Merging upstream version 125.0.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

79 files changed, 2371 insertions, 2207 deletions

diff --git a/browser/base/content/appmenu-viewcache.inc.xhtml b/browser/base/content/appmenu-viewcache.inc.xhtml
index 07b1765f18..04bba182fb 100644
--- a/browser/base/content/appmenu-viewcache.inc.xhtml
+++ b/browser/base/content/appmenu-viewcache.inc.xhtml
@@ -38,6 +38,13 @@
           </vbox>
         </toolbarbutton>
       </toolbaritem>
+      <toolbarbutton id="appMenu-profiles-button"
+                     class="subviewbutton subviewbutton-nav"
+                     data-l10n-id="appmenuitem-profiles"
+                     data-l10n-args='{ "profilename": "" }'
+                     closemenu="none"
+                     oncommand="gProfiles.updateView(this)"
+                     hidden="true"/>
       <toolbarseparator id="appMenu-fxa-separator" class="proton-zap"/>
       <toolbarbutton id="appMenu-new-tab-button2"
                      class="subviewbutton"
@@ -212,6 +219,39 @@
                    oncommand="PlacesCommandHook.showPlacesOrganizer('History'); CustomizableUI.hidePanelForNode(this);"/>
   </panelview>
 
+  <panelview id="PanelUI-profiles" flex="1">
+    <vbox class="panel-subview-body">
+      <vbox id="current-profile">
+        <image id="profile-icon-image"></image>
+        <h2 id="profile-name"></h2>
+        <hbox id="this-profile-buttons">
+          <toolbarbutton id="profiles-edit-this-delete-button"
+                         class="subviewbutton toolbarbutton-1"
+                         oncommand="switchToTabHavingURI('about:profilemanager', true)"/>
+          <toolbarbutton id="profiles-delete-this-profile-button"
+                         class="subviewbutton toolbarbutton-1"
+                         oncommand="switchToTabHavingURI('about:profilemanager', true)"/>
+        </hbox>
+      </vbox>
+      <toolbarseparator/>
+      <vbox id="profiles-list"></vbox>
+      <toolbarseparator/>
+      <toolbarbutton id="profiles-close-profile-button"
+                     class="subviewbutton"
+                     data-l10n-id="appmenu-close-profile"
+                     data-l10n-args='{ "profilename": "" }'
+                     oncommand=""/>
+      <toolbarbutton id="profiles-create-profile-button"
+                     class="subviewbutton"
+                     data-l10n-id="appmenu-create-profile"
+                     oncommand="switchToTabHavingURI('about:profilemanager', true)"/>
+      <toolbarbutton id="profiles-manage-profiles-button"
+                     class="subviewbutton"
+                     data-l10n-id="appmenu-manage-profiles"
+                     oncommand="switchToTabHavingURI('about:profilemanager', true)"/>
+    </vbox>
+  </panelview>
+
   <panelview id="appMenu-library-recentlyClosedTabs"/>
   <panelview id="appMenu-library-recentlyClosedWindows"/>
 
diff --git a/browser/base/content/browser-context.inc b/browser/base/content/browser-context.inc
index 9230c07f6a..ff4015e3d4 100644
--- a/browser/base/content/browser-context.inc
+++ b/browser/base/content/browser-context.inc
@@ -313,6 +313,9 @@
       <menuitem id="context-selectall"
                 data-l10n-id="text-action-select-all"
                 command="cmd_selectAll"/>
+      <menuitem id="context-pdfjs-highlight-selection"
+                data-l10n-id="text-action-highlight-selection"
+                oncommand="gContextMenu.pdfJSCmd('highlightSelection');"/>
       <menuitem id="context-reveal-password"
                 type="checkbox"
                 data-l10n-id="main-context-menu-reveal-password"
@@ -358,7 +361,8 @@
       <menuitem id="context-searchselect-private"
                 oncommand="BrowserSearch.loadSearchFromContext(this.searchTerms, true, this.principal, this.csp, event);"/>
       <menuitem id="context-translate-selection"
-                data-l10n-id="main-context-menu-translate-selection"/>
+                data-l10n-id="main-context-menu-translate-selection"
+                oncommand="gContextMenu.openSelectTranslationsPanel(event);"/>
 
       <menuseparator id="frame-sep"/>
       <menu id="frame" data-l10n-id="main-context-menu-frame">
diff --git a/browser/base/content/browser-ctrlTab.js b/browser/base/content/browser-ctrlTab.js
index 31617f13a3..d4d79a6886 100644
--- a/browser/base/content/browser-ctrlTab.js
+++ b/browser/base/content/browser-ctrlTab.js
@@ -581,7 +581,7 @@ var ctrlTab = {
       return;
     }
 
-    Services.els.addSystemEventListener(document, "keyup", this, false);
+    document.addEventListener("keyup", this, { mozSystemGroup: true });
 
     let tabs = gBrowser.visibleTabs;
     if (tabs.length > 2) {
@@ -706,12 +706,7 @@ var ctrlTab = {
         event.stopPropagation();
 
         if (event.keyCode === event.DOM_VK_CONTROL) {
-          Services.els.removeSystemEventListener(
-            document,
-            "keyup",
-            this,
-            false
-          );
+          document.removeEventListener("keyup", this, { mozSystemGroup: true });
 
           if (this.isOpen) {
             this.pick();
@@ -787,9 +782,9 @@ var ctrlTab = {
     tabContainer[toggleEventListener]("TabShow", this);
 
     if (enable) {
-      Services.els.addSystemEventListener(document, "keydown", this, false);
+      document.addEventListener("keydown", this, { mozSystemGroup: true });
     } else {
-      Services.els.removeSystemEventListener(document, "keydown", this, false);
+      document.removeEventListener("keydown", this, { mozSystemGroup: true });
     }
     document[toggleEventListener]("keypress", this);
     gBrowser.tabbox.handleCtrlTab = !enable;
diff --git a/browser/base/content/browser-places.js b/browser/base/content/browser-places.js
index 6992d22069..58e61f7bf7 100644
--- a/browser/base/content/browser-places.js
+++ b/browser/base/content/browser-places.js
@@ -392,7 +392,7 @@ var PlacesCommandHook = {
    */
   async bookmarkPage() {
     let browser = gBrowser.selectedBrowser;
-    let url = URL.fromURI(browser.currentURI);
+    let url = URL.fromURI(Services.io.createExposableURI(browser.currentURI));
     let info = await PlacesUtils.bookmarks.fetch({ url });
     let isNewBookmark = !info;
     let showEditUI = !isNewBookmark || StarUI.showForNewBookmarks;
@@ -490,6 +490,21 @@ var PlacesCommandHook = {
   },
 
   /**
+   * Bookmarks the given tabs loaded in the current browser.
+   * @param {Array} tabs
+   *        If no given tabs, bookmark all current tabs.
+   */
+  async bookmarkTabs(tabs) {
+    tabs = tabs ?? gBrowser.visibleTabs.filter(tab => !tab.pinned);
+    let pages = PlacesCommandHook.getUniquePages(tabs).map(
+      // Bookmark exposable url.
+      page =>
+        Object.assign(page, { uri: Services.io.createExposableURI(page.uri) })
+    );
+    await PlacesUIUtils.showBookmarkPagesDialog(pages);
+  },
+
+  /**
    * List of nsIURI objects characterizing tabs given in param.
    * Duplicates are discarded.
    */
@@ -511,24 +526,6 @@ var PlacesCommandHook = {
   },
 
   /**
-   * List of nsIURI objects characterizing the tabs currently open in the
-   * browser, modulo pinned tabs. The URIs will be in the order in which their
-   * corresponding tabs appeared and duplicates are discarded.
-   */
-  get uniqueCurrentPages() {
-    let visibleUnpinnedTabs = gBrowser.visibleTabs.filter(tab => !tab.pinned);
-    return this.getUniquePages(visibleUnpinnedTabs);
-  },
-
-  /**
-   * List of nsIURI objects characterizing the tabs currently
-   * selected in the window. Duplicates are discarded.
-   */
-  get uniqueSelectedPages() {
-    return this.getUniquePages(gBrowser.selectedTabs);
-  },
-
-  /**
    * Opens the Places Organizer.
    * @param {String} item The item to select in the organizer window,
    *                      options are (case sensitive):
diff --git a/browser/base/content/browser-profiles.js b/browser/base/content/browser-profiles.js
new file mode 100644
index 0000000000..72eca39e44
--- /dev/null
+++ b/browser/base/content/browser-profiles.js
@@ -0,0 +1,99 @@
+/* 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/. */
+
+// This file is loaded into the browser window scope.
+/* eslint-env mozilla/browser-window */
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "ProfileService",
+  "@mozilla.org/toolkit/profile-service;1",
+  "nsIToolkitProfileService"
+);
+
+var gProfiles = {
+  init() {
+    XPCOMUtils.defineLazyPreferenceGetter(
+      this,
+      "PROFILES_ENABLED",
+      "browser.profiles.enabled",
+      false,
+      this.toggleProfileButtonsVisibility.bind(this)
+    );
+
+    if (!this.PROFILES_ENABLED) {
+      return;
+    }
+
+    this.toggleProfileButtonsVisibility();
+  },
+
+  toggleProfileButtonsVisibility() {
+    let profilesButton = PanelMultiView.getViewNode(
+      document,
+      "appMenu-profiles-button"
+    );
+
+    profilesButton.hidden = !this.PROFILES_ENABLED;
+
+    if (this.PROFILES_ENABLED) {
+      document.l10n.setArgs(profilesButton, {
+        profilename: ProfileService.currentProfile?.name ?? "",
+      });
+    }
+  },
+
+  updateView(panel) {
+    this.populateSubView();
+    PanelUI.showSubView("PanelUI-profiles", panel);
+  },
+
+  async populateSubView() {
+    let closeProfileButton = PanelMultiView.getViewNode(
+      document,
+      "profiles-close-profile-button"
+    );
+    document.l10n.setArgs(closeProfileButton, {
+      profilename: ProfileService.currentProfile?.name ?? "",
+    });
+
+    let profileIconEl = PanelMultiView.getViewNode(
+      document,
+      "profile-icon-image"
+    );
+    profileIconEl.style.listStyleImage = `url(${
+      ProfileService.currentProfile?.iconURL ??
+      "chrome://branding/content/icon64.png"
+    })`;
+
+    let profileNameEl = PanelMultiView.getViewNode(document, "profile-name");
+    profileNameEl.textContent = ProfileService.currentProfile?.name ?? "";
+
+    let profilesList = PanelMultiView.getViewNode(
+      document,
+      "PanelUI-profiles"
+    ).querySelector("#profiles-list");
+    while (profilesList.lastElementChild) {
+      profilesList.lastElementChild.remove();
+    }
+
+    for (let profile of ProfileService.profiles) {
+      if (profile === ProfileService.currentProfile) {
+        continue;
+      }
+
+      let button = document.createXULElement("toolbarbutton");
+      button.setAttribute("label", profile.name);
+      button.className = "subviewbutton subviewbutton-iconic";
+      button.style.listStyleImage = `url(${
+        profile.iconURL ?? "chrome://branding/content/icon16.png"
+      })`;
+      button.onclick = () => {
+        Services.startup.createInstanceWithProfile(profile);
+      };
+
+      profilesList.appendChild(button);
+    }
+  },
+};
diff --git a/browser/base/content/browser-sets.inc b/browser/base/content/browser-sets.inc
index 019b3cc469..090e94b684 100644
--- a/browser/base/content/browser-sets.inc
+++ b/browser/base/content/browser-sets.inc
@@ -52,14 +52,14 @@
     <command id="cmd_findSelection" oncommand="gLazyFindCommand('onFindSelectionCommand')"/>
 #endif
     <command id="cmd_reportBrokenSite" oncommand="ReportBrokenSite.open(event);"/>
-    <command id="cmd_translate" oncommand="TranslationsPanel.open(event);"/>
+    <command id="cmd_translate" oncommand="FullPageTranslationsPanel.open(event);"/>
     <!-- work-around bug 392512 -->
     <command id="Browser:AddBookmarkAs"
              oncommand="PlacesCommandHook.bookmarkPage();"/>
     <command id="Browser:SearchBookmarks"
             oncommand="PlacesCommandHook.searchBookmarks();"/>
     <command id="Browser:BookmarkAllTabs"
-             oncommand="PlacesUIUtils.showBookmarkPagesDialog(PlacesCommandHook.uniqueCurrentPages);"/>
+             oncommand="PlacesCommandHook.bookmarkTabs();"/>
     <command id="Browser:Back"    oncommand="BrowserBack();" disabled="true"/>
     <command id="Browser:BackOrBackDuplicate" oncommand="BrowserBack(event);" disabled="true">
       <observes element="Browser:Back" attribute="disabled"/>
@@ -270,7 +270,7 @@
     <key id="addBookmarkAsKb" data-l10n-id="bookmark-this-page-shortcut" command="Browser:AddBookmarkAs" modifiers="accel"/>
     <key id="bookmarkAllTabsKb"
          data-l10n-id="bookmark-this-page-shortcut"
-         oncommand="PlacesUIUtils.showBookmarkPagesDialog(PlacesCommandHook.uniqueCurrentPages);"
+         oncommand="PlacesCommandHook.bookmarkTabs();"
          modifiers="accel,shift"/>
     <key id="manBookmarkKb" data-l10n-id="bookmark-show-library-shortcut" command="Browser:ShowAllBookmarks" modifiers="accel,shift"/>
     <key id="viewBookmarksSidebarKb"
diff --git a/browser/base/content/browser-sidebar.js b/browser/base/content/browser-sidebar.js
index ea6457a5c4..2d730700a6 100644
--- a/browser/base/content/browser-sidebar.js
+++ b/browser/base/content/browser-sidebar.js
@@ -266,7 +266,7 @@ var SidebarUI = {
   },
 
