get from the background page and wait it to be completed"
+  );
+  extension.sendMessage({ msg: "storage-get" });
+  let res = await extension.awaitMessage("storage-get:done");
+
+  Assert.deepEqual(
+    res,
+    {
+      ...expectedBackgroundPageData,
+      ...expectedTabData,
+    },
+    "Got the expected data set in the storage.local backend"
+  );
+
+  extension.sendMessage({ msg: "storage-changes" });
+  equal(
+    await extension.awaitMessage("storage-changes-count"),
+    2,
+    "Got the expected number of storage.onChanged event received"
+  );
+
+  contentPage.close();
+
+  await extension.unload();
+}
+
+add_task(
+  async function test_storage_local_file_backend_destroyed_context_promise() {
+    return runWithPrefs(
+      [[ExtensionStorageIDB.BACKEND_ENABLED_PREF, false]],
+      test_storage_local_call_from_destroying_context
+    );
+  }
+);
+
+add_task(
+  async function test_storage_local_idb_backend_destroyed_context_promise() {
+    return runWithPrefs(
+      [[ExtensionStorageIDB.BACKEND_ENABLED_PREF, true]],
+      test_storage_local_call_from_destroying_context
+    );
+  }
+);
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js
new file mode 100644
index 0000000000..f4a7574337
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_storage_telemetry.js
@@ -0,0 +1,369 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const { ExtensionStorageIDB } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionStorageIDB.jsm"
+);
+const { getTrimmedString } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionTelemetry.jsm"
+);
+const { TelemetryController } = ChromeUtils.import(
+  "resource://gre/modules/TelemetryController.jsm"
+);
+const { TelemetryTestUtils } = ChromeUtils.import(
+  "resource://testing-common/TelemetryTestUtils.jsm"
+);
+
+const HISTOGRAM_JSON_IDS = [
+  "WEBEXT_STORAGE_LOCAL_SET_MS",
+  "WEBEXT_STORAGE_LOCAL_GET_MS",
+];
+const KEYED_HISTOGRAM_JSON_IDS = [
+  "WEBEXT_STORAGE_LOCAL_SET_MS_BY_ADDONID",
+  "WEBEXT_STORAGE_LOCAL_GET_MS_BY_ADDONID",
+];
+
+const HISTOGRAM_IDB_IDS = [
+  "WEBEXT_STORAGE_LOCAL_IDB_SET_MS",
+  "WEBEXT_STORAGE_LOCAL_IDB_GET_MS",
+];
+const KEYED_HISTOGRAM_IDB_IDS = [
+  "WEBEXT_STORAGE_LOCAL_IDB_SET_MS_BY_ADDONID",
+  "WEBEXT_STORAGE_LOCAL_IDB_GET_MS_BY_ADDONID",
+];
+
+const HISTOGRAM_IDS = [].concat(HISTOGRAM_JSON_IDS, HISTOGRAM_IDB_IDS);
+const KEYED_HISTOGRAM_IDS = [].concat(
+  KEYED_HISTOGRAM_JSON_IDS,
+  KEYED_HISTOGRAM_IDB_IDS
+);
+
+const EXTENSION_ID1 = "@test-extension1";
+const EXTENSION_ID2 = "@test-extension2";
+
+async function test_telemetry_background() {
+  const expectedEmptyHistograms = ExtensionStorageIDB.isBackendEnabled
+    ? HISTOGRAM_JSON_IDS
+    : HISTOGRAM_IDB_IDS;
+  const expectedEmptyKeyedHistograms = ExtensionStorageIDB.isBackendEnabled
+    ? KEYED_HISTOGRAM_JSON_IDS
+    : KEYED_HISTOGRAM_IDB_IDS;
+
+  const expectedNonEmptyHistograms = ExtensionStorageIDB.isBackendEnabled
+    ? HISTOGRAM_IDB_IDS
+    : HISTOGRAM_JSON_IDS;
+  const expectedNonEmptyKeyedHistograms = ExtensionStorageIDB.isBackendEnabled
+    ? KEYED_HISTOGRAM_IDB_IDS
+    : KEYED_HISTOGRAM_JSON_IDS;
+
+  const server = createHttpServer();
+  server.registerDirectory("/data/", do_get_file("data"));
+
+  const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+  async function contentScript() {
+    await browser.storage.local.set({ a: "b" });
+    await browser.storage.local.get("a");
+    browser.test.sendMessage("contentDone");
+  }
+
+  let baseManifest = {
+    permissions: ["storage"],
+    content_scripts: [
+      {
+        matches: ["http://*/*/file_sample.html"],
+        js: ["content_script.js"],
+      },
+    ],
+  };
+
+  let baseExtInfo = {
+    async background() {
+      await browser.storage.local.set({ a: "b" });
+      await browser.storage.local.get("a");
+      browser.test.sendMessage("backgroundDone");
+    },
+    files: {
+      "content_script.js": contentScript,
+    },
+  };
+
+  let extension1 = ExtensionTestUtils.loadExtension({
+    ...baseExtInfo,
+    manifest: {
+      ...baseManifest,
+      applications: {
+        gecko: { id: EXTENSION_ID1 },
+      },
+    },
+  });
+  let extension2 = ExtensionTestUtils.loadExtension({
+    ...baseExtInfo,
+    manifest: {
+      ...baseManifest,
+      applications: {
+        gecko: { id: EXTENSION_ID2 },
+      },
+    },
+  });
+
+  clearHistograms();
+
+  let process = IS_OOP ? "extension" : "parent";
+  let snapshots = getSnapshots(process);
+  let keyedSnapshots = getKeyedSnapshots(process);
+
+  for (let id of HISTOGRAM_IDS) {
+    ok(!(id in snapshots), `No data recorded for histogram: ${id}.`);
+  }
+
+  for (let id of KEYED_HISTOGRAM_IDS) {
+    Assert.deepEqual(
+      Object.keys(keyedSnapshots[id] || {}),
+      [],
+      `No data recorded for histogram: ${id}.`
+    );
+  }
+
+  await extension1.startup();
+  await extension1.awaitMessage("backgroundDone");
+  for (let id of expectedNonEmptyHistograms) {
+    await promiseTelemetryRecorded(id, process, 1);
+  }
+  for (let id of expectedNonEmptyKeyedHistograms) {
+    await promiseKeyedTelemetryRecorded(id, process, EXTENSION_ID1, 1);
+  }
+
+  // Telemetry from extension1's background page should be recorded.
+  snapshots = getSnapshots(process);
+  keyedSnapshots = getKeyedSnapshots(process);
+
+  for (let id of expectedNonEmptyHistograms) {
+    equal(
+      valueSum(snapshots[id].values),
+      1,
+      `Data recorded for histogram: ${id}.`
+    );
+  }
+
+  for (let id of expectedNonEmptyKeyedHistograms) {
+    Assert.deepEqual(
+      Object.keys(keyedSnapshots[id]),
+      [EXTENSION_ID1],
+      `Data recorded for histogram: ${id}.`
+    );
+    equal(
+      valueSum(keyedSnapshots[id][EXTENSION_ID1].values),
+      1,
+      `Data recorded for histogram: ${id}.`
+    );
+  }
+
+  await extension2.startup();
+  await extension2.awaitMessage("backgroundDone");
+
+  for (let id of expectedNonEmptyHistograms) {
+    await promiseTelemetryRecorded(id, process, 2);
+  }
+  for (let id of expectedNonEmptyKeyedHistograms) {
+    await promiseKeyedTelemetryRecorded(id, process, EXTENSION_ID2, 1);
+  }
+
+  // Telemetry from extension2's background page should be recorded.
+  snapshots = getSnapshots(process);
+  keyedSnapshots = getKeyedSnapshots(process);
+
+  for (let id of expectedNonEmptyHistograms) {
+    equal(
+      valueSum(snapshots[id].values),
+      2,
+      `Additional data recorded for histogram: ${id}.`
+    );
+  }
+
+  for (let id of expectedNonEmptyKeyedHistograms) {
+    Assert.deepEqual(
+      Object.keys(keyedSnapshots[id]).sort(),
+      [EXTENSION_ID1, EXTENSION_ID2],
+      `Additional data recorded for histogram: ${id}.`
+    );
+    equal(
+      valueSum(keyedSnapshots[id][EXTENSION_ID2].values),
+      1,
+      `Additional data recorded for histogram: ${id}.`
+    );
+  }
+
+  await extension2.unload();
+
+  // Run a content script.
+  process = IS_OOP ? "content" : "parent";
+  let expectedCount = IS_OOP ? 1 : 3;
+  let expectedKeyedCount = IS_OOP ? 1 : 2;
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/file_sample.html`
+  );
+  await extension1.awaitMessage("contentDone");
+
+  for (let id of expectedNonEmptyHistograms) {
+    await promiseTelemetryRecorded(id, process, expectedCount);
+  }
+  for (let id of expectedNonEmptyKeyedHistograms) {
+    await promiseKeyedTelemetryRecorded(
+      id,
+      process,
+      EXTENSION_ID1,
+      expectedKeyedCount
+    );
+  }
+
+  // Telemetry from extension1's content script should be recorded.
+  snapshots = getSnapshots(process);
+  keyedSnapshots = getKeyedSnapshots(process);
+
+  for (let id of expectedNonEmptyHistograms) {
+    equal(
+      valueSum(snapshots[id].values),
+      expectedCount,
+      `Data recorded in content script for histogram: ${id}.`
+    );
+  }
+
+  for (let id of expectedNonEmptyKeyedHistograms) {
+    Assert.deepEqual(
+      Object.keys(keyedSnapshots[id]).sort(),
+      IS_OOP ? [EXTENSION_ID1] : [EXTENSION_ID1, EXTENSION_ID2],
+      `Additional data recorded for histogram: ${id}.`
+    );
+    equal(
+      valueSum(keyedSnapshots[id][EXTENSION_ID1].values),
+      expectedKeyedCount,
+      `Additional data recorded for histogram: ${id}.`
+    );
+  }
+
+  await extension1.unload();
+
+  // Telemetry for histograms that we expect to be empty.
+  for (let id of expectedEmptyHistograms) {
+    ok(!(id in snapshots), `No data recorded for histogram: ${id}.`);
+  }
+
+  for (let id of expectedEmptyKeyedHistograms) {
+    Assert.deepEqual(
+      Object.keys(keyedSnapshots[id] || {}),
+      [],
+      `No data recorded for histogram: ${id}.`
+    );
+  }
+
+  await contentPage.close();
+}
+
+add_task(async function setup() {
+  Services.prefs.setBoolPref(
+    "toolkit.telemetry.testing.overrideProductsCheck",
+    true
+  );
+
+  // Telemetry test setup needed to ensure that the builtin events are defined
+  // and they can be collected and verified.
+  await TelemetryController.testSetup();
+
+  // This is actually only needed on Android, because it does not properly support unified telemetry
+  // and so, if not enabled explicitly here, it would make these tests to fail when running on a
+  // non-Nightly build.
+  const oldCanRecordBase = Services.telemetry.canRecordBase;
+  Services.telemetry.canRecordBase = true;
+  registerCleanupFunction(() => {
+    Services.telemetry.canRecordBase = oldCanRecordBase;
+  });
+});
+
+add_task(function test_telemetry_background_file_backend() {
+  return runWithPrefs(
+    [[ExtensionStorageIDB.BACKEND_ENABLED_PREF, false]],
+    test_telemetry_background
+  );
+});
+
+add_task(function test_telemetry_background_idb_backend() {
+  return runWithPrefs(
+    [
+      [ExtensionStorageIDB.BACKEND_ENABLED_PREF, true],
+      // Set the migrated preference for the two test extension, because the
+      // first storage.local call fallbacks to run in the parent process when we
+      // don't know which is the selected backend during the extension startup
+      // and so we can't choose the telemetry histogram to use.
+      [
+        `${ExtensionStorageIDB.IDB_MIGRATED_PREF_BRANCH}.${EXTENSION_ID1}`,
+        true,
+      ],
+      [
+        `${ExtensionStorageIDB.IDB_MIGRATED_PREF_BRANCH}.${EXTENSION_ID2}`,
+        true,
+      ],
+    ],
+    test_telemetry_background
+  );
+});
+
+// This test verifies that we do record the expected telemetry event when we
+// normalize the error message for an unexpected error (an error raised internally
+// by the QuotaManager and/or IndexedDB, which it is being normalized into the generic
+// "An unexpected error occurred" error message).
+add_task(async function test_telemetry_storage_local_unexpected_error() {
+  // Clear any telemetry events collected so far.
+  Services.telemetry.clearEvents();
+
+  const methods = ["clear", "get", "remove", "set"];
+  const veryLongErrorName = `VeryLongErrorName${Array(200)
+    .fill(0)
+    .join("")}`;
+  const otherError = new Error("an error recorded as OtherError");
+
+  const recordedErrors = [
+    new DOMException("error message", "UnexpectedDOMException"),
+    new DOMException("error message", veryLongErrorName),
+    otherError,
+  ];
+
+  // We expect the following errors to not be recorded in telemetry (because they
+  // are raised on scenarios that we already expect).
+  const nonRecordedErrors = [
+    new DOMException("error message", "QuotaExceededError"),
+    new DOMException("error message", "DataCloneError"),
+  ];
+
+  const expectedEvents = [];
+
+  const errors = [].concat(recordedErrors, nonRecordedErrors);
+
+  for (let i = 0; i < errors.length; i++) {
+    const error = errors[i];
+    const storageMethod = methods[i] || "set";
+    ExtensionStorageIDB.normalizeStorageError({
+      error: errors[i],
+      extensionId: EXTENSION_ID1,
+      storageMethod,
+    });
+
+    if (recordedErrors.includes(error)) {
+      let error_name =
+        error === otherError ? "OtherError" : getTrimmedString(error.name);
+
+      expectedEvents.push({
+        value: EXTENSION_ID1,
+        object: storageMethod,
+        extra: { error_name },
+      });
+    }
+  }
+
+  await TelemetryTestUtils.assertEvents(expectedEvents, {
+    category: "extensions.data",
+    method: "storageLocalError",
+  });
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_tab_teardown.js b/toolkit/components/extensions/test/xpcshell/test_ext_tab_teardown.js
new file mode 100644
index 0000000000..ccbfddf6d2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_tab_teardown.js
@@ -0,0 +1,98 @@
+"use strict";
+
+add_task(async function test_extension_page_tabs_create_reload_and_close() {
+  let events = [];
+  {
+    let { Management } = ChromeUtils.import(
+      "resource://gre/modules/Extension.jsm",
+      null
+    );
+    let record = (type, extensionContext) => {
+      let eventType = type == "proxy-context-load" ? "load" : "unload";
+      let url = extensionContext.uri.spec;
+      let extensionId = extensionContext.extension.id;
+      events.push({ eventType, url, extensionId });
+    };
+
+    Management.on("proxy-context-load", record);
+    Management.on("proxy-context-unload", record);
+    registerCleanupFunction(() => {
+      Management.off("proxy-context-load", record);
+      Management.off("proxy-context-unload", record);
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.sendMessage("tab-url", browser.runtime.getURL("page.html"));
+    },
+    files: {
+      "page.html": `<!DOCTYPE html><meta charset="utf-8"><script src="page.js"></script>`,
+      "page.js"() {
+        browser.test.sendMessage("extension page loaded", document.URL);
+      },
+    },
+  });
+
+  await extension.startup();
+  let tabURL = await extension.awaitMessage("tab-url");
+  events.splice(0);
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(tabURL, {
+    extension,
+  });
+  let extensionPageURL = await extension.awaitMessage("extension page loaded");
+  equal(extensionPageURL, tabURL, "Loaded the expected URL");
+
+  let contextEvents = events.splice(0);
+  equal(contextEvents.length, 1, "ExtensionContext change for opening a tab");
+  equal(contextEvents[0].eventType, "load", "create ExtensionContext for tab");
+  equal(
+    contextEvents[0].url,
+    extensionPageURL,
+    "ExtensionContext URL after tab creation should be tab URL"
+  );
+
+  await contentPage.spawn(null, () => {
+    this.content.location.reload();
+  });
+  let extensionPageURL2 = await extension.awaitMessage("extension page loaded");
+
+  equal(
+    extensionPageURL,
+    extensionPageURL2,
+    "The tab's URL is expected to not change after a page reload"
+  );
+
+  contextEvents = events.splice(0);
+  equal(contextEvents.length, 2, "ExtensionContext change after tab reload");
+  equal(contextEvents[0].eventType, "unload", "unload old ExtensionContext");
+  equal(
+    contextEvents[0].url,
+    extensionPageURL,
+    "ExtensionContext URL before reload should be tab URL"
+  );
+  equal(
+    contextEvents[1].eventType,
+    "load",
+    "create new ExtensionContext for tab"
+  );
+  equal(
+    contextEvents[1].url,
+    extensionPageURL2,
+    "ExtensionContext URL after reload should be tab URL"
+  );
+
+  await contentPage.close();
+
+  contextEvents = events.splice(0);
+  equal(contextEvents.length, 1, "ExtensionContext after closing tab");
+  equal(contextEvents[0].eventType, "unload", "unload tab's ExtensionContext");
+  equal(
+    contextEvents[0].url,
+    extensionPageURL2,
+    "ExtensionContext URL at closing tab should be tab URL"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_telemetry.js
new file mode 100644
index 0000000000..8aa22f5a10
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_telemetry.js
@@ -0,0 +1,870 @@
+"use strict";
+
+const { TelemetryArchive } = ChromeUtils.import(
+  "resource://gre/modules/TelemetryArchive.jsm"
+);
+const { TelemetryUtils } = ChromeUtils.import(
+  "resource://gre/modules/TelemetryUtils.jsm"
+);
+const { TelemetryTestUtils } = ChromeUtils.import(
+  "resource://testing-common/TelemetryTestUtils.jsm"
+);
+
+const { TelemetryArchiveTesting } = ChromeUtils.import(
+  "resource://testing-common/TelemetryArchiveTesting.jsm"
+);
+
+const { TestUtils } = ChromeUtils.import(
+  "resource://testing-common/TestUtils.jsm"
+);
+
+// All tests run privileged unless otherwise specified not to.
+function createExtension(
+  backgroundScript,
+  permissions,
+  isPrivileged = true,
+  telemetry
+) {
+  let extensionData = {
+    background: backgroundScript,
+    manifest: { permissions, telemetry },
+    isPrivileged,
+  };
+
+  return ExtensionTestUtils.loadExtension(extensionData);
+}
+
+async function run(test) {
+  let extension = createExtension(
+    test.backgroundScript,
+    test.permissions || ["telemetry"],
+    test.isPrivileged,
+    test.telemetry
+  );
+  await extension.startup();
+  await extension.awaitFinish(test.doneSignal);
+  await extension.unload();
+}
+
+// Currently unsupported on Android: blocked on 1220177.
+// See 1280234 c67 for discussion.
+if (AppConstants.MOZ_BUILD_APP === "browser") {
+  add_task(async function test_telemetry_without_telemetry_permission() {
+    await run({
+      backgroundScript: () => {
+        browser.test.assertTrue(
+          !browser.telemetry,
+          "'telemetry' permission is required"
+        );
+        browser.test.notifyPass("telemetry_permission");
+      },
+      permissions: [],
+      doneSignal: "telemetry_permission",
+      isPrivileged: false,
+    });
+  });
+
+  add_task(
+    async function test_telemetry_without_telemetry_permission_privileged() {
+      await run({
+        backgroundScript: () => {
+          browser.test.assertTrue(
+            !browser.telemetry,
+            "'telemetry' permission is required"
+          );
+          browser.test.notifyPass("telemetry_permission");
+        },
+        permissions: [],
+        doneSignal: "telemetry_permission",
+      });
+    }
+  );
+
+  add_task(async function test_telemetry_scalar_add() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.scalarAdd(
+          "telemetry.test.unsigned_int_kind",
+          1
+        );
+        browser.test.notifyPass("scalar_add");
+      },
+      doneSignal: "scalar_add",
+    });
+    TelemetryTestUtils.assertScalar(
+      TelemetryTestUtils.getProcessScalars("parent", false, true),
+      "telemetry.test.unsigned_int_kind",
+      1
+    );
+  });
+
+  add_task(async function test_telemetry_scalar_add_unknown_name() {
+    let { messages } = await promiseConsoleOutput(async () => {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.scalarAdd("telemetry.test.does_not_exist", 1);
+          browser.test.notifyPass("scalar_add_unknown_name");
+        },
+        doneSignal: "scalar_add_unknown_name",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) => message.includes("Unknown scalar")),
+      "Telemetry should warn if an unknown scalar is incremented"
+    );
+  });
+
+  add_task(async function test_telemetry_scalar_add_illegal_value() {
+    await run({
+      backgroundScript: () => {
+        browser.test.assertThrows(
+          () =>
+            browser.telemetry.scalarAdd("telemetry.test.unsigned_int_kind", {}),
+          /Incorrect argument types for telemetry.scalarAdd/,
+          "The second 'value' argument to scalarAdd must be an integer, string, or boolean"
+        );
+        browser.test.notifyPass("scalar_add_illegal_value");
+      },
+      doneSignal: "scalar_add_illegal_value",
+    });
+  });
+
+  add_task(async function test_telemetry_scalar_add_invalid_keyed_scalar() {
+    let { messages } = await promiseConsoleOutput(async function() {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.scalarAdd(
+            "telemetry.test.keyed_unsigned_int",
+            1
+          );
+          browser.test.notifyPass("scalar_add_invalid_keyed_scalar");
+        },
+        doneSignal: "scalar_add_invalid_keyed_scalar",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) =>
+        message.includes("Attempting to manage a keyed scalar as a scalar")
+      ),
+      "Telemetry should warn if a scalarAdd is called for a keyed scalar"
+    );
+  });
+
+  add_task(async function test_telemetry_scalar_set() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.scalarSet("telemetry.test.boolean_kind", true);
+        browser.test.notifyPass("scalar_set");
+      },
+      doneSignal: "scalar_set",
+    });
+    TelemetryTestUtils.assertScalar(
+      TelemetryTestUtils.getProcessScalars("parent", false, true),
+      "telemetry.test.boolean_kind",
+      true
+    );
+  });
+
+  add_task(async function test_telemetry_scalar_set_unknown_name() {
+    let { messages } = await promiseConsoleOutput(async function() {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.scalarSet(
+            "telemetry.test.does_not_exist",
+            true
+          );
+          browser.test.notifyPass("scalar_set_unknown_name");
+        },
+        doneSignal: "scalar_set_unknown_name",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) => message.includes("Unknown scalar")),
+      "Telemetry should warn if an unknown scalar is set"
+    );
+  });
+
+  add_task(async function test_telemetry_scalar_set_maximum() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.scalarSetMaximum(
+          "telemetry.test.unsigned_int_kind",
+          123
+        );
+        browser.test.notifyPass("scalar_set_maximum");
+      },
+      doneSignal: "scalar_set_maximum",
+    });
+    TelemetryTestUtils.assertScalar(
+      TelemetryTestUtils.getProcessScalars("parent", false, true),
+      "telemetry.test.unsigned_int_kind",
+      123
+    );
+  });
+
+  add_task(async function test_telemetry_scalar_set_maximum_unknown_name() {
+    let { messages } = await promiseConsoleOutput(async function() {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.scalarSetMaximum(
+            "telemetry.test.does_not_exist",
+            1
+          );
+          browser.test.notifyPass("scalar_set_maximum_unknown_name");
+        },
+        doneSignal: "scalar_set_maximum_unknown_name",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) => message.includes("Unknown scalar")),
+      "Telemetry should warn if an unknown scalar is set"
+    );
+  });
+
+  add_task(async function test_telemetry_scalar_set_maximum_illegal_value() {
+    await run({
+      backgroundScript: () => {
+        browser.test.assertThrows(
+          () =>
+            browser.telemetry.scalarSetMaximum(
+              "telemetry.test.unsigned_int_kind",
+              "string"
+            ),
+          /Incorrect argument types for telemetry.scalarSetMaximum/,
+          "The second 'value' argument to scalarSetMaximum must be a scalar"
+        );
+        browser.test.notifyPass("scalar_set_maximum_illegal_value");
+      },
+      doneSignal: "scalar_set_maximum_illegal_value",
+    });
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_add() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.keyedScalarAdd(
+          "telemetry.test.keyed_unsigned_int",
+          "foo",
+          1
+        );
+        browser.test.notifyPass("keyed_scalar_add");
+      },
+      doneSignal: "keyed_scalar_add",
+    });
+    TelemetryTestUtils.assertKeyedScalar(
+      TelemetryTestUtils.getProcessScalars("parent", true, true),
+      "telemetry.test.keyed_unsigned_int",
+      "foo",
+      1
+    );
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_add_unknown_name() {
+    let { messages } = await promiseConsoleOutput(async () => {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.keyedScalarAdd(
+            "telemetry.test.does_not_exist",
+            "foo",
+            1
+          );
+          browser.test.notifyPass("keyed_scalar_add_unknown_name");
+        },
+        doneSignal: "keyed_scalar_add_unknown_name",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) => message.includes("Unknown scalar")),
+      "Telemetry should warn if an unknown keyed scalar is incremented"
+    );
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_add_illegal_value() {
+    await run({
+      backgroundScript: () => {
+        browser.test.assertThrows(
+          () =>
+            browser.telemetry.keyedScalarAdd(
+              "telemetry.test.keyed_unsigned_int",
+              "foo",
+              {}
+            ),
+          /Incorrect argument types for telemetry.keyedScalarAdd/,
+          "The second 'value' argument to keyedScalarAdd must be an integer, string, or boolean"
+        );
+        browser.test.notifyPass("keyed_scalar_add_illegal_value");
+      },
+      doneSignal: "keyed_scalar_add_illegal_value",
+    });
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_add_invalid_scalar() {
+    let { messages } = await promiseConsoleOutput(async function() {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.keyedScalarAdd(
+            "telemetry.test.unsigned_int_kind",
+            "foo",
+            1
+          );
+          browser.test.notifyPass("keyed_scalar_add_invalid_scalar");
+        },
+        doneSignal: "keyed_scalar_add_invalid_scalar",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) =>
+        message.includes(
+          "Attempting to manage a keyed scalar as a scalar (or vice-versa)"
+        )
+      ),
+      "Telemetry should warn if a scalar is incremented as a keyed scalar"
+    );
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_add_long_key() {
+    let { messages } = await promiseConsoleOutput(async () => {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.keyedScalarAdd(
+            "telemetry.test.keyed_unsigned_int",
+            "X".repeat(73),
+            1
+          );
+          browser.test.notifyPass("keyed_scalar_add_long_key");
+        },
+        doneSignal: "keyed_scalar_add_long_key",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) =>
+        message.includes("The key length must be limited to 72 characters.")
+      ),
+      "Telemetry should warn if keyed scalar's key is too long"
+    );
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_set() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.keyedScalarSet(
+          "telemetry.test.keyed_boolean_kind",
+          "foo",
+          true
+        );
+        browser.test.notifyPass("keyed_scalar_set");
+      },
+      doneSignal: "keyed_scalar_set",
+    });
+    TelemetryTestUtils.assertKeyedScalar(
+      TelemetryTestUtils.getProcessScalars("parent", true, true),
+      "telemetry.test.keyed_boolean_kind",
+      "foo",
+      true
+    );
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_set_unknown_name() {
+    let { messages } = await promiseConsoleOutput(async function() {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.keyedScalarSet(
+            "telemetry.test.does_not_exist",
+            "foo",
+            true
+          );
+          browser.test.notifyPass("keyed_scalar_set_unknown_name");
+        },
+        doneSignal: "keyed_scalar_set_unknown_name",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) => message.includes("Unknown scalar")),
+      "Telemetry should warn if an unknown keyed scalar is incremented"
+    );
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_set_long_key() {
+    let { messages } = await promiseConsoleOutput(async () => {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.keyedScalarSet(
+            "telemetry.test.keyed_unsigned_int",
+            "X".repeat(73),
+            1
+          );
+          browser.test.notifyPass("keyed_scalar_set_long_key");
+        },
+        doneSignal: "keyed_scalar_set_long_key",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) =>
+        message.includes("The key length must be limited to 72 characters")
+      ),
+      "Telemetry should warn if keyed scalar's key is too long"
+    );
+  });
+
+  add_task(async function test_telemetry_keyed_scalar_set_maximum() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.keyedScalarSetMaximum(
+          "telemetry.test.keyed_unsigned_int",
+          "foo",
+          123
+        );
+        browser.test.notifyPass("keyed_scalar_set_maximum");
+      },
+      doneSignal: "keyed_scalar_set_maximum",
+    });
+    TelemetryTestUtils.assertKeyedScalar(
+      TelemetryTestUtils.getProcessScalars("parent", true, true),
+      "telemetry.test.keyed_unsigned_int",
+      "foo",
+      123
+    );
+  });
+
+  add_task(
+    async function test_telemetry_keyed_scalar_set_maximum_unknown_name() {
+      let { messages } = await promiseConsoleOutput(async function() {
+        await run({
+          backgroundScript: async () => {
+            await browser.telemetry.keyedScalarSetMaximum(
+              "telemetry.test.does_not_exist",
+              "foo",
+              1
+            );
+            browser.test.notifyPass("keyed_scalar_set_maximum_unknown_name");
+          },
+          doneSignal: "keyed_scalar_set_maximum_unknown_name",
+        });
+      });
+      Assert.ok(
+        messages.find(({ message }) => message.includes("Unknown scalar")),
+        "Telemetry should warn if an unknown keyed scalar is set"
+      );
+    }
+  );
+
+  add_task(
+    async function test_telemetry_keyed_scalar_set_maximum_illegal_value() {
+      await run({
+        backgroundScript: () => {
+          browser.test.assertThrows(
+            () =>
+              browser.telemetry.keyedScalarSetMaximum(
+                "telemetry.test.keyed_unsigned_int",
+                "foo",
+                "string"
+              ),
+            /Incorrect argument types for telemetry.keyedScalarSetMaximum/,
+            "The third 'value' argument to keyedScalarSetMaximum must be a scalar"
+          );
+          browser.test.notifyPass("keyed_scalar_set_maximum_illegal_value");
+        },
+        doneSignal: "keyed_scalar_set_maximum_illegal_value",
+      });
+    }
+  );
+
+  add_task(async function test_telemetry_keyed_scalar_set_maximum_long_key() {
+    let { messages } = await promiseConsoleOutput(async () => {
+      await run({
+        backgroundScript: async () => {
+          await browser.telemetry.keyedScalarSetMaximum(
+            "telemetry.test.keyed_unsigned_int",
+            "X".repeat(73),
+            1
+          );
+          browser.test.notifyPass("keyed_scalar_set_maximum_long_key");
+        },
+        doneSignal: "keyed_scalar_set_maximum_long_key",
+      });
+    });
+    Assert.ok(
+      messages.find(({ message }) =>
+        message.includes("The key length must be limited to 72 characters")
+      ),
+      "Telemetry should warn if keyed scalar's key is too long"
+    );
+  });
+
+  add_task(async function test_telemetry_record_event() {
+    Services.telemetry.clearEvents();
+    Services.telemetry.setEventRecordingEnabled("telemetry.test", true);
+
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.recordEvent(
+          "telemetry.test",
+          "test1",
+          "object1"
+        );
+        browser.test.notifyPass("record_event_ok");
+      },
+      doneSignal: "record_event_ok",
+    });
+
+    TelemetryTestUtils.assertEvents(
+      [
+        {
+          category: "telemetry.test",
+          method: "test1",
+          object: "object1",
+        },
+      ],
+      { category: "telemetry.test" }
+    );
+
+    Services.telemetry.setEventRecordingEnabled("telemetry.test", false);
+    Services.telemetry.clearEvents();
+  });
+
+  // Bug 1536877
+  add_task(async function test_telemetry_record_event_value_must_be_string() {
+    Services.telemetry.clearEvents();
+    Services.telemetry.setEventRecordingEnabled("telemetry.test", true);
+
+    await run({
+      backgroundScript: async () => {
+        try {
+          await browser.telemetry.recordEvent(
+            "telemetry.test",
+            "test1",
+            "object1",
+            "value1"
+          );
+          browser.test.notifyPass("record_event_string_value");
+        } catch (ex) {
+          browser.test.fail(
+            `Unexpected exception raised during record_event_value_must_be_string: ${ex}`
+          );
+          browser.test.notifyPass("record_event_string_value");
+          throw ex;
+        }
+      },
+      doneSignal: "record_event_string_value",
+    });
+
+    TelemetryTestUtils.assertEvents(
+      [
+        {
+          category: "telemetry.test",
+          method: "test1",
+          object: "object1",
+          value: "value1",
+        },
+      ],
+      { category: "telemetry.test" }
+    );
+
+    Services.telemetry.setEventRecordingEnabled("telemetry.test", false);
+    Services.telemetry.clearEvents();
+  });
+
+  add_task(async function test_telemetry_register_scalars_string() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.registerScalars("telemetry.test.dynamic", {
+          webext_string: {
+            kind: browser.telemetry.ScalarType.STRING,
+            keyed: false,
+            record_on_release: true,
+          },
+        });
+        await browser.telemetry.scalarSet(
+          "telemetry.test.dynamic.webext_string",
+          "hello"
+        );
+        browser.test.notifyPass("register_scalars_string");
+      },
+      doneSignal: "register_scalars_string",
+    });
+    TelemetryTestUtils.assertScalar(
+      TelemetryTestUtils.getProcessScalars("parent", false, true),
+      "telemetry.test.dynamic.webext_string",
+      "hello"
+    );
+  });
+
+  add_task(async function test_telemetry_register_scalars_multiple() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.registerScalars("telemetry.test.dynamic", {
+          webext_string: {
+            kind: browser.telemetry.ScalarType.STRING,
+            keyed: false,
+            record_on_release: true,
+          },
+          webext_string_too: {
+            kind: browser.telemetry.ScalarType.STRING,
+            keyed: false,
+            record_on_release: true,
+          },
+        });
+        await browser.telemetry.scalarSet(
+          "telemetry.test.dynamic.webext_string",
+          "hello"
+        );
+        await browser.telemetry.scalarSet(
+          "telemetry.test.dynamic.webext_string_too",
+          "world"
+        );
+        browser.test.notifyPass("register_scalars_multiple");
+      },
+      doneSignal: "register_scalars_multiple",
+    });
+    const scalars = TelemetryTestUtils.getProcessScalars("parent", false, true);
+    TelemetryTestUtils.assertScalar(
+      scalars,
+      "telemetry.test.dynamic.webext_string",
+      "hello"
+    );
+    TelemetryTestUtils.assertScalar(
+      scalars,
+      "telemetry.test.dynamic.webext_string_too",
+      "world"
+    );
+  });
+
+  add_task(async function test_telemetry_register_scalars_boolean() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.registerScalars("telemetry.test.dynamic", {
+          webext_boolean: {
+            kind: browser.telemetry.ScalarType.BOOLEAN,
+            keyed: false,
+            record_on_release: true,
+          },
+        });
+        await browser.telemetry.scalarSet(
+          "telemetry.test.dynamic.webext_boolean",
+          true
+        );
+        browser.test.notifyPass("register_scalars_boolean");
+      },
+      doneSignal: "register_scalars_boolean",
+    });
+    TelemetryTestUtils.assertScalar(
+      TelemetryTestUtils.getProcessScalars("dynamic", false, true),
+      "telemetry.test.dynamic.webext_boolean",
+      true
+    );
+  });
+
+  add_task(async function test_telemetry_register_scalars_count() {
+    Services.telemetry.clearScalars();
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.registerScalars("telemetry.test.dynamic", {
+          webext_count: {
+            kind: browser.telemetry.ScalarType.COUNT,
+            keyed: false,
+            record_on_release: true,
+          },
+        });
+        await browser.telemetry.scalarSet(
+          "telemetry.test.dynamic.webext_count",
+          123
+        );
+        browser.test.notifyPass("register_scalars_count");
+      },
+      doneSignal: "register_scalars_count",
+    });
+    TelemetryTestUtils.assertScalar(
+      TelemetryTestUtils.getProcessScalars("dynamic", false, true),
+      "telemetry.test.dynamic.webext_count",
+      123
+    );
+  });
+
+  add_task(async function test_telemetry_register_events() {
+    Services.telemetry.clearEvents();
+
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.registerEvents("telemetry.test.dynamic", {
+          test1: {
+            methods: ["test1"],
+            objects: ["object1"],
+            extra_keys: [],
+          },
+        });
+        await browser.telemetry.recordEvent(
+          "telemetry.test.dynamic",
+          "test1",
+          "object1"
+        );
+        browser.test.notifyPass("register_events");
+      },
+      doneSignal: "register_events",
+    });
+
+    TelemetryTestUtils.assertEvents(
+      [
+        {
+          category: "telemetry.test.dynamic",
+          method: "test1",
+          object: "object1",
+        },
+      ],
+      { category: "telemetry.test.dynamic" },
+      { process: "dynamic" }
+    );
+  });
+
+  add_task(async function test_telemetry_submit_ping() {
+    let archiveTester = new TelemetryArchiveTesting.Checker();
+    await archiveTester.promiseInit();
+
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.submitPing("webext-test", {}, {});
+        browser.test.notifyPass("submit_ping");
+      },
+      doneSignal: "submit_ping",
+    });
+
+    await TestUtils.waitForCondition(
+      () => archiveTester.promiseFindPing("webext-test", []),
+      "Failed to find the webext-test ping"
+    );
+  });
+
+  add_task(async function test_telemetry_submit_encrypted_ping() {
+    await run({
+      backgroundScript: async () => {
+        try {
+          await browser.telemetry.submitEncryptedPing(
+            { payload: "encrypted-webext-test" },
+            {
+              schemaName: "schema-name",
+              schemaVersion: 123,
+            }
+          );
+          browser.test.fail(
+            "Expected exception without required manifest entries set."
+          );
+        } catch (e) {
+          browser.test.assertTrue(
+            e,
+            /Encrypted telemetry pings require ping_type and public_key to be set in manifest./
+          );
+          browser.test.notifyPass("submit_encrypted_ping_fail");
+        }
+      },
+      doneSignal: "submit_encrypted_ping_fail",
+    });
+
+    const telemetryManifestEntries = {
+      ping_type: "encrypted-webext-ping",
+      schemaNamespace: "schema-namespace",
+      public_key: {
+        id: "pioneer-dev-20200423",
+        key: {
+          crv: "P-256",
+          kty: "EC",
+          x: "Qqihp7EryDN2-qQ-zuDPDpy5mJD5soFBDZmzPWTmjwk",
+          y: "PiEQVUlywi2bEsA3_5D0VFrCHClCyUlLW52ajYs-5uc",
+        },
+      },
+    };
+
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.submitEncryptedPing(
+          {
+            payload: "encrypted-webext-test",
+          },
+          {
+            schemaName: "schema-name",
+            schemaVersion: 123,
+          }
+        );
+        browser.test.notifyPass("submit_encrypted_ping_pass");
+      },
+      permissions: ["telemetry"],
+      doneSignal: "submit_encrypted_ping_pass",
+      isPrivileged: true,
+      telemetry: telemetryManifestEntries,
+    });
+
+    telemetryManifestEntries.pioneer_id = true;
+    telemetryManifestEntries.study_name = "test123";
+    Services.prefs.setStringPref("toolkit.telemetry.pioneerId", "test123");
+
+    await run({
+      backgroundScript: async () => {
+        await browser.telemetry.submitEncryptedPing(
+          { payload: "encrypted-webext-test" },
+          {
+            schemaName: "schema-name",
+            schemaVersion: 123,
+          }
+        );
+        browser.test.notifyPass("submit_encrypted_ping_pass");
+      },
+      permissions: ["telemetry"],
+      doneSignal: "submit_encrypted_ping_pass",
+      isPrivileged: true,
+      telemetry: telemetryManifestEntries,
+    });
+
+    let pings;
+    await TestUtils.waitForCondition(async function() {
+      pings = await TelemetryArchive.promiseArchivedPingList();
+      return pings.length >= 3;
+    }, "Wait until we have at least 3 pings in the telemetry archive");
+
+    equal(pings.length, 3);
+    equal(pings[1].type, "encrypted-webext-ping");
+    equal(pings[2].type, "encrypted-webext-ping");
+  });
+
+  add_task(async function test_telemetry_can_upload_enabled() {
+    Services.prefs.setBoolPref(
+      TelemetryUtils.Preferences.FhrUploadEnabled,
+      true
+    );
+
+    await run({
+      backgroundScript: async () => {
+        const result = await browser.telemetry.canUpload();
+        browser.test.assertTrue(result);
+        browser.test.notifyPass("can_upload_enabled");
+      },
+      doneSignal: "can_upload_enabled",
+    });
+
+    Services.prefs.clearUserPref(TelemetryUtils.Preferences.FhrUploadEnabled);
+  });
+
+  add_task(async function test_telemetry_can_upload_disabled() {
+    Services.prefs.setBoolPref(
+      TelemetryUtils.Preferences.FhrUploadEnabled,
+      false
+    );
+
+    await run({
+      backgroundScript: async () => {
+        const result = await browser.telemetry.canUpload();
+        browser.test.assertFalse(result);
+        browser.test.notifyPass("can_upload_disabled");
+      },
+      doneSignal: "can_upload_disabled",
+    });
+
+    Services.prefs.clearUserPref(TelemetryUtils.Preferences.FhrUploadEnabled);
+  });
+}
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_test_mock.js b/toolkit/components/extensions/test/xpcshell/test_ext_test_mock.js
new file mode 100644
index 0000000000..81e07d9a9b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_test_mock.js
@@ -0,0 +1,55 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+// This test verifies that the extension mocks behave consistently, regardless
+// of test type (xpcshell vs browser test).
+// See also toolkit/components/extensions/test/browser/browser_ext_test_mock.js
+
+// Check the state of the extension object. This should be consistent between
+// browser tests and xpcshell tests.
+async function checkExtensionStartupAndUnload(ext) {
+  await ext.startup();
+  Assert.ok(ext.id, "Extension ID should be available");
+  Assert.ok(ext.uuid, "Extension UUID should be available");
+  await ext.unload();
+  // Once set nothing clears the UUID.