   updateShortcut({ keyId }) {
-    let menuitem = this._switcherPanel.querySelector(`[key="${keyId}"]`);
+    let menuitem = this._switcherPanel?.querySelector(`[key="${keyId}"]`);
     if (!menuitem) {
       // If the menu item doesn't exist yet then the accel text will be set correctly
       // upon creation so there's nothing to do now.
diff --git a/browser/base/content/browser-siteProtections.js b/browser/base/content/browser-siteProtections.js
index 5364aa74cd..c44b4d3e8e 100644
--- a/browser/base/content/browser-siteProtections.js
+++ b/browser/base/content/browser-siteProtections.js
@@ -31,8 +31,6 @@ class ProtectionCategory {
    * @param {Object} options - Category options.
    * @param {string} options.prefEnabled - ID of pref which controls the
    * category enabled state.
-   * @param {string} [options.reportBreakageLabel] - Telemetry label to use when
-   * users report TP breakage. Defaults to protection ID.
    * @param {string} [options.l10nId] - Identifier l10n strings are keyed under
    * for this category. Defaults to protection ID.
    * @param {Object} flags - Flags for this category to look for in the content
@@ -51,7 +49,7 @@ class ProtectionCategory {
    */
   constructor(
     id,
-    { prefEnabled, reportBreakageLabel, l10nId },
+    { prefEnabled, l10nId },
     {
       load,
       block,
@@ -61,7 +59,6 @@ class ProtectionCategory {
   ) {
     this._id = id;
     this.prefEnabled = prefEnabled;
-    this._reportBreakageLabel = reportBreakageLabel || id;
 
     this._flags = { load, block, shim, allow };
 
@@ -112,10 +109,6 @@ class ProtectionCategory {
     return this._enabled;
   }
 
-  get reportBreakageLabel() {
-    return this._reportBreakageLabel;
-  }
-
   /**
    * Get the category item associated with this protection from the main
    * protections panel.
@@ -333,7 +326,6 @@ let Fingerprinting =
         "fingerprinters",
         {
           prefEnabled: "privacy.trackingprotection.fingerprinting.enabled",
-          reportBreakageLabel: "fingerprinting",
         },
         {
           load: Ci.nsIWebProgressListener.STATE_LOADED_FINGERPRINTING_CONTENT,
@@ -411,7 +403,6 @@ let Cryptomining = new ProtectionCategory(
   "cryptominers",
   {
     prefEnabled: "privacy.trackingprotection.cryptomining.enabled",
-    reportBreakageLabel: "cryptomining",
   },
   {
     load: Ci.nsIWebProgressListener.STATE_LOADED_CRYPTOMINING_CONTENT,
@@ -427,7 +418,6 @@ let TrackingProtection =
         {
           l10nId: "trackingContent",
           prefEnabled: "privacy.trackingprotection.enabled",
-          reportBreakageLabel: "trackingprotection",
         },
         {
           load: null,
@@ -699,28 +689,6 @@ let ThirdPartyCookies =
       );
     }
 
-    get reportBreakageLabel() {
-      switch (this.behaviorPref) {
-        case Ci.nsICookieService.BEHAVIOR_ACCEPT:
-          return "nocookiesblocked";
-        case Ci.nsICookieService.BEHAVIOR_REJECT_FOREIGN:
-          return "allthirdpartycookiesblocked";
-        case Ci.nsICookieService.BEHAVIOR_REJECT:
-          return "allcookiesblocked";
-        case Ci.nsICookieService.BEHAVIOR_LIMIT_FOREIGN:
-          return "cookiesfromunvisitedsitesblocked";
-        default:
-          console.error(
-            `Error: Unknown cookieBehavior pref observed: ${this.behaviorPref}`
-          );
-        // fall through
-        case Ci.nsICookieService.BEHAVIOR_REJECT_TRACKER:
-          return "cookierestrictions";
-        case Ci.nsICookieService.BEHAVIOR_REJECT_TRACKER_AND_PARTITION_FOREIGN:
-          return "cookierestrictionsforeignpartitioned";
-      }
-    }
-
     isBlocking(state) {
       return (
         (state & Ci.nsIWebProgressListener.STATE_COOKIES_BLOCKED_TRACKER) !=
@@ -1099,7 +1067,6 @@ let SocialTracking =
         {
           l10nId: "socialMediaTrackers",
           prefEnabled: "privacy.socialtracking.block_cookies.enabled",
-          reportBreakageLabel: "socialtracking",
         },
         {
           load: Ci.nsIWebProgressListener.STATE_LOADED_SOCIALTRACKING_CONTENT,
@@ -1406,7 +1373,6 @@ let cookieBannerHandling = new (class {
  * Utility object to handle manipulations of the protections indicators in the UI
  */
 var gProtectionsHandler = {
-  PREF_REPORT_BREAKAGE_URL: "browser.contentblocking.reportBreakage.url",
   PREF_CB_CATEGORY: "browser.contentblocking.category",
 
   _protectionsPopup: null,
@@ -1456,18 +1422,6 @@ var gProtectionsHandler = {
       "protections-popup-mainView-panel-header-span"
     ));
   },
-  get _protectionsPopupTPSwitchBreakageLink() {
-    delete this._protectionsPopupTPSwitchBreakageLink;
-    return (this._protectionsPopupTPSwitchBreakageLink =
-      document.getElementById("protections-popup-tp-switch-breakage-link"));
-  },
-  get _protectionsPopupTPSwitchBreakageFixedLink() {
-    delete this._protectionsPopupTPSwitchBreakageFixedLink;
-    return (this._protectionsPopupTPSwitchBreakageFixedLink =
-      document.getElementById(
-        "protections-popup-tp-switch-breakage-fixed-link"
-      ));
-  },
   get _protectionsPopupTPSwitch() {
     delete this._protectionsPopupTPSwitch;
     return (this._protectionsPopupTPSwitch = document.getElementById(
@@ -1524,28 +1478,6 @@ var gProtectionsHandler = {
         "protections-popup-footer-protection-type-label"
       ));
   },
-  get _protectionsPopupSiteNotWorkingTPSwitch() {
-    delete this._protectionsPopupSiteNotWorkingTPSwitch;
-    return (this._protectionsPopupSiteNotWorkingTPSwitch =
-      document.getElementById("protections-popup-siteNotWorking-tp-switch"));
-  },
-  get _protectionsPopupSiteNotWorkingReportError() {
-    delete this._protectionsPopupSiteNotWorkingReportError;
-    return (this._protectionsPopupSiteNotWorkingReportError =
-      document.getElementById("protections-popup-sendReportView-report-error"));
-  },
-  get _protectionsPopupSendReportURL() {
-    delete this._protectionsPopupSendReportURL;
-    return (this._protectionsPopupSendReportURL = document.getElementById(
-      "protections-popup-sendReportView-collection-url"
-    ));
-  },
-  get _protectionsPopupSendReportButton() {
-    delete this._protectionsPopupSendReportButton;
-    return (this._protectionsPopupSendReportButton = document.getElementById(
-      "protections-popup-sendReportView-submit"
-    ));
-  },
   get _trackingProtectionIconTooltipLabel() {
     delete this._trackingProtectionIconTooltipLabel;
     return (this._trackingProtectionIconTooltipLabel = document.getElementById(
@@ -1580,13 +1512,6 @@ var gProtectionsHandler = {
     ));
   },
 
-  get _siteNotWorkingIssueListFonts() {
-    delete this._siteNotWorkingIssueListFonts;
-    return (this._siteNotWorkingIssueListFonts = document.getElementById(
-      "protections-panel-site-not-working-view-issue-list-fonts"
-    ));
-  },
-
   // A list of blockers that will be displayed in the categories list
   // when blockable content is detected. A blocker must be an object
   // with at least the following two properties:
@@ -1811,10 +1736,6 @@ var gProtectionsHandler = {
 
       window.addEventListener("focus", this, true);
       this._protectionsPopupTPSwitch.addEventListener("toggle", this);
-      this._protectionsPopupSiteNotWorkingTPSwitch.addEventListener(
-        "toggle",
-        this
-      );
 