+  Assert.ok(ext.uuid, "Extension UUID exists after unload");
+}
+
+AddonTestUtils.init(this);
+
+add_task(async function setup() {
+  await ExtensionTestUtils.startAddonManager();
+});
+
+add_task(async function test_MockExtension() {
+  let ext = ExtensionTestUtils.loadExtension({
+    useAddonManager: "temporary",
+    manifest: {},
+  });
+
+  Assert.equal(ext.constructor.name, "InstallableWrapper", "expected class");
+  Assert.ok(!ext.id, "Extension ID is initially unavailable");
+  Assert.ok(!ext.uuid, "Extension UUID is initially unavailable");
+  await checkExtensionStartupAndUnload(ext);
+  // When useAddonManager is set, AOMExtensionWrapper clears the ID upon unload.
+  // TODO: Fix AOMExtensionWrapper to not clear the ID after unload, and move
+  // this assertion inside |checkExtensionStartupAndUnload| (since then the
+  // behavior will be consistent across all test types).
+  Assert.ok(!ext.id, "Extension ID is cleared after unload");
+});
+
+add_task(async function test_generated_Extension() {
+  let ext = ExtensionTestUtils.loadExtension({
+    manifest: {},
+  });
+
+  Assert.equal(ext.constructor.name, "ExtensionWrapper", "expected class");
+  // Without "useAddonManager", an Extension is generated and their IDs are
+  // immediately available.
+  Assert.ok(ext.id, "Extension ID is initially available");
+  Assert.ok(ext.uuid, "Extension UUID is initially available");
+  await checkExtensionStartupAndUnload(ext);
+  Assert.ok(ext.id, "Extension ID exists after unload");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_test_wrapper.js b/toolkit/components/extensions/test/xpcshell/test_ext_test_wrapper.js
new file mode 100644
index 0000000000..1752b5a2b5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_test_wrapper.js
@@ -0,0 +1,64 @@
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "AddonManager",
+  "resource://gre/modules/AddonManager.jsm"
+);
+
+// Automatically start the background page after restarting the AddonManager.
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  false
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "43"
+);
+
+const TEST_ADDON_ID = "@some-permanent-test-addon";
+
+// Load a permanent extension that eventually unloads the extension immediately
+// after add-on startup, to set the stage as a regression test for bug 1575190.
+add_task(async function setup_wrapper() {
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      applications: { gecko: { id: TEST_ADDON_ID } },
+    },
+    background() {
+      browser.test.sendMessage("started_up");
+    },
+  });
+
+  await AddonTestUtils.promiseStartupManager();
+  await extension.startup();
+  await AddonTestUtils.promiseShutdownManager();
+
+  // Check message because it is expected to be received while `startup()` was
+  // pending resolution.
+  info("Awaiting expected started_up message 1");
+  await extension.awaitMessage("started_up");
+
+  // Load AddonManager, and unload the extension as soon as it has started.
+  await AddonTestUtils.promiseStartupManager();
+  await extension.unload();
+  await AddonTestUtils.promiseShutdownManager();
+
+  // Confirm that the extension has started when promiseStartupManager returned.
+  info("Awaiting expected started_up message 2");
+  await extension.awaitMessage("started_up");
+});
+
+// Check that the add-on from the previous test has indeed been uninstalled.
+add_task(async function restart_addon_manager_after_extension_unload() {
+  await AddonTestUtils.promiseStartupManager();
+  let addon = await AddonManager.getAddonByID(TEST_ADDON_ID);
+  equal(addon, null, "Test add-on should have been removed");
+  await AddonTestUtils.promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_trustworthy_origin.js b/toolkit/components/extensions/test/xpcshell/test_ext_trustworthy_origin.js
new file mode 100644
index 0000000000..f509ae1749
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_trustworthy_origin.js
@@ -0,0 +1,20 @@
+"use strict";
+
+/**
+ * This test is asserting that moz-extension: URLs are recognized as trustworthy local origins
+ */
+
+add_task(
+  function test_isOriginPotentiallyTrustworthnsIContentSecurityManagery() {
+    let uri = NetUtil.newURI("moz-extension://foobar/something.html");
+    let principal = Services.scriptSecurityManager.createContentPrincipal(
+      uri,
+      {}
+    );
+    Assert.equal(
+      principal.isOriginPotentiallyTrustworthy,
+      true,
+      "it is potentially trustworthy"
+    );
+  }
+);
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_unknown_permissions.js b/toolkit/components/extensions/test/xpcshell/test_ext_unknown_permissions.js
new file mode 100644
index 0000000000..9c515520e1
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_unknown_permissions.js
@@ -0,0 +1,63 @@
+"use strict";
+
+// This test expects and checks warnings for unknown permissions.
+ExtensionTestUtils.failOnSchemaWarnings(false);
+
+add_task(async function test_unknown_permissions() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "activeTab",
+        "fooUnknownPermission",
+        "http://*/",
+        "chrome://favicon/",
+      ],
+      optional_permissions: ["chrome://favicon/", "https://example.com/"],
+    },
+  });
+
+  let { messages } = await promiseConsoleOutput(() => extension.startup());
+
+  const { WebExtensionPolicy } = Cu.getGlobalForObject(
+    ChromeUtils.import("resource://gre/modules/Extension.jsm", {})
+  );
+
+  let policy = WebExtensionPolicy.getByID(extension.id);
+  Assert.deepEqual(Array.from(policy.permissions).sort(), [
+    "activeTab",
+    "http://*/*",
+  ]);
+
+  Assert.deepEqual(extension.extension.manifest.optional_permissions, [
+    "https://example.com/",
+  ]);
+
+  ok(
+    messages.some(message =>
+      /Error processing permissions\.1: Value "fooUnknownPermission" must/.test(
+        message
+      )
+    ),
+    'Got expected error for "fooUnknownPermission"'
+  );
+
+  ok(
+    messages.some(message =>
+      /Error processing permissions\.3: Value "chrome:\/\/favicon\/" must/.test(
+        message
+      )
+    ),
+    'Got expected error for "chrome://favicon/"'
+  );
+
+  ok(
+    messages.some(message =>
+      /Error processing optional_permissions\.0: Value "chrome:\/\/favicon\/" must/.test(
+        message
+      )
+    ),
+    "Got expected error from optional_permissions"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_unlimitedStorage.js b/toolkit/components/extensions/test/xpcshell/test_ext_unlimitedStorage.js
new file mode 100644
index 0000000000..6a9125c9e4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_unlimitedStorage.js
@@ -0,0 +1,213 @@
+"use strict";
+
+const {
+  createAppInfo,
+  promiseStartupManager,
+  promiseRestartManager,
+  promiseWebExtensionStartup,
+} = AddonTestUtils;
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "42", "42");
+
+const STORAGE_SITE_PERMISSIONS = [
+  "WebExtensions-unlimitedStorage",
+  "indexedDB",
+  "persistent-storage",
+];
+
+function checkSitePermissions(principal, expectedPermAction, assertMessage) {
+  for (const permName of STORAGE_SITE_PERMISSIONS) {
+    const actualPermAction = Services.perms.testPermissionFromPrincipal(
+      principal,
+      permName
+    );
+
+    equal(
+      actualPermAction,
+      expectedPermAction,
+      `The extension "${permName}" SitePermission ${assertMessage} as expected`
+    );
+  }
+}
+
+add_task(async function test_unlimitedStorage_restored_on_app_startup() {
+  const id = "test-unlimitedStorage-removed-on-app-shutdown@mozilla";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["unlimitedStorage"],
+      applications: {
+        gecko: { id },
+      },
+    },
+
+    useAddonManager: "permanent",
+  });
+
+  await promiseStartupManager();
+  await extension.startup();
+
+  const policy = WebExtensionPolicy.getByID(extension.id);
+  const principal = policy.extension.principal;
+
+  checkSitePermissions(
+    principal,
+    Services.perms.ALLOW_ACTION,
+    "has been allowed"
+  );
+
+  // Remove site permissions as it would happen if Firefox is shutting down
+  // with the "clear site permissions" setting.
+
+  Services.perms.removeFromPrincipal(
+    principal,
+    "WebExtensions-unlimitedStorage"
+  );
+  Services.perms.removeFromPrincipal(principal, "indexedDB");
+  Services.perms.removeFromPrincipal(principal, "persistent-storage");
+
+  checkSitePermissions(principal, Services.perms.UNKNOWN_ACTION, "is not set");
+
+  const onceExtensionStarted = promiseWebExtensionStartup(id);
+  await promiseRestartManager();
+  await onceExtensionStarted;
+
+  // The site permissions should have been granted again.
+  checkSitePermissions(
+    principal,
+    Services.perms.ALLOW_ACTION,
+    "has been allowed"
+  );
+
+  await extension.unload();
+});
+
+add_task(async function test_unlimitedStorage_removed_on_update() {
+  const id = "test-unlimitedStorage-removed-on-update@mozilla";
+
+  function background() {
+    browser.test.onMessage.addListener(async msg => {
+      switch (msg) {
+        case "set-storage":
+          browser.test.log(`storing data in storage.local`);
+          await browser.storage.local.set({ akey: "somevalue" });
+          browser.test.log(`data stored in storage.local successfully`);
+          break;
+        case "has-storage": {
+          browser.test.log(`checking data stored in storage.local`);
+          const data = await browser.storage.local.get(["akey"]);
+          browser.test.assertEq(
+            data.akey,
+            "somevalue",
+            "Got storage.local data"
+          );
+          break;
+        }
+        default:
+          browser.test.fail(`Unexpected test message: ${msg}`);
+      }
+
+      browser.test.sendMessage(`${msg}:done`);
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["unlimitedStorage", "storage"],
+      applications: { gecko: { id } },
+      version: "1",
+    },
+    useAddonManager: "permanent",
+  });
+
+  await extension.startup();
+
+  const policy = WebExtensionPolicy.getByID(extension.id);
+  const principal = policy.extension.principal;
+
+  checkSitePermissions(
+    principal,
+    Services.perms.ALLOW_ACTION,
+    "has been allowed"
+  );
+
+  extension.sendMessage("set-storage");
+  await extension.awaitMessage("set-storage:done");
+  extension.sendMessage("has-storage");
+  await extension.awaitMessage("has-storage:done");
+
+  // Simulate an update which do not require the unlimitedStorage permission.
+  await extension.upgrade({
+    background,
+    manifest: {
+      permissions: ["storage"],
+      applications: { gecko: { id } },
+      version: "2",
+    },
+    useAddonManager: "permanent",
+  });
+
+  const newPolicy = WebExtensionPolicy.getByID(extension.id);
+  const newPrincipal = newPolicy.extension.principal;
+
+  equal(
+    principal.spec,
+    newPrincipal.spec,
+    "upgraded extension has the expected principal"
+  );
+
+  checkSitePermissions(
+    principal,
+    Services.perms.UNKNOWN_ACTION,
+    "has been cleared"
+  );
+
+  // Verify that the previously stored data has not been
+  // removed as a side effect of removing the unlimitedStorage
+  // permission.
+  extension.sendMessage("has-storage");
+  await extension.awaitMessage("has-storage:done");
+
+  await extension.unload();
+});
+
+add_task(async function test_unlimitedStorage_origin_attributes() {
+  Services.prefs.setBoolPref("privacy.firstparty.isolate", true);
+
+  const id = "test-unlimitedStorage-origin-attributes@mozilla";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["unlimitedStorage"],
+      applications: { gecko: { id } },
+    },
+  });
+
+  await extension.startup();
+
+  let policy = WebExtensionPolicy.getByID(extension.id);
+  let principal = policy.extension.principal;
+
+  ok(
+    !principal.firstPartyDomain,
+    "extension principal has no firstPartyDomain"
+  );
+
+  let perm = Services.perms.testExactPermissionFromPrincipal(
+    principal,
+    "persistent-storage"
+  );
+  equal(
+    perm,
+    Services.perms.ALLOW_ACTION,
+    "Should have the correct permission without OAs"
+  );
+
+  await extension.unload();
+
+  Services.prefs.clearUserPref("privacy.firstparty.isolate");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_unload_frame.js b/toolkit/components/extensions/test/xpcshell/test_ext_unload_frame.js
new file mode 100644
index 0000000000..058e8b7371
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_unload_frame.js
@@ -0,0 +1,230 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+// Background and content script for testSendMessage_*
+function sendMessage_background(delayedNotifyPass) {
+  browser.runtime.onMessage.addListener((msg, sender, sendResponse) => {
+    browser.test.assertEq("from frame", msg, "Expected message from frame");
+    sendResponse("msg from back"); // Should not throw or anything like that.
+    delayedNotifyPass("Received sendMessage from closing frame");
+  });
+}
+function sendMessage_contentScript(testType) {
+  browser.runtime.sendMessage("from frame", reply => {
+    // The frame has been removed, so we should not get this callback!
+    browser.test.fail(`Unexpected reply: ${reply}`);
+  });
+  if (testType == "frame") {
+    frameElement.remove();
+  } else {
+    browser.test.sendMessage("close-window");
+  }
+}
+
+// Background and content script for testConnect_*
+function connect_background(delayedNotifyPass) {
+  browser.runtime.onConnect.addListener(port => {
+    browser.test.assertEq("port from frame", port.name);
+
+    let disconnected = false;
+    let hasMessage = false;
+    port.onDisconnect.addListener(() => {
+      browser.test.assertFalse(disconnected, "onDisconnect should fire once");
+      disconnected = true;
+      browser.test.assertTrue(
+        hasMessage,
+        "Expected onMessage before onDisconnect"
+      );
+      browser.test.assertEq(
+        null,
+        port.error,
+        "The port is implicitly closed without errors when the other context unloads"
+      );
+      delayedNotifyPass("Received onDisconnect from closing frame");
+    });
+    port.onMessage.addListener(msg => {
+      browser.test.assertFalse(hasMessage, "onMessage should fire once");
+      hasMessage = true;
+      browser.test.assertFalse(
+        disconnected,
+        "Should get message before disconnect"
+      );
+      browser.test.assertEq("from frame", msg, "Expected message from frame");
+    });
+
+    port.postMessage("reply to closing frame");
+  });
+}
+function connect_contentScript(testType) {
+  let isUnloading = false;
+  addEventListener(
+    "pagehide",
+    () => {
+      isUnloading = true;
+    },
+    { once: true }
+  );
+
+  let port = browser.runtime.connect({ name: "port from frame" });
+  port.onMessage.addListener(msg => {
+    // The background page sends a reply as soon as we call runtime.connect().
+    // It is possible that the reply reaches this frame before the
+    // window.close() request has been processed.
+    if (!isUnloading) {
+      browser.test.log(
+        `Ignorting unexpected reply ("${msg}") because the page is not being unloaded.`
+      );
+      return;
+    }
+
+    // The frame has been removed, so we should not get a reply.
+    browser.test.fail(`Unexpected reply: ${msg}`);
+  });
+  port.postMessage("from frame");
+
+  // Removing the frame or window should disconnect the port.
+  if (testType == "frame") {
+    frameElement.remove();
+  } else {
+    browser.test.sendMessage("close-window");
+  }
+}
+
+// `testType` is "window" or "frame".
+function createTestExtension(testType, backgroundScript, contentScript) {
+  // Make a roundtrip between the background page and the test runner (which is
+  // in the same process as the content script) to make sure that we record a
+  // failure in case the content script's sendMessage or onMessage handlers are
+  // called even after the frame or window was removed.
+  function delayedNotifyPass(msg) {
+    browser.test.onMessage.addListener((type, echoMsg) => {
+      if (type == "pong") {
+        browser.test.assertEq(msg, echoMsg, "Echoed reply should be the same");
+        browser.test.notifyPass(msg);
+      }
+    });
+    browser.test.log("Starting ping-pong to flush messages...");
+    browser.test.sendMessage("ping", msg);
+  }
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})(${delayedNotifyPass});`,
+    manifest: {
+      content_scripts: [
+        {
+          js: ["contentscript.js"],
+          all_frames: testType == "frame",
+          matches: ["http://example.com/data/file_sample.html"],
+        },
+      ],
+    },
+    files: {
+      "contentscript.js": `(${contentScript})("${testType}");`,
+    },
+  });
+  extension.awaitMessage("ping").then(msg => {
+    extension.sendMessage("pong", msg);
+  });
+  return extension;
+}
+
+add_task(async function testSendMessage_and_remove_frame() {
+  let extension = createTestExtension(
+    "frame",
+    sendMessage_background,
+    sendMessage_contentScript
+  );
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+
+  await contentPage.spawn(null, () => {
+    let { document } = this.content;
+    let frame = document.createElement("iframe");
+    frame.src = "/data/file_sample.html";
+    document.body.appendChild(frame);
+  });
+
+  await extension.awaitFinish("Received sendMessage from closing frame");
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function testConnect_and_remove_frame() {
+  let extension = createTestExtension(
+    "frame",
+    connect_background,
+    connect_contentScript
+  );
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+
+  await contentPage.spawn(null, () => {
+    let { document } = this.content;
+    let frame = document.createElement("iframe");
+    frame.src = "/data/file_sample.html";
+    document.body.appendChild(frame);
+  });
+
+  await extension.awaitFinish("Received onDisconnect from closing frame");
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function testSendMessage_and_remove_window() {
+  if (AppConstants.MOZ_BUILD_APP !== "browser") {
+    // We can't rely on this timing on Android.
+    return;
+  }
+
+  let extension = createTestExtension(
+    "window",
+    sendMessage_background,
+    sendMessage_contentScript
+  );
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+  await extension.awaitMessage("close-window");
+  await contentPage.close();
+
+  await extension.awaitFinish("Received sendMessage from closing frame");
+  await extension.unload();
+});
+
+add_task(async function testConnect_and_remove_window() {
+  if (AppConstants.MOZ_BUILD_APP !== "browser") {
+    // We can't rely on this timing on Android.
+    return;
+  }
+
+  let extension = createTestExtension(
+    "window",
+    connect_background,
+    connect_contentScript
+  );
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+  await extension.awaitMessage("close-window");
+  await contentPage.close();
+
+  await extension.awaitFinish("Received onDisconnect from closing frame");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_userScripts.js b/toolkit/components/extensions/test/xpcshell/test_ext_userScripts.js
new file mode 100644
index 0000000000..78114d9de4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_userScripts.js
@@ -0,0 +1,671 @@
+"use strict";
+
+const PROCESS_COUNT_PREF = "dom.ipc.processCount";
+
+const { createAppInfo } = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "49");
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function setup_test_environment() {
+  if (ExtensionTestUtils.remoteContentScripts) {
+    // Start with one content process so that we can increase the number
+    // later and test the behavior of a fresh content process.
+    Services.prefs.setIntPref(PROCESS_COUNT_PREF, 1);
+  }
+
+  // Grant the optional permissions requested.
+  function permissionObserver(subject, topic, data) {
+    if (topic == "webextension-optional-permission-prompt") {
+      let { resolve } = subject.wrappedJSObject;
+      resolve(true);
+    }
+  }
+  Services.obs.addObserver(
+    permissionObserver,
+    "webextension-optional-permission-prompt"
+  );
+  registerCleanupFunction(() => {
+    Services.obs.removeObserver(
+      permissionObserver,
+      "webextension-optional-permission-prompt"
+    );
+  });
+});
+
+// Test that there is no userScripts API namespace when the manifest doesn't include a user_scripts
+// property.
+add_task(async function test_userScripts_manifest_property_required() {
+  function background() {
+    browser.test.assertEq(
+      undefined,
+      browser.userScripts,
+      "userScripts API namespace should be undefined in the extension page"
+    );
+    browser.test.sendMessage("background-page:done");
+  }
+
+  async function contentScript() {
+    browser.test.assertEq(
+      undefined,
+      browser.userScripts,
+      "userScripts API namespace should be undefined in the content script"
+    );
+    browser.test.sendMessage("content-script:done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["http://*/*/file_sample.html"],
+      content_scripts: [
+        {
+          matches: ["http://*/*/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+        },
+      ],
+    },
+    files: {
+      "content_script.js": contentScript,
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("background-page:done");
+
+  let url = `${BASE_URL}/file_sample.html`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+
+  await extension.awaitMessage("content-script:done");
+
+  await extension.unload();
+  await contentPage.close();
+});
+
+// Test that userScripts can only matches origins that are subsumed by the extension permissions,
+// and that more origins can be allowed by requesting an optional permission.
+add_task(async function test_userScripts_matches_denied() {
+  async function background() {
+    async function registerUserScriptWithMatches(matches) {
+      const scripts = await browser.userScripts.register({
+        js: [{ code: "" }],
+        matches,
+      });
+      await scripts.unregister();
+    }
+
+    // These matches are supposed to be denied until the extension has been granted the
+    // <all_urls> origin permission.
+    const testMatches = [
+      "<all_urls>",
+      "file://*/*",
+      "https://localhost/*",
+      "http://example.com/*",
+    ];
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg === "test-denied-matches") {
+        for (let testMatch of testMatches) {
+          await browser.test.assertRejects(
+            registerUserScriptWithMatches([testMatch]),
+            /Permission denied to register a user script for/,
+            "Got the expected rejection when the extension permission does not subsume the userScript matches"
+          );
+        }
+      } else if (msg === "grant-all-urls") {
+        await browser.permissions.request({ origins: ["<all_urls>"] });
+      } else if (msg === "test-allowed-matches") {
+        for (let testMatch of testMatches) {
+          try {
+            await registerUserScriptWithMatches([testMatch]);
+          } catch (err) {
+            browser.test.fail(
+              `Unexpected rejection ${err} on matching ${JSON.stringify(
+                testMatch
+              )}`
+            );
+          }
+        }
+      } else {
+        browser.test.fail(`Received an unexpected ${msg} test message`);
+      }
+
+      browser.test.sendMessage(`${msg}:done`);
+    });
+
+    browser.test.sendMessage("background-ready");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://localhost/*"],
+      optional_permissions: ["<all_urls>"],
+      user_scripts: {},
+    },
+    background,
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("background-ready");
+
+  // Test that the matches not subsumed by the extension permissions are being denied.
+  extension.sendMessage("test-denied-matches");
+  await extension.awaitMessage("test-denied-matches:done");
+
+  // Grant the optional <all_urls> permission.
+  await withHandlingUserInput(extension, async () => {
+    extension.sendMessage("grant-all-urls");
+    await extension.awaitMessage("grant-all-urls:done");
+  });
+
+  // Test that all the matches are now subsumed by the extension permissions.
+  extension.sendMessage("test-allowed-matches");
+  await extension.awaitMessage("test-allowed-matches:done");
+
+  await extension.unload();
+});
+
+// Test that userScripts sandboxes:
+// - can be registered/unregistered from an extension page (and they are registered on both new and
+//   existing processes).
+// - have no WebExtensions APIs available
+// - are able to access the target window and document
+add_task(async function test_userScripts_no_webext_apis() {
+  async function background() {
+    const matches = ["http://localhost/*/file_sample.html*"];
+
+    const sharedCode = {
+      code: 'console.log("js code shared by multiple userScripts");',
+    };
+
+    const userScriptOptions = {
+      js: [
+        sharedCode,
+        {
+          code: `
+          window.addEventListener("load", () => {
+            const webextAPINamespaces = this.browser ? Object.keys(this.browser) : undefined;
+            document.body.innerHTML = "userScript loaded - " + JSON.stringify(webextAPINamespaces);
+          }, {once: true});
+        `,
+        },
+      ],
+      runAt: "document_start",
+      matches,
+      scriptMetadata: {
+        name: "test-user-script",
+        arrayProperty: ["el1"],
+        objectProperty: { nestedProp: "nestedValue" },
+        nullProperty: null,
+      },
+    };
+
+    let script = await browser.userScripts.register(userScriptOptions);
+
+    // Unregister and then register the same js code again, to verify that the last registered
+    // userScript doesn't get assigned a revoked blob url (otherwise Extensioncontent.jsm
+    // ScriptCache raises an error because it fails to compile the revoked blob url and the user
+    // script will never be loaded).
+    script.unregister();
+    script = await browser.userScripts.register(userScriptOptions);
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg !== "register-new-script") {
+        return;
+      }
+
+      await script.unregister();
+      await browser.userScripts.register({
+        ...userScriptOptions,
+        scriptMetadata: { name: "test-new-script" },
+        js: [
+          sharedCode,
+          {
+            code: `
+          window.addEventListener("load", () => {
+            const webextAPINamespaces = this.browser ? Object.keys(this.browser) : undefined;
+            document.body.innerHTML = "new userScript loaded - " + JSON.stringify(webextAPINamespaces);
+          }, {once: true});
+        `,
+          },
+        ],
+      });
+
+      browser.test.sendMessage("script-registered");
+    });
+
+    const scriptToRemove = await browser.userScripts.register({
+      js: [
+        sharedCode,
+        {
+          code: `
+          window.addEventListener("load", () => {
+            document.body.innerHTML = "unexpected unregistered userScript loaded";
+          }, {once: true});
+        `,
+        },
+      ],
+      runAt: "document_start",
+      matches,
+      scriptMetadata: {
+        name: "user-script-to-remove",
+      },
+    });
+
+    browser.test.assertTrue(
+      "unregister" in script,
+      "Got an unregister method on the userScript API object"
+    );
+
+    // Remove the last registered user script.
+    await scriptToRemove.unregister();
+
+    browser.test.sendMessage("background-ready");
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: ["http://localhost/*/file_sample.html"],
+      user_scripts: {},
+    },
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+
+  await extension.awaitMessage("background-ready");
+
+  let url = `${BASE_URL}/file_sample.html?testpage=1`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    url,
+    ExtensionTestUtils.remoteContentScripts ? { remote: true } : undefined
+  );
+  let result = await contentPage.spawn(undefined, async () => {
+    return {
+      textContent: this.content.document.body.textContent,
+      url: this.content.location.href,
+      readyState: this.content.document.readyState,
+    };
+  });
+  Assert.deepEqual(
+    result,
+    {
+      textContent: "userScript loaded - undefined",
+      url,
+      readyState: "complete",
+    },
+    "The userScript executed on the expected url and no access to the WebExtensions APIs"
+  );
+
+  // If the tests is running with "remote content process" mode, test that the userScript
+  // are being correctly registered in newly created processes (received as part of the sharedData).
+  if (ExtensionTestUtils.remoteContentScripts) {
+    info(
+      "Test content script are correctly created on a newly created process"
+    );
+
+    await extension.sendMessage("register-new-script");
+    await extension.awaitMessage("script-registered");
+
+    // Update the process count preference, so that we can test that the newly registered user script
+    // is propagated as expected into the newly created process.
+    Services.prefs.setIntPref(PROCESS_COUNT_PREF, 2);
+
+    const url2 = `${BASE_URL}/file_sample.html?testpage=2`;
+    let contentPage2 = await ExtensionTestUtils.loadContentPage(url2, {
+      remote: true,
+    });
+    let result2 = await contentPage2.spawn(undefined, async () => {
+      return {
+        textContent: this.content.document.body.textContent,
+        url: this.content.location.href,
+        readyState: this.content.document.readyState,
+      };
+    });
+    Assert.deepEqual(
+      result2,
+      {
+        textContent: "new userScript loaded - undefined",
+        url: url2,
+        readyState: "complete",
+      },
+      "The userScript executed on the expected url and no access to the WebExtensions APIs"
+    );
+
+    await contentPage2.close();
+  }
+
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+// This test verify that a cached script is still able to catch the document
+// while it is still loading (when we do not block the document parsing as
+// we do for a non cached script).
+add_task(async function test_cached_userScript_on_document_start() {
+  function apiScript() {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        sendTestMessage(name, params) {
+          return browser.test.sendMessage(name, params);
+        },
+      });
+    });
+  }
+
+  async function background() {
+    function userScript() {
+      this.sendTestMessage("user-script-loaded", {
+        url: window.location.href,
+        documentReadyState: document.readyState,
+      });
+    }
+
+    await browser.userScripts.register({
+      js: [
+        {
+          code: `(${userScript})();`,
+        },
+      ],
+      runAt: "document_start",
+      matches: ["http://localhost/*/file_sample.html"],
+    });
+
+    browser.test.sendMessage("user-script-registered");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://localhost/*/file_sample.html"],
+      user_scripts: {
+        api_script: "api-script.js",
+        // The following is an unexpected manifest property, that we expect to be ignored and
+        // to not prevent the test extension from being installed and run as expected.
+        unexpected_manifest_key: "test-unexpected-key",
+      },
+    },
+    background,
+    files: {
+      "api-script.js": apiScript,
+    },
+  });
+
+  ExtensionTestUtils.failOnSchemaWarnings(false);
+  await extension.startup();
+  ExtensionTestUtils.failOnSchemaWarnings(true);
+  await extension.awaitMessage("user-script-registered");
+
+  let url = `${BASE_URL}/file_sample.html`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+
+  let msg = await extension.awaitMessage("user-script-loaded");
+  Assert.deepEqual(
+    msg,
+    {
+      url,
+      documentReadyState: "loading",
+    },
+    "Got the expected url and document.readyState from a non cached user script"
+  );
+
+  // Reload the page and check that the cached content script is still able to
+  // run on document_start.
+  await contentPage.loadURL(url);
+
+  let msgFromCached = await extension.awaitMessage("user-script-loaded");
+  Assert.deepEqual(
+    msgFromCached,
+    {
+      url,
+      documentReadyState: "loading",
+    },
+    "Got the expected url and document.readyState from a cached user script"
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_userScripts_pref_disabled() {
+  async function run_userScript_on_pref_disabled_test() {
+    async function background() {
+      let promise = (async () => {
+        await browser.userScripts.register({
+          js: [
+            {
+              code:
+                "throw new Error('This userScripts should not be registered')",
+            },
+          ],
+          runAt: "document_start",
+          matches: ["<all_urls>"],
+        });
+      })();
+
+      await browser.test.assertRejects(
+        promise,
+        /userScripts APIs are currently experimental/,
+        "Got the expected error from userScripts.register when the userScripts API is disabled"
+      );
+
+      browser.test.sendMessage("background-page:done");
+    }
+
+    async function contentScript() {
+      let promise = (async () => {
+        browser.userScripts.onBeforeScript.addListener(() => {});
+      })();
+      await browser.test.assertRejects(
+        promise,
+        /userScripts APIs are currently experimental/,
+        "Got the expected error from userScripts.onBeforeScript when the userScripts API is disabled"
+      );
+
+      browser.test.sendMessage("content-script:done");
+    }
+
+    let extension = ExtensionTestUtils.loadExtension({
+      background,
+      manifest: {
+        permissions: ["http://*/*/file_sample.html"],
+        user_scripts: { api_script: "" },
+        content_scripts: [
+          {
+            matches: ["http://*/*/file_sample.html"],
+            js: ["content_script.js"],
+            run_at: "document_start",
+          },
+        ],
+      },
+      files: {
+        "content_script.js": contentScript,
+      },
+    });
+
+    await extension.startup();
+
+    await extension.awaitMessage("background-page:done");
+
+    let url = `${BASE_URL}/file_sample.html`;
+    let contentPage = await ExtensionTestUtils.loadContentPage(url);
+
+    await extension.awaitMessage("content-script:done");
+
+    await extension.unload();
+    await contentPage.close();
+  }
+
+  await runWithPrefs(
+    [["extensions.webextensions.userScripts.enabled", false]],
+    run_userScript_on_pref_disabled_test
+  );
+});
+
+// This test verify that userScripts.onBeforeScript API Event is not available without
+// a "user_scripts.api_script" property in the manifest.
+add_task(async function test_user_script_api_script_required() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://localhost/*/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_start",
+        },
+      ],
+      user_scripts: {},
+    },
+    files: {
+      "content_script.js": function() {
+        browser.test.assertEq(
+          undefined,
+          browser.userScripts && browser.userScripts.onBeforeScript,
+          "Got an undefined onBeforeScript property as expected"
+        );
+        browser.test.sendMessage("no-onBeforeScript:done");
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let url = `${BASE_URL}/file_sample.html`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+
+  await extension.awaitMessage("no-onBeforeScript:done");
+
+  await extension.unload();
+  await contentPage.close();
+});
+
+add_task(async function test_scriptMetaData() {
+  function getTestCases(isUserScriptsRegister) {
+    return [
+      // When scriptMetadata is not set (or undefined), it is treated as if it were null.
+      // In the API script, the metadata is then expected to be null.
+      isUserScriptsRegister ? undefined : null,
+
+      // Falsey
+      null,
+      "",
+      false,
+      0,
+
+      // Truthy
+      true,
+      1,
+      "non-empty string",
+
+      // Objects
+      ["some array with value"],
+      { "some object": "with value" },
+    ];
+  }
+
+  async function background(pageUrl) {
+    for (let scriptMetadata of getTestCases(true)) {
+      await browser.userScripts.register({
+        js: [{ file: "userscript.js" }],
+        runAt: "document_end",
+        allFrames: true,
+        matches: ["http://localhost/*/file_sample.html"],
+        scriptMetadata,
+      });
+    }
+
+    let f = document.createElement("iframe");
+    f.src = pageUrl;
+    document.body.append(f);
+    browser.test.sendMessage("background-page:done");
+  }
+
+  function apiScript() {
+    let testCases = getTestCases(false);
+    let i = 0;
+
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        checkMetadata() {
+          let expectation = testCases[i];
+          let metadata = script.metadata;
+          if (typeof expectation === "object" && expectation !== null) {
+            // Non-primitive values cannot be compared with assertEq,
+            // so serialize both and just verify that they are equal.
+            expectation = JSON.stringify(expectation);
+            metadata = JSON.stringify(script.metadata);
+          }
+
+          browser.test.assertEq(
+            expectation,
+            metadata,
+            `Expected metadata at call ${i}`
+          );
+          if (++i === testCases.length) {
+            browser.test.sendMessage("apiscript:done");
+          }
+        },
+      });
+    });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `${getTestCases};(${background})("${BASE_URL}/file_sample.html")`,
+    manifest: {
+      permissions: ["http://*/*/file_sample.html"],
+      user_scripts: {
+        api_script: "apiscript.js",
+      },
+    },
+    files: {
+      "apiscript.js": `${getTestCases};(${apiScript})()`,
+      "userscript.js": "checkMetadata();",
+    },
+  });
+
+  await extension.startup();
+
+  await extension.awaitMessage("background-page:done");
+  await extension.awaitMessage("apiscript:done");
+
+  await extension.unload();
+});
+
+add_task(async function test_userScriptOptions_js_property_required() {
+  function background() {
+    const userScriptOptions = {
+      runAt: "document_start",
+      matches: ["http://*/*/file_sample.html"],
+    };
+
+    browser.test.assertThrows(
+      () => browser.userScripts.register(userScriptOptions),
+      /Type error for parameter userScriptOptions \(Property \"js\" is required\)/,
+      "Got the expected error from userScripts.register when js property is missing"
+    );
+
+    browser.test.sendMessage("done");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background,
+    manifest: {
+      permissions: ["http://*/*/file_sample.html"],
+      user_scripts: {},
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_userScripts_exports.js b/toolkit/components/extensions/test/xpcshell/test_ext_userScripts_exports.js
new file mode 100644
index 0000000000..72e8a51c7f
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_userScripts_exports.js
@@ -0,0 +1,1108 @@
+"use strict";
+
+const { createAppInfo } = AddonTestUtils;
+
+AddonTestUtils.init(this);
+
+createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "49");
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+// A small utility function used to test the expected behaviors of the userScripts API method
+// wrapper.
+async function test_userScript_APIMethod({
+  apiScript,
+  userScript,
+  userScriptMetadata,
+  testFn,
+  runtimeMessageListener,
+}) {
+  async function backgroundScript(
+    userScriptFn,
+    scriptMetadata,
+    messageListener
+  ) {
+    await browser.userScripts.register({
+      js: [
+        {
+          code: `(${userScriptFn})();`,
+        },
+      ],
+      runAt: "document_end",
+      matches: ["http://localhost/*/file_sample.html"],
+      scriptMetadata,
+    });
+
+    if (messageListener) {
+      browser.runtime.onMessage.addListener(messageListener);
+    }
+
+    browser.test.sendMessage("background-ready");
+  }
+
+  function notifyFinish(failureReason) {
+    browser.test.assertEq(
+      undefined,
+      failureReason,
+      "should be completed without errors"
+    );
+    browser.test.sendMessage("test_userScript_APIMethod:done");
+  }
+
+  function assertTrue(val, message) {
+    browser.test.assertTrue(val, message);
+    if (!val) {
+      browser.test.sendMessage("test_userScript_APIMethod:done");
+      throw message;
+    }
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://localhost/*/file_sample.html"],
+      user_scripts: {
+        api_script: "api-script.js",
+      },
+    },
+    // Defines a background script that receives all the needed test parameters.
+    background: `
+        const metadata = ${JSON.stringify(userScriptMetadata)};
+        (${backgroundScript})(${userScript}, metadata, ${runtimeMessageListener})
+     `,
+    files: {
+      "api-script.js": `(${apiScript})({
+        assertTrue: ${assertTrue},
+        notifyFinish: ${notifyFinish}
+      })`,
+    },
+  });
+
+  // Load a page in a content process, register the user script and then load a
+  // new page in the existing content process.
+  let url = `${BASE_URL}/file_sample.html`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(`about:blank`);
+
+  await extension.startup();
+  await extension.awaitMessage("background-ready");
+  await contentPage.loadURL(url);
+
+  // Run any additional test-specific assertions.
+  if (testFn) {
+    await testFn({ extension, contentPage, url });
+  }
+
+  await extension.awaitMessage("test_userScript_APIMethod:done");
+
+  await extension.unload();
+  await contentPage.close();
+}
+
+add_task(async function test_apiScript_exports_simple_sync_method() {
+  function apiScript(sharedTestAPIMethods) {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      const scriptMetadata = script.metadata;
+
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIMethod(
+          stringParam,
+          numberParam,
+          boolParam,
+          nullParam,
+          undefinedParam,
+          arrayParam
+        ) {
+          browser.test.assertEq(
+            "test-user-script-exported-apis",
+            scriptMetadata.name,
+            "Got the expected value for a string scriptMetadata property"
+          );
+          browser.test.assertEq(
+            null,
+            scriptMetadata.nullProperty,
+            "Got the expected value for a null scriptMetadata property"
+          );
+          browser.test.assertTrue(
+            scriptMetadata.arrayProperty &&
+              scriptMetadata.arrayProperty.length === 1 &&
+              scriptMetadata.arrayProperty[0] === "el1",
+            "Got the expected value for an array scriptMetadata property"
+          );
+          browser.test.assertTrue(
+            scriptMetadata.objectProperty &&
+              scriptMetadata.objectProperty.nestedProp === "nestedValue",
+            "Got the expected value for an object scriptMetadata property"
+          );
+
+          browser.test.assertEq(
+            "param1",
+            stringParam,
+            "Got the expected string parameter value"
+          );
+          browser.test.assertEq(
+            123,
+            numberParam,
+            "Got the expected number parameter value"
+          );
+          browser.test.assertEq(
+            true,
+            boolParam,
+            "Got the expected boolean parameter value"
+          );
+          browser.test.assertEq(
+            null,
+            nullParam,
+            "Got the expected null parameter value"
+          );
+          browser.test.assertEq(
+            undefined,
+            undefinedParam,
+            "Got the expected undefined parameter value"
+          );
+
+          browser.test.assertEq(
+            3,
+            arrayParam.length,
+            "Got the expected length on the array param"
+          );
+          browser.test.assertTrue(
+            arrayParam.includes(1),
+            "Got the expected result when calling arrayParam.includes"
+          );
+
+          return "returned_value";
+        },
+      });
+    });
+  }
+
+  function userScript() {
+    const { assertTrue, notifyFinish, testAPIMethod } = this;
+
+    // Redefine the includes method on the Array prototype, to explicitly verify that the method
+    // redefined in the userScript is not used when accessing arrayParam.includes from the API script.
+    // eslint-disable-next-line no-extend-native
+    Array.prototype.includes = () => {
+      throw new Error("Unexpected prototype leakage");
+    };
+    const arrayParam = new Array(1, 2, 3); // eslint-disable-line no-array-constructor
+    const result = testAPIMethod(
+      "param1",
+      123,
+      true,
+      null,
+      undefined,
+      arrayParam
+    );
+
+    assertTrue(
+      result === "returned_value",
+      `userScript got an unexpected result value: ${result}`
+    );
+
+    notifyFinish();
+  }
+
+  const userScriptMetadata = {
+    name: "test-user-script-exported-apis",
+    arrayProperty: ["el1"],
+    objectProperty: { nestedProp: "nestedValue" },
+    nullProperty: null,
+  };
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+    userScriptMetadata,
+  });
+});
+
+add_task(async function test_apiScript_async_method() {
+  function apiScript(sharedTestAPIMethods) {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIMethod(param, cb, cb2, objWithCb) {
+          browser.test.assertEq(
+            "function",
+            typeof cb,
+            "Got a callback function parameter"
+          );
+          browser.test.assertTrue(
+            cb === cb2,
+            "Got the same cloned function for the same function parameter"
+          );
+
+          browser.runtime.sendMessage(param).then(bgPageRes => {
+            const cbResult = cb(script.export(bgPageRes));
+            browser.test.sendMessage("user-script-callback-return", cbResult);
+          });
+
+          return "resolved_value";
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    // Redefine Promise to verify that it doesn't break the WebExtensions internals
+    // that are going to use them.