       // Insert the info message if needed. This will be shown once and then
       // remain collapsed.
@@ -1834,10 +1755,6 @@ var gProtectionsHandler = {
     if (event.target == this._protectionsPopup) {
       window.removeEventListener("focus", this, true);
       this._protectionsPopupTPSwitch.removeEventListener("toggle", this);
-      this._protectionsPopupSiteNotWorkingTPSwitch.removeEventListener(
-        "toggle",
-        this
-      );
     }
   },
 
@@ -2163,7 +2080,7 @@ var gProtectionsHandler = {
 
     let currentlyEnabled = !this.hasException;
 
-    this.updateProtectionsToggles(currentlyEnabled);
+    this.updateProtectionsToggle(currentlyEnabled);
 
     this._notBlockingWhyLink.setAttribute(
       "tooltip",
@@ -2172,9 +2089,6 @@ var gProtectionsHandler = {
         : "protections-popup-not-blocking-why-etp-off-tooltip"
     );
 
-    // Toggle the breakage link according to the current enable state.
-    this.toggleBreakageLink();
-
     // Update the tooltip of the blocked tracker counter.
     this.maybeUpdateEarliestRecordedDateTooltip();
 
@@ -2196,28 +2110,23 @@ var gProtectionsHandler = {
   },
 
   /**
-   * Updates the "pressed" state and labels for both toggles in the different
-   * panel subviews.
+   * Updates the "pressed" state and labels for the toggle
    *
-   * @param {boolean} isPressed - Whether or not the toggles should be pressed.
+   * @param {boolean} isPressed - Whether or not the toggle should be pressed.
    *  True if ETP is enabled for a given site.
    */
-  updateProtectionsToggles(isPressed) {
+  updateProtectionsToggle(isPressed) {
     let host = gIdentityHandler.getHostForDisplay();
-    for (let toggle of [
-      this._protectionsPopupTPSwitch,
-      this._protectionsPopupSiteNotWorkingTPSwitch,
-    ]) {
-      toggle.toggleAttribute("pressed", isPressed);
-      toggle.toggleAttribute("disabled", !!this._TPSwitchCommanding);
-      document.l10n.setAttributes(
-        toggle,
-        isPressed
-          ? "protections-panel-etp-toggle-on"
-          : "protections-panel-etp-toggle-off",
-        { host }
-      );
-    }
+    let toggle = this._protectionsPopupTPSwitch;
+    toggle.toggleAttribute("pressed", isPressed);
+    toggle.toggleAttribute("disabled", !!this._TPSwitchCommanding);
+    document.l10n.setAttributes(
+      toggle,
+      isPressed
+        ? "protections-panel-etp-toggle-on"
+        : "protections-panel-etp-toggle-off",
+      { host }
+    );
   },
 
   /*
@@ -2313,10 +2222,7 @@ var gProtectionsHandler = {
     let newExceptionState =
       this._protectionsPopup.toggleAttribute("hasException");
 
-    this.updateProtectionsToggles(!newExceptionState);
-
-    // Toggle the breakage link if needed.
-    this.toggleBreakageLink();
+    this.updateProtectionsToggle(!newExceptionState);
 
     // Change the tooltip of the tracking protection icon.
     if (newExceptionState) {
@@ -2523,158 +2429,6 @@ var gProtectionsHandler = {
     ).catch(console.error);
   },
 
-  showSiteNotWorkingView() {
-    // Only show the Fonts item if we are restricting font visibility
-    if (this._fontVisibilityTrackingProtection >= 3) {
-      this._siteNotWorkingIssueListFonts.setAttribute("hidden", "true");
-    } else {
-      this._siteNotWorkingIssueListFonts.removeAttribute("hidden");
-    }
-
-    this._protectionsPopupMultiView.showSubView(
-      "protections-popup-siteNotWorkingView"
-    );
-  },
-
-  showSendReportView() {
-    // Save this URI to make sure that the user really only submits the location
-    // they see in the report breakage dialog.
-    this.reportURI = gBrowser.currentURI;
-    let urlWithoutQuery = this.reportURI.asciiSpec.replace(
-      "?" + this.reportURI.query,
-      ""
-    );
-    let commentsTextarea = document.getElementById(
-      "protections-popup-sendReportView-collection-comments"
-    );
-    commentsTextarea.value = "";
-    this._protectionsPopupSendReportURL.value = urlWithoutQuery;
-    this._protectionsPopupSiteNotWorkingReportError.hidden = true;
-    this._protectionsPopupMultiView.showSubView(
-      "protections-popup-sendReportView"
-    );
-  },
-
-  toggleBreakageLink() {
-    // The breakage link will only be shown if tracking protection is enabled
-    // for the site and the TP toggle state is on. And we won't show the
-    // link as toggling TP switch to On from Off. In order to do so, we need to
-    // know the previous TP state. We check the ContentBlockingAllowList instead
-    // of 'hasException' attribute of the protection popup for the previous
-    // since the 'hasException' will also be toggled as well as toggling the TP
-    // switch. We won't be able to know the previous TP state through the
-    // 'hasException' attribute. So we fallback to check the
-    // ContentBlockingAllowList here.
-    this._protectionsPopupTPSwitchBreakageLink.hidden =
-      ContentBlockingAllowList.includes(gBrowser.selectedBrowser) ||
-      !this.anyBlocking ||
-      !this._protectionsPopupTPSwitch.hasAttribute("pressed");
-    // The "Site Fixed?" link behaves similarly but for the opposite state.
-    this._protectionsPopupTPSwitchBreakageFixedLink.hidden =
-      !ContentBlockingAllowList.includes(gBrowser.selectedBrowser) ||
-      this._protectionsPopupTPSwitch.hasAttribute("pressed");
-  },
-
-  submitBreakageReport(uri) {
-    let reportEndpoint = Services.prefs.getStringPref(
-      this.PREF_REPORT_BREAKAGE_URL
-    );
-    if (!reportEndpoint) {
-      return;
-    }
-
-    let commentsTextarea = document.getElementById(
-      "protections-popup-sendReportView-collection-comments"
-    );
-
-    let formData = new FormData();
-    formData.set("title", uri.host);
-
-    // Leave the ? at the end of the URL to signify that this URL had its query stripped.
-    let urlWithoutQuery = uri.asciiSpec.replace(uri.query, "");
-    let body = `Full URL: ${urlWithoutQuery}\n`;
-    body += `userAgent: ${navigator.userAgent}\n`;
-
-    body += "\n**Preferences**\n";
-    body += `${TrackingProtection.prefEnabled}: ${Services.prefs.getBoolPref(
-      TrackingProtection.prefEnabled
-    )}\n`;
-    body += `${
-      TrackingProtection.prefEnabledInPrivateWindows
-    }: ${Services.prefs.getBoolPref(
-      TrackingProtection.prefEnabledInPrivateWindows
-    )}\n`;
-    body += `urlclassifier.trackingTable: ${Services.prefs.getStringPref(
-      "urlclassifier.trackingTable"
-    )}\n`;
-    body += `network.http.referer.defaultPolicy: ${Services.prefs.getIntPref(
-      "network.http.referer.defaultPolicy"
-    )}\n`;
-    body += `network.http.referer.defaultPolicy.pbmode: ${Services.prefs.getIntPref(
-      "network.http.referer.defaultPolicy.pbmode"
-    )}\n`;
-    body += `${ThirdPartyCookies.prefEnabled}: ${Services.prefs.getIntPref(
-      ThirdPartyCookies.prefEnabled
-    )}\n`;
-    body += `privacy.annotate_channels.strict_list.enabled: ${Services.prefs.getBoolPref(
-      "privacy.annotate_channels.strict_list.enabled"
-    )}\n`;
-    body += `privacy.restrict3rdpartystorage.expiration: ${Services.prefs.getIntPref(
-      "privacy.restrict3rdpartystorage.expiration"
-    )}\n`;
-    body += `${Fingerprinting.prefEnabled}: ${Services.prefs.getBoolPref(
-      Fingerprinting.prefEnabled
-    )}\n`;
-    body += `${Cryptomining.prefEnabled}: ${Services.prefs.getBoolPref(
-      Cryptomining.prefEnabled
-    )}\n`;
-    body += `privacy.globalprivacycontrol.enabled: ${Services.prefs.getBoolPref(
-      "privacy.globalprivacycontrol.enabled"
-    )}\n`;
-    body += `\nhasException: ${this.hasException}\n`;
-
-    body += "\n**Comments**\n" + commentsTextarea.value;
-
-    formData.set("body", body);
-
-    let activatedBlockers = [];
-    for (let blocker of Object.values(this.blockers)) {
-      if (blocker.activated) {
-        activatedBlockers.push(blocker.reportBreakageLabel);
-      }
-    }
-
-    formData.set("labels", activatedBlockers.join(","));
-
-    this._protectionsPopupSendReportButton.disabled = true;
-
-    fetch(reportEndpoint, {
-      method: "POST",
-      credentials: "omit",
-      body: formData,
-    })
-      .then(response => {
-        this._protectionsPopupSendReportButton.disabled = false;
-        if (!response.ok) {
-          console.error(
-            `Content Blocking report to ${reportEndpoint} failed with status ${response.status}`
-          );
-          this._protectionsPopupSiteNotWorkingReportError.hidden = false;
-        } else {
-          this._protectionsPopup.hidePopup();
-          ConfirmationHint.show(
-            this._trackingProtectionIconContainer,
-            "confirmation-hint-breakage-report-sent"
-          );
-        }
-      })
-      .catch(console.error);
-  },
-
-  onSendReportClicked() {
-    this.submitBreakageReport(this.reportURI);
-  },
-
   async maybeUpdateEarliestRecordedDateTooltip(trackerCount) {
     // If we've already updated or the popup isn't in the DOM yet, don't bother
     // doing this:
diff --git a/browser/base/content/browser.css b/browser/base/content/browser.css
index 8a2a202809..c9ebddb7f5 100644
--- a/browser/base/content/browser.css
+++ b/browser/base/content/browser.css
@@ -115,6 +115,7 @@ panelview:not([visible]) {
   flex-shrink: 0;
   min-width: 0;
   min-height: 0;
+  max-height: 100%;
 }
 
 .panel-viewcontainer[panelopen] {
@@ -934,82 +935,6 @@ toolbarpaletteitem[place="palette"] > #downloads-button > .toolbarbutton-badge-s
   display: none;
 }
 
-@media (-moz-panel-animations) and (prefers-reduced-motion: no-preference) {
-@media (-moz-platform: macos) {
-  /* On Mac, use the properties "-moz-window-transform" and "-moz-window-opacity"
-     instead of "transform" and "opacity" for these animations.
-     The -moz-window* properties apply to the whole window including the window's
-     shadow, and they don't affect the window's "shape", so the system doesn't
-     have to recompute the shadow shape during the animation. This makes them a
-     lot faster. In fact, Gecko no longer triggers shadow shape recomputations
-     for repaints.
-     These properties are not implemented on other platforms. */
-  #BMB_bookmarksPopup:not([animate="false"]) {
-    transition-property: -moz-window-transform, -moz-window-opacity;
-    transition-duration: 0.18s, 0.18s;
-    transition-timing-function:
-      var(--animation-easing-function), ease-out;
-  }
-
-  /* Only do the fade-in animation on pre-Big Sur to avoid missing shadows on
-   * Big Sur, see bug 1672091. */
-  @media (-moz-mac-big-sur-theme: 0) {
-    #BMB_bookmarksPopup:not([animate="false"]) {
-      -moz-window-opacity: 0;
-      -moz-window-transform: translateY(-70px);
-    }
-
-    #BMB_bookmarksPopup[side="bottom"]:not([animate="false"]) {
-      -moz-window-transform: translateY(70px);
-    }
-  }
-
-  /* [animate] is here only so that this rule has greater specificity than the
-   * rule right above */
-  #BMB_bookmarksPopup[animate][animate="open"] {
-    -moz-window-opacity: 1.0;
-    transition-duration: 0.18s, 0.18s;
-    -moz-window-transform: none;
-    transition-timing-function:
-      var(--animation-easing-function), ease-in-out;
-  }
-
-  #BMB_bookmarksPopup[animate][animate="cancel"] {
-    -moz-window-opacity: 0;
-    -moz-window-transform: none;
-  }
-}
-@media not (-moz-platform: macos) {
-  #BMB_bookmarksPopup:not([animate="false"]) {
-    opacity: 0;
-    transform: translateY(-70px);
-    transition-property: transform, opacity;
-    transition-duration: 0.18s, 0.18s;
-    transition-timing-function:
-      var(--animation-easing-function), ease-out;
-    will-change: transform, opacity;
-  }
-
-  #BMB_bookmarksPopup[side="bottom"]:not([animate="false"]) {
-    transform: translateY(70px);
-  }
-
-  /* [animate] is here only so that this rule has greater specificity than the
-   * rule right above */
-  #BMB_bookmarksPopup[animate][animate="open"] {
-    opacity: 1.0;
-    transition-duration: 0.18s, 0.18s;
-    transform: none;
-    transition-timing-function:
-      var(--animation-easing-function), ease-in-out;
-  }
-
-  #BMB_bookmarksPopup[animate][animate="cancel"] {
-    transform: none;
-  }
-}
-}
-
 /* Apply crisp rendering for favicons at exactly 2dppx resolution */
 @media (resolution: 2dppx) {
   .PanelUI-remotetabs-clientcontainer > toolbarbutton > .toolbarbutton-icon,
diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 4f145c4949..c91a5d4db2 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -29,7 +29,6 @@ ChromeUtils.defineESModuleGetters(this, {
   ContextualIdentityService:
     "resource://gre/modules/ContextualIdentityService.sys.mjs",
   CustomizableUI: "resource:///modules/CustomizableUI.sys.mjs",
-  Deprecated: "resource://gre/modules/Deprecated.sys.mjs",
   DevToolsSocketStatus:
     "resource://devtools/shared/security/DevToolsSocketStatus.sys.mjs",
   DownloadUtils: "resource://gre/modules/DownloadUtils.sys.mjs",
@@ -185,8 +184,13 @@ XPCOMUtils.defineLazyScriptGetter(
 );
 XPCOMUtils.defineLazyScriptGetter(
   this,
-  "TranslationsPanel",
-  "chrome://browser/content/translations/translationsPanel.js"
+  "SelectTranslationsPanel",
+  "chrome://browser/content/translations/selectTranslationsPanel.js"
+);
+XPCOMUtils.defineLazyScriptGetter(
+  this,
+  "FullPageTranslationsPanel",
+  "chrome://browser/content/translations/fullPageTranslationsPanel.js"
 );
 XPCOMUtils.defineLazyScriptGetter(
   this,
@@ -272,6 +276,11 @@ XPCOMUtils.defineLazyScriptGetter(
   "gPageStyleMenu",
   "chrome://browser/content/browser-pagestyle.js"
 );
+XPCOMUtils.defineLazyScriptGetter(
+  this,
+  "gProfiles",
+  "chrome://browser/content/browser-profiles.js"
+);
 
 // lazy service getters
 
@@ -524,13 +533,6 @@ XPCOMUtils.defineLazyPreferenceGetter(
 
 XPCOMUtils.defineLazyPreferenceGetter(
   this,
-  "gBookmarksToolbarShowInPrivate",
-  "browser.toolbars.bookmarks.showInPrivateBrowsing",
-  false
-);
-
-XPCOMUtils.defineLazyPreferenceGetter(
-  this,
   "gFxaToolbarEnabled",
   "identity.fxaccounts.toolbar.enabled",
   false,
@@ -720,6 +722,7 @@ var gInitialPages = [
   "about:welcome",
   "about:welcomeback",
   "chrome://browser/content/blanktab.html",
+  "about:profilemanager",
 ];
 
 function isInitialPage(url) {
@@ -740,22 +743,13 @@ function browserWindows() {
 }
 
 function updateBookmarkToolbarVisibility() {
-  // Bug 1846583 - hide bookmarks toolbar in PBM
-  if (
-    gUseFeltPrivacyUI &&
-    !gBookmarksToolbarShowInPrivate &&
-    PrivateBrowsingUtils.isWindowPrivate(window)
-  ) {
-    setToolbarVisibility(BookmarkingUI.toolbar, false, false, false);
-  } else {
-    BookmarkingUI.updateEmptyToolbarMessage();
-    setToolbarVisibility(
-      BookmarkingUI.toolbar,
-      gBookmarksToolbarVisibility,
-      false,
-      false
-    );
-  }
+  BookmarkingUI.updateEmptyToolbarMessage();
+  setToolbarVisibility(
+    BookmarkingUI.toolbar,
+    gBookmarksToolbarVisibility,
+    false,
+    false
+  );
 }
 
 // This is a stringbundle-like interface to gBrowserBundle, formerly a getter for
@@ -1686,13 +1680,13 @@ var gBrowserInit = {
     gBrowser.addEventListener("DOMUpdateBlockedPopups", gPopupBlockerObserver);
     gBrowser.addEventListener(
       "TranslationsParent:LanguageState",
-      TranslationsPanel
+      FullPageTranslationsPanel
     );
     gBrowser.addEventListener(
       "TranslationsParent:OfferTranslation",
-      TranslationsPanel
+      FullPageTranslationsPanel
     );
-    gBrowser.addTabsProgressListener(TranslationsPanel);
+    gBrowser.addTabsProgressListener(FullPageTranslationsPanel);
 
     window.addEventListener("AppCommand", HandleAppCommandEvent, true);
 
@@ -1705,12 +1699,10 @@ var gBrowserInit = {
 
     if (!gMultiProcessBrowser) {
       // There is a Content:Click message manually sent from content.
-      Services.els.addSystemEventListener(
-        gBrowser.tabpanels,
-        "click",
-        contentAreaClick,
-        true
-      );
+      gBrowser.tabpanels.addEventListener("click", contentAreaClick, {
+        capture: true,
+        mozSystemGroup: true,
+      });
     }
 
     // hook up UI through progress listener
@@ -2424,6 +2416,10 @@ var gBrowserInit = {
         "browser-idle-startup-tasks-finished"
       );
     });
+
+    scheduleIdleTask(() => {
+      gProfiles.init();
+    });
   },
 
   // Returns the URI(s) to load at startup if it is immediately known, or a
@@ -3035,7 +3031,7 @@ function BrowserOpenFileWindow() {
     };
 
     fp.init(
-      window,
+      window.browsingContext,
       gNavigatorBundle.getString("openFile"),
       nsIFilePicker.modeOpen
     );
@@ -3243,15 +3239,6 @@ function BrowserPageInfo(
   browsingContext,
   browser
 ) {
-  if (HTMLDocument.isInstance(documentURL)) {
-    Deprecated.warning(
-      "Please pass the location URL instead of the document " +
-        "to BrowserPageInfo() as the first argument.",
-      "https://bugzilla.mozilla.org/show_bug.cgi?id=1238180"
-    );
-    documentURL = documentURL.location;
-  }
-
   let args = { initialTab, imageElement, browsingContext, browser };
 
   documentURL = documentURL || window.gBrowser.selectedBrowser.currentURI.spec;
@@ -4549,7 +4536,23 @@ function toOpenWindowByType(inType, uri, features) {
  * @return a reference to the new window.
  */
 function OpenBrowserWindow(options = {}) {
-  return BrowserWindowTracker.openWindow({ openerWindow: window, ...options });
+  let telemetryObj = {};
+  TelemetryStopwatch.start("FX_NEW_WINDOW_MS", telemetryObj);
+
+  let win = BrowserWindowTracker.openWindow({
+    openerWindow: window,
+    ...options,
+  });
+
+  win.addEventListener(
+    "MozAfterPaint",
+    () => {
+      TelemetryStopwatch.finish("FX_NEW_WINDOW_MS", telemetryObj);
+    },
+    { once: true }
+  );
+
+  return win;
 }
 
 /**
@@ -6456,6 +6459,37 @@ function onViewToolbarsPopupShowing(aEvent, aInsertPoint) {
     return;
   }
 
+  // triggerNode can be a nested child element of a toolbaritem.
+  let toolbarItem = popup.triggerNode;
+  while (toolbarItem) {
+    let localName = toolbarItem.localName;
+    if (localName == "toolbar") {
+      toolbarItem = null;
+      break;
+    }
+    if (localName == "toolbarpaletteitem") {
+      toolbarItem = toolbarItem.firstElementChild;
+      break;
+    }
+    if (localName == "menupopup") {
+      aEvent.preventDefault();
+      aEvent.stopPropagation();
+      return;
+    }
+    let parent = toolbarItem.parentElement;
+    if (parent) {
+      if (
+        parent.classList.contains("customization-target") ||
+        parent.getAttribute("overflowfortoolbar") || // Needs to work in the overflow list as well.
+        parent.localName == "toolbarpaletteitem" ||
+        parent.localName == "toolbar"
+      ) {
+        break;
+      }
+    }
+    toolbarItem = parent;
+  }
+
   // Empty the menu
   for (var i = popup.children.length - 1; i >= 0; --i) {
     var deadItem = popup.children[i];
@@ -6509,30 +6543,7 @@ function onViewToolbarsPopupShowing(aEvent, aInsertPoint) {
     return;
   }
 