+    const { Promise } = this;
+    Promise.resolve = function() {
+      throw new Error("Promise.resolve poisoning");
+    };
+    this.Promise = function() {
+      throw new Error("Promise constructor poisoning");
+    };
+
+    const { assertTrue, notifyFinish, testAPIMethod } = this;
+
+    const cb = cbParam => {
+      return `callback param: ${JSON.stringify(cbParam)}`;
+    };
+    const cb2 = cb;
+    const asyncAPIResult = await testAPIMethod("param3", cb, cb2);
+
+    assertTrue(
+      asyncAPIResult === "resolved_value",
+      `userScript got an unexpected resolved value: ${asyncAPIResult}`
+    );
+
+    notifyFinish();
+  }
+
+  async function runtimeMessageListener(param) {
+    if (param !== "param3") {
+      browser.test.fail(`Got an unexpected message: ${param}`);
+    }
+
+    return { bgPageReply: true };
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+    runtimeMessageListener,
+    async testFn({ extension }) {
+      const res = await extension.awaitMessage("user-script-callback-return");
+      equal(
+        res,
+        `callback param: ${JSON.stringify({ bgPageReply: true })}`,
+        "Got the expected userScript callback return value"
+      );
+    },
+  });
+});
+
+add_task(async function test_apiScript_method_with_webpage_objects_params() {
+  function apiScript(sharedTestAPIMethods) {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIMethod(windowParam, documentParam) {
+          browser.test.assertEq(
+            window,
+            windowParam,
+            "Got a reference to the native window as first param"
+          );
+          browser.test.assertEq(
+            window.document,
+            documentParam,
+            "Got a reference to the native document as second param"
+          );
+
+          // Return an uncloneable webpage object, which checks that if the returned object is from a principal
+          // that is subsumed by the userScript sandbox principal, it is returned without being cloned.
+          return windowParam;
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    const { assertTrue, notifyFinish, testAPIMethod } = this;
+
+    const result = testAPIMethod(window, document);
+
+    // We expect the returned value to be the uncloneable window object.
+    assertTrue(
+      result === window,
+      `userScript got an unexpected returned value: ${result}`
+    );
+    notifyFinish();
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+  });
+});
+
+add_task(async function test_apiScript_method_got_param_with_methods() {
+  function apiScript(sharedTestAPIMethods) {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      const scriptGlobal = script.global;
+      const ScriptFunction = scriptGlobal.Function;
+
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIMethod(objWithMethods) {
+          browser.test.assertEq(
+            "objPropertyValue",
+            objWithMethods && objWithMethods.objProperty,
+            "Got the expected property on the object passed as a parameter"
+          );
+          browser.test.assertEq(
+            undefined,
+            typeof objWithMethods && objWithMethods.objMethod,
+            "XrayWrapper should deny access to a callable property"
+          );
+
+          browser.test.assertTrue(
+            objWithMethods &&
+              objWithMethods.wrappedJSObject &&
+              objWithMethods.wrappedJSObject.objMethod instanceof
+                ScriptFunction.wrappedJSObject,
+            "The callable property is accessible on the wrappedJSObject"
+          );
+
+          browser.test.assertEq(
+            "objMethodResult: p1",
+            objWithMethods &&
+              objWithMethods.wrappedJSObject &&
+              objWithMethods.wrappedJSObject.objMethod("p1"),
+            "Got the expected result when calling the method on the wrappedJSObject"
+          );
+          return true;
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    const { assertTrue, notifyFinish, testAPIMethod } = this;
+
+    let result = testAPIMethod({
+      objProperty: "objPropertyValue",
+      objMethod(param) {
+        return `objMethodResult: ${param}`;
+      },
+    });
+
+    assertTrue(
+      result === true,
+      `userScript got an unexpected returned value: ${result}`
+    );
+    notifyFinish();
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+  });
+});
+
+add_task(async function test_apiScript_method_throws_errors() {
+  function apiScript({ notifyFinish }) {
+    let proxyTrapsCount = 0;
+
+    browser.userScripts.onBeforeScript.addListener(script => {
+      const scriptGlobals = {
+        Error: script.global.Error,
+        TypeError: script.global.TypeError,
+        Proxy: script.global.Proxy,
+      };
+
+      script.defineGlobals({
+        notifyFinish,
+        testAPIMethod(errorTestName, returnRejectedPromise) {
+          let err;
+
+          switch (errorTestName) {
+            case "apiScriptError":
+              err = new Error(`${errorTestName} message`);
+              break;
+            case "apiScriptThrowsPlainString":
+              err = `${errorTestName} message`;
+              break;
+            case "apiScriptThrowsNull":
+              err = null;
+              break;
+            case "userScriptError":
+              err = new scriptGlobals.Error(`${errorTestName} message`);
+              break;
+            case "userScriptTypeError":
+              err = new scriptGlobals.TypeError(`${errorTestName} message`);
+              break;
+            case "userScriptProxyObject":
+              let proxyTarget = script.export({
+                name: "ProxyObject",
+                message: "ProxyObject message",
+              });
+              let proxyHandlers = script.export({
+                get(target, prop) {
+                  proxyTrapsCount++;
+                  switch (prop) {
+                    case "name":
+                      return "ProxyObjectGetName";
+                    case "message":
+                      return "ProxyObjectGetMessage";
+                  }
+                  return undefined;
+                },
+                getPrototypeOf() {
+                  proxyTrapsCount++;
+                  return scriptGlobals.TypeError;
+                },
+              });
+              err = new scriptGlobals.Proxy(proxyTarget, proxyHandlers);
+              break;
+            default:
+              browser.test.fail(`Unknown ${errorTestName} error testname`);
+              return undefined;
+          }
+
+          if (returnRejectedPromise) {
+            return Promise.reject(err);
+          }
+
+          throw err;
+        },
+        assertNoProxyTrapTriggered() {
+          browser.test.assertEq(
+            0,
+            proxyTrapsCount,
+            "Proxy traps should not be triggered"
+          );
+        },
+        resetProxyTrapCounter() {
+          proxyTrapsCount = 0;
+        },
+        sendResults(results) {
+          browser.test.sendMessage("test-results", results);
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    const {
+      assertNoProxyTrapTriggered,
+      notifyFinish,
+      resetProxyTrapCounter,
+      sendResults,
+      testAPIMethod,
+    } = this;
+
+    let apiThrowResults = {};
+    let apiThrowTestCases = [
+      "apiScriptError",
+      "apiScriptThrowsPlainString",
+      "apiScriptThrowsNull",
+      "userScriptError",
+      "userScriptTypeError",
+      "userScriptProxyObject",
+    ];
+    for (let errorTestName of apiThrowTestCases) {
+      try {
+        testAPIMethod(errorTestName);
+      } catch (err) {
+        // We expect that no proxy traps have been triggered by the WebExtensions internals.
+        if (errorTestName === "userScriptProxyObject") {
+          assertNoProxyTrapTriggered();
+        }
+
+        if (err instanceof Error) {
+          apiThrowResults[errorTestName] = {
+            name: err.name,
+            message: err.message,
+          };
+        } else {
+          apiThrowResults[errorTestName] = {
+            name: err && err.name,
+            message: err && err.message,
+            typeOf: typeof err,
+            value: err,
+          };
+        }
+      }
+    }
+
+    sendResults(apiThrowResults);
+
+    resetProxyTrapCounter();
+
+    let apiRejectsResults = {};
+    for (let errorTestName of apiThrowTestCases) {
+      try {
+        await testAPIMethod(errorTestName, true);
+      } catch (err) {
+        // We expect that no proxy traps have been triggered by the WebExtensions internals.
+        if (errorTestName === "userScriptProxyObject") {
+          assertNoProxyTrapTriggered();
+        }
+
+        if (err instanceof Error) {
+          apiRejectsResults[errorTestName] = {
+            name: err.name,
+            message: err.message,
+          };
+        } else {
+          apiRejectsResults[errorTestName] = {
+            name: err && err.name,
+            message: err && err.message,
+            typeOf: typeof err,
+            value: err,
+          };
+        }
+      }
+    }
+
+    sendResults(apiRejectsResults);
+
+    notifyFinish();
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+    async testFn({ extension }) {
+      const expectedResults = {
+        // Any error not explicitly raised as a userScript objects or error instance is
+        // expected to be turned into a generic error message.
+        apiScriptError: {
+          name: "Error",
+          message: "An unexpected apiScript error occurred",
+        },
+
+        // When the api script throws a primitive value, we expect to receive it unmodified on
+        // the userScript side.
+        apiScriptThrowsPlainString: {
+          typeOf: "string",
+          value: "apiScriptThrowsPlainString message",
+          name: undefined,
+          message: undefined,
+        },
+        apiScriptThrowsNull: {
+          typeOf: "object",
+          value: null,
+          name: undefined,
+          message: undefined,
+        },
+
+        // Error messages that the apiScript has explicitly created as userScript's Error
+        // global instances are expected to be passing through unmodified.
+        userScriptError: { name: "Error", message: "userScriptError message" },
+        userScriptTypeError: {
+          name: "TypeError",
+          message: "userScriptTypeError message",
+        },
+
+        // Error raised from the apiScript as userScript proxy objects are expected to
+        // be passing through unmodified.
+        userScriptProxyObject: {
+          typeOf: "object",
+          name: "ProxyObjectGetName",
+          message: "ProxyObjectGetMessage",
+        },
+      };
+
+      info(
+        "Checking results from errors raised from an apiScript exported function"
+      );
+
+      const apiThrowResults = await extension.awaitMessage("test-results");
+
+      for (let [key, expected] of Object.entries(expectedResults)) {
+        Assert.deepEqual(
+          apiThrowResults[key],
+          expected,
+          `Got the expected error object for test case "${key}"`
+        );
+      }
+
+      Assert.deepEqual(
+        Object.keys(expectedResults).sort(),
+        Object.keys(apiThrowResults).sort(),
+        "the expected and actual test case names matches"
+      );
+
+      info(
+        "Checking expected results from errors raised from an apiScript exported function"
+      );
+
+      // Verify expected results from rejected promises returned from an apiScript exported function.
+      const apiThrowRejections = await extension.awaitMessage("test-results");
+
+      for (let [key, expected] of Object.entries(expectedResults)) {
+        Assert.deepEqual(
+          apiThrowRejections[key],
+          expected,
+          `Got the expected rejected object for test case "${key}"`
+        );
+      }
+
+      Assert.deepEqual(
+        Object.keys(expectedResults).sort(),
+        Object.keys(apiThrowRejections).sort(),
+        "the expected and actual test case names matches"
+      );
+    },
+  });
+});
+
+add_task(
+  async function test_apiScript_method_ensure_xraywrapped_proxy_in_params() {
+    function apiScript(sharedTestAPIMethods) {
+      browser.userScripts.onBeforeScript.addListener(script => {
+        script.defineGlobals({
+          ...sharedTestAPIMethods,
+          testAPIMethod(...args) {
+            // Proxies are opaque when wrapped in Xrays, and the proto of an opaque object
+            // is supposed to be Object.prototype.
+            browser.test.assertEq(
+              script.global.Object.prototype,
+              Object.getPrototypeOf(args[0]),
+              "Calling getPrototypeOf on the XrayWrapped proxy object doesn't run the proxy trap"
+            );
+
+            browser.test.assertTrue(
+              Array.isArray(args[0]),
+              "Got an array object for the XrayWrapped proxy object param"
+            );
+            browser.test.assertEq(
+              undefined,
+              args[0].length,
+              "XrayWrappers deny access to the length property"
+            );
+            browser.test.assertEq(
+              undefined,
+              args[0][0],
+              "Got the expected item in the array object"
+            );
+            return true;
+          },
+        });
+      });
+    }
+
+    async function userScript() {
+      const { assertTrue, notifyFinish, testAPIMethod } = this;
+
+      let proxy = new Proxy(["expectedArrayValue"], {
+        getPrototypeOf() {
+          throw new Error("Proxy's getPrototypeOf trap");
+        },
+        get(target, prop, receiver) {
+          throw new Error("Proxy's get trap");
+        },
+      });
+
+      let result = testAPIMethod(proxy);
+
+      assertTrue(
+        result,
+        `userScript got an unexpected returned value: ${result}`
+      );
+      notifyFinish();
+    }
+
+    await test_userScript_APIMethod({
+      userScript,
+      apiScript,
+    });
+  }
+);
+
+add_task(async function test_apiScript_method_return_proxy_object() {
+  function apiScript(sharedTestAPIMethods) {
+    let proxyTrapsCount = 0;
+    let scriptTrapsCount = 0;
+
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIMethodError() {
+          return new Proxy(["expectedArrayValue"], {
+            getPrototypeOf(target) {
+              proxyTrapsCount++;
+              return Object.getPrototypeOf(target);
+            },
+          });
+        },
+        testAPIMethodOk() {
+          return new script.global.Proxy(
+            script.export(["expectedArrayValue"]),
+            script.export({
+              getPrototypeOf(target) {
+                scriptTrapsCount++;
+                return script.global.Object.getPrototypeOf(target);
+              },
+            })
+          );
+        },
+        assertNoProxyTrapTriggered() {
+          browser.test.assertEq(
+            0,
+            proxyTrapsCount,
+            "Proxy traps should not be triggered"
+          );
+        },
+        assertScriptProxyTrapsCount(expected) {
+          browser.test.assertEq(
+            expected,
+            scriptTrapsCount,
+            "Script Proxy traps should have been triggered"
+          );
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    const {
+      assertTrue,
+      assertNoProxyTrapTriggered,
+      assertScriptProxyTrapsCount,
+      notifyFinish,
+      testAPIMethodError,
+      testAPIMethodOk,
+    } = this;
+
+    let error;
+    try {
+      let result = testAPIMethodError();
+      notifyFinish(
+        `Unexpected returned value while expecting error: ${result}`
+      );
+      return;
+    } catch (err) {
+      error = err;
+    }
+
+    assertTrue(
+      error &&
+        error.message.includes("Return value not accessible to the userScript"),
+      `Got an unexpected error message: ${error}`
+    );
+
+    error = undefined;
+    try {
+      let result = testAPIMethodOk();
+      assertScriptProxyTrapsCount(0);
+      if (!(result instanceof Array)) {
+        notifyFinish(`Got an unexpected result: ${result}`);
+        return;
+      }
+      assertScriptProxyTrapsCount(1);
+    } catch (err) {
+      error = err;
+    }
+
+    assertTrue(!error, `Got an unexpected error: ${error}`);
+
+    assertNoProxyTrapTriggered();
+
+    notifyFinish();
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+  });
+});
+
+add_task(async function test_apiScript_returns_functions() {
+  function apiScript(sharedTestAPIMethods) {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIReturnsFunction() {
+          // Return a function with provides the same kind of behavior
+          // of the API methods exported as globals.
+          return script.export(() => window);
+        },
+        testAPIReturnsObjWithMethod() {
+          return script.export({
+            getWindow() {
+              return window;
+            },
+          });
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    const {
+      assertTrue,
+      notifyFinish,
+      testAPIReturnsFunction,
+      testAPIReturnsObjWithMethod,
+    } = this;
+
+    let resultFn = testAPIReturnsFunction();
+    assertTrue(
+      typeof resultFn === "function",
+      `userScript got an unexpected returned value: ${typeof resultFn}`
+    );
+
+    let fnRes = resultFn();
+    assertTrue(
+      fnRes === window,
+      `Got an unexpected value from the returned function: ${fnRes}`
+    );
+
+    let resultObj = testAPIReturnsObjWithMethod();
+    let actualTypeof = resultObj && typeof resultObj.getWindow;
+    assertTrue(
+      actualTypeof === "function",
+      `Returned object does not have the expected getWindow method: ${actualTypeof}`
+    );
+
+    let methodRes = resultObj.getWindow();
+    assertTrue(
+      methodRes === window,
+      `Got an unexpected value from the returned method: ${methodRes}`
+    );
+
+    notifyFinish();
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+  });
+});
+
+add_task(
+  async function test_apiScript_method_clone_non_subsumed_returned_values() {
+    function apiScript(sharedTestAPIMethods) {
+      browser.userScripts.onBeforeScript.addListener(script => {
+        script.defineGlobals({
+          ...sharedTestAPIMethods,
+          testAPIMethodReturnOk() {
+            return script.export({
+              objKey1: {
+                nestedProp: "nestedvalue",
+              },
+              window,
+            });
+          },
+          testAPIMethodExplicitlyClonedError() {
+            let result = script.export({ apiScopeObject: undefined });
+
+            browser.test.assertThrows(
+              () => {
+                result.apiScopeObject = { disallowedProp: "disallowedValue" };
+              },
+              /Not allowed to define cross-origin object as property on .* XrayWrapper/,
+              "Assigning a property to a xRayWrapper is expected to throw"
+            );
+
+            // Let the exception to be raised, so that we check that the actual underlying
+            // error message is not leaking in the userScript (replaced by the generic
+            // "An unexpected apiScript error occurred" error message).
+            result.apiScopeObject = { disallowedProp: "disallowedValue" };
+          },
+        });
+      });
+    }
+
+    async function userScript() {
+      const {
+        assertTrue,
+        notifyFinish,
+        testAPIMethodReturnOk,
+        testAPIMethodExplicitlyClonedError,
+      } = this;
+
+      let result = testAPIMethodReturnOk();
+
+      assertTrue(
+        result &&
+          "objKey1" in result &&
+          result.objKey1.nestedProp === "nestedvalue",
+        `userScript got an unexpected returned value: ${result}`
+      );
+
+      assertTrue(
+        result.window === window,
+        `userScript should have access to the window property: ${result.window}`
+      );
+
+      let error;
+      try {
+        result = testAPIMethodExplicitlyClonedError();
+        notifyFinish(
+          `Unexpected returned value while expecting error: ${result}`
+        );
+        return;
+      } catch (err) {
+        error = err;
+      }
+
+      // We expect the generic "unexpected apiScript error occurred" to be raised to the
+      // userScript code.
+      assertTrue(
+        error &&
+          error.message.includes("An unexpected apiScript error occurred"),
+        `Got an unexpected error message: ${error}`
+      );
+
+      notifyFinish();
+    }
+
+    await test_userScript_APIMethod({
+      userScript,
+      apiScript,
+    });
+  }
+);
+
+add_task(async function test_apiScript_method_export_primitive_types() {
+  function apiScript(sharedTestAPIMethods) {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIMethod(typeToExport) {
+          switch (typeToExport) {
+            case "boolean":
+              return script.export(true);
+            case "number":
+              return script.export(123);
+            case "string":
+              return script.export("a string");
+            case "symbol":
+              return script.export(Symbol("a symbol"));
+          }
+          return undefined;
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    const { assertTrue, notifyFinish, testAPIMethod } = this;
+
+    let v = testAPIMethod("boolean");
+    assertTrue(v === true, `Should export a boolean`);
+
+    v = testAPIMethod("number");
+    assertTrue(v === 123, `Should export a number`);
+
+    v = testAPIMethod("string");
+    assertTrue(v === "a string", `Should export a string`);
+
+    v = testAPIMethod("symbol");
+    assertTrue(typeof v === "symbol", `Should export a symbol`);
+
+    notifyFinish();
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+  });
+});
+
+add_task(
+  async function test_apiScript_method_avoid_unnecessary_params_cloning() {
+    function apiScript(sharedTestAPIMethods) {
+      browser.userScripts.onBeforeScript.addListener(script => {
+        script.defineGlobals({
+          ...sharedTestAPIMethods,
+          testAPIMethodReturnsParam(param) {
+            return param;
+          },
+          testAPIMethodReturnsUnwrappedParam(param) {
+            return param.wrappedJSObject;
+          },
+        });
+      });
+    }
+
+    async function userScript() {
+      const {
+        assertTrue,
+        notifyFinish,
+        testAPIMethodReturnsParam,
+        testAPIMethodReturnsUnwrappedParam,
+      } = this;
+
+      let obj = {};
+
+      let result = testAPIMethodReturnsParam(obj);
+
+      assertTrue(
+        result === obj,
+        `Expect returned value to be strictly equal to the API method parameter`
+      );
+
+      result = testAPIMethodReturnsUnwrappedParam(obj);
+
+      assertTrue(
+        result === obj,
+        `Expect returned value to be strictly equal to the unwrapped API method parameter`
+      );
+
+      notifyFinish();
+    }
+
+    await test_userScript_APIMethod({
+      userScript,
+      apiScript,
+    });
+  }
+);
+
+add_task(async function test_apiScript_method_export_sparse_arrays() {
+  function apiScript(sharedTestAPIMethods) {
+    browser.userScripts.onBeforeScript.addListener(script => {
+      script.defineGlobals({
+        ...sharedTestAPIMethods,
+        testAPIMethod() {
+          const sparseArray = [];
+          sparseArray[3] = "third-element";
+          sparseArray[5] = "fifth-element";
+          return script.export(sparseArray);
+        },
+      });
+    });
+  }
+
+  async function userScript() {
+    const { assertTrue, notifyFinish, testAPIMethod } = this;
+
+    const result = testAPIMethod(window, document);
+
+    // We expect the returned value to be the uncloneable window object.
+    assertTrue(
+      result && result.length === 6,
+      `the returned value should be an array of the expected length: ${result}`
+    );
+    assertTrue(
+      result[3] === "third-element",
+      `the third array element should have the expected value: ${result[3]}`
+    );
+    assertTrue(
+      result[5] === "fifth-element",
+      `the fifth array element should have the expected value: ${result[5]}`
+    );
+    assertTrue(
+      result[0] === undefined,
+      `the first array element should have the expected value: ${result[0]}`
+    );
+    assertTrue(!("0" in result), "Holey array should still be holey");
+
+    notifyFinish();
+  }
+
+  await test_userScript_APIMethod({
+    userScript,
+    apiScript,
+  });
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_userScripts_telemetry.js b/toolkit/components/extensions/test/xpcshell/test_ext_userScripts_telemetry.js
new file mode 100644
index 0000000000..08d61d1e85
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_userScripts_telemetry.js
@@ -0,0 +1,175 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const HISTOGRAM = "WEBEXT_USER_SCRIPT_INJECTION_MS";
+const HISTOGRAM_KEYED = "WEBEXT_USER_SCRIPT_INJECTION_MS_BY_ADDONID";
+
+const server = createHttpServer();
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;
+
+add_task(async function test_userScripts_telemetry() {
+  function apiScript() {
+    browser.userScripts.onBeforeScript.addListener(userScript => {
+      const scriptMetadata = userScript.metadata;
+
+      userScript.defineGlobals({
+        US_test_sendMessage(msg, data) {
+          browser.test.sendMessage(msg, { data, scriptMetadata });
+        },
+      });
+    });
+  }
+
+  async function background() {
+    const code = `
+      US_test_sendMessage("userScript-run", {location: window.location.href});
+    `;
+    await browser.userScripts.register({
+      js: [{ code }],
+      matches: ["http://*/*/file_sample.html"],
+      runAt: "document_end",
+      scriptMetadata: {
+        name: "test-user-script-telemetry",
+      },
+    });
+
+    browser.test.sendMessage("userScript-registered");
+  }
+
+  Services.prefs.setBoolPref(
+    "toolkit.telemetry.testing.overrideProductsCheck",
+    true
+  );
+
+  let testExtensionDef = {
+    manifest: {
+      permissions: ["http://*/*/file_sample.html"],
+      user_scripts: {
+        api_script: "api-script.js",
+      },
+    },
+    background,
+    files: {
+      "api-script.js": apiScript,
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(testExtensionDef);
+  let extension2 = ExtensionTestUtils.loadExtension(testExtensionDef);
+  let contentPage = await ExtensionTestUtils.loadContentPage("about:blank");
+
+  clearHistograms();
+
+  let process = IS_OOP ? "content" : "parent";
+  ok(
+    !(HISTOGRAM in getSnapshots(process)),
+    `No data recorded for histogram: ${HISTOGRAM}.`
+  );
+  ok(
+    !(HISTOGRAM_KEYED in getKeyedSnapshots(process)),
+    `No data recorded for keyed histogram: ${HISTOGRAM_KEYED}.`
+  );
+
+  await extension.startup();
+  await extension.awaitMessage("userScript-registered");
+
+  let extensionId = extension.extension.id;
+
+  ok(
+    !(HISTOGRAM in getSnapshots(process)),
+    `No data recorded for histogram after startup: ${HISTOGRAM}.`
+  );
+  ok(
+    !(HISTOGRAM_KEYED in getKeyedSnapshots(process)),
+    `No data recorded for keyed histogram: ${HISTOGRAM_KEYED}.`
+  );
+
+  let url = `${BASE_URL}/file_sample.html`;
+  contentPage.loadURL(url);
+  const res = await extension.awaitMessage("userScript-run");
+  Assert.deepEqual(
+    res,
+    {
+      data: { location: url },
+      scriptMetadata: { name: "test-user-script-telemetry" },
+    },
+    "The userScript has been executed on the content page as expected"
+  );
+
+  await promiseTelemetryRecorded(HISTOGRAM, process, 1);
+  await promiseKeyedTelemetryRecorded(HISTOGRAM_KEYED, process, extensionId, 1);
+
+  equal(
+    valueSum(getSnapshots(process)[HISTOGRAM].values),
+    1,
+    `Data recorded for histogram: ${HISTOGRAM}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId].values),
+    1,
+    `Data recorded for histogram: ${HISTOGRAM_KEYED} with key ${extensionId}.`
+  );
+
+  await contentPage.close();
+  await extension.unload();
+
+  await extension2.startup();
+  await extension2.awaitMessage("userScript-registered");
+  let extensionId2 = extension2.extension.id;
+
+  equal(
+    valueSum(getSnapshots(process)[HISTOGRAM].values),
+    1,
+    `No data recorded for histogram after startup: ${HISTOGRAM}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId].values),
+    1,
+    `No new data recorded for histogram after extension2 startup: ${HISTOGRAM_KEYED} with key ${extensionId}.`
+  );
+  ok(
+    !(extensionId2 in getKeyedSnapshots(process)[HISTOGRAM_KEYED]),
+    `No data recorded for histogram after startup: ${HISTOGRAM_KEYED} with key ${extensionId2}.`
+  );
+
+  contentPage = await ExtensionTestUtils.loadContentPage(url);
+  const res2 = await extension2.awaitMessage("userScript-run");
+  Assert.deepEqual(
+    res2,
+    {
+      data: { location: url },
+      scriptMetadata: { name: "test-user-script-telemetry" },
+    },
+    "The userScript has been executed on the content page as expected"
+  );
+
+  await promiseTelemetryRecorded(HISTOGRAM, process, 2);
+  await promiseKeyedTelemetryRecorded(
+    HISTOGRAM_KEYED,
+    process,
+    extensionId2,
+    1
+  );
+
+  equal(
+    valueSum(getSnapshots(process)[HISTOGRAM].values),
+    2,
+    `Data recorded for histogram: ${HISTOGRAM}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId].values),
+    1,
+    `No new data recorded for histogram: ${HISTOGRAM_KEYED} with key ${extensionId}.`
+  );
+  equal(
+    valueSum(getKeyedSnapshots(process)[HISTOGRAM_KEYED][extensionId2].values),
+    1,
+    `Data recorded for histogram: ${HISTOGRAM_KEYED} with key ${extensionId2}.`
+  );
+
+  await contentPage.close();
+  await extension2.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_auth.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_auth.js
new file mode 100644
index 0000000000..c616d162a5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_auth.js
@@ -0,0 +1,425 @@
+"use strict";
+
+const HOSTS = new Set(["example.com"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+const BASE_URL = "http://example.com";
+
+// Save seen realms for cache checking.
+let realms = new Set([]);
+
+server.registerPathHandler("/authenticate.sjs", (request, response) => {
+  let url = new URL(`${BASE_URL}${request.path}?${request.queryString}`);
+  let realm = url.searchParams.get("realm") || "mochitest";
+  let proxy_realm = url.searchParams.get("proxy_realm");
+
+  function checkAuthorization(authorization) {
+    let expected_user = url.searchParams.get("user");
+    if (!expected_user) {
+      return true;
+    }
+    let expected_pass = url.searchParams.get("pass");
+    let actual_user, actual_pass;
+    let authHeader = request.getHeader("Authorization");
+    let match = /Basic (.+)/.exec(authHeader);
+    if (match.length != 2) {
+      throw new Error("Couldn't parse auth header: " + authHeader);
+    }
+    let userpass = atob(match[1]); // no atob() :-(
+    match = /(.*):(.*)/.exec(userpass);
+    if (match.length != 3) {
+      throw new Error("Couldn't decode auth header: " + userpass);
+    }
+    actual_user = match[1];
+    actual_pass = match[2];
+    return expected_user === actual_user && expected_pass === actual_pass;
+  }
+
+  response.setHeader("Content-Type", "text/plain; charset=UTF-8", false);
+  if (proxy_realm && !request.hasHeader("Proxy-Authorization")) {
+    // We're not testing anything that requires checking the proxy auth user/password.
+    response.setStatusLine("1.0", 407, "Proxy authentication required");
+    response.setHeader(
+      "Proxy-Authenticate",
+      `basic realm="${proxy_realm}"`,
+      true
+    );
+    response.write("proxy auth required");
+  } else if (
+    !(
+      realms.has(realm) &&
+      request.hasHeader("Authorization") &&
+      checkAuthorization()
+    )
+  ) {
+    realms.add(realm);
+    response.setStatusLine(request.httpVersion, 401, "Authentication required");
+    response.setHeader("WWW-Authenticate", `basic realm="${realm}"`, true);
+    response.write("auth required");
+  } else {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.write("ok, got authorization");
+  }
+});
+
+function getExtension(bgConfig) {
+  function background(config) {
+    let path = config.path;
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.log(
+          `onBeforeRequest called with ${details.requestId} ${details.url}`
+        );
+        browser.test.sendMessage("onBeforeRequest");
+        return (
+          config.onBeforeRequest.hasOwnProperty("result") &&
+          config.onBeforeRequest.result
+        );
+      },
+      { urls: [path] },
+      config.onBeforeRequest.hasOwnProperty("extra")
+        ? config.onBeforeRequest.extra
+        : []
+    );
+    browser.webRequest.onAuthRequired.addListener(
+      details => {
+        browser.test.log(
+          `onAuthRequired called with ${details.requestId} ${details.url}`
+        );
+        browser.test.assertEq(
+          config.realm,
+          details.realm,
+          "providing www authorization"
+        );
+        browser.test.sendMessage("onAuthRequired");
+        return (
+          config.onAuthRequired.hasOwnProperty("result") &&
+          config.onAuthRequired.result
+        );
+      },
+      { urls: [path] },
+      config.onAuthRequired.hasOwnProperty("extra")
+        ? config.onAuthRequired.extra
+        : []
+    );
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        browser.test.log(
+          `onCompleted called with ${details.requestId} ${details.url}`
+        );
+        browser.test.sendMessage("onCompleted");
+      },
+      { urls: [path] }
+    );
+    browser.webRequest.onErrorOccurred.addListener(
+      details => {
+        browser.test.log(
+          `onErrorOccurred called with ${JSON.stringify(details)}`
+        );
+        browser.test.sendMessage("onErrorOccurred");
+      },
+      { urls: [path] }
+    );
+  }
+
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", bgConfig.path],
+    },
+    background: `(${background})(${JSON.stringify(bgConfig)})`,
+  });
+}
+
+add_task(async function test_webRequest_auth() {
+  let config = {
+    path: `${BASE_URL}/*`,
+    realm: `webRequest_auth${Math.random()}`,
+    onBeforeRequest: {
+      extra: ["blocking"],
+    },
+    onAuthRequired: {
+      extra: ["blocking"],
+      result: {
+        authCredentials: {
+          username: "testuser",
+          password: "testpass",
+        },
+      },
+    },
+  };
+
+  let extension = getExtension(config);
+  await extension.startup();
+
+  let requestUrl = `${BASE_URL}/authenticate.sjs?realm=${config.realm}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(requestUrl);
+  await Promise.all([
+    extension.awaitMessage("onBeforeRequest"),
+    extension.awaitMessage("onAuthRequired").then(() => {
+      return Promise.all([
+        extension.awaitMessage("onBeforeRequest"),
+        extension.awaitMessage("onCompleted"),
+      ]);
+    }),
+  ]);
+  await contentPage.close();
+
+  // Second time around to test cached credentials
+  contentPage = await ExtensionTestUtils.loadContentPage(requestUrl);
+  await Promise.all([
+    extension.awaitMessage("onBeforeRequest"),
+    extension.awaitMessage("onCompleted"),
+  ]);
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_webRequest_auth_cancelled() {
+  // Test that any auth listener can cancel.
+  let config = {
+    path: `${BASE_URL}/*`,
+    realm: `webRequest_auth${Math.random()}`,
+    onBeforeRequest: {
+      extra: ["blocking"],
+    },
+    onAuthRequired: {
+      extra: ["blocking"],
+      result: {
+        authCredentials: {
+          username: "testuser",
+          password: "testpass",
+        },
+      },
+    },
+  };
+
+  let ex1 = getExtension(config);
+  config.onAuthRequired.result = { cancel: true };
+  let ex2 = getExtension(config);
+  await ex1.startup();
+  await ex2.startup();
+
+  let requestUrl = `${BASE_URL}/authenticate.sjs?realm=${config.realm}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(requestUrl);
+  await Promise.all([
+    ex1.awaitMessage("onBeforeRequest"),
+    ex1.awaitMessage("onAuthRequired"),
+    ex1.awaitMessage("onErrorOccurred"),
+    ex2.awaitMessage("onBeforeRequest"),
+    ex2.awaitMessage("onAuthRequired"),
+    ex2.awaitMessage("onErrorOccurred"),
+  ]);
+
+  await contentPage.close();
+  await ex1.unload();
+  await ex2.unload();
+});
+
+add_task(async function test_webRequest_auth_nonblocking() {
+  let config = {
+    path: `${BASE_URL}/*`,
+    realm: `webRequest_auth${Math.random()}`,
+    onBeforeRequest: {
+      extra: ["blocking"],
+    },
+    onAuthRequired: {
+      extra: ["blocking"],
+      result: {
+        authCredentials: {
+          username: "testuser",
+          password: "testpass",
+        },
+      },
+    },
+  };
+
+  let ex1 = getExtension(config);
+  // non-blocking ext tries to cancel but cannot.
+  delete config.onBeforeRequest.extra;
+  delete config.onAuthRequired.extra;
+  config.onAuthRequired.result = { cancel: true };
+  let ex2 = getExtension(config);
+  await ex1.startup();
+  await ex2.startup();
+
+  let requestUrl = `${BASE_URL}/authenticate.sjs?realm=${config.realm}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(requestUrl);
+  await Promise.all([
+    ex1.awaitMessage("onBeforeRequest"),
+    ex1.awaitMessage("onAuthRequired").then(() => {
+      return Promise.all([
+        ex1.awaitMessage("onBeforeRequest"),
+        ex1.awaitMessage("onCompleted"),
+      ]);
+    }),
+    ex2.awaitMessage("onBeforeRequest"),
+    ex2.awaitMessage("onAuthRequired").then(() => {
+      return Promise.all([
+        ex2.awaitMessage("onBeforeRequest"),
+        ex2.awaitMessage("onCompleted"),
+      ]);
+    }),
+  ]);
+
+  await contentPage.close();
+  Services.obs.notifyObservers(null, "net:clear-active-logins");
+  await ex1.unload();
+  await ex2.unload();
+});
+
+add_task(async function test_webRequest_auth_blocking_noreturn() {
+  // The first listener is blocking but doesn't return anything.  The second
+  // listener cancels the request.
+  let config = {
+    path: `${BASE_URL}/*`,
+    realm: `webRequest_auth${Math.random()}`,
+    onBeforeRequest: {
+      extra: ["blocking"],
+    },
+    onAuthRequired: {
+      extra: ["blocking"],
+    },
+  };
+
+  let ex1 = getExtension(config);
+  config.onAuthRequired.result = { cancel: true };
+  let ex2 = getExtension(config);
+  await ex1.startup();
+  await ex2.startup();
+
+  let requestUrl = `${BASE_URL}/authenticate.sjs?realm=${config.realm}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(requestUrl);
+  await Promise.all([
+    ex1.awaitMessage("onBeforeRequest"),
+    ex1.awaitMessage("onAuthRequired"),
+    ex1.awaitMessage("onErrorOccurred"),
+    ex2.awaitMessage("onBeforeRequest"),
+    ex2.awaitMessage("onAuthRequired"),
+    ex2.awaitMessage("onErrorOccurred"),
+  ]);
+
+  await contentPage.close();
+  await ex1.unload();
+  await ex2.unload();
+});
+
+add_task(async function test_webRequest_duelingAuth() {
+  let config = {
+    path: `${BASE_URL}/*`,
+    realm: `webRequest_auth${Math.random()}`,
+    onBeforeRequest: {
+      extra: ["blocking"],
+    },
+    onAuthRequired: {
+      extra: ["blocking"],
+    },
+  };
+  let exNone = getExtension(config);
+  await exNone.startup();
+
+  let authCredentials = {
+    username: `testuser_da1${Math.random()}`,
+    password: `testpass_da1${Math.random()}`,
+  };
+  config.onAuthRequired.result = { authCredentials };
+  let ex1 = getExtension(config);
+  await ex1.startup();
+
+  config.onAuthRequired.result = {};
+  let exEmpty = getExtension(config);
+  await exEmpty.startup();
+
+  config.onAuthRequired.result = {
+    authCredentials: {
+      username: `testuser_da2${Math.random()}`,
+      password: `testpass_da2${Math.random()}`,
+    },
+  };
+  let ex2 = getExtension(config);
+  await ex2.startup();
+
+  let requestUrl = `${BASE_URL}/authenticate.sjs?realm=${config.realm}&user=${authCredentials.username}&pass=${authCredentials.password}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(requestUrl);
+  await Promise.all([
+    exNone.awaitMessage("onBeforeRequest"),
+    exNone.awaitMessage("onAuthRequired").then(() => {
+      return Promise.all([
+        exNone.awaitMessage("onBeforeRequest"),
+        exNone.awaitMessage("onCompleted"),
+      ]);
+    }),
+    exEmpty.awaitMessage("onBeforeRequest"),
+    exEmpty.awaitMessage("onAuthRequired").then(() => {
+      return Promise.all([
+        exEmpty.awaitMessage("onBeforeRequest"),
+        exEmpty.awaitMessage("onCompleted"),
+      ]);
+    }),
+    ex1.awaitMessage("onBeforeRequest"),
+    ex1.awaitMessage("onAuthRequired").then(() => {
+      return Promise.all([
+        ex1.awaitMessage("onBeforeRequest"),
+        ex1.awaitMessage("onCompleted"),
+      ]);
+    }),
+    ex2.awaitMessage("onBeforeRequest"),
+    ex2.awaitMessage("onAuthRequired").then(() => {
+      return Promise.all([
+        ex2.awaitMessage("onBeforeRequest"),
+        ex2.awaitMessage("onCompleted"),
+      ]);
+    }),
+  ]);
+
+  await Promise.all([
+    await contentPage.close(),
+    exNone.unload(),
+    exEmpty.unload(),
+    ex1.unload(),
+    ex2.unload(),
+  ]);
+});
+
+add_task(async function test_webRequest_auth_proxy() {
+  function background(permissionPath) {
+    let proxyOk = false;
+    browser.webRequest.onAuthRequired.addListener(
+      details => {
+        browser.test.log(
+          `handlingExt onAuthRequired called with ${details.requestId} ${details.url}`
+        );
+        if (details.isProxy) {
+          browser.test.succeed("providing proxy authorization");
+          proxyOk = true;
+          return { authCredentials: { username: "puser", password: "ppass" } };
+        }
+        browser.test.assertTrue(
+          proxyOk,
+          "providing www authorization after proxy auth"
+        );
+        browser.test.sendMessage("done");
+        return { authCredentials: { username: "auser", password: "apass" } };
+      },
+      { urls: [permissionPath] },
+      ["blocking"]
+    );
+  }
+
+  let handlingExt = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", `${BASE_URL}/*`],
+    },
+    background: `(${background})("${BASE_URL}/*")`,
+  });
+
+  await handlingExt.startup();
+
+  let requestUrl = `${BASE_URL}/authenticate.sjs?realm=webRequest_auth${Math.random()}&proxy_realm=proxy_auth${Math.random()}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(requestUrl);
+
+  await handlingExt.awaitMessage("done");
+  await contentPage.close();
+  await handlingExt.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cached.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cached.js
new file mode 100644
index 0000000000..c18c75a580
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cached.js
@@ -0,0 +1,311 @@
+"use strict";
+
+const BASE_URL = "http://example.com";
+const FETCH_ORIGIN = "http://example.com/data/file_sample.html";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+server.registerPathHandler("/status", (request, response) => {
+  let IfNoneMatch = request.hasHeader("If-None-Match")
+    ? request.getHeader("If-None-Match")
+    : "";
+
+  switch (IfNoneMatch) {
+    case "1234567890":
+      response.setStatusLine("1.1", 304, "Not Modified");
+      response.setHeader("Content-Type", "text/html", false);
+      response.setHeader("Etag", "1234567890", false);
+      break;
+    case "":
+      response.setStatusLine("1.1", 200, "OK");
+      response.setHeader("Content-Type", "text/html", false);
+      response.setHeader("Etag", "1234567890", false);
+      response.write("ok");
+      break;
+    default:
+      throw new Error(`Unexpected If-None-Match: ${IfNoneMatch}`);
+  }
+});
+
+// This test initialises a cache entry with a CSP header, then
+// loads the cached entry and replaces the CSP header with
+// a new one.  We test in onResponseStarted that the header
+// is what we expect.
+add_task(async function test_replaceResponseHeaders() {
+  Services.prefs.setBoolPref("network.http.rcwn.enabled", false);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      function replaceHeader(headers, newHeader) {
+        headers = headers.filter(header => header.name !== newHeader.name);
+        headers.push(newHeader);
+        return headers;
+      }
+      let testHeaders = [
+        {
+          name: "Content-Security-Policy",
+          value: "object-src 'none'; script-src 'none'",
+        },
+        {
+          name: "Content-Security-Policy",
+          value: "object-src 'none'; script-src https:",
+        },
+      ];
+      browser.webRequest.onHeadersReceived.addListener(
+        details => {
+          if (!details.fromCache) {
+            // Add a CSP header on the initial request
+            details.responseHeaders.push(testHeaders[0]);
+            return {
+              responseHeaders: details.responseHeaders,
+            };
+          }
+          // Test that the header added during the initial request is
+          // now in the cached response.
+          let header = details.responseHeaders.filter(header => {
+            browser.test.log(`header ${header.name} = ${header.value}`);
+            return header.name == "Content-Security-Policy";
+          });
+          browser.test.assertEq(
+            header[0].value,
+            testHeaders[0].value,
+            "pre-cached header exists"
+          );
+          // Replace the cached value so we can test overriding the header that was cached.