-  // triggerNode can be a nested child element of a toolbaritem.
-  let toolbarItem = popup.triggerNode;
-
-  if (toolbarItem && toolbarItem.localName == "toolbarpaletteitem") {
-    toolbarItem = toolbarItem.firstElementChild;
-  } else if (toolbarItem && toolbarItem.localName != "toolbar") {
-    while (toolbarItem && toolbarItem.parentElement) {
-      let parent = toolbarItem.parentElement;
-      if (
-        (parent.classList &&
-          parent.classList.contains("customization-target")) ||
-        parent.getAttribute("overflowfortoolbar") || // Needs to work in the overflow list as well.
-        parent.localName == "toolbarpaletteitem" ||
-        parent.localName == "toolbar"
-      ) {
-        break;
-      }
-      toolbarItem = parent;
-    }
-  } else {
-    toolbarItem = null;
-  }
-
-  let showTabStripItems = toolbarItem && toolbarItem.id == "tabbrowser-tabs";
+  let showTabStripItems = toolbarItem?.id == "tabbrowser-tabs";
   for (let node of popup.querySelectorAll(
     'menuitem[contexttype="toolbaritem"]'
   )) {
@@ -6588,9 +6599,7 @@ function onViewToolbarsPopupShowing(aEvent, aInsertPoint) {
   }
 
   let movable =
-    toolbarItem &&
-    toolbarItem.id &&
-    CustomizableUI.isWidgetRemovable(toolbarItem);
+    toolbarItem?.id && CustomizableUI.isWidgetRemovable(toolbarItem);
   if (movable) {
     if (CustomizableUI.isSpecialWidget(toolbarItem.id)) {
       moveToPanel.setAttribute("disabled", true);
diff --git a/browser/base/content/browser.js.globals b/browser/base/content/browser.js.globals
new file mode 100644
index 0000000000..c767bb5beb
--- /dev/null
+++ b/browser/base/content/browser.js.globals
@@ -0,0 +1,305 @@
+[
+  "XPCOMUtils",
+  "AppConstants",
+  "gBrowser",
+  "gContextMenu",
+  "gMultiProcessBrowser",
+  "gFissionBrowser",
+  "gBrowserAllowScriptsToCloseInitialTabs",
+  "gEditUIVisible",
+  "gReduceMotionSetting",
+  "gReduceMotionOverride",
+  "shouldSuppressPopupNotifications",
+  "gLazyFindCommand",
+  "gPageIcons",
+  "gInitialPages",
+  "isInitialPage",
+  "browserWindows",
+  "updateBookmarkToolbarVisibility",
+  "gNavigatorBundle",
+  "gScreenshots",
+  "updateFxaToolbarMenu",
+  "UpdateBackForwardCommands",
+  "updatePrintCommands",
+  "SetClickAndHoldHandlers",
+  "gClickAndHoldListenersOnElement",
+  "gSessionHistoryObserver",
+  "gStoragePressureObserver",
+  "gPopupBlockerObserver",
+  "gKeywordURIFixup",
+  "_createNullPrincipalFromTabUserContextId",
+  "_resolveDelayedStartup",
+  "delayedStartupPromise",
+  "gBrowserInit",
+  "HandleAppCommandEvent",
+  "gotoHistoryIndex",
+  "BrowserForward",
+  "BrowserBack",
+  "BrowserHandleBackspace",
+  "BrowserHandleShiftBackspace",
+  "BrowserStop",
+  "BrowserReloadOrDuplicate",
+  "BrowserReload",
+  "kSkipCacheFlags",
+  "BrowserReloadSkipCache",
+  "BrowserHome",
+  "loadOneOrMoreURIs",
+  "openLocation",
+  "BrowserOpenTab",
+  "gLastOpenDirectory",
+  "BrowserOpenFileWindow",
+  "BrowserCloseTabOrWindow",
+  "BrowserTryToCloseWindow",
+  "getLoadContext",
+  "readFromClipboard",
+  "BrowserViewSourceOfDocument",
+  "BrowserViewSource",
+  "BrowserPageInfo",
+  "UpdateUrlbarSearchSplitterState",
+  "UpdatePopupNotificationsVisibility",
+  "PageProxyClickHandler",
+  "BrowserOnClick",
+  "getMeOutOfHere",
+  "getDefaultHomePage",
+  "BrowserFullScreen",
+  "BrowserReloadWithFlags",
+  "getPEMString",
+  "browserDragAndDrop",
+  "homeButtonObserver",
+  "openHomeDialog",
+  "newTabButtonObserver",
+  "newWindowButtonObserver",
+  "BrowserSearch",
+  "CreateContainerTabMenu",
+  "FillHistoryMenu",
+  "BrowserDownloadsUI",
+  "toOpenWindowByType",
+  "OpenBrowserWindow",
+  "updateEditUIVisibility",
+  "gFileMenu",
+  "gShareUtils",
+  "openNewUserContextTab",
+  "XULBrowserWindow",
+  "LinkTargetDisplay",
+  "CombinedStopReload",
+  "TabsProgressListener",
+  "nsBrowserAccess",
+  "showFullScreenViewContextMenuItems",
+  "onViewToolbarsPopupShowing",
+  "onViewToolbarCommand",
+  "setToolbarVisibility",
+  "updateToggleControlLabel",
+  "TabletModeUpdater",
+  "gTabletModePageCounter",
+  "displaySecurityInfo",
+  "gUIDensity",
+  "nodeToTooltipMap",
+  "nodeToShortcutMap",
+  "gDynamicTooltipCache",
+  "GetDynamicShortcutTooltipText",
+  "UpdateDynamicShortcutTooltipText",
+  "hrefAndLinkNodeForClickEvent",
+  "contentAreaClick",
+  "handleLinkClick",
+  "middleMousePaste",
+  "handleDroppedLink",
+  "BrowserForceEncodingDetection",
+  "ToolbarContextMenu",
+  "BrowserOffline",
+  "CanvasPermissionPromptHelper",
+  "WebAuthnPromptHelper",
+  "CanCloseWindow",
+  "WindowIsClosing",
+  "warnAboutClosingWindow",
+  "MailIntegration",
+  "BrowserOpenAddonsMgr",
+  "AddKeywordForSearchField",
+  "restoreLastClosedTabOrWindowOrSession",
+  "undoCloseTab",
+  "undoCloseWindow",
+  "ReportFalseDeceptiveSite",
+  "ReportSiteIssue",
+  "gRemoteControl",
+  "gPrivateBrowsingUI",
+  "switchToTabHavingURI",
+  "RestoreLastSessionObserver",
+  "MenuTouchModeObserver",
+  "safeModeRestart",
+  "duplicateTabIn",
+  "MousePosTracker",
+  "ToolbarIconColor",
+  "PanicButtonNotifier",
+  "SafeBrowsingNotificationBox",
+  "TabDialogBox",
+  "TabModalPromptBox",
+  "gDialogBox",
+  "ConfirmationHint",
+  "FirefoxViewHandler",
+  "AMTelemetry",
+  "AboutNewTab",
+  "AboutReaderParent",
+  "AddonManager",
+  "BrowserSearchTelemetry",
+  "BrowserTelemetryUtils",
+  "BrowserUIUtils",
+  "BrowserUsageTelemetry",
+  "BrowserWindowTracker",
+  "CFRPageActions",
+  "Color",
+  "ContentAnalysis",
+  "ContextualIdentityService",
+  "CustomizableUI",
+  "DevToolsSocketStatus",
+  "DownloadUtils",
+  "DownloadsCommon",
+  "E10SUtils",
+  "ExtensionsUI",
+  "FirefoxViewNotificationManager",
+  "HomePage",
+  "isProductURL",
+  "LightweightThemeConsumer",
+  "LoginHelper",
+  "LoginManagerParent",
+  "MigrationUtils",
+  "NetUtil",
+  "NewTabPagePreloading",
+  "NewTabUtils",
+  "NimbusFeatures",
+  "OpenInTabsUtils",
+  "PageActions",
+  "PageThumbs",
+  "PanelMultiView",
+  "PanelView",
+  "PictureInPicture",
+  "PlacesTransactions",
+  "PlacesUIUtils",
+  "PlacesUtils",
+  "Pocket",
+  "PrivateBrowsingUtils",
+  "ProcessHangMonitor",
+  "PromptUtils",
+  "ReaderMode",
+  "ResetPBMPanel",
+  "ReportBrokenSite",
+  "SafeBrowsing",
+  "Sanitizer",
+  "SaveToPocket",
+  "ScreenshotsUtils",
+  "SearchUIUtils",
+  "SessionStartup",
+  "SessionStore",
+  "ShoppingSidebarParent",
+  "ShoppingSidebarManager",
+  "ShortcutUtils",
+  "SiteDataManager",
+  "SitePermissions",
+  "SubDialog",
+  "SubDialogManager",
+  "TabCrashHandler",
+  "TabModalPrompt",
+  "TabsSetupFlowManager",
+  "TelemetryEnvironment",
+  "TranslationsParent",
+  "UITour",
+  "UpdateUtils",
+  "URILoadingHelper",
+  "UrlbarInput",
+  "UrlbarPrefs",
+  "UrlbarProviderSearchTips",
+  "UrlbarTokenizer",
+  "UrlbarUtils",
+  "UrlbarValueFormatter",
+  "Weave",
+  "WebNavigationFrames",
+  "webrtcUI",
+  "WebsiteFilter",
+  "ZoomUI",
+  "fxAccounts",
+  "PlacesTreeView",
+  "PlacesInsertionPoint",
+  "PlacesController",
+  "PlacesControllerDragHelper",
+  "PrintUtils",
+  "ZoomManager",
+  "FullZoom",
+  "PanelUI",
+  "gViewSourceUtils",
+  "gTabsPanel",
+  "BrowserAddonUI",
+  "gExtensionsNotifications",
+  "gUnifiedExtensions",
+  "gXPInstallObserver",
+  "ctrlTab",
+  "CustomizationHandler",
+  "AutoHideMenubar",
+  "PointerLock",
+  "FullScreen",
+  "gIdentityHandler",
+  "gPermissionPanel",
+  "SelectTranslationsPanel",
+  "FullPageTranslationsPanel",
+  "gProtectionsHandler",
+  "gGestureSupport",
+  "gHistorySwipeAnimation",
+  "gSafeBrowsing",
+  "gSync",
+  "gBrowserThumbnails",
+  "openContextMenu",
+  "nsContextMenu",
+  "DownloadsPanel",
+  "DownloadsOverlayLoader",
+  "DownloadsView",
+  "DownloadsViewUI",
+  "DownloadsViewController",
+  "DownloadsSummary",
+  "DownloadsFooter",
+  "DownloadsBlockedSubview",
+  "DownloadsButton",
+  "DownloadsIndicatorView",
+  "gEditItemOverlay",
+  "gGfxUtils",
+  "pktUI",
+  "ToolbarKeyboardNavigator",
+  "A11yUtils",
+  "gSharedTabWarning",
+  "gPageStyleMenu",
+  "gProfiles",
+  "ContentPrefService2",
+  "classifierService",
+  "Favicons",
+  "WindowsUIUtils",
+  "BrowserHandler",
+  "Marionette",
+  "RemoteAgent",
+  "Marionette",
+  "RemoteAgent",
+  "RTL_UI",
+  "gBrandBundle",
+  "gBrowserBundle",
+  "gCustomizeMode",
+  "gNavToolbox",
+  "gURLBar",
+  "ReferrerInfo",
+  "gNotificationBox",
+  "InlineSpellCheckerUI",
+  "PopupNotifications",
+  "MacUserActivityUpdater",
+  "Win7Features",
+  "gToolbarKeyNavEnabled",
+  "gBookmarksToolbarVisibility",
+  "gFxaToolbarEnabled",
+  "gFxaToolbarAccessed",
+  "gAddonAbuseReportEnabled",
+  "gAlwaysOpenPanel",
+  "gMiddleClickNewTabUsesPasteboard",
+  "gScreenshotsDisabled",
+  "gPrintEnabled",
+  "gScreenshotsComponentEnabled",
+  "gTranslationsEnabled",
+  "gUseFeltPrivacyUI",
+  "gReduceMotion",
+  "gFindBar",
+  "gFindBarInitialized",
+  "gFindBarPromise",
+  "BrowserSearch"
+]
diff --git a/browser/base/content/browser.xhtml b/browser/base/content/browser.xhtml
index b4886fb5f7..1dcdd02cd1 100644
--- a/browser/base/content/browser.xhtml
+++ b/browser/base/content/browser.xhtml
@@ -98,6 +98,8 @@
   <link rel="localization" href="preview/select-translations.ftl"/>
   <link rel="localization" href="browser/shopping.ftl"/>
   <link rel="localization" href="preview/shopping.ftl"/>
+  <link rel="localization" href="preview/profiles.ftl"/>
+  <link rel="localization" href="preview/onboarding.ftl"/>
 
   <title data-l10n-id="browser-main-window-title"></title>
 
diff --git a/browser/base/content/contentTheme.js b/browser/base/content/contentTheme.js
index 805fc778c0..3c46b80bec 100644
--- a/browser/base/content/contentTheme.js
+++ b/browser/base/content/contentTheme.js
@@ -137,7 +137,7 @@
   /**
    * ContentThemeController handles theme updates sent by the frame script.
    * To be able to use ContentThemeController, you must add your page to the whitelist
-   * in LightweightThemeChildListener.jsm
+   * in LightweightThemeChild.sys.mjs
    */
   const ContentThemeController = {
     /**
diff --git a/browser/base/content/main-popupset.inc.xhtml b/browser/base/content/main-popupset.inc.xhtml
index 4074f35ffc..bff8d98b27 100644
--- a/browser/base/content/main-popupset.inc.xhtml
+++ b/browser/base/content/main-popupset.inc.xhtml
@@ -36,10 +36,10 @@
     <menuitem id="context_bookmarkSelectedTabs"
               hidden="true"
               data-lazy-l10n-id="bookmark-selected-tabs"
-              oncommand="PlacesUIUtils.showBookmarkPagesDialog(PlacesCommandHook.uniqueSelectedPages);"/>
+              oncommand="PlacesCommandHook.bookmarkTabs(gBrowser.selectedTabs);"/>
     <menuitem id="context_bookmarkTab"
               data-lazy-l10n-id="tab-context-bookmark-tab"
-              oncommand="PlacesUIUtils.showBookmarkPagesDialog(PlacesCommandHook.getUniquePages([TabContextMenu.contextTab]));"/>
+              oncommand="PlacesCommandHook.bookmarkTabs([TabContextMenu.contextTab]);"/>
     <menu id="context_moveTabOptions"
           data-lazy-l10n-id="tab-context-move-tabs"
           data-l10n-args='{"tabCount": 1}'>
@@ -326,11 +326,11 @@
               data-lazy-l10n-id="toolbar-context-menu-reload-selected-tabs"/>
     <menuitem id="toolbar-context-bookmarkSelectedTab"
               contexttype="tabbar"
-              oncommand="PlacesUIUtils.showBookmarkPagesDialog(PlacesCommandHook.uniqueSelectedPages);"
+              oncommand="PlacesCommandHook.bookmarkTabs(gBrowser.selectedTabs);"
               data-lazy-l10n-id="toolbar-context-menu-bookmark-selected-tab"/>
     <menuitem id="toolbar-context-bookmarkSelectedTabs"
               contexttype="tabbar"
-              oncommand="PlacesUIUtils.showBookmarkPagesDialog(PlacesCommandHook.uniqueSelectedPages);"
+              oncommand="PlacesCommandHook.bookmarkTabs(gBrowser.selectedTabs);"
               data-lazy-l10n-id="toolbar-context-menu-bookmark-selected-tabs"/>
     <menuitem id="toolbar-context-selectAllTabs"
               contexttype="tabbar"
@@ -496,7 +496,8 @@
 #include ../../components/controlcenter/content/permissionPanel.inc.xhtml
 #include ../../components/controlcenter/content/protectionsPanel.inc.xhtml
 #include ../../components/downloads/content/downloadsPanel.inc.xhtml
-#include ../../components/translations/content/translationsPanel.inc.xhtml
+#include ../../components/translations/content/selectTranslationsPanel.inc.xhtml
+#include ../../components/translations/content/fullPageTranslationsPanel.inc.xhtml
 #include browser-allTabsMenu.inc.xhtml
 
   <tooltip id="dynamic-shortcut-tooltip"
@@ -624,38 +625,38 @@
   </menupopup>
 
   <menupopup id="translations-panel-settings-menupopup"
-             onpopupshown="TranslationsPanel.handleSettingsPopupShownEvent()"
-             onpopuphidden="TranslationsPanel.handleSettingsPopupHiddenEvent()">
+             onpopupshown="FullPageTranslationsPanel.handleSettingsPopupShownEvent()"
+             onpopuphidden="FullPageTranslationsPanel.handleSettingsPopupHiddenEvent()">
     <menuitem class="always-offer-translations-menuitem"
               data-l10n-id="translations-panel-settings-always-offer-translation"
               type="checkbox"
               checked="false"
               autocheck="false"
-              oncommand="TranslationsPanel.onAlwaysOfferTranslations()"/>
+              oncommand="FullPageTranslationsPanel.onAlwaysOfferTranslations()"/>
     <menuitem class="always-translate-language-menuitem"
               data-l10n-id="translations-panel-settings-always-translate-unknown-language"
               type="checkbox"
               checked="false"
               autocheck="false"
-              oncommand="TranslationsPanel.onAlwaysTranslateLanguage()"/>
+              oncommand="FullPageTranslationsPanel.onAlwaysTranslateLanguage()"/>
     <menuitem class="never-translate-language-menuitem"
               data-l10n-id="translations-panel-settings-never-translate-unknown-language"
               type="checkbox"
               checked="false"
               autocheck="false"
-              oncommand="TranslationsPanel.onNeverTranslateLanguage()"/>
+              oncommand="FullPageTranslationsPanel.onNeverTranslateLanguage()"/>
     <menuseparator/>
     <menuitem class="never-translate-site-menuitem"
               data-l10n-id="translations-panel-settings-never-translate-site"
               type="checkbox"
               checked="false"
               autocheck="false"
-              oncommand="TranslationsPanel.onNeverTranslateSite()"/>
+              oncommand="FullPageTranslationsPanel.onNeverTranslateSite()"/>
     <menuseparator/>
     <menuitem class="manage-languages-menuitem"
               data-l10n-id="translations-panel-settings-manage-languages"
-              oncommand="TranslationsPanel.openManageLanguages()"/>
+              oncommand="FullPageTranslationsPanel.openManageLanguages()"/>
     <menuitem data-l10n-id="translations-panel-settings-about2"
-              oncommand="TranslationsPanel.onAboutTranslations()"/>
+              oncommand="FullPageTranslationsPanel.onAboutTranslations()"/>
   </menupopup>
 </popupset>
diff --git a/browser/base/content/moz.build b/browser/base/content/moz.build
index f91487920f..1dd7dccb5f 100644
--- a/browser/base/content/moz.build
+++ b/browser/base/content/moz.build
@@ -151,6 +151,9 @@ with Files("browser-pageActions.js"):
 with Files("browser-places.js"):
     BUG_COMPONENT = ("Firefox", "Bookmarks & History")
 
+with Files("browser-profiles.js"):
+    BUG_COMPONENT = ("Firefox", "Profiles")
+
 with Files("browser-safebrowsing.js"):
     BUG_COMPONENT = ("Toolkit", "Safe Browsing")
 
diff --git a/browser/base/content/navigator-toolbox.inc.xhtml b/browser/base/content/navigator-toolbox.inc.xhtml
index dce7bacdb3..fc19910726 100644
--- a/browser/base/content/navigator-toolbox.inc.xhtml
+++ b/browser/base/content/navigator-toolbox.inc.xhtml
@@ -371,8 +371,8 @@
                     role="button"
                     data-l10n-id="urlbar-translations-button2"
                     hidden="true"
-                    onclick="TranslationsPanel.open(event);"
-                    onkeypress="TranslationsPanel.open(event);">
+                    onclick="FullPageTranslationsPanel.open(event);"
+                    onkeypress="FullPageTranslationsPanel.open(event);">
                 <image class="urlbar-icon" id="translations-button-icon" />
                 <image class="urlbar-icon" id="translations-button-circle-arrows" />
                 <html:span id="translations-button-locale" aria-hidden="true" />
@@ -610,7 +610,7 @@
                    oncommand="BookmarkingUI.onCommand(event);">
       <menupopup id="BMB_bookmarksPopup"
                  is="places-popup-arrow"
-                 class="toolbar-menupopup"
+                 class="toolbar-menupopup animatable-menupopup"
                  placespopup="true"
                  context="placesContext"
                  openInTabs="children"
diff --git a/browser/base/content/nsContextMenu.js b/browser/base/content/nsContextMenu.js
index 4e313e7f01..031a32dddf 100644
--- a/browser/base/content/nsContextMenu.js
+++ b/browser/base/content/nsContextMenu.js
@@ -107,6 +107,14 @@ function openContextMenu(aMessage, aBrowser, aActor) {
 }
 
 class nsContextMenu {
+  /**
+   * A promise to retrieve the translations language pair
+   * if the context menu was opened in a context relevant to
+   * open the SelectTranslationsPanel.
+   * @type {Promise<{fromLang: string, toLang: string}>}
+   */
+  #translationsLangPairPromise;
+
   constructor(aXulMenu, aIsShift) {
     // Get contextual info.
     this.setContext();
@@ -328,7 +336,9 @@ class nsContextMenu {
     InlineSpellCheckerUI.clearDictionaryListFromMenu();
     InlineSpellCheckerUI.uninit();
     if (
-      Cu.isModuleLoaded("resource://gre/modules/LoginManagerContextMenu.jsm")
+      Cu.isESModuleLoaded(
+        "resource://gre/modules/LoginManagerContextMenu.sys.mjs"
+      )
     ) {
       nsContextMenu.LoginManagerContextMenu.clearLoginsFromMenu(document);
     }
@@ -384,6 +394,11 @@ class nsContextMenu {
       this.showItem(id, this.inPDFEditor);
     }
 