+          return {
+            responseHeaders: replaceHeader(
+              details.responseHeaders,
+              testHeaders[1]
+            ),
+          };
+        },
+        {
+          urls: ["http://example.com/*/file_sample.html?r=*"],
+        },
+        ["blocking", "responseHeaders"]
+      );
+      browser.webRequest.onResponseStarted.addListener(
+        details => {
+          let needle = details.fromCache ? testHeaders[1] : testHeaders[0];
+          let header = details.responseHeaders.filter(header => {
+            browser.test.log(`header ${header.name} = ${header.value}`);
+            return header.name == needle.name && header.value == needle.value;
+          });
+          browser.test.assertEq(
+            header.length,
+            1,
+            "header exists with correct value"
+          );
+          if (details.fromCache) {
+            browser.test.sendMessage("from-cache");
+          }
+        },
+        {
+          urls: ["http://example.com/*/file_sample.html?r=*"],
+        },
+        ["responseHeaders"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  let url = `${BASE_URL}/data/file_sample.html?r=${Math.random()}`;
+  await ExtensionTestUtils.fetch(FETCH_ORIGIN, url);
+  await ExtensionTestUtils.fetch(FETCH_ORIGIN, url);
+  await extension.awaitMessage("from-cache");
+
+  await extension.unload();
+});
+
+// This test initialises a cache entry with a CSP header, then
+// loads the cached entry and adds a second CSP header.  We also
+// test that the browser has the CSP entries we expect.
+add_task(async function test_addCSPHeaders() {
+  Services.prefs.setBoolPref("network.http.rcwn.enabled", false);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      let testHeaders = [
+        {
+          name: "Content-Security-Policy",
+          value: "object-src 'none'; script-src 'none'",
+        },
+        {
+          name: "Content-Security-Policy",
+          value: "object-src 'none'; script-src https:",
+        },
+      ];
+      browser.webRequest.onHeadersReceived.addListener(
+        details => {
+          if (!details.fromCache) {
+            details.responseHeaders.push(testHeaders[0]);
+            return {
+              responseHeaders: details.responseHeaders,
+            };
+          }
+          browser.test.log("cached request received");
+          details.responseHeaders.push(testHeaders[1]);
+          return {
+            responseHeaders: details.responseHeaders,
+          };
+        },
+        {
+          urls: ["http://example.com/*/file_sample.html?r=*"],
+        },
+        ["blocking", "responseHeaders"]
+      );
+      browser.webRequest.onCompleted.addListener(
+        details => {
+          let { name, value } = testHeaders[0];
+          if (details.fromCache) {
+            value = `${value}, ${testHeaders[1].value}`;
+          }
+          let header = details.responseHeaders.filter(header => {
+            browser.test.log(`header ${header.name} = ${header.value}`);
+            return header.name == name && header.value == value;
+          });
+          browser.test.assertEq(
+            header.length,
+            1,
+            "header exists with correct value"
+          );
+          if (details.fromCache) {
+            browser.test.sendMessage("from-cache");
+          }
+        },
+        {
+          urls: ["http://example.com/*/file_sample.html?r=*"],
+        },
+        ["responseHeaders"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  let url = `${BASE_URL}/data/file_sample.html?r=${Math.random()}`;
+  let contentPage = await ExtensionTestUtils.loadContentPage(url);
+  equal(contentPage.browser.csp.policyCount, 1, "expected 1 policy");
+  equal(
+    contentPage.browser.csp.getPolicy(0),
+    "object-src 'none'; script-src 'none'",
+    "expected policy"
+  );
+  await contentPage.close();
+
+  contentPage = await ExtensionTestUtils.loadContentPage(url);
+  equal(contentPage.browser.csp.policyCount, 2, "expected 2 policies");
+  equal(
+    contentPage.browser.csp.getPolicy(0),
+    "object-src 'none'; script-src 'none'",
+    "expected first policy"
+  );
+  equal(
+    contentPage.browser.csp.getPolicy(1),
+    "object-src 'none'; script-src https:",
+    "expected second policy"
+  );
+
+  await extension.awaitMessage("from-cache");
+  await contentPage.close();
+
+  await extension.unload();
+});
+
+// This test verifies that a content type changed during
+// onHeadersReceived is cached.  We initialize the cache,
+// then load against a url that will specifically return
+// a 304 status code.
+add_task(async function test_addContentTypeHeaders() {
+  Services.prefs.setBoolPref("network.http.rcwn.enabled", false);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onBeforeSendHeaders.addListener(
+        details => {
+          browser.test.log(`onBeforeSendHeaders ${JSON.stringify(details)}\n`);
+        },
+        {
+          urls: ["http://example.com/status*"],
+        },
+        ["blocking", "requestHeaders"]
+      );
+      browser.webRequest.onHeadersReceived.addListener(
+        details => {
+          browser.test.log(`onHeadersReceived ${JSON.stringify(details)}\n`);
+          if (!details.fromCache) {
+            browser.test.sendMessage("statusCode", details.statusCode);
+            const mime = details.responseHeaders.find(header => {
+              return header.value && header.name === "content-type";
+            });
+            if (mime) {
+              mime.value = "text/plain";
+            } else {
+              details.responseHeaders.push({
+                name: "content-type",
+                value: "text/plain",
+              });
+            }
+            return {
+              responseHeaders: details.responseHeaders,
+            };
+          }
+        },
+        {
+          urls: ["http://example.com/status*"],
+        },
+        ["blocking", "responseHeaders"]
+      );
+      browser.webRequest.onCompleted.addListener(
+        details => {
+          browser.test.log(`onCompleted ${JSON.stringify(details)}\n`);
+          const mime = details.responseHeaders.find(header => {
+            return header.value && header.name === "content-type";
+          });
+          browser.test.sendMessage("contentType", mime.value);
+        },
+        {
+          urls: ["http://example.com/status*"],
+        },
+        ["responseHeaders"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/status`
+  );
+  equal(await extension.awaitMessage("statusCode"), "200", "status OK");
+  equal(
+    await extension.awaitMessage("contentType"),
+    "text/plain",
+    "plain text header"
+  );
+  await contentPage.close();
+
+  contentPage = await ExtensionTestUtils.loadContentPage(`${BASE_URL}/status`);
+  equal(await extension.awaitMessage("statusCode"), "304", "not modified");
+  equal(
+    await extension.awaitMessage("contentType"),
+    "text/plain",
+    "plain text header"
+  );
+  await contentPage.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cancelWithReason.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cancelWithReason.js
new file mode 100644
index 0000000000..de9ed535b3
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_cancelWithReason.js
@@ -0,0 +1,69 @@
+"use strict";
+
+const server = createHttpServer();
+const gServerUrl = `http://localhost:${server.identity.primaryPort}`;
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+add_task(async function test_cancel_with_reason() {
+  let ext = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "cancel@test" } },
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        () => {
+          return { cancel: true };
+        },
+        { urls: ["*://*/*"] },
+        ["blocking"]
+      );
+    },
+  });
+  await ext.startup();
+
+  let data = await new Promise(resolve => {
+    let ssm = Services.scriptSecurityManager;
+
+    let channel = NetUtil.newChannel({
+      uri: `${gServerUrl}/dummy`,
+      loadingPrincipal: ssm.createContentPrincipalFromOrigin(
+        "http://localhost"
+      ),
+      contentPolicyType: Ci.nsIContentPolicy.TYPE_XMLHTTPREQUEST,
+      securityFlags: Ci.nsILoadInfo.SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+    });
+
+    channel.asyncOpen({
+      QueryInterface: ChromeUtils.generateQI(["nsIStreamListener"]),
+
+      onStartRequest(request) {},
+
+      onStopRequest(request, statusCode) {
+        let properties = request.QueryInterface(Ci.nsIPropertyBag);
+        let id = properties.getProperty("cancelledByExtension");
+        let reason = request.loadInfo.requestBlockingReason;
+        resolve({ reason, id });
+      },
+
+      onDataAvailable() {},
+    });
+  });
+
+  Assert.equal(
+    Ci.nsILoadInfo.BLOCKING_REASON_EXTENSION_WEBREQUEST,
+    data.reason,
+    "extension cancelled request"
+  );
+  Assert.equal(
+    ext.id,
+    data.id,
+    "extension id attached to channel property bag"
+  );
+  await ext.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_download.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_download.js
new file mode 100644
index 0000000000..75acb39000
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_download.js
@@ -0,0 +1,43 @@
+"use strict";
+
+// Test for Bug 1579911: Check that download requests created by the
+// downloads.download API can be observed by extensions.
+add_task(async function testDownload() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "downloads",
+        "https://example.com/*",
+      ],
+    },
+    background: async function() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.sendMessage("request_intercepted");
+          return { cancel: true };
+        },
+        {
+          urls: ["https://example.com/downloadtest"],
+        },
+        ["blocking"]
+      );
+
+      browser.downloads.onChanged.addListener(delta => {
+        browser.test.assertEq(delta.state.current, "interrupted");
+        browser.test.sendMessage("done");
+      });
+
+      await browser.downloads.download({
+        url: "https://example.com/downloadtest",
+        filename: "example.txt",
+      });
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("request_intercepted");
+  await extension.awaitMessage("done");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterResponseData.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterResponseData.js
new file mode 100644
index 0000000000..27f4ff01e8
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterResponseData.js
@@ -0,0 +1,523 @@
+"use strict";
+
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+
+const HOSTS = new Set(["example.com", "example.org", "example.net"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+const FETCH_ORIGIN = "http://example.com/dummy";
+
+server.registerDirectory("/data/", do_get_file("data"));
+
+server.registerPathHandler("/redirect", (request, response) => {
+  let params = new URLSearchParams(request.queryString);
+  response.setStatusLine(request.httpVersion, 302, "Moved Temporarily");
+  response.setHeader("Location", params.get("redirect_uri"));
+  response.setHeader("Access-Control-Allow-Origin", "*");
+});
+
+server.registerPathHandler("/redirect301", (request, response) => {
+  let params = new URLSearchParams(request.queryString);
+  response.setStatusLine(request.httpVersion, 301, "Moved Permanently");
+  response.setHeader("Location", params.get("redirect_uri"));
+  response.setHeader("Access-Control-Allow-Origin", "*");
+});
+
+server.registerPathHandler("/script302.js", (request, response) => {
+  response.setStatusLine(request.httpVersion, 302, "Moved Temporarily");
+  response.setHeader("Location", "http://example.com/script.js");
+});
+
+server.registerPathHandler("/script.js", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "application/javascript");
+  response.write(String.raw`console.log("HELLO!");`);
+});
+
+server.registerPathHandler("/302.html", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html");
+  response.write(String.raw`
+    <script type="application/javascript" src="http://example.com/script302.js"></script>
+  `);
+});
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Access-Control-Allow-Origin", "*");
+  response.write("ok");
+});
+
+server.registerPathHandler("/dummy.xhtml", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "application/xhtml+xml");
+  response.write(String.raw`<?xml version="1.0"?>
+    <html xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
+      <head/>
+      <body/>
+    </html>
+  `);
+});
+
+server.registerPathHandler("/lorem.html.gz", async (request, response) => {
+  response.processAsync();
+
+  response.setHeader(
+    "Content-Type",
+    "Content-Type: text/html; charset=utf-8",
+    false
+  );
+  response.setHeader("Content-Encoding", "gzip", false);
+
+  let data = await OS.File.read(do_get_file("data/lorem.html.gz").path);
+  response.write(String.fromCharCode(...new Uint8Array(data)));
+
+  response.finish();
+});
+
+// Test re-encoding the data stream for bug 1590898.
+add_task(async function test_stream_encoding_data() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        request => {
+          let filter = browser.webRequest.filterResponseData(request.requestId);
+          let decoder = new TextDecoder("utf-8");
+          let encoder = new TextEncoder();
+
+          filter.ondata = event => {
+            let str = decoder.decode(event.data, { stream: true });
+            filter.write(encoder.encode(str));
+            filter.disconnect();
+          };
+        },
+        {
+          urls: ["http://example.com/lorem.html.gz"],
+          types: ["main_frame"],
+        },
+        ["blocking"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/lorem.html.gz"
+  );
+
+  let content = await contentPage.spawn(null, () => {
+    return this.content.document.body.textContent;
+  });
+
+  ok(
+    content.includes("Lorem ipsum dolor sit amet"),
+    `expected content received`
+  );
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+// Tests that the stream filter request is added to the document's load
+// group, and blocks an XML document's load event until after the filter
+// stops sending data.
+add_task(async function test_xml_document_loadgroup_blocking() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        request => {
+          let filter = browser.webRequest.filterResponseData(request.requestId);
+
+          let data = [];
+          filter.ondata = event => {
+            data.push(event.data);
+          };
+          filter.onstop = async () => {
+            browser.test.sendMessage("phase", "original-onstop");
+
+            // Make a few trips through the event loop.
+            for (let i = 0; i < 10; i++) {
+              await new Promise(resolve => setTimeout(resolve, 0));
+            }
+
+            for (let buffer of data) {
+              filter.write(buffer);
+            }
+            browser.test.sendMessage("phase", "filter-onstop");
+            filter.close();
+          };
+        },
+        {
+          urls: ["http://example.com/dummy.xhtml"],
+        },
+        ["blocking"]
+      );
+    },
+
+    files: {
+      "content_script.js"() {
+        browser.test.sendMessage("phase", "content-script-start");
+        window.addEventListener(
+          "DOMContentLoaded",
+          () => {
+            browser.test.sendMessage("phase", "content-script-domload");
+          },
+          { once: true }
+        );
+        window.addEventListener(
+          "load",
+          () => {
+            browser.test.sendMessage("phase", "content-script-load");
+          },
+          { once: true }
+        );
+      },
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+
+      content_scripts: [
+        {
+          matches: ["http://example.com/dummy.xhtml"],
+          run_at: "document_start",
+          js: ["content_script.js"],
+        },
+      ],
+    },
+  });
+
+  await extension.startup();
+
+  const EXPECTED = [
+    "original-onstop",
+    "filter-onstop",
+    "content-script-start",
+    "content-script-domload",
+    "content-script-load",
+  ];
+
+  let done = new Promise(resolve => {
+    let phases = [];
+    extension.onMessage("phase", phase => {
+      phases.push(phase);
+      if (phases.length === EXPECTED.length) {
+        resolve(phases);
+      }
+    });
+  });
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy.xhtml"
+  );
+
+  deepEqual(await done, EXPECTED, "Things happened, and in the right order");
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_filter_content_fetch() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      let pending = [];
+
+      browser.webRequest.onBeforeRequest.addListener(
+        data => {
+          let filter = browser.webRequest.filterResponseData(data.requestId);
+
+          let url = new URL(data.url);
+
+          if (url.searchParams.get("redirect_uri")) {
+            pending.push(
+              new Promise(resolve => {
+                filter.onerror = resolve;
+              }).then(() => {
+                browser.test.assertEq(
+                  "Channel redirected",
+                  filter.error,
+                  "Got correct error for redirected filter"
+                );
+              })
+            );
+          }
+
+          filter.onstart = () => {
+            filter.write(new TextEncoder().encode(data.url));
+          };
+          filter.ondata = event => {
+            let str = new TextDecoder().decode(event.data);
+            browser.test.assertEq(
+              "ok",
+              str,
+              `Got unfiltered data for ${data.url}`
+            );
+          };
+          filter.onstop = () => {
+            filter.close();
+          };
+        },
+        {
+          urls: ["<all_urls>"],
+        },
+        ["blocking"]
+      );
+
+      browser.test.onMessage.addListener(async msg => {
+        if (msg === "done") {
+          await Promise.all(pending);
+          browser.test.notifyPass("stream-filter");
+        }
+      });
+    },
+
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "http://example.com/",
+        "http://example.org/",
+      ],
+    },
+  });
+
+  await extension.startup();
+
+  let results = [
+    ["http://example.com/dummy", "http://example.com/dummy"],
+    ["http://example.org/dummy", "http://example.org/dummy"],
+    ["http://example.net/dummy", "ok"],
+    [
+      "http://example.com/redirect?redirect_uri=http://example.com/dummy",
+      "http://example.com/dummy",
+    ],
+    [
+      "http://example.com/redirect?redirect_uri=http://example.org/dummy",
+      "http://example.org/dummy",
+    ],
+    ["http://example.com/redirect?redirect_uri=http://example.net/dummy", "ok"],
+    [
+      "http://example.net/redirect?redirect_uri=http://example.com/dummy",
+      "http://example.com/dummy",
+    ],
+  ].map(async ([url, expectedResponse]) => {
+    let text = await ExtensionTestUtils.fetch(FETCH_ORIGIN, url);
+    equal(text, expectedResponse, `Expected response for ${url}`);
+  });
+
+  await Promise.all(results);
+
+  extension.sendMessage("done");
+  await extension.awaitFinish("stream-filter");
+  await extension.unload();
+});
+
+add_task(async function test_filter_301() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onHeadersReceived.addListener(
+        data => {
+          if (data.statusCode !== 200) {
+            return;
+          }
+          let filter = browser.webRequest.filterResponseData(data.requestId);
+
+          filter.onstop = () => {
+            filter.close();
+            browser.test.notifyPass("stream-filter");
+          };
+          filter.onerror = () => {
+            browser.test.fail(`unexpected ${filter.error}`);
+          };
+        },
+        {
+          urls: ["<all_urls>"],
+        },
+        ["blocking"]
+      );
+    },
+
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "http://example.com/",
+        "http://example.org/",
+      ],
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/redirect301?redirect_uri=http://example.org/dummy"
+  );
+
+  await extension.awaitFinish("stream-filter");
+
+  await contentPage.close();
+  await extension.unload();
+});
+
+add_task(async function test_filter_302() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          let filter = browser.webRequest.filterResponseData(details.requestId);
+          browser.test.sendMessage("filter-created");
+
+          filter.ondata = event => {
+            const script = "forceError();";
+            filter.write(
+              new Uint8Array(new TextEncoder("utf-8").encode(script))
+            );
+            filter.close();
+            browser.test.sendMessage("filter-ondata");
+          };
+
+          filter.onerror = () => {
+            browser.test.assertEq(filter.error, "Channel redirected");
+            browser.test.sendMessage("filter-redirect");
+          };
+        },
+        {
+          urls: ["http://example.com/*.js"],
+        },
+        ["blocking"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  let { messages } = await promiseConsoleOutput(async () => {
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      "http://example.com/302.html"
+    );
+
+    await extension.awaitMessage("filter-created");
+    await extension.awaitMessage("filter-redirect");
+    await extension.awaitMessage("filter-created");
+    await extension.awaitMessage("filter-ondata");
+    await contentPage.close();
+  });
+  AddonTestUtils.checkMessages(messages, {
+    expected: [{ message: /forceError is not defined/ }],
+  });
+
+  await extension.unload();
+});
+
+add_task(async function test_alternate_cached_data() {
+  Services.prefs.setBoolPref("dom.script_loader.bytecode_cache.enabled", true);
+  Services.prefs.setIntPref("dom.script_loader.bytecode_cache.strategy", -1);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          let filter = browser.webRequest.filterResponseData(details.requestId);
+          let decoder = new TextDecoder("utf-8");
+          let encoder = new TextEncoder();
+
+          filter.ondata = event => {
+            let str = decoder.decode(event.data, { stream: true });
+            filter.write(encoder.encode(str));
+            filter.disconnect();
+            browser.test.assertTrue(
+              str.startsWith(`"use strict";`),
+              "ondata received decoded data"
+            );
+            browser.test.sendMessage("onBeforeRequest");
+          };
+
+          filter.onerror = () => {
+            // onBeforeRequest will always beat the cache race, so we should always
+            // get valid data in ondata.
+            browser.test.fail("error-received", filter.error);
+          };
+        },
+        {
+          urls: ["http://example.com/data/file_script_good.js"],
+        },
+        ["blocking"]
+      );
+      browser.webRequest.onHeadersReceived.addListener(
+        details => {
+          let filter = browser.webRequest.filterResponseData(details.requestId);
+          let decoder = new TextDecoder("utf-8");
+          let encoder = new TextEncoder();
+
+          // Because cache is always a race, intermittently we will succesfully
+          // beat the cache, in which case we pass in ondata.  If cache wins,
+          // we pass in onerror.
+          // Running the test with --verify hits this cache race issue, as well
+          // it seems that the cache primarily looses on linux1804.
+          let gotone = false;
+          filter.ondata = event => {
+            browser.test.assertFalse(gotone, "cache lost the race");
+            gotone = true;
+            let str = decoder.decode(event.data, { stream: true });
+            filter.write(encoder.encode(str));
+            filter.disconnect();
+            browser.test.assertTrue(
+              str.startsWith(`"use strict";`),
+              "ondata received decoded data"
+            );
+            browser.test.sendMessage("onHeadersReceived");
+          };
+
+          filter.onerror = () => {
+            browser.test.assertFalse(gotone, "cache won the race");
+            gotone = true;
+            browser.test.assertEq(
+              filter.error,
+              "Channel is delivering cached alt-data"
+            );
+            browser.test.sendMessage("onHeadersReceived");
+          };
+        },
+        {
+          urls: ["http://example.com/data/file_script_bad.js"],
+        },
+        ["blocking"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/*"],
+    },
+  });
+
+  // Prime the cache so we have the script byte-cached.
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_script.html"
+  );
+  await contentPage.close();
+
+  await extension.startup();
+
+  let page_cached = await await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_script.html"
+  );
+  await Promise.all([
+    extension.awaitMessage("onBeforeRequest"),
+    extension.awaitMessage("onHeadersReceived"),
+  ]);
+  await page_cached.close();
+  await extension.unload();
+
+  Services.prefs.clearUserPref("dom.script_loader.bytecode_cache.enabled");
+  Services.prefs.clearUserPref("dom.script_loader.bytecode_cache.strategy");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterTypes.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterTypes.js
new file mode 100644
index 0000000000..643a375ff0
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filterTypes.js
@@ -0,0 +1,85 @@
+"use strict";
+
+AddonTestUtils.init(this);
+
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerPathHandler("/", (request, response) => {
+  response.setHeader("Content-Tpe", "text/plain", false);
+  response.write("OK");
+});
+
+add_task(async function test_all_webRequest_ResourceTypes() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "*://example.com/*"],
+    },
+    background() {
+      browser.test.onMessage.addListener(async msg => {
+        browser.webRequest[msg.event].addListener(
+          () => {},
+          { urls: ["*://example.com/*"], ...msg.filter },
+          ["blocking"]
+        );
+        // Call an API method implemented in the parent process to
+        // be sure that the webRequest listener has been registered
+        // in the parent process as well.
+        await browser.runtime.getBrowserInfo();
+        browser.test.sendMessage(`webRequest-listener-registered`);
+      });
+    },
+  });
+
+  await extension.startup();
+
+  const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+  const webRequestSchema = Schemas.privilegedSchemaJSON
+    .get("chrome://extensions/content/schemas/web_request.json")
+    .deserialize({});
+  const ResourceType = webRequestSchema[1].types.filter(
+    type => type.id == "ResourceType"
+  )[0];
+  ok(
+    ResourceType && ResourceType.enum,
+    "Found ResourceType in the web_request.json schema"
+  );
+  info(
+    "Register webRequest.onBeforeRequest event listener for all supported ResourceType"
+  );
+
+  let { messages } = await promiseConsoleOutput(async () => {
+    ExtensionTestUtils.failOnSchemaWarnings(false);
+    extension.sendMessage({
+      event: "onBeforeRequest",
+      filter: {
+        // Verify that the resourceType not supported is going to be ignored
+        // and all the ones supported does not trigger a ChannelWrapper.matches
+        // exception once the listener is being triggered.
+        types: [].concat(ResourceType.enum, "not-supported-resource-type"),
+      },
+    });
+    await extension.awaitMessage("webRequest-listener-registered");
+    ExtensionTestUtils.failOnSchemaWarnings();
+
+    await ExtensionTestUtils.fetch(
+      "http://example.com/dummy",
+      "http://example.com"
+    );
+  });
+
+  AddonTestUtils.checkMessages(messages, {
+    expected: [
+      { message: /Warning processing types: .* "not-supported-resource-type"/ },
+    ],
+    forbidden: [{ message: /JavaScript Error: "ChannelWrapper.matches/ }],
+  });
+  info("No ChannelWrapper.matches errors have been logged");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filter_urls.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filter_urls.js
new file mode 100644
index 0000000000..af0d8594f4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_filter_urls.js
@@ -0,0 +1,35 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+AddonTestUtils.init(this);
+
+add_task(async function test_invalid_urls_in_webRequest_filter() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "https://example.com/*"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(() => {}, {
+        urls: ["htt:/example.com/*"],
+        types: ["main_frame"],
+      });
+    },
+  });
+  let { messages } = await promiseConsoleOutput(async () => {
+    await extension.startup();
+    await extension.unload();
+  });
+  AddonTestUtils.checkMessages(
+    messages,
+    {
+      expected: [
+        {
+          message: /ExtensionError: Invalid url pattern: htt:\/example.com\/*/,
+        },
+      ],
+    },
+    true
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_from_extension_page.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_from_extension_page.js
new file mode 100644
index 0000000000..b63d14cd16
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_from_extension_page.js
@@ -0,0 +1,57 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerPathHandler("/HELLO", (req, res) => {
+  res.write("BYE");
+});
+
+add_task(async function request_from_extension_page() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["http://example.com/", "webRequest", "webRequestBlocking"],
+    },
+    files: {
+      "tab.html": `<!DOCTYPE html><script src="tab.js"></script>`,
+      "tab.js": async function() {
+        browser.webRequest.onHeadersReceived.addListener(
+          details => {
+            let { responseHeaders } = details;
+            responseHeaders.push({
+              name: "X-Added-by-Test",
+              value: "TheValue",
+            });
+            return { responseHeaders };
+          },
+          {
+            urls: ["http://example.com/HELLO"],
+          },
+          ["blocking", "responseHeaders"]
+        );
+
+        // Ensure that listener is registered (workaround for bug 1300234).
+        await browser.runtime.getPlatformInfo();
+
+        let response = await fetch("http://example.com/HELLO");
+        browser.test.assertEq(
+          "TheValue",
+          response.headers.get("X-added-by-test"),
+          "expected response header from webRequest listener"
+        );
+        browser.test.assertEq(
+          await response.text(),
+          "BYE",
+          "Expected response from server"
+        );
+        browser.test.sendMessage("done");
+      },
+    },
+  });
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `moz-extension://${extension.uuid}/tab.html`,
+    { extension }
+  );
+  await extension.awaitMessage("done");
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_host.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_host.js
new file mode 100644
index 0000000000..425d83560d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_host.js
@@ -0,0 +1,99 @@
+"use strict";
+
+const HOSTS = new Set(["example.com", "example.org"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+const BASE_URL = "http://example.com";
+const FETCH_ORIGIN = "http://example.com/dummy";
+
+server.registerPathHandler("/return_headers.sjs", (request, response) => {
+  response.setHeader("Content-Type", "text/plain", false);
+
+  let headers = {};
+  for (let { data: header } of request.headers) {
+    headers[header] = request.getHeader(header);
+  }
+
+  response.write(JSON.stringify(headers));
+});
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+function getExtension(permission = "<all_urls>") {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", permission],
+    },
+    background() {
+      browser.webRequest.onBeforeSendHeaders.addListener(
+        details => {
+          details.requestHeaders.push({ name: "Host", value: "example.org" });
+          return { requestHeaders: details.requestHeaders };
+        },
+        { urls: ["<all_urls>"] },
+        ["blocking", "requestHeaders"]
+      );
+    },
+  });
+}
+
+add_task(async function test_host_header_accepted() {
+  let extension = getExtension();
+  await extension.startup();
+  let headers = JSON.parse(
+    await ExtensionTestUtils.fetch(
+      FETCH_ORIGIN,
+      `${BASE_URL}/return_headers.sjs`
+    )
+  );
+
+  equal(headers.host, "example.org", "Host header was set on request");
+
+  await extension.unload();
+});
+
+add_task(async function test_host_header_denied() {
+  let extension = getExtension(`${BASE_URL}/`);
+
+  await extension.startup();
+
+  let headers = JSON.parse(
+    await ExtensionTestUtils.fetch(
+      FETCH_ORIGIN,
+      `${BASE_URL}/return_headers.sjs`
+    )
+  );
+
+  equal(headers.host, "example.com", "Host header was not set on request");
+
+  await extension.unload();
+});
+
+add_task(async function test_host_header_restricted() {
+  Services.prefs.setCharPref(
+    "extensions.webextensions.restrictedDomains",
+    "example.org"
+  );
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("extensions.webextensions.restrictedDomains");
+  });
+
+  let extension = getExtension();
+
+  await extension.startup();
+
+  let headers = JSON.parse(
+    await ExtensionTestUtils.fetch(
+      FETCH_ORIGIN,
+      `${BASE_URL}/return_headers.sjs`
+    )
+  );
+
+  equal(headers.host, "example.com", "Host header was not set on request");
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_incognito.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_incognito.js
new file mode 100644
index 0000000000..cc84791aaf
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_incognito.js
@@ -0,0 +1,81 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_incognito_webrequest_access() {
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  let pb_extension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        async details => {
+          browser.test.assertTrue(details.incognito, "incognito flag is set");
+        },
+        { urls: ["<all_urls>"], incognito: true },
+        ["blocking"]
+      );
+
+      browser.webRequest.onBeforeRequest.addListener(
+        async details => {
+          browser.test.assertFalse(
+            details.incognito,
+            "incognito flag is not set"
+          );
+          browser.test.notifyPass("webRequest.spanning");
+        },
+        { urls: ["<all_urls>"], incognito: false },
+        ["blocking"]
+      );
+    },
+  });
+  await pb_extension.startup();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        async details => {
+          browser.test.assertFalse(
+            details.incognito,
+            "incognito flag is not set"
+          );
+          browser.test.notifyPass("webRequest");
+        },
+        { urls: ["<all_urls>"] },
+        ["blocking"]
+      );
+    },
+  });
+  // Load non-incognito extension to check that private requests are invisible to it.
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy",
+    { privateBrowsing: true }
+  );
+  await contentPage.close();
+
+  contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+  await extension.awaitFinish("webRequest");
+  await pb_extension.awaitFinish("webRequest.spanning");
+  await contentPage.close();
+
+  await pb_extension.unload();
+  await extension.unload();
+
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_mergecsp.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_mergecsp.js
new file mode 100644
index 0000000000..06dd0f54ef
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_mergecsp.js
@@ -0,0 +1,214 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+const server = createHttpServer({
+  hosts: ["example.net", "example.com"],
+});
+server.registerDirectory("/data/", do_get_file("data"));
+
+const pageContent = `<!DOCTYPE html>
+  <script id="script1" src="/data/file_script_good.js"></script>
+  <script id="script3" src="//example.com/data/file_script_bad.js"></script>
+  <img id="img1" src='/data/file_image_good.png'>
+  <img id="img3" src='//example.com/data/file_image_good.png'>
+`;
+
+server.registerPathHandler("/", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html");
+  if (request.queryString) {
+    response.setHeader(
+      "Content-Security-Policy",
+      decodeURIComponent(request.queryString)
+    );
+  }
+  response.write(pageContent);
+});
+
+let extensionData = {
+  manifest: {
+    permissions: ["webRequest", "webRequestBlocking", "*://example.net/*"],
+  },
+  background() {
+    let csp_value = undefined;
+    browser.test.onMessage.addListener(function(msg, expectedCount) {
+      csp_value = msg;
+      browser.test.sendMessage("csp-set");
+    });
+    browser.webRequest.onHeadersReceived.addListener(
+      e => {
+        browser.test.log(`onHeadersReceived ${e.requestId} ${e.url}`);
+        if (csp_value === undefined) {
+          browser.test.assertTrue(false, "extension called before CSP was set");
+        }
+        if (csp_value !== null) {
+          e.responseHeaders = e.responseHeaders.filter(
+            i => i.name.toLowerCase() != "content-security-policy"
+          );
+          if (csp_value !== "") {
+            e.responseHeaders.push({
+              name: "Content-Security-Policy",
+              value: csp_value,
+            });
+          }
+        }
+        return { responseHeaders: e.responseHeaders };
+      },
+      { urls: ["*://example.net/*"] },
+      ["blocking", "responseHeaders"]
+    );
+  },
+};
+
+/**
+ * Test a combination of Content Security Policies against first/third party images/scripts.
+ * @param {string} site_csp The CSP to be sent by the site, or null.
+ * @param {string} ext1_csp The CSP to be sent by the first extension,
+ *                          "" to remove the header, or null to not modify it.
+ * @param {string} ext2_csp The CSP to be sent by the first extension,
+ *                          "" to remove the header, or null to not modify it.
+ * @param {Object} expect   Object containing information which resources are expected to be loaded.
+ * @param {Object} expect.img1_loaded    image from a first party origin.
+ * @param {Object} expect.img3_loaded    image from a third party origin.
+ * @param {Object} expect.script1_loaded script from a first party origin.
+ * @param {Object} expect.script3_loaded script from a third party origin.
+ */
+async function test_csp(site_csp, ext1_csp, ext2_csp, expect) {
+  let extension1 = await ExtensionTestUtils.loadExtension(extensionData);
+  let extension2 = await ExtensionTestUtils.loadExtension(extensionData);
+  await extension1.startup();
+  await extension2.startup();
+  extension1.sendMessage(ext1_csp);
+  extension2.sendMessage(ext2_csp);
+  await extension1.awaitMessage("csp-set");
+  await extension2.awaitMessage("csp-set");
+
+  let csp_value = encodeURIComponent(site_csp || "");
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `http://example.net/?${csp_value}`
+  );
+  let results = await contentPage.spawn(null, async () => {
+    let img1 = this.content.document.getElementById("img1");
+    let img3 = this.content.document.getElementById("img3");
+    return {
+      img1_loaded: img1.complete && img1.naturalWidth > 0,
+      img3_loaded: img3.complete && img3.naturalWidth > 0,
+      // Note: "good" and "bad" are just placeholders; they don't mean anything.
+      script1_loaded: !!this.content.document.getElementById("good"),
+      script3_loaded: !!this.content.document.getElementById("bad"),
+    };
+  });
+
+  await contentPage.close();
+  await extension1.unload();
+  await extension2.unload();
+
+  let action = {
+    true: "loaded",
+    false: "blocked",
+  };
+
+  info(`test_csp: From "${site_csp}" to "${ext1_csp}" to "${ext2_csp}"`);
+
+  equal(
+    expect.img1_loaded,
+    results.img1_loaded,
+    `expected first party image to be ${action[expect.img1_loaded]}`
+  );
+  equal(
+    expect.img3_loaded,
+    results.img3_loaded,
+    `expected third party image to be ${action[expect.img3_loaded]}`
+  );
+  equal(
+    expect.script1_loaded,
+    results.script1_loaded,
+    `expected first party script to be ${action[expect.script1_loaded]}`
+  );
+  equal(
+    expect.script3_loaded,
+    results.script3_loaded,
+    `expected third party script to be ${action[expect.script3_loaded]}`
+  );
+}
+
+add_task(async function test_webRequest_mergecsp() {
+  await test_csp("default-src *", "script-src 'none'", null, {
+    img1_loaded: true,
+    img3_loaded: true,
+    script1_loaded: false,
+    script3_loaded: false,
+  });
+  await test_csp(null, "script-src 'none'", null, {
+    img1_loaded: true,
+    img3_loaded: true,
+    script1_loaded: false,
+    script3_loaded: false,
+  });
+  await test_csp("default-src *", "script-src 'none'", "img-src 'none'", {
+    img1_loaded: false,
+    img3_loaded: false,
+    script1_loaded: false,
+    script3_loaded: false,
+  });
+  await test_csp(null, "script-src 'none'", "img-src 'none'", {
+    img1_loaded: false,
+    img3_loaded: false,
+    script1_loaded: false,
+    script3_loaded: false,
+  });
+  await test_csp(
+    "default-src *",
+    "img-src example.com",
+    "img-src example.org",
+    {
+      img1_loaded: false,
+      img3_loaded: false,
+      script1_loaded: true,
+      script3_loaded: true,
+    }
+  );
+});
+
+add_task(async function test_remove_and_replace_csp() {
+  // CSP removed, CSP added.
+  await test_csp("img-src 'self'", "", "img-src example.com", {
+    img1_loaded: false,
+    img3_loaded: true,
+    script1_loaded: true,
+    script3_loaded: true,
+  });
+
+  // CSP removed, CSP added.
+  await test_csp("default-src 'none'", "", "img-src example.com", {
+    img1_loaded: false,
+    img3_loaded: true,
+    script1_loaded: true,
+    script3_loaded: true,
+  });
+
+  // CSP replaced - regression test for bug 1635781.
+  await test_csp("default-src 'none'", "img-src example.com", null, {
+    img1_loaded: false,
+    img3_loaded: true,
+    script1_loaded: true,
+    script3_loaded: true,
+  });
+
+  // CSP unchanged, CSP replaced - regression test for bug 1635781.
+  await test_csp("default-src 'none'", null, "img-src example.com", {
+    img1_loaded: false,
+    img3_loaded: true,
+    script1_loaded: true,
+    script3_loaded: true,
+  });
+
+  // CSP replaced, CSP removed.
+  await test_csp("default-src 'none'", "img-src example.com", "", {
+    img1_loaded: true,
+    img3_loaded: true,
+    script1_loaded: true,
+    script3_loaded: true,
+  });
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_permission.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_permission.js
new file mode 100644
index 0000000000..530deaa1a7
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_permission.js
@@ -0,0 +1,154 @@
+"use strict";
+
+const PREF_DISABLE_SECURITY =
+  "security.turn_off_all_security_so_that_" +
+  "viruses_can_take_over_this_computer";
+
+const HOSTS = new Set(["example.com", "example.org"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+const BASE_URL = "http://example.com";
+
+server.registerDirectory("/data/", do_get_file("data"));
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_permissions() {
+  function background() {
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        if (details.url.includes("_original")) {
+          let redirectUrl = details.url
+            .replace("example.org", "example.com")
+            .replace("_original", "_redirected");
+          return { redirectUrl };
+        }
+        return {};
+      },
+      { urls: ["<all_urls>"] },
+      ["blocking"]
+    );
+  }
+
+  let extensionData = {
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background,
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  const frameScript = () => {
+    const messageListener = {
+      async receiveMessage({ target, messageName, recipient, data, name }) {
+        /* globals content */
+        let doc = content.document;
+        let iframe = doc.createElement("iframe");
+        doc.body.appendChild(iframe);
+
+        let promise = new Promise(resolve => {
+          let listener = event => {
+            content.removeEventListener("message", listener);
+            resolve(event.data);
+          };
+          content.addEventListener("message", listener);
+        });
+
+        iframe.setAttribute(
+          "src",
+          "http://example.com/data/file_WebRequest_permission_original.html"
+        );
+        let result = await promise;
+        doc.body.removeChild(iframe);
+        return result;
+      },
+    };
+
+    const { MessageChannel } = ChromeUtils.import(
+      "resource://gre/modules/MessageChannel.jsm"
+    );
+    MessageChannel.addListener(this, "Test:Check", messageListener);
+  };
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/dummy`
+  );
+  await contentPage.loadFrameScript(frameScript);
+
+  let results = await contentPage.sendMessage("Test:Check", {});
+  equal(
+    results.page,
+    "redirected",
+    "Regular webRequest redirect works on an unprivileged page"
+  );
+  equal(
+    results.script,
+    "redirected",
+    "Regular webRequest redirect works from an unprivileged page"
+  );
+
+  Services.prefs.setBoolPref(PREF_DISABLE_SECURITY, true);
+  Services.prefs.setBoolPref("extensions.webapi.testing", true);
+  Services.prefs.setBoolPref("extensions.webapi.testing.http", true);
+
+  results = await contentPage.sendMessage("Test:Check", {});
+  equal(
+    results.page,
+    "original",
+    "webRequest redirect fails on a privileged page"
+  );
+  equal(
+    results.script,
+    "original",
+    "webRequest redirect fails from a privileged page"
+  );
+
+  await extension.unload();
+  await contentPage.close();
+});
+
+add_task(async function test_no_webRequestBlocking_error() {
+  function background() {
+    const expectedError =
+      "Using webRequest.addListener with the blocking option " +
+      "requires the 'webRequestBlocking' permission.";
+
+    const blockingEvents = [
+      "onBeforeRequest",
+      "onBeforeSendHeaders",
+      "onHeadersReceived",
+      "onAuthRequired",
+    ];
+
+    for (let eventName of blockingEvents) {
+      browser.test.assertThrows(
+        () => {
+          browser.webRequest[eventName].addListener(
+            details => {},
+            { urls: ["<all_urls>"] },
+            ["blocking"]
+          );
+        },
+        expectedError,
+        `Got the expected exception for a blocking webRequest.${eventName} listener`
+      );
+    }
+  }
+
+  const extensionData = {
+    manifest: { permissions: ["webRequest", "<all_urls>"] },
+    background,
+  };
+
+  const extension = ExtensionTestUtils.loadExtension(extensionData);
+
+  await extension.startup();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_StreamFilter.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_StreamFilter.js
new file mode 100644
index 0000000000..f8d329c85b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_StreamFilter.js
@@ -0,0 +1,129 @@
+"use strict";
+
+// StreamFilters should be closed upon a redirect.
+//
+// Some redirects are already tested in other tests:
+// - test_ext_webRequest_filterResponseData.js tests fetch requests.
+// - test_ext_webRequest_viewsource_StreamFilter.js tests view-source documents.
+//
+// Usually, redirects are caught in StreamFilterParent::OnStartRequest, but due
+// to the fact that AttachStreamFilter is deferred for document requests, OSR is
+// not called and the cleanup is triggered from nsHttpChannel::ReleaseListeners.
+
+const server = createHttpServer({ hosts: ["example.com", "example.org"] });
+
+server.registerPathHandler("/redir", (request, response) => {
+  response.setStatusLine(request.httpVersion, 302, "Found");
+  response.setHeader("Location", "/target");
+});
+server.registerPathHandler("/target", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+server.registerPathHandler("/RedirectToRedir.html", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html; charset=utf-8");
+  response.write("<script>location.href='http://example.com/redir';</script>");
+});
+server.registerPathHandler("/iframeWithRedir.html", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html; charset=utf-8");
+  response.write("<iframe src='http://example.com/redir'></iframe>");
+});
+
+function loadRedirectCatcherExtension() {
+  return ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "*://*/*"],
+    },
+    background() {
+      const closeCounts = {};
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          let expectedError = "Channel redirected";
+          if (details.type === "main_frame" || details.type === "sub_frame") {
+            // Message differs for the reason stated at the top of this file.
+            // TODO bug 1683862: Make error message more accurate.
+            expectedError = "Invalid request ID";
+          }
+
+          closeCounts[details.requestId] = 0;
+
+          let filter = browser.webRequest.filterResponseData(details.requestId);
+          filter.onstart = () => {
+            filter.disconnect();
+            browser.test.fail("Unexpected filter.onstart");
+          };
+          filter.onerror = function() {
+            closeCounts[details.requestId]++;
+            browser.test.assertEq(expectedError, filter.error, "filter.error");
+          };
+        },
+        { urls: ["*://*/redir"] },
+        ["blocking"]
+      );
+      browser.webRequest.onCompleted.addListener(
+        details => {
+          // filter.onerror from the redirect request should be called before
+          // webRequest.onCompleted of the redirection target. Regression test
+          // for bug 1683189.
+          browser.test.assertEq(
+            1,
+            closeCounts[details.requestId],
+            "filter from initial, redirected request should have been closed"
+          );
+          browser.test.log("Intentionally canceling view-source request");
+          browser.test.sendMessage("req_end", details.type);
+        },
+        { urls: ["*://*/target"] }
+      );
+    },
+  });
+}
+
+add_task(async function redirect_document() {
+  let extension = loadRedirectCatcherExtension();
+  await extension.startup();
+
+  {
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      "http://example.com/redir"
+    );
+    equal(await extension.awaitMessage("req_end"), "main_frame", "is top doc");
+    await contentPage.close();
+  }
+
+  {
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      "http://example.com/iframeWithRedir.html"
+    );
+    equal(await extension.awaitMessage("req_end"), "sub_frame", "is sub doc");
+    await contentPage.close();
+  }
+
+  await extension.unload();
+});
+
+// Cross-origin redirect = process switch.
+add_task(async function redirect_document_cross_origin() {
+  let extension = loadRedirectCatcherExtension();
+  await extension.startup();
+
+  {
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      "http://example.org/RedirectToRedir.html"
+    );
+    equal(await extension.awaitMessage("req_end"), "main_frame", "is top doc");
+    await contentPage.close();
+  }
+
+  {
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      "http://example.org/iframeWithRedir.html"
+    );
+    equal(await extension.awaitMessage("req_end"), "sub_frame", "is sub doc");
+    await contentPage.close();
+  }
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_mozextension.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_mozextension.js
new file mode 100644
index 0000000000..e390e3348e
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_redirect_mozextension.js
@@ -0,0 +1,47 @@
+"use strict";
+
+// See: https://bugzilla.mozilla.org/show_bug.cgi?id=1573456
+add_task(async function test_mozextension_page_loaded_in_extension_process() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "https://example.com/*",
+      ],
+      web_accessible_resources: ["test.html"],
+    },
+    files: {
+      "test.html": '<!DOCTYPE html><script src="test.js"></script>',
+      "test.js": () => {
+        browser.test.assertTrue(
+          browser.webRequest,
+          "webRequest API should be available"
+        );
+
+        browser.test.sendMessage("test_done");
+      },
+    },
+    background: () => {
+      browser.webRequest.onBeforeRequest.addListener(
+        () => {
+          return {
+            redirectUrl: browser.runtime.getURL("test.html"),
+          };
+        },
+        { urls: ["*://*/redir"] },
+        ["blocking"]
+      );
+    },
+  });
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "https://example.com/redir"
+  );
+
+  await extension.awaitMessage("test_done");
+
+  await extension.unload();
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_requestSize.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_requestSize.js
new file mode 100644
index 0000000000..69238fb057
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_requestSize.js
@@ -0,0 +1,57 @@
+"use strict";
+
+const server = createHttpServer();
+const gServerUrl = `http://localhost:${server.identity.primaryPort}`;
+
+const EXTENSION_DATA = {
+  manifest: {
+    name: "Simple extension test",
+    version: "1.0",
+    manifest_version: 2,
+    description: "",
+
+    permissions: ["webRequest", "<all_urls>"],
+  },
+
+  async background() {
+    browser.test.log("background script running");
+
+    browser.webRequest.onBeforeSendHeaders.addListener(
+      async details => {
+        browser.test.assertTrue(details.requestSize == 0, "no requestSize");
+        browser.test.assertTrue(details.responseSize == 0, "no responseSize");
+        browser.test.log(`details.requestSize: ${details.requestSize}`);
+        browser.test.log(`details.responseSize: ${details.responseSize}`);
+        browser.test.sendMessage("check");
+      },
+      { urls: ["*://*/*"] }
+    );
+
+    browser.webRequest.onCompleted.addListener(
+      async details => {
+        browser.test.assertTrue(details.requestSize > 100, "have requestSize");
+        browser.test.assertTrue(
+          details.responseSize > 100,
+          "have responseSize"
+        );
+        browser.test.log(`details.requestSize: ${details.requestSize}`);
+        browser.test.log(`details.responseSize: ${details.responseSize}`);
+        browser.test.sendMessage("done");
+      },
+      { urls: ["*://*/*"] }
+    );
+  },
+};
+
+add_task(async function test_request_response_size() {
+  let ext = ExtensionTestUtils.loadExtension(EXTENSION_DATA);
+  await ext.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${gServerUrl}/dummy`
+  );
+  await ext.awaitMessage("check");
+  await ext.awaitMessage("done");
+  await contentPage.close();
+  await ext.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_responseBody.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_responseBody.js
new file mode 100644
index 0000000000..d3715684f9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_responseBody.js
@@ -0,0 +1,765 @@
+"use strict";
+
+/* eslint-disable mozilla/no-arbitrary-setTimeout */
+/* eslint-disable no-shadow */
+
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+const { ExtensionTestCommon } = ChromeUtils.import(
+  "resource://testing-common/ExtensionTestCommon.jsm"
+);
+
+const HOSTS = new Set(["example.com"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+const BASE_URL = "http://example.com";
+const FETCH_ORIGIN = "http://example.com/data/file_sample.html";
+
+const SEQUENTIAL = false;
+
+const PARTS = [
+  `<!DOCTYPE html>
+    <html lang="en">
+    <head>
+      <meta charset="UTF-8">
+      <title></title>
+    </head>
+    <body>`,
+  "Lorem ipsum dolor sit amet, <br>",
+  "consectetur adipiscing elit, <br>",
+  "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. <br>",
+  "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. <br>",
+  "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. <br>",
+  "Excepteur sint occaecat cupidatat non proident, <br>",
+  "sunt in culpa qui officia deserunt mollit anim id est laborum.<br>",
+  `
+    </body>
+    </html>`,
+].map(part => `${part}\n`);
+
+const TIMEOUT = AppConstants.DEBUG ? 4000 : 800;
+
+function delay(timeout = TIMEOUT) {
+  return new Promise(resolve => setTimeout(resolve, timeout));
+}
+
+server.registerPathHandler("/slow_response.sjs", async (request, response) => {
+  response.processAsync();
+
+  response.setHeader("Content-Type", "text/html", false);
+  response.setHeader("Cache-Control", "no-cache", false);
+
+  await delay();
+
+  for (let part of PARTS) {
+    try {
+      response.write(part);
+    } catch (e) {
+      // This fails if we attempt to write data after the connection has
+      // been closed.
+      break;
+    }
+    await delay();
+  }
+
+  response.finish();
+});
+
+server.registerPathHandler("/lorem.html.gz", async (request, response) => {
+  response.processAsync();
+
+  response.setHeader(
+    "Content-Type",
+    "Content-Type: text/html; charset=utf-8",
+    false
+  );
+  response.setHeader("Content-Encoding", "gzip", false);
+
+  let data = await OS.File.read(do_get_file("data/lorem.html.gz").path);
+  response.write(String.fromCharCode(...new Uint8Array(data)));
+
+  response.finish();
+});
+
+server.registerPathHandler("/multipart", async (request, response) => {
+  response.processAsync();
+
+  response.setHeader(
+    "Content-Type",
+    'Content-Type: multipart/x-mixed-replace; boundary="testingtesting"',
+    false
+  );
+
+  response.write("--testingtesting\n");
+  response.write(PARTS.join(""));
+  response.write("--testingtesting--\n");
+
+  response.finish();
+});
+
+server.registerPathHandler("/multipart2", async (request, response) => {
+  response.processAsync();
+
+  response.setHeader(
+    "Content-Type",
+    'Content-Type: multipart/x-mixed-replace; boundary="testingtesting"',
+    false
+  );
+
+  response.write("--testingtesting\n");
+  response.write(PARTS.join(""));
+  response.write("--testingtesting\n");
+  response.write(PARTS.join(""));
+  response.write("--testingtesting--\n");
+
+  response.finish();
+});
+
+server.registerDirectory("/data/", do_get_file("data"));
+
+const TASKS = [
+  {
+    url: "slow_response.sjs",
+    task(filter, resolve, num) {
+      let decoder = new TextDecoder("utf-8");
+
+      browser.test.assertEq(
+        "uninitialized",
+        filter.status,
+        `(${num}): Got expected initial status`
+      );
+
+      filter.onstart = event => {
+        browser.test.assertEq(
+          "transferringdata",
+          filter.status,
+          `(${num}): Got expected onStart status`
+        );
+      };
+
+      filter.onstop = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected onStop event while disconnected`
+        );
+      };
+
+      let n = 0;
+      filter.ondata = async event => {
+        let str = decoder.decode(event.data, { stream: true });
+
+        if (n < 3) {
+          browser.test.assertEq(
+            JSON.stringify(PARTS[n]),
+            JSON.stringify(str),
+            `(${num}): Got expected part`
+          );
+        }
+        n++;
+
+        filter.write(event.data);
+
+        if (n == 3) {
+          filter.suspend();
+
+          browser.test.assertEq(
+            "suspended",
+            filter.status,
+            `(${num}): Got expected suspended status`
+          );
+
+          let fail = () => {
+            browser.test.fail(
+              `(${num}): Got unexpected data event while suspended`
+            );
+          };
+          filter.addEventListener("data", fail);
+
+          await delay(TIMEOUT * 3);
+
+          browser.test.assertEq(
+            "suspended",
+            filter.status,
+            `(${num}): Got expected suspended status`
+          );
+
+          filter.removeEventListener("data", fail);
+          filter.resume();
+          browser.test.assertEq(
+            "transferringdata",
+            filter.status,
+            `(${num}): Got expected resumed status`
+          );
+        } else if (n > 4) {
+          filter.disconnect();
+
+          filter.addEventListener("data", () => {
+            browser.test.fail(
+              `(${num}): Got unexpected data event while disconnected`
+            );
+          });
+
+          browser.test.assertEq(
+            "disconnected",
+            filter.status,
+            `(${num}): Got expected disconnected status`
+          );
+
+          resolve();
+        }
+      };
+
+      filter.onerror = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected error event: ${filter.error}`
+        );
+      };
+    },
+    verify(response) {
+      equal(response, PARTS.join(""), "Got expected final HTML");
+    },
+  },
+  {
+    url: "slow_response.sjs",
+    task(filter, resolve, num) {
+      let decoder = new TextDecoder("utf-8");
+
+      filter.onstop = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected onStop event while disconnected`
+        );
+      };
+
+      let n = 0;
+      filter.ondata = async event => {
+        let str = decoder.decode(event.data, { stream: true });
+
+        if (n < 3) {
+          browser.test.assertEq(
+            JSON.stringify(PARTS[n]),
+            JSON.stringify(str),
+            `(${num}): Got expected part`
+          );
+        }
+        n++;
+
+        filter.write(event.data);
+
+        if (n == 3) {
+          filter.suspend();
+
+          await delay(TIMEOUT * 3);
+
+          filter.disconnect();
+
+          resolve();
+        }
+      };
+
+      filter.onerror = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected error event: ${filter.error}`
+        );
+      };
+    },
+    verify(response) {
+      equal(response, PARTS.join(""), "Got expected final HTML");
+    },
+  },
+  {
+    url: "slow_response.sjs",
+    task(filter, resolve, num) {
+      let encoder = new TextEncoder("utf-8");
+
+      filter.onstop = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected onStop event while disconnected`
+        );
+      };
+
+      let n = 0;
+      filter.ondata = async event => {
+        n++;
+
+        filter.write(event.data);
+
+        function checkState(state) {
+          browser.test.assertEq(
+            state,
+            filter.status,
+            `(${num}): Got expected status`
+          );
+        }
+        if (n == 3) {
+          filter.resume();
+          checkState("transferringdata");
+          filter.suspend();
+          checkState("suspended");
+          filter.suspend();
+          checkState("suspended");
+          filter.resume();
+          checkState("transferringdata");
+          filter.suspend();
+          checkState("suspended");
+
+          await delay(TIMEOUT * 3);
+
+          checkState("suspended");
+          filter.disconnect();
+          checkState("disconnected");
+
+          for (let method of ["suspend", "resume", "close"]) {
+            browser.test.assertThrows(
+              () => {
+                filter[method]();
+              },
+              /.*/,
+              `(${num}): ${method}() should throw while disconnected`
+            );
+          }
+
+          browser.test.assertThrows(
+            () => {
+              filter.write(encoder.encode("Foo bar"));
+            },
+            /.*/,
+            `(${num}): write() should throw while disconnected`
+          );
+
+          filter.disconnect();
+
+          resolve();
+        }
+      };
+
+      filter.onerror = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected error event: ${filter.error}`
+        );
+      };
+    },
+    verify(response) {
+      equal(response, PARTS.join(""), "Got expected final HTML");
+    },
+  },
+  {
+    url: "slow_response.sjs",
+    task(filter, resolve, num) {
+      let encoder = new TextEncoder("utf-8");
+      let decoder = new TextDecoder("utf-8");
+
+      filter.onstop = event => {
+        browser.test.fail(`(${num}): Got unexpected onStop event while closed`);
+      };
+
+      browser.test.assertThrows(
+        () => {
+          filter.write(encoder.encode("Foo bar"));
+        },
+        /.*/,
+        `(${num}): write() should throw prior to connection`
+      );
+
+      let n = 0;
+      filter.ondata = async event => {
+        n++;
+
+        filter.write(event.data);
+
+        browser.test.log(
+          `(${num}): Got part ${n}: ${JSON.stringify(
+            decoder.decode(event.data)
+          )}`
+        );
+
+        function checkState(state) {
+          browser.test.assertEq(
+            state,
+            filter.status,
+            `(${num}): Got expected status`
+          );
+        }
+        if (n == 3) {
+          filter.close();
+
+          checkState("closed");
+
+          for (let method of ["suspend", "resume", "disconnect"]) {
+            browser.test.assertThrows(
+              () => {
+                filter[method]();
+              },
+              /.*/,
+              `(${num}): ${method}() should throw while closed`
+            );
+          }
+
+          browser.test.assertThrows(
+            () => {
+              filter.write(encoder.encode("Foo bar"));
+            },
+            /.*/,
+            `(${num}): write() should throw while closed`
+          );
+
+          filter.close();
+
+          resolve();
+        }
+      };
+
+      filter.onerror = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected error event: ${filter.error}`
+        );
+      };
+    },
+    verify(response) {
+      equal(response, PARTS.slice(0, 3).join(""), "Got expected final HTML");
+    },
+  },
+  {
+    url: "lorem.html.gz",
+    task(filter, resolve, num) {
+      let response = "";
+      let decoder = new TextDecoder("utf-8");
+
+      filter.onstart = event => {
+        browser.test.log(`(${num}): Request start`);
+      };
+
+      filter.onstop = event => {
+        browser.test.assertEq(
+          "finishedtransferringdata",
+          filter.status,
+          `(${num}): Got expected onStop status`
+        );
+
+        filter.close();
+        browser.test.assertEq(
+          "closed",
+          filter.status,
+          `Got expected closed status`
+        );
+
+        browser.test.assertEq(
+          JSON.stringify(PARTS.join("")),
+          JSON.stringify(response),
+          `(${num}): Got expected response`
+        );
+
+        resolve();
+      };
+
+      filter.ondata = event => {
+        let str = decoder.decode(event.data, { stream: true });
+        response += str;
+
+        filter.write(event.data);
+      };
+
+      filter.onerror = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected error event: ${filter.error}`
+        );
+      };
+    },
+    verify(response) {
+      equal(response, PARTS.join(""), "Got expected final HTML");
+    },
+  },
+  {
+    url: "multipart",
+    task(filter, resolve, num) {
+      filter.onstart = event => {
+        browser.test.log(`(${num}): Request start`);
+      };
+
+      filter.onstop = event => {
+        filter.disconnect();
+        resolve();
+      };
+
+      filter.ondata = event => {
+        filter.write(event.data);
+      };
+
+      filter.onerror = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected error event: ${filter.error}`
+        );
+      };
+    },
+    verify(response) {
+      equal(
+        response,
+        "--testingtesting\n" + PARTS.join("") + "--testingtesting--\n",
+        "Got expected final HTML"
+      );
+    },
+  },
+  {
+    url: "multipart2",
+    task(filter, resolve, num) {
+      filter.onstart = event => {
+        browser.test.log(`(${num}): Request start`);
+      };
+
+      filter.onstop = event => {
+        filter.disconnect();
+        resolve();
+      };
+
+      filter.ondata = event => {
+        filter.write(event.data);
+      };
+
+      filter.onerror = event => {
+        browser.test.fail(
+          `(${num}): Got unexpected error event: ${filter.error}`
+        );
+      };
+    },
+    verify(response) {
+      equal(
+        response,
+        "--testingtesting\n" +
+          PARTS.join("") +
+          "--testingtesting\n" +
+          PARTS.join("") +
+          "--testingtesting--\n",
+        "Got expected final HTML"
+      );
+    },
+  },
+];
+
+function serializeTest(test, num) {
+  let url = `${test.url}?test_num=${num}`;
+  let task = ExtensionTestCommon.serializeFunction(test.task);
+
+  return `{url: ${JSON.stringify(url)}, task: ${task}}`;
+}
+
+add_task(async function() {
+  function background(TASKS) {
+    async function runTest(test, num, details) {
+      browser.test.log(`Running test #${num}: ${details.url}`);
+
+      let filter = browser.webRequest.filterResponseData(details.requestId);
+
+      try {
+        await new Promise(resolve => {
+          test.task(filter, resolve, num, details);
+        });
+      } catch (e) {
+        browser.test.fail(
+          `Task #${num} threw an unexpected exception: ${e} :: ${e.stack}`
+        );
+      }
+
+      browser.test.log(`Finished test #${num}: ${details.url}`);
+      browser.test.sendMessage(`finished-${num}`);
+    }
+
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        for (let [num, test] of TASKS.entries()) {
+          if (details.url.endsWith(test.url)) {
+            runTest(test, num, details);
+            break;
+          }
+        }
+      },
+      {
+        urls: ["http://example.com/*?test_num=*"],
+      },
+      ["blocking"]
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `
+      const PARTS = ${JSON.stringify(PARTS)};
+      const TIMEOUT = ${TIMEOUT};
+
+      ${delay}
+
+      (${background})([${TASKS.map(serializeTest)}])
+    `,
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  async function runTest(test, num) {
+    let url = `${BASE_URL}/${test.url}?test_num=${num}`;
+
+    let body = await ExtensionTestUtils.fetch(FETCH_ORIGIN, url);
+
+    await extension.awaitMessage(`finished-${num}`);
+
+    info(`Verifying test #${num}: ${url}`);
+    await test.verify(body);
+  }
+
+  if (SEQUENTIAL) {
+    for (let [num, test] of TASKS.entries()) {
+      await runTest(test, num);
+    }
+  } else {
+    await Promise.all(TASKS.map(runTest));
+  }
+
+  await extension.unload();
+});
+
+// Test that registering a listener for a cached response does not cause a crash.
+add_task(async function test_cachedResponse() {
+  if (AppConstants.platform === "android") {
+    return;
+  }
+  Services.prefs.setBoolPref("network.http.rcwn.enabled", false);
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onHeadersReceived.addListener(
+        data => {
+          let filter = browser.webRequest.filterResponseData(data.requestId);
+
+          filter.onstop = event => {
+            filter.close();
+          };
+          filter.ondata = event => {
+            filter.write(event.data);
+          };
+
+          if (data.fromCache) {
+            browser.test.sendMessage("from-cache");
+          }
+        },
+        {
+          urls: ["http://example.com/*/file_sample.html?r=*"],
+        },
+        ["blocking"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  let url = `${BASE_URL}/data/file_sample.html?r=${Math.random()}`;
+  await ExtensionTestUtils.fetch(FETCH_ORIGIN, url);
+  await ExtensionTestUtils.fetch(FETCH_ORIGIN, url);
+  await extension.awaitMessage("from-cache");
+
+  await extension.unload();
+});
+
+// Test that finishing transferring data doesn't overwrite an existing closing/closed state.
+add_task(async function test_late_close() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        data => {
+          let filter = browser.webRequest.filterResponseData(data.requestId);
+
+          filter.onstop = event => {
+            browser.test.fail("Should not receive onstop after close()");
+            browser.test.assertEq(
+              "closed",
+              filter.status,
+              "Filter status should still be 'closed'"
+            );
+            browser.test.assertThrows(() => {
+              filter.close();
+            });
+          };
+          filter.ondata = event => {
+            filter.write(event.data);
+            filter.close();
+
+            browser.test.sendMessage(`done-${data.url}`);
+          };
+        },
+        {
+          urls: ["http://example.com/*/file_sample.html?*"],
+        },
+        ["blocking"]
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+
+  // This issue involves a race, so several requests in parallel to increase
+  // the chances of triggering it.
+  let urls = [];
+  for (let i = 0; i < 32; i++) {
+    urls.push(`${BASE_URL}/data/file_sample.html?r=${Math.random()}`);
+  }
+
+  await Promise.all(
+    urls.map(url => ExtensionTestUtils.fetch(FETCH_ORIGIN, url))
+  );
+  await Promise.all(urls.map(url => extension.awaitMessage(`done-${url}`)));
+
+  await extension.unload();
+});
+
+add_task(async function test_permissions() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      browser.test.assertEq(
+        undefined,
+        browser.webRequest.filterResponseData,
+        "filterResponseData is undefined without blocking permissions"
+      );
+    },
+
+    manifest: {
+      permissions: ["webRequest", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+  await extension.unload();
+});
+
+add_task(async function test_invalidId() {
+  let extension = ExtensionTestUtils.loadExtension({
+    async background() {
+      let filter = browser.webRequest.filterResponseData("34159628");
+
+      await new Promise(resolve => {
+        filter.onerror = resolve;
+      });
+
+      browser.test.assertEq(
+        "Invalid request ID",
+        filter.error,
+        "Got expected error"
+      );
+
+      browser.test.notifyPass("invalid-request-id");
+    },
+
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("invalid-request-id");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_set_cookie.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_set_cookie.js
new file mode 100644
index 0000000000..e40bc4f8b4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_set_cookie.js
@@ -0,0 +1,308 @@
+"use strict";
+
+const HOSTS = new Set(["example.com"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+server.registerDirectory("/data/", do_get_file("data"));
+
+server.registerPathHandler(
+  "/file_webrequestblocking_set_cookie.html",
+  (request, response) => {
+    response.setStatusLine(request.httpVersion, 200, "OK");
+    response.setHeader("Content-Type", "text/html", false);
+    response.setHeader("Set-Cookie", "reqcookie=reqvalue", false);
+    response.write("<!DOCTYPE html><html></html>");
+  }
+);
+
+add_task(async function test_modifying_cookies_from_onHeadersReceived() {
+  async function background() {
+    /**
+     * Check that all the cookies described by `prefixes` are in the cookie jar.
+     *
+     * @param {Array.string} prefixes
+     *   Zero or more prefixes, describing cookies that are expected to be set
+     *   in the current cookie jar.  Each prefix describes both a cookie
+     *   name and corresponding value.  For example, if the string "ext"
+     *   is passed as an argument, then this function expects to see
+     *   a cookie called "extcookie" and corresponding value of "extvalue".
+     */
+    async function checkCookies(prefixes) {
+      const numPrefixes = prefixes.length;
+      const currentCookies = await browser.cookies.getAll({});
+      browser.test.assertEq(
+        numPrefixes,
+        currentCookies.length,
+        `${numPrefixes} cookies were set`
+      );
+
+      for (let cookiePrefix of prefixes) {
+        let cookieName = `${cookiePrefix}cookie`;
+        let expectedCookieValue = `${cookiePrefix}value`;
+        let fetchedCookie = await browser.cookies.getAll({ name: cookieName });
+        browser.test.assertEq(
+          1,
+          fetchedCookie.length,
+          `Found 1 cookie with name "${cookieName}"`
+        );
+        browser.test.assertEq(
+          expectedCookieValue,
+          fetchedCookie[0] && fetchedCookie[0].value,
+          `Cookie "${cookieName}" has expected value of "${expectedCookieValue}"`
+        );
+      }
+    }
+
+    function awaitMessage(expectedMsg) {
+      return new Promise(resolve => {
+        browser.test.onMessage.addListener(function listener(msg) {
+          if (msg === expectedMsg) {
+            browser.test.onMessage.removeListener(listener);
+            resolve();
+          }
+        });
+      });
+    }
+
+    /**
+     * Opens the given test file as a content page.
+     *
+     * @param {string} filename
+     *   The name of a html file relative to the test server root.
+     *
+     * @returns {Promise}
+     */
+    function openContentPage(filename) {
+      let promise = awaitMessage("url-loaded");
+      browser.test.sendMessage(
+        "load-url",
+        `http://example.com/${filename}?nocache=${Math.random()}`
+      );
+      return promise;
+    }
+
+    /**
+     * Tests that expected cookies are in the cookie jar after opening a file.
+     *
+     * @param {string} filename
+     *   The name of a html file in the
+     *   "toolkit/components/extensions/test/mochitest" directory.
+     * @param {?Array.string} prefixes
+     *   Zero or more prefixes, describing cookies that are expected to be set
+     *   in the current cookie jar.  Each prefix describes both a cookie
+     *   name and corresponding value.  For example, if the string "ext"
+     *   is passed as an argument, then this function expects to see
+     *   a cookie called "extcookie" and corresponding value of "extvalue".
+     *   If undefined, then no checks are automatically performed, and the
+     *   caller should provide a callback to perform the checks.
+     * @param {?Function} callback
+     *   An optional async callback function that, if provided, will be called
+     *   with an object that contains windowId and tabId parameters.
+     *   Callers can use this callback to apply extra tests about the state of
+     *   the cookie jar, or to query the state of the opened page.
+     */
+    async function testCookiesWithFile(filename, prefixes, callback) {
+      await browser.browsingData.removeCookies({});
+      await openContentPage(filename);
+
+      if (prefixes !== undefined) {
+        await checkCookies(prefixes);
+      }
+
+      if (callback !== undefined) {
+        await callback();
+      }
+      let promise = awaitMessage("url-unloaded");
+      browser.test.sendMessage("unload-url");
+      await promise;
+    }
+
+    const filter = {
+      urls: ["<all_urls>"],
+      types: ["main_frame", "sub_frame"],
+    };
+
+    const headersReceivedInfoSpec = ["blocking", "responseHeaders"];
+
+    const onHeadersReceived = details => {
+      details.responseHeaders.push({
+        name: "Set-Cookie",
+        value: "extcookie=extvalue",
+      });
+
+      return {
+        responseHeaders: details.responseHeaders,
+      };
+    };
+    browser.webRequest.onHeadersReceived.addListener(
+      onHeadersReceived,
+      filter,
+      headersReceivedInfoSpec
+    );
+
+    // First, perform a request that should not set any cookies, and check
+    // that the cookie the extension sets is the only cookie in the
+    // cookie jar.
+    await testCookiesWithFile("data/file_sample.html", ["ext"]);
+
+    // Next, perform a request that will set on cookie (reqcookie=reqvalue)
+    // and check that two cookies wind up in the cookie jar (the request
+    // set cookie, and the extension set cookie).
+    await testCookiesWithFile("file_webrequestblocking_set_cookie.html", [
+      "ext",
+      "req",
+    ]);
+
+    // Third, register another onHeadersReceived handler that also
+    // sets a cookie (thirdcookie=thirdvalue), to make sure modifications from
+    // multiple onHeadersReceived listeners are merged correctly.
+    const thirdOnHeadersRecievedListener = details => {
+      details.responseHeaders.push({
+        name: "Set-Cookie",
+        value: "thirdcookie=thirdvalue",
+      });
+
+      browser.test.log(JSON.stringify(details.responseHeaders));
+
+      return {
+        responseHeaders: details.responseHeaders,
+      };
+    };
+    browser.webRequest.onHeadersReceived.addListener(
+      thirdOnHeadersRecievedListener,
+      filter,
+      headersReceivedInfoSpec
+    );
+    await testCookiesWithFile("file_webrequestblocking_set_cookie.html", [
+      "ext",
+      "req",
+      "third",
+    ]);
+    browser.webRequest.onHeadersReceived.removeListener(onHeadersReceived);
+    browser.webRequest.onHeadersReceived.removeListener(
+      thirdOnHeadersRecievedListener
+    );
+
+    // Fourth, test to make sure that extensions can remove cookies
+    // using onHeadersReceived too, by 1. making a request that
+    // sets a cookie (reqcookie=reqvalue), 2. having the extension remove
+    // that cookie by removing that header, and 3. adding a new cookie
+    // (extcookie=extvalue).
+    const fourthOnHeadersRecievedListener = details => {
+      // Remove the cookie set by the request (reqcookie=reqvalue).
+      const newHeaders = details.responseHeaders.filter(
+        cookie => cookie.name !== "set-cookie"
+      );
+
+      // And then add a new cookie in its place (extcookie=extvalue).
+      newHeaders.push({
+        name: "Set-Cookie",
+        value: "extcookie=extvalue",
+      });
+
+      return {
+        responseHeaders: newHeaders,
+      };
+    };
+    browser.webRequest.onHeadersReceived.addListener(
+      fourthOnHeadersRecievedListener,
+      filter,
+      headersReceivedInfoSpec
+    );
+    await testCookiesWithFile("file_webrequestblocking_set_cookie.html", [
+      "ext",
+    ]);
+    browser.webRequest.onHeadersReceived.removeListener(
+      fourthOnHeadersRecievedListener
+    );
+
+    // Fifth, check that extensions are able to overwrite headers set by
+    // pages. In this test, make a request that will set "reqcookie=reqvalue",
+    // and add a listener that sets "reqcookie=changedvalue".  Check
+    // to make sure that the cookie jar contains "reqcookie=changedvalue"
+    // and not "reqcookie=reqvalue".
+    const fifthOnHeadersRecievedListener = details => {
+      // Remove the cookie set by the request (reqcookie=reqvalue).
+      const newHeaders = details.responseHeaders.filter(
+        cookie => cookie.name !== "set-cookie"
+      );
+
+      // And then add a new cookie in its place (reqcookie=changedvalue).
+      newHeaders.push({
+        name: "Set-Cookie",
+        value: "reqcookie=changedvalue",
+      });
+
+      return {
+        responseHeaders: newHeaders,
+      };
+    };
+    browser.webRequest.onHeadersReceived.addListener(
+      fifthOnHeadersRecievedListener,
+      filter,
+      headersReceivedInfoSpec
+    );
+
+    await testCookiesWithFile(
+      "file_webrequestblocking_set_cookie.html",
+      undefined,
+      async () => {
+        const currentCookies = await browser.cookies.getAll({});
+        browser.test.assertEq(1, currentCookies.length, `1 cookie was set`);
+
+        const cookieName = "reqcookie";
+        const expectedCookieValue = "changedvalue";
+        const fetchedCookie = await browser.cookies.getAll({
+          name: cookieName,
+        });
+
+        browser.test.assertEq(
+          1,
+          fetchedCookie.length,
+          `Found 1 cookie with name "${cookieName}"`
+        );
+        browser.test.assertEq(
+          expectedCookieValue,
+          fetchedCookie[0] && fetchedCookie[0].value,
+          `Cookie "${cookieName}" has expected value of "${expectedCookieValue}"`
+        );
+      }
+    );
+    browser.webRequest.onHeadersReceived.removeListener(
+      fifthOnHeadersRecievedListener
+    );
+
+    browser.test.notifyPass("cookie modifying extension");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: [
+        "browsingData",
+        "cookies",
+        "webNavigation",
+        "webRequest",
+        "webRequestBlocking",
+        "<all_urls>",
+      ],
+    },
+    background,
+  });
+
+  let contentPage = null;
+  extension.onMessage("load-url", async url => {
+    ok(!contentPage, "Should have no content page to unload");
+    contentPage = await ExtensionTestUtils.loadContentPage(url);
+    extension.sendMessage("url-loaded");
+  });
+  extension.onMessage("unload-url", async () => {
+    await contentPage.close();
+    contentPage = null;
+    extension.sendMessage("url-unloaded");
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("cookie modifying extension");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup.js
new file mode 100644
index 0000000000..0528d97298
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup.js
@@ -0,0 +1,603 @@
+"use strict";
+
+// Delay loading until createAppInfo is called and setup.
+ChromeUtils.defineModuleGetter(
+  this,
+  "AddonManager",
+  "resource://gre/modules/AddonManager.jsm"
+);
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+
+// The app and platform version here should be >= of the version set in the extensions.webExtensionsMinPlatformVersion preference,
+// otherwise test_persistent_listener_after_staged_update will fail because no compatible updates will be found.
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "42",
+  "42"
+);
+
+let {
+  promiseRestartManager,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+let scopes = AddonManager.SCOPE_PROFILE | AddonManager.SCOPE_APPLICATION;
+Services.prefs.setIntPref("extensions.enabledScopes", scopes);
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  true
+);
+
+function trackEvents(wrapper) {
+  let events = new Map();
+  for (let event of ["background-page-event", "start-background-page"]) {
+    events.set(event, false);
+    wrapper.extension.once(event, () => events.set(event, true));
+  }
+  return events;
+}
+
+async function testPersistentRequestStartup(extension, events, expect) {
+  equal(
+    events.get("background-page-event"),
+    expect.background,
+    "Should have gotten a background page event"
+  );
+  equal(
+    events.get("start-background-page"),
+    false,
+    "Background page should not be started"
+  );
+
+  Services.obs.notifyObservers(null, "browser-delayed-startup-finished");
+  await ExtensionParent.browserPaintedPromise;
+
+  equal(
+    events.get("start-background-page"),
+    expect.delayedStart,
+    "Should have gotten start-background-page event"
+  );
+
+  if (expect.request) {
+    await extension.awaitMessage("got-request");
+    ok(true, "Background page loaded and received webRequest event");
+  }
+}
+
+// Test that a non-blocking listener during startup does not immediately
+// start the background page, but the event is queued until the background
+// page is started.
+add_task(async function test_1() {
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      permissions: ["webRequest", "http://example.com/"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.sendMessage("got-request");
+        },
+        { urls: ["http://example.com/data/file_sample.html"] }
+      );
+    },
+  });
+
+  await extension.startup();
+
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  let events = trackEvents(extension);
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+
+  await testPersistentRequestStartup(extension, events, {
+    background: true,
+    delayedStart: true,
+    request: true,
+  });
+
+  await extension.unload();
+
+  await promiseShutdownManager();
+});
+
+// Tests that filters are handled properly: if we have a blocking listener
+// with a filter, a request that does not match the filter does not get
+// suspended and does not start the background page.
+add_task(async function test_2() {
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      permissions: [
+        "webRequest",
+        "webRequestBlocking",
+        "http://test1.example.com/",
+      ],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.fail("Listener should not have been called");
+        },
+        { urls: ["http://test1.example.com/*"] },
+        ["blocking"]
+      );
+
+      browser.test.sendMessage("ready");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  let events = trackEvents(extension);
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+
+  await testPersistentRequestStartup(extension, events, {
+    background: false,
+    delayedStart: false,
+    request: false,
+  });
+
+  Services.obs.notifyObservers(null, "sessionstore-windows-restored");
+  await extension.awaitMessage("ready");
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
+
+// Tests that moving permission to optional retains permission and that the
+// persistent listeners are used as expected.
+add_task(async function test_persistent_listener_after_sideload_upgrade() {
+  let id = "permission-sideload-upgrade@test";
+  let extensionData = {
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: { gecko: { id } },
+      permissions: ["webRequest", "http://example.com/"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.sendMessage("got-request");
+        },
+        { urls: ["http://example.com/data/file_sample.html"] }
+      );
+    },
+  };
+  let xpi = AddonTestUtils.createTempWebExtensionFile(extensionData);
+
+  let extension = ExtensionTestUtils.expectExtension(id);
+  await AddonTestUtils.manuallyInstall(xpi);
+  await promiseStartupManager();
+  await extension.awaitStartup();
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+  await extension.awaitMessage("got-request");
+
+  await promiseShutdownManager();
+
+  // Prepare a sideload update for the extension.
+  extensionData.manifest.version = "2.0";
+  extensionData.manifest.permissions = ["http://example.com/"];
+  extensionData.manifest.optional_permissions = ["webRequest"];
+  xpi = AddonTestUtils.createTempWebExtensionFile(extensionData);
+  await AddonTestUtils.manuallyInstall(xpi);
+
+  ExtensionParent._resetStartupPromises();
+  await promiseStartupManager();
+  await extension.awaitStartup();
+  let events = trackEvents(extension);
+
+  // Verify webRequest permission.
+  let policy = WebExtensionPolicy.getByID(id);
+  ok(policy.hasPermission("webRequest"), "addon webRequest permission added");
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+
+  await testPersistentRequestStartup(extension, events, {
+    background: true,
+    delayedStart: true,
+    request: true,
+  });
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
+
+// Utility to install builtin addon
+async function installBuiltinExtension(extensionData) {
+  let xpi = await AddonTestUtils.createTempWebExtensionFile(extensionData);
+
+  // The built-in location requires a resource: URL that maps to a
+  // jar: or file: URL.  This would typically be something bundled
+  // into omni.ja but for testing we just use a temp file.
+  let base = Services.io.newURI(`jar:file:${xpi.path}!/`);
+  let resProto = Services.io
+    .getProtocolHandler("resource")
+    .QueryInterface(Ci.nsIResProtocolHandler);
+  resProto.setSubstitution("ext-test", base);
+  return AddonManager.installBuiltinAddon("resource://ext-test/");
+}
+
+function promisePostponeInstall(install) {
+  return new Promise((resolve, reject) => {
+    let listener = {
+      onInstallFailed: () => {
+        install.removeListener(listener);
+        reject(new Error("extension installation should not have failed"));
+      },
+      onInstallEnded: () => {
+        install.removeListener(listener);
+        reject(
+          new Error(
+            `extension installation should not have ended for ${install.addon.id}`
+          )
+        );
+      },
+      onInstallPostponed: () => {
+        install.removeListener(listener);
+        resolve();
+      },
+    };
+
+    install.addListener(listener);
+    install.install();
+  });
+}
+
+// Tests that moving permission to optional retains permission and that the
+// persistent listeners are used as expected.
+add_task(
+  async function test_persistent_listener_after_builtin_location_upgrade() {
+    let id = "permission-builtin-upgrade@test";
+    let extensionData = {
+      useAddonManager: "permanent",
+      manifest: {
+        version: "1.0",
+        applications: { gecko: { id } },
+        permissions: ["webRequest", "http://example.com/"],
+      },
+
+      async background() {
+        browser.runtime.onUpdateAvailable.addListener(() => {
+          browser.test.sendMessage("postponed");
+        });
+
+        browser.webRequest.onBeforeRequest.addListener(
+          details => {
+            browser.test.sendMessage("got-request");
+          },
+          { urls: ["http://example.com/data/file_sample.html"] }
+        );
+      },
+    };
+    await promiseStartupManager();
+    // If we use an extension wrapper via ExtensionTestUtils.expectExtension
+    // it will continue to handle messages even after the update, resulting
+    // in errors when it receives additional messages without any awaitMessage.
+    let promiseExtension = AddonTestUtils.promiseWebExtensionStartup(id);
+    await installBuiltinExtension(extensionData);
+    let extv1 = await promiseExtension;
+
+    // Prepare an update for the extension.
+    extensionData.manifest.version = "2.0";
+    let xpi = AddonTestUtils.createTempWebExtensionFile(extensionData);
+    let install = await AddonManager.getInstallForFile(xpi);
+
+    // Install the update and wait for the onUpdateAvailable event to complete.
+    let promiseUpdate = new Promise(resolve =>
+      extv1.once("test-message", (kind, msg) => {
+        if (msg == "postponed") {
+          resolve();
+        }
+      })
+    );
+    await Promise.all([promisePostponeInstall(install), promiseUpdate]);
+    await promiseShutdownManager();
+
+    // restarting allows upgrade to proceed
+    ExtensionParent._resetStartupPromises();
+    let extension = ExtensionTestUtils.expectExtension(id);
+    await promiseStartupManager();
+    await extension.awaitStartup();
+    let events = trackEvents(extension);
+
+    await ExtensionTestUtils.fetch(
+      "http://example.com/",
+      "http://example.com/data/file_sample.html"
+    );
+
+    await testPersistentRequestStartup(extension, events, {
+      background: true,
+      delayedStart: true,
+      request: true,
+    });
+
+    await extension.unload();
+
+    // remove the builtin addon which will have restarted now.
+    let addon = await AddonManager.getAddonByID(id);
+    await addon.uninstall();
+
+    await promiseShutdownManager();
+  }
+);
+
+// Tests that moving permission to optional during a staged upgrade retains permission
+// and that the persistent listeners are used as expected.
+add_task(async function test_persistent_listener_after_staged_upgrade() {
+  AddonManager.checkUpdateSecurity = false;
+  let id = "persistent-staged-upgrade@test";
+
+  // register an update file.