+    this.showItem(
+      "context-pdfjs-highlight-selection",
+      this.pdfEditorStates?.hasSelectedText
+    );
+
     if (!this.inPDFEditor) {
       return;
     }
@@ -1379,9 +1394,7 @@ class nsContextMenu {
 
   useGeneratedPassword() {
     nsContextMenu.LoginManagerContextMenu.useGeneratedPassword(
-      this.targetIdentifier,
-      this.contentData.documentURIObject,
-      this.browser
+      this.targetIdentifier
     );
   }
 
@@ -2514,9 +2527,65 @@ class nsContextMenu {
   }
 
   /**
-   * Displays or hides as well as localizes the translate-selection item in the context menu.
+   * Opens the SelectTranslationsPanel singleton instance.
+   *
+   * @param {Event} event - The triggering event for opening the panel.
+   */
+  openSelectTranslationsPanel(event) {
+    SelectTranslationsPanel.open(event, this.#translationsLangPairPromise);
+  }
+
+  /**
+   * Localizes the translate-selection menuitem.
+   *
+   * The item will either be localized with a target language's display name
+   * or localized in a generic way without a target language.
+   *
+   * @param {Element} translateSelectionItem
+   * @returns {Promise<void>}
    */
-  async showTranslateSelectionItem() {
+  async localizeTranslateSelectionItem(translateSelectionItem) {
+    const { toLang } = await this.#translationsLangPairPromise;
+
+    if (toLang) {
+      // A valid to-language exists, so localize the menuitem for that language.
+      let displayName;
+
+      try {
+        const displayNames = new Services.intl.DisplayNames(undefined, {
+          type: "language",
+        });
+        displayName = displayNames.of(toLang);
+      } catch {
+        // Services.intl.DisplayNames.of threw, do nothing.
+      }
+
+      if (displayName) {
+        document.l10n.setAttributes(
+          translateSelectionItem,
+          this.isTextSelected
+            ? "main-context-menu-translate-selection-to-language"
+            : "main-context-menu-translate-link-text-to-language",
+          { language: displayName }
+        );
+        return;
+      }
+    }
+
+    // Either no to-language exists, or an error occurred,
+    // so localize the menuitem without a target language.
+    document.l10n.setAttributes(
+      translateSelectionItem,
+      this.isTextSelected
+        ? "main-context-menu-translate-selection"
+        : "main-context-menu-translate-link-text"
+    );
+  }
+
+  /**
+   * Displays or hides the translate-selection item in the context menu.
+   */
+  showTranslateSelectionItem() {
     const translateSelectionItem = document.getElementById(
       "context-translate-selection"
     );
@@ -2528,7 +2597,7 @@ class nsContextMenu {
     );
 
     // Selected text takes precedence over link text.
-    const translatableText = this.isTextSelected
+    const textToTranslate = this.isTextSelected
       ? this.selectedText.trim()
       : this.linkTextStr.trim();
 
@@ -2536,7 +2605,7 @@ class nsContextMenu {
       // Only show the item if the feature is enabled.
       !(translationsEnabled && selectTranslationsEnabled) ||
       // If there is no text to translate, we have nothing to do.
-      translatableText.length === 0 ||
+      textToTranslate.length === 0 ||
       // We do not allow translating selections on top of Full Page Translations.
       nsContextMenu.#isFullPageTranslationsActive();
 
@@ -2544,39 +2613,9 @@ class nsContextMenu {
       return;
     }
 
-    const preferredLanguages =
-      nsContextMenu.TranslationsParent.getPreferredLanguages();
-    const topPreferredLanguage = preferredLanguages[0];
-
-    if (topPreferredLanguage) {
-      const { language } = await nsContextMenu.LanguageDetector.detectLanguage(
-        translatableText
-      );
-      if (topPreferredLanguage !== language) {
-        try {
-          const dn = new Services.intl.DisplayNames(undefined, {
-            type: "language",
-          });
-          document.l10n.setAttributes(
-            translateSelectionItem,
-            this.isTextSelected
-              ? "main-context-menu-translate-selection-to-language"
-              : "main-context-menu-translate-link-text-to-language",
-            { language: dn.of(topPreferredLanguage) }
-          );
-          return;
-        } catch {
-          // Services.intl.DisplayNames.of threw, do nothing.
-        }
-      }
-    }
-
-    document.l10n.setAttributes(
-      translateSelectionItem,
-      this.isTextSelected
-        ? "main-context-menu-translate-selection"
-        : "main-context-menu-translate-link-text"
-    );
+    this.#translationsLangPairPromise =
+      SelectTranslationsPanel.getLangPairPromise(textToTranslate);
+    this.localizeTranslateSelectionItem(translateSelectionItem);
   }
 
   // Formats the 'Search <engine> for "<selection or link text>"' context menu.
@@ -2681,8 +2720,6 @@ class nsContextMenu {
 
 ChromeUtils.defineESModuleGetters(nsContextMenu, {
   DevToolsShim: "chrome://devtools-startup/content/DevToolsShim.sys.mjs",
-  LanguageDetector:
-    "resource://gre/modules/translation/LanguageDetector.sys.mjs",
   LoginManagerContextMenu:
     "resource://gre/modules/LoginManagerContextMenu.sys.mjs",
   TranslationsParent: "resource://gre/actors/TranslationsParent.sys.mjs",
diff --git a/browser/base/content/pageinfo/pageInfo.js b/browser/base/content/pageinfo/pageInfo.js
index 178e28ad65..f3999a7cc5 100644
--- a/browser/base/content/pageinfo/pageInfo.js
+++ b/browser/base/content/pageinfo/pageInfo.js
@@ -686,7 +686,7 @@ async function selectSaveFolder(aCallback) {
     }
   };
 
-  fp.init(window, titleText, nsIFilePicker.modeGetFolder);
+  fp.init(window.browsingContext, titleText, nsIFilePicker.modeGetFolder);
   fp.appendFilters(nsIFilePicker.filterAll);
   try {
     let initialDir = Services.prefs.getComplexValue(
diff --git a/browser/base/content/popup-notifications.inc b/browser/base/content/popup-notifications.inc
index e554bca50b..daee34e6fe 100644
--- a/browser/base/content/popup-notifications.inc
+++ b/browser/base/content/popup-notifications.inc
@@ -78,7 +78,7 @@
       <popupnotificationcontent orient="vertical">
         <label data-l10n-id="panel-save-update-username" control="password-notification-username" class="password-notification-label"></label>
         <stack>
-          <html:input id="password-notification-username" 
+          <html:input id="password-notification-username"
                       type="text"
                       class="ac-has-end-icon"
                       autocompletesearch="login-doorhanger-username"
@@ -132,7 +132,7 @@
       <popupnotificationcontent id="addon-install-blocked-content" orient="vertical">
         <description id="addon-install-blocked-message" class="popup-notification-description"></description>
         <hbox>
-          <html:a 
+          <html:a
               is="moz-support-link"
               id="addon-install-blocked-info"
               class="popup-notification-learnmore-link"
@@ -261,7 +261,7 @@
     <popupnotification id="address-save-update-notification" class="address-capture-notification" hidden="true">
       <popupnotificationcontent class="address-save-update-notification-content" orient="vertical">
         <html:div class="address-capture-header">
-          <html:p/>
+          <html:h1/>
         </html:div>
         <html:div class="address-capture-description">
           <html:p/>
@@ -274,7 +274,7 @@
     <popupnotification id="address-edit-notification" class="address-capture-notification" hidden="true">
       <popupnotificationcontent class="address-edit-notification-content" orient="vertical">
         <html:div class="address-capture-header">
-          <html:p/>
+          <html:h1/>
         </html:div>
         <html:div class="address-capture-content">
         </html:div>
diff --git a/browser/base/content/sanitizeDialog.js b/browser/base/content/sanitizeDialog.js
index 2be0d500d5..09a7d927df 100644
--- a/browser/base/content/sanitizeDialog.js
+++ b/browser/base/content/sanitizeDialog.js
@@ -38,6 +38,14 @@ Preferences.addAll([
   { id: "privacy.cpd.siteSettings", type: "bool" },
   { id: "privacy.sanitize.timeSpan", type: "int" },
   { id: "privacy.clearOnShutdown.history", type: "bool" },
+  { id: "privacy.clearHistory.historyFormDataAndDownloads", type: "bool" },
+  { id: "privacy.clearHistory.cookiesAndStorage", type: "bool" },
+  { id: "privacy.clearHistory.cache", type: "bool" },
+  { id: "privacy.clearHistory.siteSettings", type: "bool" },
+  { id: "privacy.clearSiteData.historyFormDataAndDownloads", type: "bool" },
+  { id: "privacy.clearSiteData.cookiesAndStorage", type: "bool" },
+  { id: "privacy.clearSiteData.cache", type: "bool" },
+  { id: "privacy.clearSiteData.siteSettings", type: "bool" },
   {
     id: "privacy.clearOnShutdown_v2.historyFormDataAndDownloads",
     type: "bool",
@@ -76,12 +84,6 @@ var gSanitizePromptDialog = {
     this.siteDataSizes = {};
     this.cacheSize = [];
 
-    if (!lazy.USE_OLD_DIALOG) {
-      this._cookiesAndSiteDataCheckbox =
-        document.getElementById("cookiesAndStorage");
-      this._cacheCheckbox = document.getElementById("cache");
-    }
-
     let arg = window.arguments?.[0] || {};
 
     // These variables decide which context the dialog has been opened in
@@ -93,17 +95,6 @@ var gSanitizePromptDialog = {
       this._inClearSiteDataNewDialog = arg.mode == "clearSiteData";
     }
 
-    // Clear site data has it's own default checked boxes, all other entry points
-    // follow the clear history default prefs
-    this.defaultCheckedByContext = {
-      clearHistory: [
-        "historyFormDataAndDownloads",
-        "cookiesAndStorage",
-        "cache",
-      ],
-      clearSiteData: ["cookiesAndStorage", "cache"],
-    };
-
     if (arg.inBrowserWindow) {
       this._dialog.setAttribute("inbrowserwindow", "true");
       this._observeTitleForChanges();
@@ -119,7 +110,7 @@ var gSanitizePromptDialog = {
     if (!lazy.USE_OLD_DIALOG) {
       // Begin collecting how long it takes to load from here
       let timerId = Glean.privacySanitize.loadTime.start();
-
+      this._dataSizesUpdated = false;
       this.dataSizesFinishedUpdatingPromise = this.getAndUpdateDataSizes()
         .then(() => {
           // We're done loading, stop telemetry here
@@ -138,50 +129,42 @@ var gSanitizePromptDialog = {
     let clearPrivateDataGroupbox = document.getElementById(
       "clearPrivateDataGroupbox"
     );
+    let clearSiteDataGroupbox = document.getElementById(
+      "clearSiteDataGroupbox"
+    );
 
     let okButtonl10nID = "sanitize-button-ok";
     if (this._inClearOnShutdownNewDialog) {
       okButtonl10nID = "sanitize-button-ok-on-shutdown";
       this._dialog.setAttribute("inClearOnShutdown", "true");
-      // remove the clear private data groupbox element
-      clearPrivateDataGroupbox.remove();
 