+  AddonTestUtils.registerJSON(server, "/test_update.json", {
+    addons: {
+      "persistent-staged-upgrade@test": {
+        updates: [
+          {
+            version: "2.0",
+            update_link:
+              "http://example.com/addons/test_settings_staged_restart.xpi",
+          },
+        ],
+      },
+    },
+  });
+
+  let extensionData = {
+    useAddonManager: "permanent",
+    manifest: {
+      version: "2.0",
+      applications: {
+        gecko: { id, update_url: `http://example.com/test_update.json` },
+      },
+      permissions: ["http://example.com/"],
+      optional_permissions: ["webRequest"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.sendMessage("got-request");
+        },
+        { urls: ["http://example.com/data/file_sample.html"] }
+      );
+      // Force a staged updated.
+      browser.runtime.onUpdateAvailable.addListener(async details => {
+        if (details && details.version) {
+          // This should be the version of the pending update.
+          browser.test.assertEq("2.0", details.version, "correct version");
+          browser.test.sendMessage("delay");
+        }
+      });
+    },
+  };
+
+  // Prepare the update first.
+  server.registerFile(
+    `/addons/test_settings_staged_restart.xpi`,
+    AddonTestUtils.createTempWebExtensionFile(extensionData)
+  );
+
+  // Prepare the extension that will be updated.
+  extensionData.manifest.version = "1.0";
+  extensionData.manifest.permissions = ["webRequest", "http://example.com/"];
+  delete extensionData.manifest.optional_permissions;
+
+  await promiseStartupManager();
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+  await extension.awaitMessage("got-request");
+  ok(true, "Initial version received webRequest event");
+
+  let addon = await AddonManager.getAddonByID(id);
+  Assert.equal(addon.version, "1.0", "1.0 is loaded");
+
+  let update = await AddonTestUtils.promiseFindAddonUpdates(addon);
+  let install = update.updateAvailable;
+  Assert.ok(install, `install is available ${update.error}`);
+
+  await AddonTestUtils.promiseCompleteAllInstalls([install]);
+
+  Assert.equal(
+    install.state,
+    AddonManager.STATE_POSTPONED,
+    "update is staged for install"
+  );
+  await extension.awaitMessage("delay");
+
+  await promiseShutdownManager();
+
+  // restarting allows upgrade to proceed
+  ExtensionParent._resetStartupPromises();
+  await promiseStartupManager();
+  await extension.awaitStartup();
+  let events = trackEvents(extension);
+
+  // Verify webRequest permission.
+  let policy = WebExtensionPolicy.getByID(id);
+  ok(policy.hasPermission("webRequest"), "addon webRequest permission added");
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+
+  await testPersistentRequestStartup(extension, events, {
+    background: true,
+    delayedStart: true,
+    request: true,
+  });
+
+  await extension.unload();
+  await promiseShutdownManager();
+  AddonManager.checkUpdateSecurity = true;
+});
+
+// Tests that removing the permission releases the persistent listener.
+add_task(async function test_persistent_listener_after_permission_removal() {
+  let id = "persistent-staged-remove@test";
+
+  // register an update file.
+  AddonTestUtils.registerJSON(server, "/test_remove.json", {
+    addons: {
+      "persistent-staged-remove@test": {
+        updates: [
+          {
+            version: "2.0",
+            update_link:
+              "http://example.com/addons/test_settings_staged_remove.xpi",
+          },
+        ],
+      },
+    },
+  });
+
+  let extensionData = {
+    useAddonManager: "permanent",
+    manifest: {
+      version: "2.0",
+      applications: {
+        gecko: { id, update_url: `http://example.com/test_remove.json` },
+      },
+      permissions: ["tabs", "http://example.com/"],
+    },
+
+    background() {
+      browser.test.sendMessage("loaded");
+    },
+  };
+
+  // Prepare the update first.
+  server.registerFile(
+    `/addons/test_settings_staged_remove.xpi`,
+    AddonTestUtils.createTempWebExtensionFile(extensionData)
+  );
+
+  await promiseStartupManager();
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      version: "1.0",
+      applications: {
+        gecko: { id, update_url: `http://example.com/test_remove.json` },
+      },
+      permissions: ["webRequest", "http://example.com/"],
+    },
+
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.sendMessage("got-request");
+        },
+        { urls: ["http://example.com/data/file_sample.html"] }
+      );
+      // Force a staged updated.
+      browser.runtime.onUpdateAvailable.addListener(async details => {
+        if (details && details.version) {
+          // This should be the version of the pending update.
+          browser.test.assertEq("2.0", details.version, "correct version");
+          browser.test.sendMessage("delay");
+        }
+      });
+    },
+  });
+
+  await extension.startup();
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+  await extension.awaitMessage("got-request");
+  ok(true, "Initial version received webRequest event");
+
+  let addon = await AddonManager.getAddonByID(id);
+  Assert.equal(addon.version, "1.0", "1.0 is loaded");
+
+  let update = await AddonTestUtils.promiseFindAddonUpdates(addon);
+  let install = update.updateAvailable;
+  Assert.ok(install, `install is available ${update.error}`);
+
+  await AddonTestUtils.promiseCompleteAllInstalls([install]);
+
+  Assert.equal(
+    install.state,
+    AddonManager.STATE_POSTPONED,
+    "update is staged for install"
+  );
+  await extension.awaitMessage("delay");
+
+  await promiseShutdownManager();
+
+  // restarting allows upgrade to proceed
+  await promiseStartupManager();
+  let events = trackEvents(extension);
+  await extension.awaitStartup();
+
+  // Verify webRequest permission.
+  let policy = WebExtensionPolicy.getByID(id);
+  ok(
+    !policy.hasPermission("webRequest"),
+    "addon webRequest permission removed"
+  );
+
+  await ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+
+  await testPersistentRequestStartup(extension, events, {
+    background: false,
+    delayedStart: false,
+    request: false,
+  });
+
+  Services.obs.notifyObservers(null, "sessionstore-windows-restored");
+
+  await extension.awaitMessage("loaded");
+  ok(true, "Background page loaded");
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup_StreamFilter.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup_StreamFilter.js
new file mode 100644
index 0000000000..c8c18fcf19
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_startup_StreamFilter.js
@@ -0,0 +1,84 @@
+"use strict";
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "43"
+);
+
+let {
+  promiseRestartManager,
+  promiseShutdownManager,
+  promiseStartupManager,
+} = AddonTestUtils;
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+Services.prefs.setBoolPref(
+  "extensions.webextensions.background-delayed-startup",
+  true
+);
+
+// Test that a blocking listener that uses filterResponseData() works
+// properly (i.e., that the delayed call to registerTraceableChannel
+// works properly).
+add_task(async function test_StreamFilter_at_restart() {
+  const DATA = `<!DOCTYPE html>
+<html>
+<body>
+  <h1>This is a modified page</h1>
+</body>
+</html>`;
+
+  function background(data) {
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        let filter = browser.webRequest.filterResponseData(details.requestId);
+        filter.onstop = () => {
+          let encoded = new TextEncoder("utf-8").encode(data);
+          filter.write(encoded);
+          filter.close();
+        };
+      },
+      { urls: ["http://example.com/data/file_sample.html"] },
+      ["blocking"]
+    );
+  }
+
+  await promiseStartupManager();
+
+  let extension = ExtensionTestUtils.loadExtension({
+    useAddonManager: "permanent",
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+
+    background: `(${background})(${uneval(DATA)})`,
+  });
+
+  await extension.startup();
+
+  await promiseRestartManager();
+  await extension.awaitStartup();
+
+  let dataPromise = ExtensionTestUtils.fetch(
+    "http://example.com/",
+    "http://example.com/data/file_sample.html"
+  );
+
+  Services.obs.notifyObservers(null, "browser-delayed-startup-finished");
+  let data = await dataPromise;
+
+  equal(
+    data,
+    DATA,
+    "Stream filter was properly installed for a load during startup"
+  );
+
+  await extension.unload();
+  await promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_style_cache.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_style_cache.js
new file mode 100644
index 0000000000..296bee3685
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_style_cache.js
@@ -0,0 +1,49 @@
+"use strict";
+
+const BASE = "http://example.com/data/";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_stylesheet_cache() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background() {
+      const SHEET_URI = "http://example.com/data/file_stylesheet_cache.css";
+      let firstFound = false;
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.assertEq(
+            details.url,
+            firstFound ? SHEET_URI + "?2" : SHEET_URI
+          );
+          firstFound = true;
+          browser.test.sendMessage("stylesheet found");
+        },
+        { urls: ["<all_urls>"], types: ["stylesheet"] },
+        ["blocking"]
+      );
+    },
+  });
+
+  await extension.startup();
+
+  let cp = await ExtensionTestUtils.loadContentPage(
+    BASE + "file_stylesheet_cache.html"
+  );
+
+  await extension.awaitMessage("stylesheet found");
+
+  // Need to use the same ContentPage so that the remote process the page ends
+  // up in is the same.
+  await cp.loadURL(BASE + "file_stylesheet_cache_2.html");
+
+  await extension.awaitMessage("stylesheet found");
+
+  await cp.close();
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_suspend.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_suspend.js
new file mode 100644
index 0000000000..48505c9a1b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_suspend.js
@@ -0,0 +1,294 @@
+"use strict";
+
+const HOSTS = new Set(["example.com"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+const BASE_URL = "http://example.com";
+const FETCH_ORIGIN = "http://example.com/dummy";
+
+server.registerPathHandler("/return_headers.sjs", (request, response) => {
+  response.setHeader("Content-Type", "text/plain", false);
+
+  let headers = {};
+  for (let { data: header } of request.headers) {
+    headers[header.toLowerCase()] = request.getHeader(header);
+  }
+
+  response.write(JSON.stringify(headers));
+});
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+add_task(async function test_suspend() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", `${BASE_URL}/`],
+    },
+
+    background() {
+      browser.webRequest.onBeforeSendHeaders.addListener(
+        details => {
+          // Make sure that returning undefined or a promise that resolves to
+          // undefined does not break later handlers.
+        },
+        { urls: ["<all_urls>"] },
+        ["blocking", "requestHeaders"]
+      );
+
+      browser.webRequest.onBeforeSendHeaders.addListener(
+        details => {
+          return Promise.resolve();
+        },
+        { urls: ["<all_urls>"] },
+        ["blocking", "requestHeaders"]
+      );
+
+      browser.webRequest.onBeforeSendHeaders.addListener(
+        details => {
+          let requestHeaders = details.requestHeaders.concat({
+            name: "Foo",
+            value: "Bar",
+          });
+
+          return new Promise(resolve => {
+            // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+            setTimeout(resolve, 500);
+          }).then(() => {
+            return { requestHeaders };
+          });
+        },
+        { urls: ["<all_urls>"] },
+        ["blocking", "requestHeaders"]
+      );
+    },
+  });
+
+  await extension.startup();
+
+  let headers = JSON.parse(
+    await ExtensionTestUtils.fetch(
+      FETCH_ORIGIN,
+      `${BASE_URL}/return_headers.sjs`
+    )
+  );
+
+  equal(
+    headers.foo,
+    "Bar",
+    "Request header was correctly set on suspended request"
+  );
+
+  await extension.unload();
+});
+
+// Test that requests that were canceled while suspended for a blocking
+// listener are correctly resumed.
+add_task(async function test_error_resume() {
+  let observer = channel => {
+    if (
+      channel instanceof Ci.nsIHttpChannel &&
+      channel.URI.spec === "http://example.com/dummy"
+    ) {
+      Services.obs.removeObserver(observer, "http-on-before-connect");
+
+      // Wait until the next tick to make sure this runs after WebRequest observers.
+      Promise.resolve().then(() => {
+        channel.cancel(Cr.NS_BINDING_ABORTED);
+      });
+    }
+  };
+
+  Services.obs.addObserver(observer, "http-on-before-connect");
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", `${BASE_URL}/`],
+    },
+
+    background() {
+      browser.webRequest.onBeforeSendHeaders.addListener(
+        details => {
+          browser.test.log(`onBeforeSendHeaders({url: ${details.url}})`);
+
+          if (details.url === "http://example.com/dummy") {
+            browser.test.sendMessage("got-before-send-headers");
+          }
+        },
+        { urls: ["<all_urls>"] },
+        ["blocking"]
+      );
+
+      browser.webRequest.onErrorOccurred.addListener(
+        details => {
+          browser.test.log(`onErrorOccurred({url: ${details.url}})`);
+
+          if (details.url === "http://example.com/dummy") {
+            browser.test.sendMessage("got-error-occurred");
+          }
+        },
+        { urls: ["<all_urls>"] }
+      );
+    },
+  });
+
+  await extension.startup();
+
+  try {
+    await ExtensionTestUtils.fetch(FETCH_ORIGIN, `${BASE_URL}/dummy`);
+    ok(false, "Fetch should have failed.");
+  } catch (e) {
+    ok(true, "Got expected error.");
+  }
+
+  await extension.awaitMessage("got-before-send-headers");
+  await extension.awaitMessage("got-error-occurred");
+
+  // Wait for the next tick so the onErrorRecurred response can be
+  // processed before shutting down the extension.
+  await new Promise(resolve => executeSoon(resolve));
+
+  await extension.unload();
+});
+
+// Test that response header modifications take effect before onStartRequest fires.
+add_task(async function test_set_responseHeaders() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "http://example.com/"],
+    },
+
+    background() {
+      browser.webRequest.onHeadersReceived.addListener(
+        details => {
+          browser.test.log(`onHeadersReceived({url: ${details.url}})`);
+
+          details.responseHeaders.push({ name: "foo", value: "bar" });
+
+          return { responseHeaders: details.responseHeaders };
+        },
+        { urls: ["http://example.com/?modify_headers"] },
+        ["blocking", "responseHeaders"]
+      );
+    },
+  });
+
+  await extension.startup();
+
+  await new Promise(resolve => setTimeout(resolve, 0));
+
+  let resolveHeaderPromise;
+  let headerPromise = new Promise(resolve => {
+    resolveHeaderPromise = resolve;
+  });
+  {
+    const { Services } = ChromeUtils.import(
+      "resource://gre/modules/Services.jsm"
+    );
+
+    let ssm = Services.scriptSecurityManager;
+
+    let channel = NetUtil.newChannel({
+      uri: "http://example.com/?modify_headers",
+      loadingPrincipal: ssm.createContentPrincipalFromOrigin(
+        "http://example.com"
+      ),
+      contentPolicyType: Ci.nsIContentPolicy.TYPE_XMLHTTPREQUEST,
+      securityFlags: Ci.nsILoadInfo.SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+    });
+
+    channel.asyncOpen({
+      QueryInterface: ChromeUtils.generateQI(["nsIStreamListener"]),
+
+      onStartRequest(request) {
+        request.QueryInterface(Ci.nsIHttpChannel);
+
+        try {
+          resolveHeaderPromise(request.getResponseHeader("foo"));
+        } catch (e) {
+          resolveHeaderPromise(null);
+        }
+        request.cancel(Cr.NS_BINDING_ABORTED);
+      },
+
+      onStopRequest() {},
+
+      onDataAvailable() {
+        throw new Components.Exception("", Cr.NS_ERROR_FAILURE);
+      },
+    });
+  }
+
+  let headerValue = await headerPromise;
+  equal(headerValue, "bar", "Expected Foo header value");
+
+  await extension.unload();
+});
+
+// Test that exceptions raised from a blocking webRequest listener that returns
+// a promise are logged as expected.
+add_task(async function test_logged_error_on_promise_result() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", `${BASE_URL}/`],
+    },
+
+    background() {
+      async function onBeforeRequest() {
+        throw new Error("Expected webRequest exception from a promise result");
+      }
+
+      let exceptionRaised = false;
+
+      browser.webRequest.onBeforeRequest.addListener(
+        () => {
+          if (exceptionRaised) {
+            return;
+          }
+
+          // We only need to raise the exception once.
+          exceptionRaised = true;
+          return onBeforeRequest();
+        },
+        {
+          urls: ["http://example.com/*"],
+          types: ["main_frame"],
+        },
+        ["blocking"]
+      );
+
+      browser.webRequest.onBeforeRequest.addListener(
+        () => {
+          browser.test.sendMessage("web-request-event-received");
+        },
+        {
+          urls: ["http://example.com/*"],
+          types: ["main_frame"],
+        },
+        ["blocking"]
+      );
+    },
+  });
+
+  let { messages } = await promiseConsoleOutput(async () => {
+    await extension.startup();
+
+    let contentPage = await ExtensionTestUtils.loadContentPage(
+      `${BASE_URL}/dummy`
+    );
+    await extension.awaitMessage("web-request-event-received");
+    await contentPage.close();
+  });
+
+  ok(
+    messages.some(msg =>
+      /Expected webRequest exception from a promise result/.test(msg.message)
+    ),
+    "Got expected console message"
+  );
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_urlclassification.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_urlclassification.js
new file mode 100644
index 0000000000..9c2296c7da
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_urlclassification.js
@@ -0,0 +1,33 @@
+"use strict";
+
+const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+
+/**
+ * If this test fails, likely nsIClassifiedChannel has added or changed a
+ * CLASSIFIED_* flag.  Those changes must be in sync with
+ * ChannelWrapper.webidl/cpp and the web_request.json schema file.
+ */
+add_task(async function test_webrequest_url_classification_enum() {
+  // use normalizeManifest to get the schema loaded.
+  await ExtensionTestUtils.normalizeManifest({ permissions: ["webRequest"] });
+
+  let ns = Schemas.getNamespace("webRequest");
+  let schema_enum = ns.get("UrlClassificationFlags").enumeration;
+  ok(
+    !!schema_enum.length,
+    `UrlClassificationFlags: ${JSON.stringify(schema_enum)}`
+  );
+
+  let prefix = /^(?:CLASSIFIED_)/;
+  let entries = 0;
+  for (let c of Object.keys(Ci.nsIClassifiedChannel).filter(name =>
+    prefix.test(name)
+  )) {
+    let entry = c.replace(prefix, "").toLowerCase();
+    if (!entry.startsWith("socialtracking")) {
+      ok(schema_enum.includes(entry), `schema ${entry} is in IDL`);
+      entries++;
+    }
+  }
+  equal(schema_enum.length, entries, "same number of entries");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_userContextId.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_userContextId.js
new file mode 100644
index 0000000000..9710aa5990
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_userContextId.js
@@ -0,0 +1,41 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_userContextId_webrequest() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        async details => {
+          browser.test.assertEq(
+            details.cookieStoreId,
+            "firefox-container-2",
+            "cookieStoreId is set"
+          );
+          browser.test.notifyPass("webRequest");
+        },
+        { urls: ["<all_urls>"] },
+        ["blocking"]
+      );
+    },
+  });
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy",
+    { userContextId: 2 }
+  );
+  await extension.awaitFinish("webRequest");
+
+  await extension.unload();
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource.js
new file mode 100644
index 0000000000..35b713e59b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource.js
@@ -0,0 +1,95 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+add_task(async function test_webRequest_viewsource() {
+  function background(serverPort) {
+    browser.proxy.onRequest.addListener(
+      details => {
+        if (details.url === `http://example.com:${serverPort}/dummy`) {
+          browser.test.assertTrue(
+            true,
+            "viewsource protocol worked in proxy request"
+          );
+          browser.test.sendMessage("proxied");
+        }
+      },
+      { urls: ["<all_urls>"] }
+    );
+
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.assertEq(
+          `http://example.com:${serverPort}/redirect`,
+          details.url,
+          "viewsource protocol worked in webRequest"
+        );
+        browser.test.sendMessage("viewed");
+        return { redirectUrl: `http://example.com:${serverPort}/dummy` };
+      },
+      { urls: ["http://example.com/redirect"] },
+      ["blocking"]
+    );
+
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.assertEq(
+          `http://example.com:${serverPort}/dummy`,
+          details.url,
+          "viewsource protocol worked in webRequest"
+        );
+        browser.test.sendMessage("redirected");
+        return { cancel: true };
+      },
+      { urls: ["http://example.com/dummy"] },
+      ["blocking"]
+    );
+
+    browser.webRequest.onCompleted.addListener(
+      details => {
+        // If cancel fails we get onCompleted.
+        browser.test.fail("onCompleted received");
+      },
+      { urls: ["http://example.com/dummy"] }
+    );
+
+    browser.webRequest.onErrorOccurred.addListener(
+      details => {
+        browser.test.assertEq(
+          details.error,
+          "NS_ERROR_ABORT",
+          "request cancelled"
+        );
+        browser.test.sendMessage("cancelled");
+      },
+      { urls: ["http://example.com/dummy"] }
+    );
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["proxy", "webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background: `(${background})(${server.identity.primaryPort})`,
+  });
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `view-source:http://example.com:${server.identity.primaryPort}/redirect`
+  );
+
+  await Promise.all([
+    extension.awaitMessage("proxied"),
+    extension.awaitMessage("viewed"),
+    extension.awaitMessage("redirected"),
+    extension.awaitMessage("cancelled"),
+  ]);
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource_StreamFilter.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource_StreamFilter.js
new file mode 100644
index 0000000000..ccb46eb4db
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_viewsource_StreamFilter.js
@@ -0,0 +1,144 @@
+"use strict";
+
+const server = createHttpServer();
+const BASE_URL = `http://127.0.0.1:${server.identity.primaryPort}`;
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+server.registerPathHandler("/redir", (request, response) => {
+  response.setStatusLine(request.httpVersion, 303, "See Other");
+  response.setHeader("Location", `${BASE_URL}/dummy`);
+});
+
+async function testViewSource(viewSourceUrl) {
+  function background(BASE_URL) {
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.assertEq(`${BASE_URL}/dummy`, details.url, "expected URL");
+        browser.test.assertEq("main_frame", details.type, "details.type");
+
+        let filter = browser.webRequest.filterResponseData(details.requestId);
+        filter.onstart = () => {
+          filter.write(new TextEncoder().encode("PREFIX_"));
+        };
+        filter.ondata = event => {
+          filter.write(event.data);
+        };
+        filter.onstop = () => {
+          filter.write(new TextEncoder().encode("_SUFFIX"));
+          filter.disconnect();
+          browser.test.notifyPass("filter_end");
+        };
+        filter.onerror = () => {
+          browser.test.fail(`Unexpected error: ${filter.error}`);
+          browser.test.notifyFail("filter_end");
+        };
+      },
+      { urls: ["*://*/dummy"] },
+      ["blocking"]
+    );
+    browser.webRequest.onBeforeRequest.addListener(
+      details => {
+        browser.test.assertEq(`${BASE_URL}/redir`, details.url, "Got redirect");
+
+        let filter = browser.webRequest.filterResponseData(details.requestId);
+        filter.onstop = () => {
+          filter.disconnect();
+          browser.test.fail("Unexpected onstop for redirect");
+          browser.test.sendMessage("redirect_done");
+        };
+        filter.onerror = () => {
+          browser.test.assertEq(
+            // TODO bug 1683862: must be "Channel redirected", but it is not
+            // because document requests are handled differently compared to
+            // other requests, see the comment at the top of
+            // test_ext_webRequest_redirect_StreamFilter.js.
+            "Invalid request ID",
+            filter.error,
+            "Expected error in filter.onerror"
+          );
+          browser.test.sendMessage("redirect_done");
+        };
+      },
+      { urls: ["*://*/redir"] },
+      ["blocking"]
+    );
+  }
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "*://*/*"],
+    },
+    background: `(${background})(${JSON.stringify(BASE_URL)})`,
+  });
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(viewSourceUrl);
+  if (viewSourceUrl.includes("/redir")) {
+    info("Awaiting observed completion of redirection request");
+    await extension.awaitMessage("redirect_done");
+  }
+  info("Awaiting completion of StreamFilter on request");
+  await extension.awaitFinish("filter_end");
+  let contentText = await contentPage.spawn(null, () => {
+    return this.content.document.body.textContent;
+  });
+  equal(contentText, "PREFIX_ok_SUFFIX", "view-source response body");
+  await contentPage.close();
+  await extension.unload();
+}
+
+add_task(async function test_StreamFilter_viewsource() {
+  await testViewSource(`view-source:${BASE_URL}/dummy`);
+});
+
+add_task(async function test_StreamFilter_viewsource_redirect_target() {
+  await testViewSource(`view-source:${BASE_URL}/redir`);
+});
+
+// Sanity check: nothing bad happens if the underlying response is aborted.
+add_task(async function test_StreamFilter_viewsource_cancel() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "*://*/*"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          let filter = browser.webRequest.filterResponseData(details.requestId);
+          filter.onstart = () => {
+            filter.disconnect();
+            browser.test.fail("Unexpected filter.onstart");
+            browser.test.notifyFail("filter_end");
+          };
+          filter.onerror = () => {
+            browser.test.assertEq("Invalid request ID", filter.error, "Error?");
+            browser.test.notifyPass("filter_end");
+          };
+        },
+        { urls: ["*://*/dummy"] },
+        ["blocking"]
+      );
+      browser.webRequest.onHeadersReceived.addListener(
+        () => {
+          browser.test.log("Intentionally canceling view-source request");
+          return { cancel: true };
+        },
+        { urls: ["*://*/dummy"] },
+        ["blocking"]
+      );
+    },
+  });
+  await extension.startup();
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    `${BASE_URL}/dummy`
+  );
+  await extension.awaitFinish("filter_end");
+  let contentText = await contentPage.spawn(null, () => {
+    return this.content.document.body.textContent;
+  });
+  equal(contentText, "", "view-source request should have been canceled");
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_webSocket.js b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_webSocket.js
new file mode 100644
index 0000000000..7e34d2b0b3
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_webRequest_webSocket.js
@@ -0,0 +1,55 @@
+"use strict";
+
+const HOSTS = new Set(["example.com"]);
+
+const server = createHttpServer({ hosts: HOSTS });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.write("ok");
+});
+
+add_task(async function test_webSocket() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+    },
+    background() {
+      browser.webRequest.onBeforeRequest.addListener(
+        details => {
+          browser.test.assertEq(
+            "ws:",
+            new URL(details.url).protocol,
+            "ws protocol worked"
+          );
+          browser.test.notifyPass("websocket");
+        },
+        { urls: ["ws://example.com/*"] },
+        ["blocking"]
+      );
+
+      browser.test.onMessage.addListener(msg => {
+        let ws = new WebSocket("ws://example.com/dummy");
+        ws.onopen = e => {
+          ws.send("data");
+        };
+        ws.onclose = e => {};
+        ws.onerror = e => {};
+        ws.onmessage = e => {
+          ws.close();
+        };
+      });
+      browser.test.sendMessage("ready");
+    },
+  });
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  extension.sendMessage("go");
+  await extension.awaitFinish("websocket");
+
+  // Wait until the next tick so that listener responses are processed
+  // before we unload.
+  await new Promise(executeSoon);
+
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_web_accessible_resources.js b/toolkit/components/extensions/test/xpcshell/test_ext_web_accessible_resources.js
new file mode 100644
index 0000000000..a1a387b5a4
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_web_accessible_resources.js
@@ -0,0 +1,150 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com", "example.org"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+let image = atob(
+  "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAA" +
+    "ACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII="
+);
+const IMAGE_ARRAYBUFFER = Uint8Array.from(image, byte => byte.charCodeAt(0))
+  .buffer;
+
+async function testImageLoading(src, expectedAction) {
+  let imageLoadingPromise = new Promise((resolve, reject) => {
+    let cleanupListeners;
+    let testImage = document.createElement("img");
+    // Set the src via wrappedJSObject so the load is triggered with the
+    // content page's principal rather than ours.
+    testImage.wrappedJSObject.setAttribute("src", src);
+
+    let loadListener = () => {
+      cleanupListeners();
+      resolve(expectedAction === "loaded");
+    };
+
+    let errorListener = () => {
+      cleanupListeners();
+      resolve(expectedAction === "blocked");
+    };
+
+    cleanupListeners = () => {
+      testImage.removeEventListener("load", loadListener);
+      testImage.removeEventListener("error", errorListener);
+    };
+
+    testImage.addEventListener("load", loadListener);
+    testImage.addEventListener("error", errorListener);
+
+    document.body.appendChild(testImage);
+  });
+
+  let success = await imageLoadingPromise;
+  browser.runtime.sendMessage({
+    name: "image-loading",
+    expectedAction,
+    success,
+  });
+}
+
+add_task(async function test_web_accessible_resources_csp() {
+  function background() {
+    browser.runtime.onMessage.addListener((msg, sender) => {
+      if (msg.name === "image-loading") {
+        browser.test.assertTrue(msg.success, `Image was ${msg.expectedAction}`);
+        browser.test.sendMessage(`image-${msg.expectedAction}`);
+      } else {
+        browser.test.sendMessage(msg);
+      }
+    });
+
+    browser.test.sendMessage("background-ready");
+  }
+
+  function content() {
+    window.addEventListener("message", function rcv(event) {
+      browser.runtime.sendMessage("script-ran");
+      window.removeEventListener("message", rcv);
+    });
+
+    testImageLoading(browser.extension.getURL("image.png"), "loaded");
+
+    let testScriptElement = document.createElement("script");
+    // Set the src via wrappedJSObject so the load is triggered with the
+    // content page's principal rather than ours.
+    testScriptElement.wrappedJSObject.setAttribute(
+      "src",
+      browser.extension.getURL("test_script.js")
+    );
+    document.head.appendChild(testScriptElement);
+    browser.runtime.sendMessage("script-loaded");
+  }
+
+  function testScript() {
+    window.postMessage("test-script-loaded", "*");
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/*/file_csp.html"],
+          run_at: "document_end",
+          js: ["content_script_helper.js", "content_script.js"],
+        },
+      ],
+      web_accessible_resources: ["image.png", "test_script.js"],
+    },
+    background,
+    files: {
+      "content_script_helper.js": `${testImageLoading}`,
+      "content_script.js": content,
+      "test_script.js": testScript,
+      "image.png": IMAGE_ARRAYBUFFER,
+    },
+  });
+
+  await Promise.all([
+    extension.startup(),
+    extension.awaitMessage("background-ready"),
+  ]);
+
+  let page = await ExtensionTestUtils.loadContentPage(
+    `http://example.com/data/file_sample.html`
+  );
+  await page.spawn(null, () => {
+    let { Services } = ChromeUtils.import(
+      "resource://gre/modules/Services.jsm"
+    );
+    this.obs = {
+      events: [],
+      observe(subject, topic, data) {
+        this.events.push(subject.QueryInterface(Ci.nsIURI).spec);
+      },
+      done() {
+        Services.obs.removeObserver(this, "csp-on-violate-policy");
+        return this.events;
+      },
+    };
+    Services.obs.addObserver(this.obs, "csp-on-violate-policy");
+    content.location.href = "http://example.com/data/file_csp.html";
+  });
+
+  await Promise.all([
+    extension.awaitMessage("image-loaded"),
+    extension.awaitMessage("script-loaded"),
+    extension.awaitMessage("script-ran"),
+  ]);
+
+  let events = await page.spawn(null, () => this.obs.done());
+  equal(events.length, 2, "Two items were rejected by CSP");
+  for (let url of events) {
+    ok(
+      url.includes("file_image_bad.png") || url.includes("file_script_bad.js"),
+      `Expected file: ${url} rejected by CSP`
+    );
+  }
+
+  await page.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_xhr_capabilities.js b/toolkit/components/extensions/test/xpcshell/test_ext_xhr_capabilities.js
new file mode 100644
index 0000000000..640e5be0de
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_xhr_capabilities.js
@@ -0,0 +1,72 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function test_xhr_capabilities() {
+  let extension = ExtensionTestUtils.loadExtension({
+    background() {
+      let xhr = new XMLHttpRequest();
+      xhr.open("GET", browser.extension.getURL("bad.xml"));
+
+      browser.test.sendMessage("result", {
+        name: "Background script XHRs should not be privileged",
+        result: xhr.channel === undefined,
+      });
+
+      xhr.onload = () => {
+        browser.test.sendMessage("result", {
+          name: "Background script XHRs should not yield <parsererrors>",
+          result: xhr.responseXML === null,
+        });
+      };
+      xhr.send();
+    },
+
+    manifest: {
+      content_scripts: [
+        {
+          matches: ["http://example.com/data/file_sample.html"],
+          js: ["content_script.js"],
+        },
+      ],
+      web_accessible_resources: ["bad.xml"],
+    },
+
+    files: {
+      "bad.xml": "<xml",
+      "content_script.js"() {
+        let xhr = new XMLHttpRequest();
+        xhr.open("GET", browser.extension.getURL("bad.xml"));
+
+        browser.test.sendMessage("result", {
+          name: "Content script XHRs should not be privileged",
+          result: xhr.channel === undefined,
+        });
+
+        xhr.onload = () => {
+          browser.test.sendMessage("result", {
+            name: "Content script XHRs should not yield <parsererrors>",
+            result: xhr.responseXML === null,
+          });
+        };
+        xhr.send();
+      },
+    },
+  });
+
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+
+  // We expect four test results from the content/background scripts.
+  for (let i = 0; i < 4; ++i) {
+    let result = await extension.awaitMessage("result");
+    ok(result.result, result.name);
+  }
+
+  await contentPage.close();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_extension_permissions_migration.js b/toolkit/components/extensions/test/xpcshell/test_extension_permissions_migration.js
new file mode 100644
index 0000000000..9e168107ff
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_extension_permissions_migration.js
@@ -0,0 +1,99 @@
+"use strict";
+
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+const { ExtensionPermissions } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionPermissions.jsm"
+);
+
+add_task(async function setup() {
+  // Bug 1646182: Force ExtensionPermissions to run in rkv mode, because this
+  // test does not make sense with the legacy method (which will be removed in
+  // the above bug).
+  await ExtensionPermissions._uninit();
+});
+
+const GOOD_JSON_FILE = {
+  "wikipedia@search.mozilla.org": {
+    permissions: ["internal:privateBrowsingAllowed"],
+    origins: [],
+  },
+  "amazon@search.mozilla.org": {
+    permissions: ["internal:privateBrowsingAllowed"],
+    origins: [],
+  },
+  "doh-rollout@mozilla.org": {
+    permissions: ["internal:privateBrowsingAllowed"],
+    origins: [],
+  },
+};
+
+const BAD_JSON_FILE = {
+  "test@example.org": "what",
+};
+
+const BAD_FILE = "what is this { } {";
+
+const gOldSettingsJSON = do_get_profile().clone();
+gOldSettingsJSON.append("extension-preferences.json");
+
+async function test_file(json, extensionIds, expected, fileDeleted) {
+  await ExtensionPermissions._resetVersion();
+  await ExtensionPermissions._uninit();
+
+  await OS.File.writeAtomic(gOldSettingsJSON.path, json, {
+    encoding: "utf-8",
+  });
+
+  for (let extensionId of extensionIds) {
+    let permissions = await ExtensionPermissions.get(extensionId);
+    Assert.deepEqual(permissions, expected, "permissions match");
+  }
+
+  Assert.equal(
+    await OS.File.exists(gOldSettingsJSON.path),
+    !fileDeleted,
+    "old file was deleted"
+  );
+}
+
+add_task(async function test_migrate_good_json() {
+  let expected = {
+    permissions: ["internal:privateBrowsingAllowed"],
+    origins: [],
+  };
+
+  await test_file(
+    JSON.stringify(GOOD_JSON_FILE),
+    [
+      "wikipedia@search.mozilla.org",
+      "amazon@search.mozilla.org",
+      "doh-rollout@mozilla.org",
+    ],
+    expected,
+    /* fileDeleted */ true
+  );
+});
+
+add_task(async function test_migrate_bad_json() {
+  let expected = { permissions: [], origins: [] };
+
+  await test_file(
+    BAD_FILE,
+    ["test@example.org"],
+    expected,
+    /* fileDeleted */ false
+  );
+  await OS.File.remove(gOldSettingsJSON.path);
+});
+
+add_task(async function test_migrate_bad_file() {
+  let expected = { permissions: [], origins: [] };
+
+  await test_file(
+    JSON.stringify(BAD_JSON_FILE),
+    ["test2@example.org"],
+    expected,
+    /* fileDeleted */ false
+  );
+  await OS.File.remove(gOldSettingsJSON.path);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_load_all_api_modules.js b/toolkit/components/extensions/test/xpcshell/test_load_all_api_modules.js
new file mode 100644
index 0000000000..54a24233e2
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_load_all_api_modules.js
@@ -0,0 +1,172 @@
+"use strict";
+
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+
+const BASE_SCHEMA = "chrome://extensions/content/schemas/manifest.json";
+
+const CATEGORY_EXTENSION_MODULES = "webextension-modules";
+const CATEGORY_EXTENSION_SCHEMAS = "webextension-schemas";
+const CATEGORY_EXTENSION_SCRIPTS = "webextension-scripts";
+
+const CATEGORY_EXTENSION_SCRIPTS_ADDON = "webextension-scripts-addon";
+const CATEGORY_EXTENSION_SCRIPTS_CONTENT = "webextension-scripts-content";
+const CATEGORY_EXTENSION_SCRIPTS_DEVTOOLS = "webextension-scripts-devtools";
+
+let schemaURLs = new Set();
+schemaURLs.add("chrome://extensions/content/schemas/experiments.json");
+
+// Helper class used to load the API modules similarly to the apiManager
+// defined in ExtensionParent.jsm.
+class FakeAPIManager extends ExtensionCommon.SchemaAPIManager {
+  constructor(processType = "main") {
+    super(processType, Schemas);
+    this.initialized = false;
+  }
+
+  getModuleJSONURLs() {
+    return Array.from(
+      Services.catMan.enumerateCategory(CATEGORY_EXTENSION_MODULES),
+      ({ value }) => value
+    );
+  }
+
+  async lazyInit() {
+    if (this.initialized) {
+      return;
+    }
+
+    this.initialized = true;
+
+    let modulesPromise = this.loadModuleJSON(this.getModuleJSONURLs());
+
+    let scriptURLs = [];
+    for (let { value } of Services.catMan.enumerateCategory(
+      CATEGORY_EXTENSION_SCRIPTS
+    )) {
+      scriptURLs.push(value);
+    }
+
+    let scripts = await Promise.all(
+      scriptURLs.map(url => ChromeUtils.compileScript(url))
+    );
+
+    this.initModuleData(await modulesPromise);
+
+    this.initGlobal();
+    for (let script of scripts) {
+      script.executeInGlobal(this.global);
+    }
+
+    // Load order matters here. The base manifest defines types which are
+    // extended by other schemas, so needs to be loaded first.
+    await Schemas.load(BASE_SCHEMA).then(() => {
+      let promises = [];
+      for (let { value } of Services.catMan.enumerateCategory(
+        CATEGORY_EXTENSION_SCHEMAS
+      )) {
+        promises.push(Schemas.load(value));
+      }
+      for (let [url, { content }] of this.schemaURLs) {
+        promises.push(Schemas.load(url, content));
+      }
+      for (let url of schemaURLs) {
+        promises.push(Schemas.load(url));
+      }
+      return Promise.all(promises).then(() => {
+        Schemas.updateSharedSchemas();
+      });
+    });
+  }
+
+  async loadAllModules(reverseOrder = false) {
+    await this.lazyInit();
+
+    let apiModuleNames = Array.from(this.modules.keys())
+      .filter(moduleName => {
+        let moduleDesc = this.modules.get(moduleName);
+        return moduleDesc && !!moduleDesc.url;
+      })
+      .sort();
+
+    apiModuleNames = reverseOrder ? apiModuleNames.reverse() : apiModuleNames;
+
+    for (let apiModule of apiModuleNames) {
+      info(
+        `Loading apiModule ${apiModule}: ${this.modules.get(apiModule).url}`
+      );
+      await this.asyncLoadModule(apiModule);
+    }
+  }
+}
+
+// Specialized helper class used to test loading "child process" modules (similarly to the
+// SchemaAPIManagers sub-classes defined in ExtensionPageChild.jsm and ExtensionContent.jsm).
+class FakeChildProcessAPIManager extends FakeAPIManager {
+  constructor({ processType, categoryScripts }) {
+    super(processType, Schemas);
+
+    this.categoryScripts = categoryScripts;
+  }
+
+  async lazyInit() {
+    if (!this.initialized) {
+      this.initialized = true;
+      this.initGlobal();
+      for (let { value } of Services.catMan.enumerateCategory(
+        this.categoryScripts
+      )) {
+        await this.loadScript(value);
+      }
+    }
+  }
+}
+
+async function test_loading_api_modules(createAPIManager) {
+  let fakeAPIManager;
+
+  info("Load API modules in alphabetic order");
+
+  fakeAPIManager = createAPIManager();
+  await fakeAPIManager.loadAllModules();
+
+  info("Load API modules in reverse order");
+
+  fakeAPIManager = createAPIManager();
+  await fakeAPIManager.loadAllModules(true);
+}
+
+add_task(function test_loading_main_process_api_modules() {
+  return test_loading_api_modules(() => {
+    return new FakeAPIManager();
+  });
+});
+
+add_task(function test_loading_extension_process_modules() {
+  return test_loading_api_modules(() => {
+    return new FakeChildProcessAPIManager({
+      processType: "addon",
+      categoryScripts: CATEGORY_EXTENSION_SCRIPTS_ADDON,
+    });
+  });
+});
+
+add_task(function test_loading_devtools_modules() {
+  return test_loading_api_modules(() => {
+    return new FakeChildProcessAPIManager({
+      processType: "devtools",
+      categoryScripts: CATEGORY_EXTENSION_SCRIPTS_DEVTOOLS,
+    });
+  });
+});
+
+add_task(async function test_loading_content_process_modules() {
+  return test_loading_api_modules(() => {
+    return new FakeChildProcessAPIManager({
+      processType: "content",
+      categoryScripts: CATEGORY_EXTENSION_SCRIPTS_CONTENT,
+    });
+  });
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_locale_converter.js b/toolkit/components/extensions/test/xpcshell/test_locale_converter.js
new file mode 100644
index 0000000000..6729639cc9
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_locale_converter.js
@@ -0,0 +1,146 @@
+"use strict";
+
+const convService = Cc["@mozilla.org/streamConverters;1"].getService(
+  Ci.nsIStreamConverterService
+);
+
+const UUID = "72b61ee3-aceb-476c-be1b-0822b036c9f1";
+const ADDON_ID = "test@web.extension";
+const URI = NetUtil.newURI(`moz-extension://${UUID}/file.css`);
+
+const FROM_TYPE = "application/vnd.mozilla.webext.unlocalized";
+const TO_TYPE = "text/css";
+
+function StringStream(string) {
+  let stream = Cc["@mozilla.org/io/string-input-stream;1"].createInstance(
+    Ci.nsIStringInputStream
+  );
+
+  stream.data = string;
+  return stream;
+}
+
+// Initialize the policy service with a stub localizer for our
+// add-on ID.
+add_task(async function init() {
+  let policy = new WebExtensionPolicy({
+    id: ADDON_ID,
+    mozExtensionHostname: UUID,
+    baseURL: "file:///",
+
+    allowedOrigins: new MatchPatternSet([]),
+
+    localizeCallback(string) {
+      return string.replace(/__MSG_(.*?)__/g, "<localized-$1>");
+    },
+  });
+
+  policy.active = true;
+
+  registerCleanupFunction(() => {
+    policy.active = false;
+  });
+});
+
+// Test that the synchronous converter works as expected with a
+// simple string.
+add_task(async function testSynchronousConvert() {
+  let stream = StringStream("Foo __MSG_xxx__ bar __MSG_yyy__ baz");
+
+  let resultStream = convService.convert(stream, FROM_TYPE, TO_TYPE, URI);
+
+  let result = NetUtil.readInputStreamToString(
+    resultStream,
+    resultStream.available()
+  );
+
+  equal(result, "Foo <localized-xxx> bar <localized-yyy> baz");
+});
+
+// Test that the asynchronous converter works as expected with input
+// split into multiple chunks, and a boundary in the middle of a
+// replacement token.
+add_task(async function testAsyncConvert() {
+  let listener;
+  let awaitResult = new Promise((resolve, reject) => {
+    listener = {
+      QueryInterface: ChromeUtils.generateQI(["nsIStreamListener"]),
+
+      onDataAvailable(request, inputStream, offset, count) {
+        this.resultParts.push(
+          NetUtil.readInputStreamToString(inputStream, count)
+        );
+      },
+
+      onStartRequest() {
+        ok(!("resultParts" in this));
+        this.resultParts = [];
+      },
+
+      onStopRequest(request, context, statusCode) {
+        if (!Components.isSuccessCode(statusCode)) {
+          reject(new Error(statusCode));
+        }
+
+        resolve(this.resultParts.join("\n"));
+      },
+    };
+  });
+
+  let parts = ["Foo __MSG_x", "xx__ bar __MSG_yyy__ baz"];
+
+  let converter = convService.asyncConvertData(
+    FROM_TYPE,
+    TO_TYPE,
+    listener,
+    URI
+  );
+  converter.onStartRequest(null, null);
+
+  for (let part of parts) {
+    converter.onDataAvailable(null, StringStream(part), 0, part.length);
+  }
+
+  converter.onStopRequest(null, null, Cr.NS_OK);
+
+  let result = await awaitResult;
+  equal(result, "Foo <localized-xxx> bar <localized-yyy> baz");
+});
+
+// Test that attempting to initialize a converter with the URI of a
+// nonexistent WebExtension fails.
+add_task(async function testInvalidUUID() {
+  let uri = NetUtil.newURI(
+    "moz-extension://eb4f3be8-41c9-4970-aa6d-b84d1ecc02b2/file.css"
+  );
+  let stream = StringStream("Foo __MSG_xxx__ bar __MSG_yyy__ baz");
+
+  // Assert.throws raise a TypeError exception when the expected param
+  // is an arrow function. (See Bug 1237961 for rationale)
+  let expectInvalidContextException = function(e) {
+    return e.result === Cr.NS_ERROR_INVALID_ARG && /Invalid context/.test(e);
+  };
+
+  Assert.throws(() => {
+    convService.convert(stream, FROM_TYPE, TO_TYPE, uri);
+  }, expectInvalidContextException);
+
+  Assert.throws(() => {
+    let listener = {
+      QueryInterface: ChromeUtils.generateQI(["nsIStreamListener"]),
+    };
+
+    convService.asyncConvertData(FROM_TYPE, TO_TYPE, listener, uri);
+  }, expectInvalidContextException);
+});
+
+// Test that an empty stream does not throw an NS_ERROR_ILLEGAL_VALUE.
+add_task(async function testEmptyStream() {
+  let stream = StringStream("");
+  let resultStream = convService.convert(stream, FROM_TYPE, TO_TYPE, URI);
+  equal(
+    resultStream.available(),
+    0,
+    "Size of output stream should match size of input stream"
+  );
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_locale_data.js b/toolkit/components/extensions/test/xpcshell/test_locale_data.js
new file mode 100644
index 0000000000..32155a7c91
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_locale_data.js
@@ -0,0 +1,221 @@
+"use strict";
+
+AddonTestUtils.init(this);
+AddonTestUtils.overrideCertDB();
+AddonTestUtils.createAppInfo(
+  "xpcshell@tests.mozilla.org",
+  "XPCShell",
+  "1",
+  "42"
+);
+
+const { ExtensionData } = ChromeUtils.import(
+  "resource://gre/modules/Extension.jsm"
+);
+
+async function generateAddon(data) {
+  let xpi = AddonTestUtils.createTempWebExtensionFile(data);
+
+  let fileURI = Services.io.newFileURI(xpi);
+  let jarURI = NetUtil.newURI(`jar:${fileURI.spec}!/`);
+
+  let extension = new ExtensionData(jarURI);
+  await extension.loadManifest();
+
+  return extension;
+}
+
+add_task(async function testMissingDefaultLocale() {
+  let extension = await generateAddon({
+    files: {
+      "_locales/en_US/messages.json": {},
+    },
+  });
+
+  equal(extension.errors.length, 0, "No errors reported");
+
+  await extension.initAllLocales();
+
+  equal(extension.errors.length, 1, "One error reported");
+
+  info(`Got error: ${extension.errors[0]}`);
+
+  ok(
+    extension.errors[0].includes('"default_locale" property is required'),
+    "Got missing default_locale error"
+  );
+});
+
+add_task(async function testInvalidDefaultLocale() {
+  let extension = await generateAddon({
+    manifest: {
+      default_locale: "en",
+    },
+
+    files: {
+      "_locales/en_US/messages.json": {},
+    },
+  });
+
+  equal(extension.errors.length, 1, "One error reported");
+
+  info(`Got error: ${extension.errors[0]}`);
+
+  ok(
+    extension.errors[0].includes(
+      "Loading locale file _locales/en/messages.json"
+    ),
+    "Got invalid default_locale error"
+  );
+
+  await extension.initAllLocales();
+
+  equal(extension.errors.length, 2, "Two errors reported");
+
+  info(`Got error: ${extension.errors[1]}`);
+
+  ok(
+    extension.errors[1].includes('"default_locale" property must correspond'),
+    "Got invalid default_locale error"
+  );
+});
+
+add_task(async function testUnexpectedDefaultLocale() {
+  let extension = await generateAddon({
+    manifest: {
+      default_locale: "en_US",
+    },
+  });
+
+  equal(extension.errors.length, 1, "One error reported");
+
+  info(`Got error: ${extension.errors[0]}`);
+
+  ok(
+    extension.errors[0].includes(
+      "Loading locale file _locales/en-US/messages.json"
+    ),
+    "Got invalid default_locale error"
+  );
+
+  await extension.initAllLocales();
+
+  equal(extension.errors.length, 2, "One error reported");
+
+  info(`Got error: ${extension.errors[1]}`);
+
+  ok(
+    extension.errors[1].includes('"default_locale" property must correspond'),
+    "Got unexpected default_locale error"
+  );
+});
+
+add_task(async function testInvalidSyntax() {
+  let extension = await generateAddon({
+    manifest: {
+      default_locale: "en_US",
+    },
+
+    files: {
+      "_locales/en_US/messages.json":
+        '{foo: {message: "bar", description: "baz"}}',
+    },
+  });
+
+  equal(extension.errors.length, 1, "No errors reported");
+
+  info(`Got error: ${extension.errors[0]}`);
+
+  ok(
+    extension.errors[0].includes(
+      "Loading locale file _locales/en_US/messages.json: SyntaxError"
+    ),
+    "Got syntax error"
+  );
+
+  await extension.initAllLocales();
+
+  equal(extension.errors.length, 2, "One error reported");
+
+  info(`Got error: ${extension.errors[1]}`);
+
+  ok(
+    extension.errors[1].includes(
+      "Loading locale file _locales/en_US/messages.json: SyntaxError"
+    ),
+    "Got syntax error"
+  );
+});
+
+add_task(async function testExtractLocalizedManifest() {
+  let extension = await generateAddon({
+    manifest: {
+      name: "__MSG_extensionName__",
+      default_locale: "en_US",
+      icons: {
+        "16": "__MSG_extensionIcon__",
+      },
+    },
+
+    files: {
+      "_locales/en_US/messages.json": `{
+        "extensionName": {"message": "foo"},
+        "extensionIcon": {"message": "icon-en.png"}
+      }`,
+      "_locales/de_DE/messages.json": `{
+        "extensionName": {"message": "bar"},
+        "extensionIcon": {"message": "icon-de.png"}
+      }`,
+    },
+  });
+
+  await extension.loadManifest();
+  equal(extension.manifest.name, "foo", "name localized");
+  equal(extension.manifest.icons["16"], "icon-en.png", "icons localized");
+
+  let manifest = await extension.getLocalizedManifest("de-DE");
+  ok(extension.localeData.has("de-DE"), "has de_DE locale");
+  equal(manifest.name, "bar", "name localized");
+  equal(manifest.icons["16"], "icon-de.png", "icons localized");
+
+  await Assert.rejects(
+    extension.getLocalizedManifest("xx-XX"),
+    /does not contain the locale xx-XX/,
+    "xx-XX does not exist"
+  );
+});
+
+add_task(async function testRestartThenExtractLocalizedManifest() {
+  await AddonTestUtils.promiseStartupManager();
+
+  let wrapper = ExtensionTestUtils.loadExtension({
+    manifest: {
+      name: "__MSG_extensionName__",
+      default_locale: "en_US",
+    },
+    useAddonManager: "permanent",
+    files: {
+      "_locales/en_US/messages.json": '{"extensionName": {"message": "foo"}}',
+      "_locales/de_DE/messages.json": '{"extensionName": {"message": "bar"}}',
+    },
+  });
+
+  await wrapper.startup();
+
+  await AddonTestUtils.promiseRestartManager();
+  await wrapper.startupPromise;
+
+  let { extension } = wrapper;
+  let manifest = await extension.getLocalizedManifest("de-DE");
+  ok(extension.localeData.has("de-DE"), "has de_DE locale");
+  equal(manifest.name, "bar", "name localized");
+
+  await Assert.rejects(
+    extension.getLocalizedManifest("xx-XX"),
+    /does not contain the locale xx-XX/,
+    "xx-XX does not exist"
+  );
+
+  await wrapper.unload();
+  await AddonTestUtils.promiseShutdownManager();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_native_manifests.js b/toolkit/components/extensions/test/xpcshell/test_native_manifests.js
new file mode 100644
index 0000000000..ca32517fd5
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_native_manifests.js
@@ -0,0 +1,443 @@
+"use strict";
+
+const { AsyncShutdown } = ChromeUtils.import(
+  "resource://gre/modules/AsyncShutdown.jsm"
+);
+const { ExtensionCommon } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+const { NativeManifests } = ChromeUtils.import(
+  "resource://gre/modules/NativeManifests.jsm"
+);
+const { FileUtils } = ChromeUtils.import(
+  "resource://gre/modules/FileUtils.jsm"
+);
+const { Schemas } = ChromeUtils.import("resource://gre/modules/Schemas.jsm");
+const { Subprocess, SubprocessImpl } = ChromeUtils.import(
+  "resource://gre/modules/Subprocess.jsm",
+  null
+);
+const { NativeApp } = ChromeUtils.import(
+  "resource://gre/modules/NativeMessaging.jsm"
+);
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
+
+let registry = null;
+if (AppConstants.platform == "win") {
+  var { MockRegistry } = ChromeUtils.import(
+    "resource://testing-common/MockRegistry.jsm"
+  );
+  registry = new MockRegistry();
+  registerCleanupFunction(() => {
+    registry.shutdown();
+  });
+}
+
+const REGPATH = "Software\\Mozilla\\NativeMessagingHosts";
+
+const BASE_SCHEMA = "chrome://extensions/content/schemas/manifest.json";
+
+const TYPE_SLUG =
+  AppConstants.platform === "linux"
+    ? "native-messaging-hosts"
+    : "NativeMessagingHosts";
+
+let dir = FileUtils.getDir("TmpD", ["NativeManifests"]);
+dir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+let userDir = dir.clone();
+userDir.append("user");
+userDir.create(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+let globalDir = dir.clone();
+globalDir.append("global");
+globalDir.create(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+OS.File.makeDir(OS.Path.join(userDir.path, TYPE_SLUG));
+OS.File.makeDir(OS.Path.join(globalDir.path, TYPE_SLUG));
+
+let dirProvider = {
+  getFile(property) {
+    if (property == "XREUserNativeManifests") {
+      return userDir.clone();
+    } else if (property == "XRESysNativeManifests") {
+      return globalDir.clone();
+    }
+    return null;
+  },
+};
+
+Services.dirsvc.registerProvider(dirProvider);
+
+registerCleanupFunction(() => {
+  Services.dirsvc.unregisterProvider(dirProvider);
+  dir.remove(true);
+});
+
+function writeManifest(path, manifest) {
+  if (typeof manifest != "string") {
+    manifest = JSON.stringify(manifest);
+  }
+  return OS.File.writeAtomic(path, manifest);
+}
+
+let PYTHON;
+add_task(async function setup() {
+  await Schemas.load(BASE_SCHEMA);
+
+  const env = Cc["@mozilla.org/process/environment;1"].getService(
+    Ci.nsIEnvironment
+  );
+  try {
+    PYTHON = await Subprocess.pathSearch(env.get("PYTHON"));
+  } catch (e) {
+    notEqual(
+      PYTHON,
+      null,
+      `Can't find a suitable python interpreter ${e.message}`
+    );
+  }
+});
+
+let global = this;
+
+// Test of NativeManifests.lookupApplication() begin here...
+let context = {
+  extension: {
+    id: "extension@tests.mozilla.org",
+  },
+  envType: "addon_parent",
+  url: null,
+  jsonStringify(...args) {
+    return JSON.stringify(...args);
+  },
+  cloneScope: global,
+  logError() {},
+  preprocessors: {},
+  callOnClose: () => {},
+  forgetOnClose: () => {},
+};
+
+class MockContext extends ExtensionCommon.BaseContext {
+  constructor(extensionId) {
+    let fakeExtension = { id: extensionId };
+    super("addon_parent", fakeExtension);
+    this.sandbox = Cu.Sandbox(global);
+  }
+
+  get cloneScope() {
+    return global;
+  }
+
+  get principal() {
+    return Cu.getObjectPrincipal(this.sandbox);
+  }
+}
+
+let templateManifest = {
+  name: "test",
+  description: "this is only a test",
+  path: "/bin/cat",
+  type: "stdio",
+  allowed_extensions: ["extension@tests.mozilla.org"],
+};
+
+function lookupApplication(app, ctx) {
+  return NativeManifests.lookupManifest("stdio", app, ctx);
+}
+
+add_task(async function test_nonexistent_manifest() {
+  let result = await lookupApplication("test", context);
+  equal(
+    result,
+    null,
+    "lookupApplication returns null for non-existent application"
+  );
+});
+
+const USER_TEST_JSON = OS.Path.join(userDir.path, TYPE_SLUG, "test.json");
+
+add_task(async function test_nonexistent_manifest_with_registry_entry() {
+  if (registry) {
+    registry.setValue(
+      Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+      `${REGPATH}\\test`,
+      "",
+      USER_TEST_JSON
+    );
+  }
+
+  await OS.File.remove(USER_TEST_JSON);
+  let { messages, result } = await promiseConsoleOutput(() =>
+    lookupApplication("test", context)
+  );
+  equal(
+    result,
+    null,
+    "lookupApplication returns null for non-existent manifest"
+  );
+
+  let noSuchFileErrors = messages.filter(logMessage =>
+    logMessage.message.includes(
+      "file is referenced in the registry but does not exist"
+    )
+  );
+
+  if (registry) {
+    equal(
+      noSuchFileErrors.length,
+      1,
+      "lookupApplication logs a non-existent manifest file pointed to by the registry"
+    );
+  } else {
+    equal(
+      noSuchFileErrors.length,
+      0,
+      "lookupApplication does not log about registry on non-windows platforms"
+    );
+  }
+});
+
+add_task(async function test_good_manifest() {
+  await writeManifest(USER_TEST_JSON, templateManifest);
+  if (registry) {
+    registry.setValue(
+      Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+      `${REGPATH}\\test`,
+      "",
+      USER_TEST_JSON
+    );
+  }
+
+  let result = await lookupApplication("test", context);
+  notEqual(result, null, "lookupApplication finds a good manifest");
+  equal(
+    result.path,
+    USER_TEST_JSON,
+    "lookupApplication returns the correct path"
+  );
+  deepEqual(
+    result.manifest,
+    templateManifest,
+    "lookupApplication returns the manifest contents"
+  );
+});
+
+add_task(async function test_invalid_json() {
+  await writeManifest(USER_TEST_JSON, "this is not valid json");
+  let result = await lookupApplication("test", context);
+  equal(result, null, "lookupApplication ignores bad json");
+});
+
+add_task(async function test_invalid_name() {
+  let manifest = Object.assign({}, templateManifest);
+  manifest.name = "../test";
+  await writeManifest(USER_TEST_JSON, manifest);
+  let result = await lookupApplication("test", context);
+  equal(result, null, "lookupApplication ignores an invalid name");
+});
+
+add_task(async function test_name_mismatch() {
+  let manifest = Object.assign({}, templateManifest);
+  manifest.name = "not test";
+  await writeManifest(USER_TEST_JSON, manifest);
+  let result = await lookupApplication("test", context);
+  let what = AppConstants.platform == "win" ? "registry key" : "json filename";
+  equal(
+    result,
+    null,
+    `lookupApplication ignores mistmatch between ${what} and name property`
+  );
+});
+
+add_task(async function test_missing_props() {
+  const PROPS = ["name", "description", "path", "type", "allowed_extensions"];
+  for (let prop of PROPS) {
+    let manifest = Object.assign({}, templateManifest);
+    delete manifest[prop];
+
+    await writeManifest(USER_TEST_JSON, manifest);
+    let result = await lookupApplication("test", context);
+    equal(result, null, `lookupApplication ignores missing ${prop}`);
+  }
+});
+
+add_task(async function test_invalid_type() {
+  let manifest = Object.assign({}, templateManifest);
+  manifest.type = "bogus";
+  await writeManifest(USER_TEST_JSON, manifest);
+  let result = await lookupApplication("test", context);
+  equal(result, null, "lookupApplication ignores invalid type");
+});
+
+add_task(async function test_no_allowed_extensions() {
+  let manifest = Object.assign({}, templateManifest);
+  manifest.allowed_extensions = [];
+  await writeManifest(USER_TEST_JSON, manifest);
+  let result = await lookupApplication("test", context);
+  equal(
+    result,
+    null,
+    "lookupApplication ignores manifest with no allowed_extensions"
+  );
+});
+
+const GLOBAL_TEST_JSON = OS.Path.join(globalDir.path, TYPE_SLUG, "test.json");
+let globalManifest = Object.assign({}, templateManifest);
+globalManifest.description = "This manifest is from the systemwide directory";
+
+add_task(async function good_manifest_system_dir() {
+  await OS.File.remove(USER_TEST_JSON);
+  await writeManifest(GLOBAL_TEST_JSON, globalManifest);
+  if (registry) {
+    registry.setValue(
+      Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+      `${REGPATH}\\test`,
+      "",
+      null
+    );
+    registry.setValue(
+      Ci.nsIWindowsRegKey.ROOT_KEY_LOCAL_MACHINE,
+      `${REGPATH}\\test`,
+      "",
+      GLOBAL_TEST_JSON
+    );
+  }
+
+  let where =
+    AppConstants.platform == "win" ? "registry location" : "directory";
+  let result = await lookupApplication("test", context);
+  notEqual(
+    result,
+    null,
+    `lookupApplication finds a manifest in the system-wide ${where}`
+  );
+  equal(
+    result.path,
+    GLOBAL_TEST_JSON,
+    `lookupApplication returns path in the system-wide ${where}`
+  );
+  deepEqual(
+    result.manifest,
+    globalManifest,
+    `lookupApplication returns manifest contents from the system-wide ${where}`
+  );
+});
+
+add_task(async function test_user_dir_precedence() {
+  await writeManifest(USER_TEST_JSON, templateManifest);
+  if (registry) {
+    registry.setValue(
+      Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+      `${REGPATH}\\test`,
+      "",
+      USER_TEST_JSON
+    );
+  }
+  // global test.json and LOCAL_MACHINE registry key on windows are
+  // still present from the previous test
+
+  let result = await lookupApplication("test", context);
+  notEqual(
+    result,
+    null,
+    "lookupApplication finds a manifest when entries exist in both user-specific and system-wide locations"
+  );
+  equal(
+    result.path,
+    USER_TEST_JSON,
+    "lookupApplication returns the user-specific path when user-specific and system-wide entries both exist"
+  );
+  deepEqual(
+    result.manifest,
+    templateManifest,
+    "lookupApplication returns user-specific manifest contents with user-specific and system-wide entries both exist"
+  );
+});
+
+// Test shutdown handling in NativeApp
+add_task(async function test_native_app_shutdown() {
+  const SCRIPT = String.raw`
+import signal
+import struct
+import sys
+
+signal.signal(signal.SIGTERM, signal.SIG_IGN)
+
+stdin = getattr(sys.stdin, 'buffer', sys.stdin)
+stdout = getattr(sys.stdout, 'buffer', sys.stdout)
+
+while True:
+    rawlen = stdin.read(4)
+    if len(rawlen) == 0:
+        signal.pause()
+    msglen = struct.unpack('@I', rawlen)[0]
+    msg = stdin.read(msglen)
+
+    stdout.write(struct.pack('@I', msglen))
+    stdout.write(msg)
+`;
+
+  let scriptPath = OS.Path.join(userDir.path, TYPE_SLUG, "wontdie.py");
+  let manifestPath = OS.Path.join(userDir.path, TYPE_SLUG, "wontdie.json");
+
+  const ID = "native@tests.mozilla.org";
+  let manifest = {
+    name: "wontdie",
+    description: "test async shutdown of native apps",
+    type: "stdio",
+    allowed_extensions: [ID],
+  };
+
+  if (AppConstants.platform == "win") {
+    await OS.File.writeAtomic(scriptPath, SCRIPT);
+
+    let batPath = OS.Path.join(userDir.path, TYPE_SLUG, "wontdie.bat");
+    let batBody = `@ECHO OFF\n${PYTHON} -u "${scriptPath}" %*\n`;
+    await OS.File.writeAtomic(batPath, batBody);
+    await OS.File.setPermissions(batPath, { unixMode: 0o755 });
+
+    manifest.path = batPath;
+    await writeManifest(manifestPath, manifest);
+
+    registry.setValue(
+      Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
+      `${REGPATH}\\wontdie`,
+      "",
+      manifestPath
+    );
+  } else {
+    await OS.File.writeAtomic(scriptPath, `#!${PYTHON} -u\n${SCRIPT}`);
+    await OS.File.setPermissions(scriptPath, { unixMode: 0o755 });
+    manifest.path = scriptPath;
+    await writeManifest(manifestPath, manifest);
+  }
+
+  let mockContext = new MockContext(ID);
+  let app = new NativeApp(mockContext, "wontdie");
+
+  // send a message and wait for the reply to make sure the app is running
+  let MSG = "test";
+  let recvPromise = new Promise(resolve => {
+    let listener = (what, msg) => {
+      equal(msg, MSG, "Received test message");
+      app.off("message", listener);
+      resolve();
+    };
+    app.on("message", listener);
+  });
+
+  let buffer = NativeApp.encodeMessage(mockContext, MSG);
+  app.send(new StructuredCloneHolder(buffer));
+  await recvPromise;
+
+  app._cleanup();
+
+  info("waiting for async shutdown");
+  Services.prefs.setBoolPref("toolkit.asyncshutdown.testing", true);
+  AsyncShutdown.profileBeforeChange._trigger();
+  Services.prefs.clearUserPref("toolkit.asyncshutdown.testing");
+
+  let procs = await SubprocessImpl.Process.getWorker().call("getProcesses", []);
+  equal(procs.size, 0, "native process exited");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_proxy_incognito.js b/toolkit/components/extensions/test/xpcshell/test_proxy_incognito.js
new file mode 100644
index 0000000000..0763c60abe
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_proxy_incognito.js
@@ -0,0 +1,103 @@
+"use strict";
+
+/* eslint no-unused-vars: ["error", {"args": "none", "varsIgnorePattern": "^(FindProxyForURL)$"}] */
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_incognito_proxy_onRequest_access() {
+  // No specific support exists in the proxy api for this test,
+  // rather it depends on functionality existing in ChannelWrapper
+  // that prevents notification of private channels if the
+  // extension does not have permission.
+  Services.prefs.setBoolPref("extensions.allowPrivateBrowsingByDefault", false);
+
+  // This extension will fail if it gets a private request.
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["proxy", "<all_urls>"],
+    },
+    async background() {
+      browser.proxy.onRequest.addListener(
+        async details => {
+          browser.test.assertFalse(
+            details.incognito,
+            "incognito flag is not set"
+          );
+          browser.test.notifyPass("proxy.onRequest");
+        },
+        { urls: ["<all_urls>"], types: ["main_frame"] }
+      );
+
+      // Actual call arguments do not matter here.
+      await browser.test.assertRejects(
+        browser.proxy.settings.set({
+          value: {
+            proxyType: "none",
+          },
+        }),
+        /proxy.settings requires private browsing permission/,
+        "proxy.settings requires private browsing permission."
+      );
+
+      browser.test.sendMessage("ready");
+    },
+  });
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  let pextension = ExtensionTestUtils.loadExtension({
+    incognitoOverride: "spanning",
+    manifest: {
+      permissions: ["proxy", "<all_urls>"],
+    },
+    background() {
+      browser.proxy.onRequest.addListener(
+        async details => {
+          browser.test.assertTrue(
+            details.incognito,
+            "incognito flag is set with filter"
+          );
+          browser.test.sendMessage("proxy.onRequest.private");
+        },
+        { urls: ["<all_urls>"], types: ["main_frame"], incognito: true }
+      );
+
+      browser.proxy.onRequest.addListener(
+        async details => {
+          browser.test.assertFalse(
+            details.incognito,
+            "incognito flag is not set with filter"
+          );
+          browser.test.notifyPass("proxy.onRequest.spanning");
+        },
+        { urls: ["<all_urls>"], types: ["main_frame"], incognito: false }
+      );
+    },
+  });
+  await pextension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy",
+    { privateBrowsing: true }
+  );
+  await pextension.awaitMessage("proxy.onRequest.private");
+  await contentPage.close();
+
+  contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy"
+  );
+  await extension.awaitFinish("proxy.onRequest");
+  await pextension.awaitFinish("proxy.onRequest.spanning");
+  await contentPage.close();
+
+  await pextension.unload();
+  await extension.unload();
+
+  Services.prefs.clearUserPref("extensions.allowPrivateBrowsingByDefault");
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_proxy_info_results.js b/toolkit/components/extensions/test/xpcshell/test_proxy_info_results.js
new file mode 100644
index 0000000000..c222642d52
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_proxy_info_results.js
@@ -0,0 +1,469 @@
+"use strict";
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "gProxyService",
+  "@mozilla.org/network/protocol-proxy-service;1",
+  "nsIProtocolProxyService"
+);
+
+const TRANSPARENT_PROXY_RESOLVES_HOST =
+  Ci.nsIProxyInfo.TRANSPARENT_PROXY_RESOLVES_HOST;
+
+let extension;
+add_task(async function setup() {
+  let extensionData = {
+    manifest: {
+      permissions: ["proxy", "<all_urls>"],
+    },
+    background() {
+      let settings = { proxy: null };
+
+      browser.proxy.onError.addListener(error => {
+        browser.test.log(`error received ${error.message}`);
+        browser.test.sendMessage("proxy-error-received", error);
+      });
+      browser.test.onMessage.addListener((message, data) => {
+        if (message === "set-proxy") {
+          settings.proxy = data.proxy;
+          browser.test.sendMessage("proxy-set", settings.proxy);
+        }
+      });
+      browser.proxy.onRequest.addListener(
+        () => {
+          return settings.proxy;
+        },
+        { urls: ["<all_urls>"] }
+      );
+    },
+  };
+  extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+});
+
+async function setupProxyResult(proxy) {
+  extension.sendMessage("set-proxy", { proxy });
+  let proxyInfoSent = await extension.awaitMessage("proxy-set");
+  deepEqual(
+    proxyInfoSent,
+    proxy,
+    "got back proxy data from the proxy listener"
+  );
+}
+
+async function testProxyResolution(test) {
+  let { uri, proxy, expected } = test;
+  let errorMsg;
+  if (expected.error) {
+    errorMsg = extension.awaitMessage("proxy-error-received");
+  }
+  let proxyInfo = await new Promise((resolve, reject) => {
+    let channel = NetUtil.newChannel({
+      uri,
+      loadUsingSystemPrincipal: true,
+    });
+
+    gProxyService.asyncResolve(channel, 0, {
+      onProxyAvailable(req, uri, pi, status) {
+        resolve(pi && pi.QueryInterface(Ci.nsIProxyInfo));
+      },
+    });
+  });
+
+  let expectedProxyInfo = expected.proxyInfo;
+  if (expected.error) {
+    equal(proxyInfo, null, "Expected proxyInfo to be null");
+    equal((await errorMsg).message, expected.error, "error received");
+  } else if (proxy == null) {
+    equal(proxyInfo, expectedProxyInfo, "proxy is direct");
+  } else {
+    for (
+      let proxyUsed = proxyInfo;
+      proxyUsed;
+      proxyUsed = proxyUsed.failoverProxy
+    ) {
+      let {
+        type,
+        host,
+        port,
+        username,
+        password,
+        proxyDNS,
+        failoverTimeout,
+      } = expectedProxyInfo;
+      equal(proxyUsed.host, host, `Expected proxy host to be ${host}`);
+      equal(proxyUsed.port, port, `Expected proxy port to be ${port}`);
+      equal(proxyUsed.type, type, `Expected proxy type to be ${type}`);
+      // May be null or undefined depending on use of newProxyInfoWithAuth or newProxyInfo
+      equal(
+        proxyUsed.username || "",
+        username || "",
+        `Expected proxy username to be ${username}`
+      );
+      equal(
+        proxyUsed.password || "",
+        password || "",
+        `Expected proxy password to be ${password}`
+      );
+      equal(
+        proxyUsed.flags,
+        proxyDNS == undefined ? 0 : proxyDNS,
+        `Expected proxyDNS to be ${proxyDNS}`
+      );
+      // Default timeout is 10
+      equal(
+        proxyUsed.failoverTimeout,
+        failoverTimeout || 10,
+        `Expected failoverTimeout to be ${failoverTimeout}`
+      );
+      expectedProxyInfo = expectedProxyInfo.failoverProxy;
+    }
+  }
+}
+
+add_task(async function test_proxyInfo_results() {
+  let tests = [
+    {
+      proxy: 5,
+      expected: {
+        error: "ProxyInfoData: proxyData must be an object or array of objects",
+      },
+    },
+    {
+      proxy: "INVALID",
+      expected: {
+        error: "ProxyInfoData: proxyData must be an object or array of objects",
+      },
+    },
+    {
+      proxy: {
+        type: "socks",
+      },
+      expected: {
+        error: 'ProxyInfoData: Invalid proxy server host: "undefined"',
+      },
+    },
+    {
+      proxy: [
+        {
+          type: "pptp",
+          host: "foo.bar",
+          port: 1080,
+          username: "mungosantamaria",
+          password: "pass123",
+          proxyDNS: true,
+          failoverTimeout: 3,
+        },
+        {
+          type: "http",
+          host: "192.168.1.1",
+          port: 1128,
+          username: "mungosantamaria",
+          password: "word321",
+        },
+      ],
+      expected: {
+        error: 'ProxyInfoData: Invalid proxy server type: "pptp"',
+      },
+    },
+    {
+      proxy: [
+        {
+          type: "http",
+          host: "foo.bar",
+          port: 65536,
+          username: "mungosantamaria",
+          password: "pass123",
+          proxyDNS: true,
+          failoverTimeout: 3,
+        },
+        {
+          type: "http",
+          host: "192.168.1.1",
+          port: 3128,
+          username: "mungosantamaria",
+          password: "word321",
+        },
+      ],
+      expected: {
+        error:
+          "ProxyInfoData: Proxy server port 65536 outside range 1 to 65535",
+      },
+    },
+    {
+      proxy: [
+        {
+          type: "http",
+          host: "foo.bar",
+          port: 3128,
+          proxyAuthorizationHeader: "test",
+        },
+      ],
+      expected: {
+        error: 'ProxyInfoData: ProxyAuthorizationHeader requires type "https"',
+      },
+    },
+    {
+      proxy: [
+        {
+          type: "http",
+          host: "foo.bar",
+          port: 3128,
+          connectionIsolationKey: 1234,
+        },
+      ],
+      expected: {
+        error: 'ProxyInfoData: Invalid proxy connection isolation key: "1234"',
+      },
+    },
+    {
+      proxy: [{ type: "direct" }],
+      expected: {
+        proxyInfo: null,
+      },
+    },
+    {
+      proxy: {
+        host: "1.2.3.4",
+        port: "8080",
+        type: "http",
+        failoverProxy: null,
+      },
+      expected: {
+        proxyInfo: {
+          host: "1.2.3.4",
+          port: "8080",
+          type: "http",
+          failoverProxy: null,
+        },
+      },
+    },
+    {
+      uri: "ftp://mozilla.org",
+      proxy: {
+        host: "1.2.3.4",
+        port: "8180",
+        type: "http",
+        failoverProxy: null,
+      },
+      expected: {
+        proxyInfo: {
+          host: "1.2.3.4",
+          port: "8180",
+          type: "http",
+          failoverProxy: null,
+        },
+      },
+    },
+    {
+      proxy: {
+        host: "2.3.4.5",
+        port: "8181",
+        type: "http",
+        failoverProxy: null,
+      },
+      expected: {
+        proxyInfo: {
+          host: "2.3.4.5",
+          port: "8181",
+          type: "http",
+          failoverProxy: null,
+        },
+      },
+    },
+    {
+      proxy: {
+        host: "1.2.3.4",
+        port: "8080",
+        type: "http",
+        failoverProxy: {
+          host: "4.4.4.4",
+          port: "9000",
+          type: "socks",
+          failoverProxy: {
+            type: "direct",
+            host: null,
+            port: -1,
+          },
+        },
+      },
+      expected: {
+        proxyInfo: {
+          host: "1.2.3.4",
+          port: "8080",
+          type: "http",
+          failoverProxy: {
+            host: "4.4.4.4",
+            port: "9000",
+            type: "socks",
+            failoverProxy: {
+              type: "direct",
+              host: null,
+              port: -1,
+            },
+          },
+        },
+      },
+    },
+    {
+      proxy: [{ type: "http", host: "foo.bar", port: 3128 }],
+      expected: {
+        proxyInfo: {
+          host: "foo.bar",
+          port: "3128",
+          type: "http",
+        },
+      },
+    },
+    {
+      proxy: {
+        host: "foo.bar",
+        port: "1080",
+        type: "socks",
+      },
+      expected: {
+        proxyInfo: {
+          host: "foo.bar",
+          port: "1080",
+          type: "socks",
+        },
+      },
+    },
+    {
+      proxy: {
+        host: "foo.bar",
+        port: "1080",
+        type: "socks4",
+      },
+      expected: {
+        proxyInfo: {
+          host: "foo.bar",
+          port: "1080",
+          type: "socks4",
+        },
+      },
+    },
+    {
+      proxy: [{ type: "https", host: "foo.bar", port: 3128 }],
+      expected: {
+        proxyInfo: {
+          host: "foo.bar",
+          port: "3128",
+          type: "https",
+        },
+      },
+    },
+    {
+      proxy: [
+        {
+          type: "socks",
+          host: "foo.bar",
+          port: 1080,
+          username: "mungo",
+          password: "santamaria123",
+          proxyDNS: true,
+          failoverTimeout: 5,
+        },
+      ],
+      expected: {
+        proxyInfo: {
+          type: "socks",
+          host: "foo.bar",
+          port: 1080,
+          username: "mungo",
+          password: "santamaria123",
+          failoverTimeout: 5,
+          failoverProxy: null,
+          proxyDNS: TRANSPARENT_PROXY_RESOLVES_HOST,
+        },
+      },
+    },
+    {
+      proxy: [
+        {
+          type: "socks",
+          host: "foo.bar",
+          port: 1080,
+          username: "johnsmith",
+          password: "pass123",
+          proxyDNS: true,
+          failoverTimeout: 3,
+        },
+        { type: "http", host: "192.168.1.1", port: 3128 },
+        { type: "https", host: "192.168.1.2", port: 1121, failoverTimeout: 1 },
+        {
+          type: "socks",
+          host: "192.168.1.3",
+          port: 1999,
+          proxyDNS: true,
+          username: "mungosantamaria",
+          password: "foobar",
+        },
+      ],
+      expected: {
+        proxyInfo: {
+          type: "socks",
+          host: "foo.bar",
+          port: 1080,
+          proxyDNS: true,
+          username: "johnsmith",
+          password: "pass123",
+          failoverTimeout: 3,
+          failoverProxy: {
+            host: "192.168.1.1",
+            port: 3128,
+            type: "http",
+            failoverProxy: {
+              host: "192.168.1.2",
+              port: 1121,
+              type: "https",
+              failoverTimeout: 1,
+              failoverProxy: {
+                host: "192.168.1.3",
+                port: 1999,
+                type: "socks",
+                proxyDNS: TRANSPARENT_PROXY_RESOLVES_HOST,
+                username: "mungosantamaria",
+                password: "foobar",
+                failoverProxy: {
+                  type: "direct",
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+    {
+      proxy: [
+        {
+          type: "https",
+          host: "foo.bar",
+          port: 3128,
+          proxyAuthorizationHeader: "test",
+          connectionIsolationKey: "key",
+        },
+      ],
+      expected: {
+        proxyInfo: {
+          host: "foo.bar",
+          port: "3128",
+          type: "https",
+          proxyAuthorizationHeader: "test",
+          connectionIsolationKey: "key",
+        },
+      },
+    },
+  ];
+  for (let test of tests) {
+    await setupProxyResult(test.proxy);
+    if (!test.uri) {
+      test.uri = "http://www.mozilla.org/";
+    }
+    await testProxyResolution(test);
+  }
+});
+
+add_task(async function shutdown() {
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_proxy_listener.js b/toolkit/components/extensions/test/xpcshell/test_proxy_listener.js
new file mode 100644
index 0000000000..5dc099baf6
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_proxy_listener.js
@@ -0,0 +1,318 @@
+"use strict";
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "gProxyService",
+  "@mozilla.org/network/protocol-proxy-service;1",
+  "nsIProtocolProxyService"
+);
+
+const TRANSPARENT_PROXY_RESOLVES_HOST =
+  Ci.nsIProxyInfo.TRANSPARENT_PROXY_RESOLVES_HOST;
+
+function getProxyInfo(url = "http://www.mozilla.org/") {
+  return new Promise((resolve, reject) => {
+    let channel = NetUtil.newChannel({
+      uri: url,
+      loadUsingSystemPrincipal: true,
+    });
+
+    gProxyService.asyncResolve(channel, 0, {
+      onProxyAvailable(req, uri, pi, status) {
+        resolve(pi);
+      },
+    });
+  });
+}
+
+const testData = [
+  {
+    // An ExtensionError is thrown for this, but we are unable to catch it as we
+    // do with the PAC script api.  In this case, we expect null for proxyInfo.
+    proxyInfo: "not_defined",
+    expected: {
+      proxyInfo: null,
+    },
+  },
+  {
+    proxyInfo: 1,
+    expected: {
+      error: {
+        message:
+          "ProxyInfoData: proxyData must be an object or array of objects",
+      },
+    },
+  },
+  {
+    proxyInfo: [
+      {
+        type: "socks",
+        host: "foo.bar",
+        port: 1080,
+        username: "johnsmith",
+        password: "pass123",
+        proxyDNS: true,
+        failoverTimeout: 3,
+      },
+      { type: "http", host: "192.168.1.1", port: 3128 },
+      { type: "https", host: "192.168.1.2", port: 1121, failoverTimeout: 1 },
+      {
+        type: "socks",
+        host: "192.168.1.3",
+        port: 1999,
+        proxyDNS: true,
+        username: "mungosantamaria",
+        password: "foobar",
+      },
+      { type: "direct" },
+    ],
+    expected: {
+      proxyInfo: {
+        type: "socks",
+        host: "foo.bar",
+        port: 1080,
+        proxyDNS: true,
+        username: "johnsmith",
+        password: "pass123",
+        failoverTimeout: 3,
+        failoverProxy: {
+          host: "192.168.1.1",
+          port: 3128,
+          type: "http",
+          failoverProxy: {
+            host: "192.168.1.2",
+            port: 1121,
+            type: "https",
+            failoverTimeout: 1,
+            failoverProxy: {
+              host: "192.168.1.3",
+              port: 1999,
+              type: "socks",
+              proxyDNS: TRANSPARENT_PROXY_RESOLVES_HOST,
+              username: "mungosantamaria",
+              password: "foobar",
+              failoverProxy: {
+                type: "direct",
+              },
+            },
+          },
+        },
+      },
+    },
+  },
+];
+
+add_task(async function test_proxy_listener() {
+  let extensionData = {
+    manifest: {
+      permissions: ["proxy", "<all_urls>"],
+    },
+    background() {
+      // Some tests generate multiple errors, we'll just rely on the first.
+      let seenError = false;
+      let proxyInfo;
+      browser.proxy.onError.addListener(error => {
+        if (!seenError) {
+          browser.test.sendMessage("proxy-error-received", error);
+          seenError = true;
+        }
+      });
+
+      browser.proxy.onRequest.addListener(
+        details => {
+          browser.test.log(`onRequest ${JSON.stringify(details)}`);
+          if (proxyInfo == "not_defined") {
+            return not_defined; // eslint-disable-line no-undef
+          }
+          return proxyInfo;
+        },
+        { urls: ["<all_urls>"] }
+      );
+
+      browser.test.onMessage.addListener((message, data) => {
+        if (message === "set-proxy") {
+          seenError = false;
+          proxyInfo = data.proxyInfo;
+        }
+      });
+
+      browser.test.sendMessage("ready");
+    },
+  };
+
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  await extension.awaitMessage("ready");
+
+  for (let test of testData) {
+    extension.sendMessage("set-proxy", test);
+    let testError = test.expected.error;
+    let errorWait = testError && extension.awaitMessage("proxy-error-received");
+
+    let proxyInfo = await getProxyInfo();
+    let expectedProxyInfo = test.expected.proxyInfo;
+
+    if (testError) {
+      info("waiting for error data");
+      let error = await errorWait;
+      equal(error.message, testError.message, "Correct error message received");
+      equal(proxyInfo, null, "no proxyInfo received");
+    } else if (expectedProxyInfo === null) {
+      equal(proxyInfo, null, "no proxyInfo received");
+    } else {
+      for (
+        let proxyUsed = proxyInfo;
+        proxyUsed;
+        proxyUsed = proxyUsed.failoverProxy
+      ) {
+        let {
+          type,
+          host,
+          port,
+          username,
+          password,
+          proxyDNS,
+          failoverTimeout,
+        } = expectedProxyInfo;
+        equal(proxyUsed.host, host, `Expected proxy host to be ${host}`);
+        equal(proxyUsed.port, port || -1, `Expected proxy port to be ${port}`);
+        equal(proxyUsed.type, type, `Expected proxy type to be ${type}`);
+        // May be null or undefined depending on use of newProxyInfoWithAuth or newProxyInfo
+        equal(
+          proxyUsed.username || "",
+          username || "",
+          `Expected proxy username to be ${username}`
+        );
+        equal(
+          proxyUsed.password || "",
+          password || "",
+          `Expected proxy password to be ${password}`
+        );
+        equal(
+          proxyUsed.flags,
+          proxyDNS == undefined ? 0 : proxyDNS,
+          `Expected proxyDNS to be ${proxyDNS}`
+        );
+        // Default timeout is 10
+        equal(
+          proxyUsed.failoverTimeout,
+          failoverTimeout || 10,
+          `Expected failoverTimeout to be ${failoverTimeout}`
+        );
+        expectedProxyInfo = expectedProxyInfo.failoverProxy;
+      }
+      ok(!expectedProxyInfo, "no left over failoverProxy");
+    }
+  }
+
+  await extension.unload();
+});
+
+async function getExtension(expectedProxyInfo) {
+  function background(proxyInfo) {
+    browser.test.log(
+      `testing proxy.onRequest with proxyInfo = ${JSON.stringify(proxyInfo)}`
+    );
+    browser.proxy.onRequest.addListener(
+      details => {
+        return proxyInfo;
+      },
+      { urls: ["<all_urls>"] }
+    );
+  }
+  let extensionData = {
+    manifest: {
+      permissions: ["proxy", "<all_urls>"],
+    },
+    background: `(${background})(${JSON.stringify(expectedProxyInfo)})`,
+  };
+  let extension = ExtensionTestUtils.loadExtension(extensionData);
+  await extension.startup();
+  return extension;
+}
+
+add_task(async function test_passthrough() {
+  let ext1 = await getExtension(null);
+  let ext2 = await getExtension({ host: "1.2.3.4", port: 8888, type: "https" });
+
+  // Also use a restricted url to test the ability to proxy those.
+  let proxyInfo = await getProxyInfo("https://addons.mozilla.org/");
+
+  equal(proxyInfo.host, "1.2.3.4", `second extension won`);
+  equal(proxyInfo.port, "8888", `second extension won`);
+  equal(proxyInfo.type, "https", `second extension won`);
+
+  await ext2.unload();
+
+  proxyInfo = await getProxyInfo();
+  equal(proxyInfo, null, `expected no proxy`);
+  await ext1.unload();
+});
+
+add_task(async function test_ftp() {
+  Services.prefs.setBoolPref("network.ftp.enabled", true);
+  let extension = await getExtension({
+    host: "1.2.3.4",
+    port: 8888,
+    type: "http",
+  });
+
+  let proxyInfo = await getProxyInfo("ftp://somewhere.mozilla.org/");
+
+  equal(proxyInfo.host, "1.2.3.4", `proxy host correct`);
+  equal(proxyInfo.port, "8888", `proxy port correct`);
+  equal(proxyInfo.type, "http", `proxy type correct`);
+
+  await extension.unload();
+  Services.prefs.clearUserPref("network.ftp.enabled");
+});
+
+add_task(async function test_ftp_disabled() {
+  Services.prefs.setBoolPref("network.ftp.enabled", false);
+  let extension = await getExtension({
+    host: "1.2.3.4",
+    port: 8888,
+    type: "http",
+  });
+
+  let proxyInfo = await getProxyInfo("ftp://somewhere.mozilla.org/");
+
+  equal(
+    proxyInfo,
+    null,
+    `proxy of ftp request is not available when ftp is disabled`
+  );
+
+  await extension.unload();
+  Services.prefs.clearUserPref("network.ftp.enabled");
+});
+
+add_task(async function test_ws() {
+  let proxyRequestCount = 0;
+  let proxy = createHttpServer();
+  proxy.registerPathHandler("CONNECT", (request, response) => {
+    response.setStatusLine(request.httpVersion, 404, "Proxy not found");
+    ++proxyRequestCount;
+  });
+
+  let extension = await getExtension({
+    host: proxy.identity.primaryHost,
+    port: proxy.identity.primaryPort,
+    type: "http",
+  });
+
+  // We need a page to use the WebSocket constructor, so let's use an extension.
+  let dummy = ExtensionTestUtils.loadExtension({
+    background() {
+      // The connection will not be upgraded to WebSocket, so it will close.
+      let ws = new WebSocket("wss://example.net/");
+      ws.onclose = () => browser.test.sendMessage("websocket_closed");
+    },
+  });
+  await dummy.startup();
+  await dummy.awaitMessage("websocket_closed");
+  await dummy.unload();
+
+  equal(proxyRequestCount, 1, "Expected one proxy request");
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_proxy_userContextId.js b/toolkit/components/extensions/test/xpcshell/test_proxy_userContextId.js
new file mode 100644
index 0000000000..5dea560e02
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_proxy_userContextId.js
@@ -0,0 +1,43 @@
+"use strict";
+
+const server = createHttpServer({ hosts: ["example.com"] });
+
+server.registerPathHandler("/dummy", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  response.setHeader("Content-Type", "text/html", false);
+  response.write("<!DOCTYPE html><html></html>");
+});
+
+add_task(async function test_userContextId_proxy_onRequest() {
+  // This extension will succeed if it gets a request
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["proxy", "<all_urls>"],
+    },
+    background() {
+      browser.proxy.onRequest.addListener(
+        async details => {
+          if (details.url != "http://example.com/dummy") {
+            return;
+          }
+          browser.test.assertEq(
+            details.cookieStoreId,
+            "firefox-container-2",
+            "cookieStoreId is set"
+          );
+          browser.test.notifyPass("proxy.onRequest");
+        },
+        { urls: ["<all_urls>"] }
+      );
+    },
+  });
+  await extension.startup();
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/dummy",
+    { userContextId: 2 }
+  );
+  await extension.awaitFinish("proxy.onRequest");
+  await extension.unload();
+  await contentPage.close();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_webRequest_ancestors.js b/toolkit/components/extensions/test/xpcshell/test_webRequest_ancestors.js
new file mode 100644
index 0000000000..7c083c7805
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_webRequest_ancestors.js
@@ -0,0 +1,79 @@
+"use strict";
+
+var { WebRequest } = ChromeUtils.import(
+  "resource://gre/modules/WebRequest.jsm"
+);
+var { PromiseUtils } = ChromeUtils.import(
+  "resource://gre/modules/PromiseUtils.jsm"
+);
+var { ExtensionParent } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionParent.jsm"
+);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+add_task(async function setup() {
+  // When WebRequest.jsm is used directly instead of through ext-webRequest.js,
+  // ExtensionParent.apiManager is not automatically initialized. Do it here.
+  await ExtensionParent.apiManager.lazyInit();
+});
+
+add_task(async function test_ancestors_exist() {
+  let deferred = PromiseUtils.defer();
+  function onBeforeRequest(details) {
+    info(`onBeforeRequest ${details.url}`);
+    ok(
+      typeof details.frameAncestors === "object",
+      `ancestors exists [${typeof details.frameAncestors}]`
+    );
+    deferred.resolve();
+  }
+
+  WebRequest.onBeforeRequest.addListener(
+    onBeforeRequest,
+    { urls: new MatchPatternSet(["http://example.com/*"]) },
+    ["blocking"]
+  );
+
+  let contentPage = await ExtensionTestUtils.loadContentPage(
+    "http://example.com/data/file_sample.html"
+  );
+  await deferred.promise;
+  await contentPage.close();
+
+  WebRequest.onBeforeRequest.removeListener(onBeforeRequest);
+});
+
+add_task(async function test_ancestors_null() {
+  let deferred = PromiseUtils.defer();
+  function onBeforeRequest(details) {
+    info(`onBeforeRequest ${details.url}`);
+    ok(details.frameAncestors === undefined, "ancestors do not exist");
+    deferred.resolve();
+  }
+
+  WebRequest.onBeforeRequest.addListener(onBeforeRequest, null, ["blocking"]);
+
+  function fetch(url) {
+    return new Promise((resolve, reject) => {
+      let xhr = new XMLHttpRequest();
+      xhr.mozBackgroundRequest = true;
+      xhr.open("GET", url);
+      xhr.onload = () => {
+        resolve(xhr.responseText);
+      };
+      xhr.onerror = () => {
+        reject(xhr.status);
+      };
+      // use a different contextId to avoid auth cache.
+      xhr.setOriginAttributes({ userContextId: 1 });
+      xhr.send();
+    });
+  }
+
+  await fetch("http://example.com/data/file_sample.html");
+  await deferred.promise;
+
+  WebRequest.onBeforeRequest.removeListener(onBeforeRequest);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_webRequest_cookies.js b/toolkit/components/extensions/test/xpcshell/test_webRequest_cookies.js
new file mode 100644
index 0000000000..d13b2be40d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_webRequest_cookies.js
@@ -0,0 +1,102 @@
+"use strict";
+
+var { WebRequest } = ChromeUtils.import(
+  "resource://gre/modules/WebRequest.jsm"
+);
+
+var { ExtensionParent } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionParent.jsm"
+);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerPathHandler("/", (request, response) => {
+  response.setStatusLine(request.httpVersion, 200, "OK");
+  if (request.hasHeader("Cookie")) {
+    let value = request.getHeader("Cookie");
+    if (value == "blinky=1") {
+      response.setHeader("Set-Cookie", "dinky=1", false);
+    }
+    response.write("cookie-present");
+  } else {
+    response.setHeader("Set-Cookie", "foopy=1", false);
+    response.write("cookie-not-present");
+  }
+});
+
+const URL = "http://example.com/";
+
+var countBefore = 0;
+var countAfter = 0;
+
+function onBeforeSendHeaders(details) {
+  if (details.url != URL) {
+    return undefined;
+  }
+
+  countBefore++;
+
+  info(`onBeforeSendHeaders ${details.url}`);
+  let found = false;
+  let headers = [];
+  for (let { name, value } of details.requestHeaders) {
+    info(`Saw header ${name} '${value}'`);
+    if (name == "Cookie") {
+      equal(value, "foopy=1", "Cookie is correct");
+      headers.push({ name, value: "blinky=1" });
+      found = true;
+    } else {
+      headers.push({ name, value });
+    }
+  }
+  ok(found, "Saw cookie header");
+  equal(countBefore, 1, "onBeforeSendHeaders hit once");
+
+  return { requestHeaders: headers };
+}
+
+function onResponseStarted(details) {
+  if (details.url != URL) {
+    return;
+  }
+
+  countAfter++;
+
+  info(`onResponseStarted ${details.url}`);
+  let found = false;
+  for (let { name, value } of details.responseHeaders) {
+    info(`Saw header ${name} '${value}'`);
+    if (name == "set-cookie") {
+      equal(value, "dinky=1", "Cookie is correct");
+      found = true;
+    }
+  }
+  ok(found, "Saw cookie header");
+  equal(countAfter, 1, "onResponseStarted hit once");
+}
+
+add_task(async function setup() {
+  // When WebRequest.jsm is used directly instead of through ext-webRequest.js,
+  // ExtensionParent.apiManager is not automatically initialized. Do it here.
+  await ExtensionParent.apiManager.lazyInit();
+});
+
+add_task(async function filter_urls() {
+  // First load the URL so that we set cookie foopy=1.
+  let contentPage = await ExtensionTestUtils.loadContentPage(URL);
+  await contentPage.close();
+
+  // Now load with WebRequest set up.
+  WebRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, null, [
+    "blocking",
+    "requestHeaders",
+  ]);
+  WebRequest.onResponseStarted.addListener(onResponseStarted, null, [
+    "responseHeaders",
+  ]);
+
+  contentPage = await ExtensionTestUtils.loadContentPage(URL);
+  await contentPage.close();
+
+  WebRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
+  WebRequest.onResponseStarted.removeListener(onResponseStarted);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_webRequest_filtering.js b/toolkit/components/extensions/test/xpcshell/test_webRequest_filtering.js
new file mode 100644
index 0000000000..156ba6267d
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_webRequest_filtering.js
@@ -0,0 +1,182 @@
+"use strict";
+
+var { WebRequest } = ChromeUtils.import(
+  "resource://gre/modules/WebRequest.jsm"
+);
+
+var { ExtensionParent } = ChromeUtils.import(
+  "resource://gre/modules/ExtensionParent.jsm"
+);
+
+const server = createHttpServer({ hosts: ["example.com"] });
+server.registerDirectory("/data/", do_get_file("data"));
+
+const BASE = "http://example.com/data/";
+const URL = BASE + "/file_WebRequest_page2.html";
+
+var requested = [];
+
+function onBeforeRequest(details) {
+  info(`onBeforeRequest ${details.url}`);
+  if (details.url.startsWith(BASE)) {
+    requested.push(details.url);
+  }
+}
+
+var sendHeaders = [];
+
+function onBeforeSendHeaders(details) {
+  info(`onBeforeSendHeaders ${details.url}`);
+  if (details.url.startsWith(BASE)) {
+    sendHeaders.push(details.url);
+  }
+}
+
+var completed = [];
+
+function onResponseStarted(details) {
+  if (details.url.startsWith(BASE)) {
+    completed.push(details.url);
+  }
+}
+
+const expected_urls = [
+  BASE + "/file_style_good.css",
+  BASE + "/file_style_bad.css",
+  BASE + "/file_style_redirect.css",
+];
+
+function resetExpectations() {
+  requested.length = 0;
+  sendHeaders.length = 0;
+  completed.length = 0;
+}
+
+function removeDupes(list) {
+  let j = 0;
+  for (let i = 1; i < list.length; i++) {
+    if (list[i] != list[j]) {
+      j++;
+      if (i != j) {
+        list[j] = list[i];
+      }
+    }
+  }
+  list.length = j + 1;
+}
+
+function compareLists(list1, list2, kind) {
+  list1.sort();
+  removeDupes(list1);
+  list2.sort();
+  removeDupes(list2);
+  equal(String(list1), String(list2), `${kind} URLs correct`);
+}
+
+async function openAndCloseContentPage(url) {
+  let contentPage = await ExtensionTestUtils.loadContentPage(URL);
+  // Clear the sheet cache so that it doesn't interact with following tests: A
+  // stylesheet with the same URI loaded from the same origin doesn't otherwise
+  // guarantee that onBeforeRequest and so on happen, because it may not need
+  // to go through necko at all.
+  await contentPage.spawn(null, () =>
+    content.windowUtils.clearSharedStyleSheetCache()
+  );
+  await contentPage.close();
+}
+
+add_task(async function setup() {
+  // Disable rcwn to make cache behavior deterministic.
+  Services.prefs.setBoolPref("network.http.rcwn.enabled", false);
+
+  // When WebRequest.jsm is used directly instead of through ext-webRequest.js,
+  // ExtensionParent.apiManager is not automatically initialized. Do it here.
+  await ExtensionParent.apiManager.lazyInit();
+});
+
+add_task(async function filter_urls() {
+  let filter = { urls: new MatchPatternSet(["*://*/*_style_*"]) };
+
+  WebRequest.onBeforeRequest.addListener(onBeforeRequest, filter, ["blocking"]);
+  WebRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, filter, [
+    "blocking",
+  ]);
+  WebRequest.onResponseStarted.addListener(onResponseStarted, filter);
+
+  await openAndCloseContentPage(URL);
+
+  compareLists(requested, expected_urls, "requested");
+  compareLists(sendHeaders, expected_urls, "sendHeaders");
+  compareLists(completed, expected_urls, "completed");
+
+  WebRequest.onBeforeRequest.removeListener(onBeforeRequest);
+  WebRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
+  WebRequest.onResponseStarted.removeListener(onResponseStarted);
+});
+
+add_task(async function filter_types() {
+  resetExpectations();
+  let filter = { types: ["stylesheet"] };
+
+  WebRequest.onBeforeRequest.addListener(onBeforeRequest, filter, ["blocking"]);
+  WebRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, filter, [
+    "blocking",
+  ]);
+  WebRequest.onResponseStarted.addListener(onResponseStarted, filter);
+
+  await openAndCloseContentPage(URL);
+
+  compareLists(requested, expected_urls, "requested");
+  compareLists(sendHeaders, expected_urls, "sendHeaders");
+  compareLists(completed, expected_urls, "completed");
+
+  WebRequest.onBeforeRequest.removeListener(onBeforeRequest);
+  WebRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
+  WebRequest.onResponseStarted.removeListener(onResponseStarted);
+});
+
+add_task(async function filter_windowId() {
+  resetExpectations();
+  // Check that adding windowId will exclude non-matching requests.
+  // test_ext_webrequest_filter.html provides coverage for matching requests.
+  let filter = { urls: new MatchPatternSet(["*://*/*_style_*"]), windowId: 0 };
+
+  WebRequest.onBeforeRequest.addListener(onBeforeRequest, filter, ["blocking"]);
+  WebRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, filter, [
+    "blocking",
+  ]);
+  WebRequest.onResponseStarted.addListener(onResponseStarted, filter);
+
+  await openAndCloseContentPage(URL);
+
+  compareLists(requested, [], "requested");
+  compareLists(sendHeaders, [], "sendHeaders");
+  compareLists(completed, [], "completed");
+
+  WebRequest.onBeforeRequest.removeListener(onBeforeRequest);
+  WebRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
+  WebRequest.onResponseStarted.removeListener(onResponseStarted);
+});
+
+add_task(async function filter_tabId() {
+  resetExpectations();
+  // Check that adding tabId will exclude non-matching requests.
+  // test_ext_webrequest_filter.html provides coverage for matching requests.
+  let filter = { urls: new MatchPatternSet(["*://*/*_style_*"]), tabId: 0 };
+
+  WebRequest.onBeforeRequest.addListener(onBeforeRequest, filter, ["blocking"]);
+  WebRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, filter, [
+    "blocking",
+  ]);
+  WebRequest.onResponseStarted.addListener(onResponseStarted, filter);
+
+  await openAndCloseContentPage(URL);
+
+  compareLists(requested, [], "requested");
+  compareLists(sendHeaders, [], "sendHeaders");
+  compareLists(completed, [], "completed");
+
+  WebRequest.onBeforeRequest.removeListener(onBeforeRequest);
+  WebRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
+  WebRequest.onResponseStarted.removeListener(onResponseStarted);
+});
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-common-e10s.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-common-e10s.ini
new file mode 100644
index 0000000000..332921e685
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-common-e10s.ini
@@ -0,0 +1,13 @@
+# Similar to xpcshell-common.ini, except tests here only run
+# when e10s is enabled (with or without out-of-process extensions).
+
+[test_ext_webRequest_filterResponseData.js]
+# tsan failure is for test_filter_301 timing out, bug 1674773
+skip-if = tsan || os == "android" && debug
+[test_ext_webRequest_redirect_StreamFilter.js]
+[test_ext_webRequest_responseBody.js]
+skip-if = os == "android" && debug
+[test_ext_webRequest_startup_StreamFilter.js]
+skip-if = os == "android" && debug
+[test_ext_webRequest_viewsource_StreamFilter.js]
+skip-if = tsan # Bug 1683730
\ No newline at end of file
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
new file mode 100644
index 0000000000..32d76194bb
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
@@ -0,0 +1,260 @@
+[DEFAULT]
+# Some tests of downloads.download() expect a file picker, which is only shown
+# by default when the browser.download.useDownloadDir pref is set to true. This
+# is the case on desktop Firefox, but not on Thunderbird.
+# Force pref value to true to get download tests to pass on Thunderbird.
+prefs = browser.download.useDownloadDir=true
+
+[test_change_remote_mode.js]
+[test_ext_MessageManagerProxy.js]
+skip-if = os == 'android' # Bug 1545439
+[test_ext_activityLog.js]
+[test_ext_alarms.js]
+[test_ext_alarms_does_not_fire.js]
+[test_ext_alarms_periodic.js]
+[test_ext_alarms_replaces.js]
+[test_ext_api_permissions.js]
+[test_ext_background_api_injection.js]
+[test_ext_background_early_shutdown.js]
+[test_ext_background_generated_load_events.js]
+[test_ext_background_generated_reload.js]
+[test_ext_background_global_history.js]
+skip-if = os == "android" # Android does not use Places for history.
+[test_ext_background_private_browsing.js]
+[test_ext_background_runtime_connect_params.js]
+[test_ext_background_sub_windows.js]
+[test_ext_background_teardown.js]
+[test_ext_background_telemetry.js]
+[test_ext_background_window_properties.js]
+skip-if = os == "android"
+[test_ext_browserSettings.js]
+[test_ext_browserSettings_homepage.js]
+skip-if = appname == "thunderbird" || os == "android"
+[test_ext_browsingData.js]
+[test_ext_browsingData_cookies_cache.js]
+[test_ext_browsingData_cookies_cookieStoreId.js]
+[test_ext_captivePortal.js]
+# As with test_captive_portal_service.js, we use the same limits here.
+skip-if = appname == "thunderbird" || os == "android" || (os == "mac" && debug) # CP service is disabled on Android, macosx1014/debug due to 1564534
+run-sequentially = node server exceptions dont replay well
+[test_ext_captivePortal_url.js]
+# As with test_captive_portal_service.js, we use the same limits here.
+skip-if = appname == "thunderbird" || os == "android" || (os == "mac" && debug) # CP service is disabled on Android, macosx1014/debug due to 1564534
+run-sequentially = node server exceptions dont replay well
+[test_ext_cookieBehaviors.js]
+skip-if = appname == "thunderbird" || tsan # Bug 1683730
+[test_ext_cookies_firstParty.js]
+skip-if = appname == "thunderbird" || os == "android" || tsan # Android: Bug 1680132. tsan: Bug 1683730 
+[test_ext_cookies_samesite.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_content_security_policy.js]
+skip-if = (os == "win" && debug) #Bug 1485567
+[test_ext_contentscript_api_injection.js]
+[test_ext_contentscript_async_loading.js]
+skip-if = os == 'android' && debug # The generated script takes too long to load on Android debug
+[test_ext_contentscript_context.js]
+skip-if = tsan # Bug 1683730
+[test_ext_contentscript_context_isolation.js]
+skip-if = tsan # Bug 1683730
+[test_ext_contentscript_create_iframe.js]
+[test_ext_contentscript_csp.js]
+[test_ext_contentscript_css.js]
+[test_ext_contentscript_exporthelpers.js]
+[test_ext_contentscript_in_background.js]
+[test_ext_contentscript_restrictSchemes.js]
+[test_ext_contentscript_teardown.js]
+skip-if = tsan # Bug 1683730
+[test_ext_contentscript_unregister_during_loadContentScript.js]
+[test_ext_contentscript_xml_prettyprint.js]
+[test_ext_contextual_identities.js]
+skip-if = appname == "thunderbird" || os == "android" # Containers are not exposed to android.
+[test_ext_debugging_utils.js]
+[test_ext_dns.js]
+skip-if = socketprocess_networking || os == "android" # Android: Bug 1680132
+[test_ext_downloads.js]
+[test_ext_downloads_cookies.js]
+skip-if = os == "android" # downloads API needs to be implemented in GeckoView - bug 1538348
+[test_ext_downloads_download.js]
+skip-if = appname == "thunderbird" || os == "android" || tsan # tsan: bug 1612707
+[test_ext_downloads_misc.js]
+skip-if = os == "android" || (os=='linux' && bits==32) || tsan # linux32: bug 1324870, tsan: bug 1612707
+[test_ext_downloads_private.js]
+skip-if = os == "android"
+[test_ext_downloads_search.js]
+skip-if = os == "android" || tsan # tsan: bug 1612707
+[test_ext_downloads_urlencoded.js]
+skip-if = os == "android"
+[test_ext_error_location.js]
+[test_ext_eventpage_warning.js]
+[test_ext_experiments.js]
+[test_ext_extension.js]
+[test_ext_extensionPreferencesManager.js]
+[test_ext_extensionSettingsStore.js]
+[test_ext_extension_content_telemetry.js]
+skip-if = os == "android" # checking for telemetry needs to be updated: 1384923
+[test_ext_extension_startup_failure.js]
+[test_ext_extension_startup_telemetry.js]
+[test_ext_file_access.js]
+[test_ext_geckoProfiler_control.js]
+skip-if = os == "android" || tsan # Not shipped on Android. tsan: bug 1612707
+[test_ext_geturl.js]
+[test_ext_idle.js]
+[test_ext_incognito.js]
+skip-if = appname == "thunderbird"
+[test_ext_l10n.js]
+[test_ext_localStorage.js]
+[test_ext_management.js]
+skip-if = (os == "win" && !debug) #Bug 1419183 disable on Windows
+[test_ext_management_uninstall_self.js]
+[test_ext_messaging_startup.js]
+skip-if = appname == "thunderbird" || (os == "android" && debug)
+[test_ext_networkStatus.js]
+[test_ext_notifications_incognito.js]
+skip-if = appname == "thunderbird"
+[test_ext_notifications_unsupported.js]
+[test_ext_onmessage_removelistener.js]
+skip-if = true # This test no longer tests what it is meant to test.
+[test_ext_permission_xhr.js]
+[test_ext_persistent_events.js]
+[test_ext_privacy.js]
+skip-if = appname == "thunderbird" || (os == "android" && debug) || (os == "linux" && !debug) #Bug 1625455
+[test_ext_privacy_disable.js]
+skip-if = appname == "thunderbird"
+[test_ext_privacy_update.js]
+[test_ext_proxy_authorization_via_proxyinfo.js]
+skip-if = true # Bug 1622433 needs h2 proxy implementation
+[test_ext_proxy_config.js]
+skip-if = appname == "thunderbird" || os == "android" # Android: Bug 1680132
+[test_ext_proxy_onauthrequired.js]
+[test_ext_proxy_settings.js]
+skip-if = appname == "thunderbird" || os == "android" # proxy settings are not supported on android
+[test_ext_proxy_socks.js]
+skip-if = socketprocess_networking
+run-sequentially = TCPServerSocket fails otherwise
+[test_ext_proxy_speculative.js]
+skip-if = ccov && os == 'linux' # bug 1607581
+[test_ext_proxy_startup.js]
+skip-if = ccov && os == 'linux' # bug 1607581
+[test_ext_redirects.js]
+skip-if = os == "android" && debug
+[test_ext_runtime_connect_no_receiver.js]
+[test_ext_runtime_getBrowserInfo.js]
+[test_ext_runtime_getPlatformInfo.js]
+[test_ext_runtime_id.js]
+skip-if = ccov && os == 'linux' # bug 1607581
+[test_ext_runtime_messaging_self.js]
+[test_ext_runtime_onInstalled_and_onStartup.js]
+[test_ext_runtime_ports.js]
+[test_ext_runtime_ports_gc.js]
+[test_ext_runtime_sendMessage.js]
+[test_ext_runtime_sendMessage_errors.js]
+[test_ext_runtime_sendMessage_multiple.js]
+[test_ext_runtime_sendMessage_no_receiver.js]
+[test_ext_same_site_cookies.js]
+[test_ext_same_site_redirects.js]
+[test_ext_sandbox_var.js]
+[test_ext_schema.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_shared_workers.js]
+[test_ext_shutdown_cleanup.js]
+[test_ext_simple.js]
+[test_ext_startupData.js]
+[test_ext_startup_cache.js]
+skip-if = os == "android"
+[test_ext_startup_perf.js]
+[test_ext_startup_request_handler.js]
+[test_ext_storage_local.js]
+skip-if = os == "android" && debug
+[test_ext_storage_idb_data_migration.js]
+skip-if = appname == "thunderbird" || (os == "android" && debug)
+[test_ext_storage_content_local.js]
+skip-if = os == "android" && debug
+[test_ext_storage_content_sync.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_storage_content_sync_kinto.js]
+skip-if = os == "android" && debug
+[test_ext_storage_quota_exceeded_errors.js]
+skip-if = os == "android" # Bug 1564871
+[test_ext_storage_managed.js]
+skip-if = os == "android"
+[test_ext_storage_managed_policy.js]
+skip-if = appname == "thunderbird" || os == "android"
+[test_ext_storage_sanitizer.js]
+skip-if = appname == "thunderbird" || os == "android" # Android: Bug 1680132
+[test_ext_storage_sync.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_storage_sync_kinto.js]
+skip-if = appname == "thunderbird" || os == "android"
+[test_ext_storage_sync_kinto_crypto.js]
+skip-if = appname == "thunderbird" || os == "android"
+[test_ext_storage_tab.js]
+[test_ext_storage_telemetry.js]
+skip-if = os == "android" # checking for telemetry needs to be updated: 1384923
+[test_ext_tab_teardown.js]
+skip-if = os == 'android' # Bug 1258975 on android.
+[test_ext_telemetry.js]
+[test_ext_trustworthy_origin.js]
+[test_ext_unlimitedStorage.js]
+[test_ext_unload_frame.js]
+skip-if = true # Too frequent intermittent failures
+[test_ext_userScripts.js]
+[test_ext_userScripts_exports.js]
+[test_ext_userScripts_telemetry.js]
+[test_ext_webRequest_auth.js]
+skip-if = os == "android" && debug
+[test_ext_webRequest_cached.js]
+skip-if = os == "android" # Bug 1573511
+[test_ext_webRequest_cancelWithReason.js]
+[test_ext_webRequest_download.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_webRequest_filterTypes.js]
+[test_ext_webRequest_from_extension_page.js]
+[test_ext_webRequest_incognito.js]
+skip-if = os == "android" && debug
+[test_ext_webRequest_filter_urls.js]
+[test_ext_webRequest_host.js]
+skip-if = os == "android" && debug
+[test_ext_webRequest_mergecsp.js]
+skip-if = tsan # Bug 1683730
+[test_ext_webRequest_permission.js]
+skip-if = os == "android" && debug
+[test_ext_webRequest_redirect_mozextension.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_webRequest_requestSize.js]
+skip-if = socketprocess_networking
+[test_ext_webRequest_set_cookie.js]
+skip-if = appname == "thunderbird"
+[test_ext_webRequest_startup.js]
+skip-if = os == "android" # bug 1683159
+[test_ext_webRequest_style_cache.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_webRequest_suspend.js]
+[test_ext_webRequest_userContextId.js]
+[test_ext_webRequest_viewsource.js]
+[test_ext_webRequest_webSocket.js]
+skip-if = appname == "thunderbird"
+[test_ext_xhr_capabilities.js]
+[test_native_manifests.js]
+subprocess = true
+skip-if = os == "android"
+[test_ext_permissions.js]
+skip-if = appname == "thunderbird" || os == "android" # Bug 1350559
+[test_ext_permissions_api.js]
+skip-if = appname == "thunderbird" || os == "android" # Bug 1350559
+[test_ext_permissions_migrate.js]
+skip-if = appname == "thunderbird" || os == "android" # Bug 1350559
+[test_ext_permissions_uninstall.js]
+skip-if = appname == "thunderbird" || os == "android" # Bug 1350559
+[test_proxy_listener.js]
+skip-if = appname == "thunderbird"
+[test_proxy_incognito.js]
+skip-if = os == "android" # incognito not supported on android
+[test_proxy_info_results.js]
+[test_proxy_userContextId.js]
+[test_webRequest_ancestors.js]
+[test_webRequest_cookies.js]
+[test_webRequest_filtering.js]
+[test_ext_brokenlinks.js]
+skip-if = os == "android" # Android: Bug 1680132
+[test_ext_performance_counters.js]
+skip-if = appname == "thunderbird" || os == "android"
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-content.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-content.ini
new file mode 100644
index 0000000000..0950f7a9d3
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-content.ini
@@ -0,0 +1,22 @@
+[DEFAULT]
+prefs =
+  javascript.options.experimental.private_fields=true
+
+[test_ext_i18n.js]
+skip-if = os == "android" || (os == "win" && debug) || (os == "linux")
+[test_ext_i18n_css.js]
+[test_ext_contentscript.js]
+[test_ext_contentscript_about_blank_start.js]
+[test_ext_contentscript_canvas_tainting.js]
+[test_ext_contentscript_scriptCreated.js]
+[test_ext_contentscript_triggeringPrincipal.js]
+skip-if = os == "android" || (os == "win" && debug) || tsan || socketprocess_networking # Windows: Bug 1438796, tsan: bug 1612707, Android: Bug 1680132
+[test_ext_contentscript_xrays.js]
+[test_ext_contentScripts_register.js]
+[test_ext_contexts_gc.js]
+[test_ext_adoption_with_xrays.js]
+[test_ext_adoption_with_private_field_xrays.js]
+skip-if = !nightly_build
+[test_ext_shadowdom.js]
+skip-if = ccov && os == 'linux' # bug 1607581
+[test_ext_web_accessible_resources.js]
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-e10s.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-e10s.ini
new file mode 100644
index 0000000000..228492d00b
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-e10s.ini
@@ -0,0 +1,28 @@
+[DEFAULT]
+head = head.js head_e10s.js
+tail =
+firefox-appdir = browser
+skip-if = appname == "thunderbird" || os == "android"
+dupe-manifest =
+support-files =
+  data/**
+  xpcshell-content.ini
+tags = webextensions webextensions-e10s
+
+# services.settings.server/default_bucket:
+# Make sure that loading the default settings for url-classifier-skip-urls
+# doesn't interfere with running our tests while IDB operations are in
+# flight by overriding the default remote settings bucket pref name to
+# ensure that the IDB database isn't created in the first place.
+prefs =
+  services.settings.server=http://localhost:7777/remote-settings-dummy/v1
+  services.settings.default_bucket=nonexistent-bucket-foo
+
+[include:xpcshell-common-e10s.ini]
+[include:xpcshell-content.ini]
+
+# Tests that need to run with e10s only must NOT be placed here,
+# but in xpcshell-common-e10s.ini.
+# A test here will only run on one configuration, e10s + in-process extensions,
+# while the primary target is e10s + out-of-process extensions.
+# xpcshell-common-e10s.ini runs in both configurations.
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-legacy-ep.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-legacy-ep.ini
new file mode 100644
index 0000000000..2df5e54b68
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-legacy-ep.ini
@@ -0,0 +1,23 @@
+[DEFAULT]
+head = head.js head_remote.js head_e10s.js head_legacy_ep.js
+tail =
+firefox-appdir = browser
+skip-if = appname == "thunderbird" || os == "android"
+dupe-manifest =
+
+# services.settings.server/default_bucket:
+# Make sure that loading the default settings for url-classifier-skip-urls
+# doesn't interfere with running our tests while IDB operations are in
+# flight by overriding the default remote settings bucket pref name to
+# ensure that the IDB database isn't created in the first place.
+prefs =
+  services.settings.server=http://localhost:7777/remote-settings-dummy/v1
+  services.settings.default_bucket=nonexistent-bucket-foo
+
+# Bug 1646182: Test the legacy ExtensionPermission backend until we fully
+# migrate to rkv
+[test_ext_permissions.js]
+[test_ext_permissions_api.js]
+[test_ext_permissions_migrate.js]
+[test_ext_permissions_uninstall.js]
+[test_ext_proxy_config.js]
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini
new file mode 100644
index 0000000000..2ccd923230
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-remote.ini
@@ -0,0 +1,30 @@
+[DEFAULT]
+head = head.js head_remote.js head_e10s.js head_telemetry.js head_sync.js head_storage.js
+tail =
+firefox-appdir = browser
+skip-if = os == "android"
+dupe-manifest =
+support-files =
+  data/**
+  xpcshell-content.ini
+tags = webextensions remote-webextensions
+
+# services.settings.server/default_bucket:
+# Make sure that loading the default settings for url-classifier-skip-urls
+# doesn't interfere with running our tests while IDB operations are in
+# flight by overriding the default remote settings bucket pref name to
+# ensure that the IDB database isn't created in the first place.
+prefs =
+  services.settings.server=http://localhost:7777/remote-settings-dummy/v1
+  services.settings.default_bucket=nonexistent-bucket-foo
+
+[include:xpcshell-common.ini]
+[include:xpcshell-common-e10s.ini]
+[include:xpcshell-content.ini]
+
+[test_ext_contentscript_perf_observers.js] # Inexplicably, PerformanceObserver used in the test doesn't fire in non-e10s mode.
+skip-if = tsan
+[test_ext_contentscript_xorigin_frame.js]
+[test_WebExtensionContentScript.js]
+[test_ext_ipcBlob.js]
+skip-if = os == 'android' && processor == 'x86_64'
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell.ini b/toolkit/components/extensions/test/xpcshell/xpcshell.ini
new file mode 100644
index 0000000000..27086a31ef
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell.ini
@@ -0,0 +1,89 @@
+[DEFAULT]
+head = head.js head_telemetry.js head_sync.js head_storage.js
+firefox-appdir = browser
+dupe-manifest =
+support-files =
+  data/**
+  xpcshell-content.ini
+tags = webextensions in-process-webextensions
+
+# services.settings.server/default_bucket:
+# Make sure that loading the default settings for url-classifier-skip-urls
+# doesn't interfere with running our tests while IDB operations are in
+# flight by overriding the default remote settings bucket pref name to
+# ensure that the IDB database isn't created in the first place.
+prefs =
+  services.settings.server=http://localhost:7777/remote-settings-dummy/v1
+  services.settings.default_bucket=nonexistent-bucket-foo
+
+# This file contains tests which are not affected by multi-process
+# configuration, or do not support out-of-process content or extensions
+# for one reason or another.
+#
+# Tests which are affected by remote content or remote extensions should
+# go in one of:
+#
+#  - xpcshell-common.ini
+#    For tests which should run in all configurations.
+#  - xpcshell-common-e10s.ini
+#    For tests which should run in all configurations where e10s is enabled.
+#  - xpcshell-remote.ini
+#    For tests which should only run with both remote extensions and remote content.
+#  - xpcshell-content.ini
+#    For tests which rely on content pages, and should run in all configurations.
+#  - xpcshell-e10s.ini
+#    For tests which rely on content pages, and should only run with remote content
+#    but in-process extensions.
+
+[test_ExtensionStorageSync_migration_kinto.js]
+skip-if = os == 'android' # Not shipped on Android
+[test_MatchPattern.js]
+[test_StorageSyncService.js]
+skip-if = os == 'android' && processor == 'x86_64'
+[test_WebExtensionPolicy.js]
+
+[test_csp_custom_policies.js]
+[test_csp_validator.js]
+[test_ext_contexts.js]
+[test_ext_json_parser.js]
+[test_ext_geckoProfiler_schema.js]
+skip-if = os == 'android' # Not shipped on Android
+[test_ext_manifest.js]
+skip-if = toolkit == 'android' # browser_action icon testing not supported on android
+[test_ext_manifest_content_security_policy.js]
+[test_ext_manifest_incognito.js]
+[test_ext_indexedDB_principal.js]
+[test_ext_manifest_minimum_chrome_version.js]
+[test_ext_manifest_minimum_opera_version.js]
+[test_ext_manifest_themes.js]
+[test_ext_permission_warnings.js]
+[test_ext_schemas.js]
+[test_ext_schemas_roots.js]
+[test_ext_schemas_async.js]
+[test_ext_schemas_allowed_contexts.js]
+[test_ext_schemas_interactive.js]
+skip-if = os == 'android' && processor == 'x86_64'
+[test_ext_schemas_manifest_permissions.js]
+skip-if = os == 'android' && processor == 'x86_64'
+[test_ext_schemas_privileged.js]
+skip-if = os == 'android' && processor == 'x86_64'
+[test_ext_schemas_revoke.js]
+[test_ext_test_mock.js]
+skip-if = os == 'android' && processor == 'x86_64'
+[test_ext_test_wrapper.js]
+[test_ext_unknown_permissions.js]
+skip-if = os == 'android' && processor == 'x86_64'
+[test_ext_webRequest_urlclassification.js]
+[test_extension_permissions_migration.js]
+[test_load_all_api_modules.js]
+[test_locale_converter.js]
+[test_locale_data.js]
+skip-if = os == 'android' && processor == 'x86_64'
+
+[test_ext_runtime_sendMessage_args.js]
+skip-if = os == 'android' && processor == 'x86_64'
+
+[include:xpcshell-common.ini]
+run-if = os == 'android' # Android has no remote extensions, Bug 1535365
+[include:xpcshell-content.ini]
+run-if = os == 'android' # Android has no remote extensions, Bug 1535365
-- 
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