+      // remove the other groupbox elements that aren't related to the context
+      // the dialog is opened in
+      clearPrivateDataGroupbox.remove();
+      clearSiteDataGroupbox.remove();
       // If this is the first time the user is opening the new clear on shutdown
       // dialog, migrate their prefs
-      Sanitizer.maybeMigrateSanitizeOnShutdownPrefs();
+      Sanitizer.maybeMigratePrefs("clearOnShutdown");
     } else if (!lazy.USE_OLD_DIALOG) {
       okButtonl10nID = "sanitize-button-ok2";
-      // remove the clear on shutdown groupbox element
       clearOnShutdownGroupbox.remove();
-    }
-    document.l10n.setAttributes(OKButton, okButtonl10nID);
-
-    // update initial checkbox values based on the context the dialog is opened
-    // from (history, site data). Categories are not remembered
-    // from the last time the dialog was used.
-    if (!lazy.USE_OLD_DIALOG && !this._inClearOnShutdownNewDialog) {
-      let defaults = this.defaultCheckedByContext.clearHistory;
       if (this._inClearSiteDataNewDialog) {
-        defaults = this.defaultCheckedByContext.clearSiteData;
+        clearPrivateDataGroupbox.remove();
+        // we do not need to migrate prefs for clear site data,
+        // since we decided to keep the default options for
+        // privacy.clearSiteData.* to stay consistent with old behaviour
+        // of the clear site data dialog box
+      } else {
+        clearSiteDataGroupbox.remove();
+        Sanitizer.maybeMigratePrefs("cpd");
       }
+    }
+    document.l10n.setAttributes(OKButton, okButtonl10nID);
 
-      this._allCheckboxes = document.querySelectorAll(
-        "#clearPrivateDataGroupbox .clearingItemCheckbox"
-      );
-      this._allCheckboxes.forEach(checkbox => {
-        let pref = checkbox.id;
-        let value = false;
-        if (defaults.includes(pref)) {
-          value = true;
-          checkbox.checked = value;
-        }
-
-        // Add event listeners to the checkboxes to ensure that the clear button is
-        // disabled if no checkboxes are checked
-        checkbox.addEventListener("command", _ =>
-          this.updateAcceptButtonState()
-        );
-      });
+    if (!lazy.USE_OLD_DIALOG) {
+      this._cookiesAndSiteDataCheckbox =
+        document.getElementById("cookiesAndStorage");
+      this._cacheCheckbox = document.getElementById("cache");
     }
 
     document.addEventListener("dialogaccept", e => {
@@ -191,10 +174,13 @@ var gSanitizePromptDialog = {
         if (!lazy.USE_OLD_DIALOG) {
           this.reportTelemetry("clear");
         }
+
         this.sanitize(e);
       }
     });
 
+    this._allCheckboxes = document.querySelectorAll("checkbox[preference]");
+
     this.registerSyncFromPrefListeners();
 
     // we want to show the warning box for all cases except clear on shutdown
@@ -222,8 +208,6 @@ var gSanitizePromptDialog = {
     if (!lazy.USE_OLD_DIALOG) {
       this.reportTelemetry("open");
     }
-
-    await this.dataSizesFinishedUpdatingPromise;
   },
 
   updateAcceptButtonState() {
@@ -306,6 +290,7 @@ var gSanitizePromptDialog = {
         ignoreTimespan: !range,
         range,
       };
+
       let itemsToClear = this.getItemsToClear();
       Sanitizer.sanitize(itemsToClear, options)
         .catch(console.error)
@@ -347,14 +332,9 @@ var gSanitizePromptDialog = {
    * Return the boolean prefs that correspond to the checkboxes on the dialog.
    */
   _getItemPrefs() {
-    return Preferences.getAll().filter(pref => {
-      // The timespan pref isn't a bool, so don't return it
-      if (pref.id == "privacy.sanitize.timeSpan") {
-        return false;
-      }
-      // In the old dialog, cpd.downloads isn't controlled by a checkbox
-      return !(lazy.USE_OLD_DIALOG && pref.id == "privacy.cpd.downloads");
-    });
+    return Array.from(this._allCheckboxes).map(checkbox =>
+      checkbox.getAttribute("preference")
+    );
   },
 
   /**
@@ -367,7 +347,7 @@ var gSanitizePromptDialog = {
     // and (in the old dialog) privacy.cpd.downloads which is not controlled
     // directly by a checkbox).
     var found = this._getItemPrefs().some(
-      pref => !!pref.value && !pref.disabled
+      pref => Preferences.get(pref).value === true
     );
 
     try {
@@ -417,6 +397,8 @@ var gSanitizePromptDialog = {
       );
     }
     this.cacheSize = lazy.DownloadUtils.convertByteUnits(cacheSize);
+
+    this._dataSizesUpdated = true;
     this.updateDataSizesInUI();
   },
 
@@ -441,7 +423,7 @@ var gSanitizePromptDialog = {
     // elements.
     var prefs = this._getItemPrefs();
     for (let i = 0; i < prefs.length; ++i) {
-      var p = prefs[i];
+      var p = Preferences.get(prefs[i]);
       Services.prefs.setBoolPref(p.id, p.value);
     }
   },
@@ -492,6 +474,10 @@ var gSanitizePromptDialog = {
    * Updates data sizes displayed based on new selected timespan
    */
   updateDataSizesInUI() {
+    if (!this._dataSizesUpdated) {
+      return;
+    }
+
     const TIMESPAN_SELECTION_MAP = {
       0: "TIMESPAN_EVERYTHING",
       1: "TIMESPAN_HOUR",
@@ -531,11 +517,7 @@ var gSanitizePromptDialog = {
     }
 
     let items = [];
-    let clearPrivateDataGroupbox = document.getElementById(
-      "clearPrivateDataGroupbox"
-    );
-
-    for (let cb of clearPrivateDataGroupbox.querySelectorAll("checkbox")) {
+    for (let cb of this._allCheckboxes) {
       if (cb.checked) {
         items.push(cb.id);
       }
diff --git a/browser/base/content/sanitize_v2.xhtml b/browser/base/content/sanitize_v2.xhtml
index 97ad484e5f..4d74e140a3 100644
--- a/browser/base/content/sanitize_v2.xhtml
+++ b/browser/base/content/sanitize_v2.xhtml
@@ -108,6 +108,7 @@
           <checkbox
             class="clearingItemCheckbox"
             data-l10n-id="item-history-form-data-downloads"
+            preference="privacy.clearHistory.historyFormDataAndDownloads"
             id="historyFormDataAndDownloads"
           />
           <description
@@ -123,6 +124,7 @@
             class="clearingItemCheckbox"
             data-l10n-id="item-cookies-site-data"
             aria-describedby="cookies-site-data-description"
+            preference="privacy.clearHistory.cookiesAndStorage"
             id="cookiesAndStorage"
           />
           <description
@@ -138,6 +140,7 @@
             class="clearingItemCheckbox"
             data-l10n-id="item-cached-content"
             aria-describedby="cached-content-description"
+            preference="privacy.clearHistory.cache"
             id="cache"
           />
           <description
@@ -153,6 +156,72 @@
             class="clearingItemCheckbox"
             data-l10n-id="item-site-prefs"
             aria-describedby="site-prefs-description"
+            preference="privacy.clearHistory.siteSettings"
+            id="siteSettings"
+          />
+          <description
+            id="site-prefs-description"
+            data-l10n-id="item-site-prefs-description"
+            class="sanitizeCheckboxDescription text-deemphasized"
+          />
+        </vbox>
+      </hbox>
+    </groupbox>
+    <groupbox id="clearSiteDataGroupbox">
+      <hbox class="checkboxWithDescription">
+        <vbox>
+          <checkbox
+            class="clearingItemCheckbox"
+            data-l10n-id="item-history-form-data-downloads"
+            preference="privacy.clearSiteData.historyFormDataAndDownloads"
+            id="historyFormDataAndDownloads"
+          />
+          <description
+            id="history-form-data-description"
+            data-l10n-id="item-history-form-data-downloads-description"
+            class="sanitizeCheckboxDescription text-deemphasized"
+          />
+        </vbox>
+      </hbox>
+      <hbox class="checkboxWithDescription">
+        <vbox>
+          <checkbox
+            class="clearingItemCheckbox"
+            data-l10n-id="item-cookies-site-data"
+            aria-describedby="cookies-site-data-description"
+            preference="privacy.clearSiteData.cookiesAndStorage"
+            id="cookiesAndStorage"
+          />
+          <description
+            id="cookies-site-data-description"
+            data-l10n-id="item-cookies-site-data-description"
+            class="sanitizeCheckboxDescription text-deemphasized"
+          />
+        </vbox>
+      </hbox>
+      <hbox class="checkboxWithDescription">
+        <vbox>
+          <checkbox
+            class="clearingItemCheckbox"
+            data-l10n-id="item-cached-content"
+            aria-describedby="cached-content-description"
+            preference="privacy.clearSiteData.cache"
+            id="cache"
+          />
+          <description
+            id="cached-content-description"
+            data-l10n-id="item-cached-content-description"
+            class="sanitizeCheckboxDescription text-deemphasized"
+          />
+        </vbox>
+      </hbox>
+      <hbox class="checkboxWithDescription">
+        <vbox>
+          <checkbox
+            class="clearingItemCheckbox"
+            data-l10n-id="item-site-prefs"
+            aria-describedby="site-prefs-description"
+            preference="privacy.clearSiteData.siteSettings"
             id="siteSettings"
           />
           <description
diff --git a/browser/base/content/tabbrowser-tab.js b/browser/base/content/tabbrowser-tab.js
index 01bb7ee90b..ed3d4bb727 100644
--- a/browser/base/content/tabbrowser-tab.js
+++ b/browser/base/content/tabbrowser-tab.js
@@ -350,7 +350,20 @@
           count: affectedTabsLength,
         });
       }
-      this._mouseenter();
+
+      if (this.hidden || this.closing) {
+        return;
+      }
+
+      let tabToWarm = this.mOverCloseButton
+        ? gBrowser._findTabToBlurTo(this)
+        : this;
+      gBrowser.warmupTab(tabToWarm);
+
+      // If the previous target wasn't part of this tab then this is a mouseenter event.
+      if (!this.contains(event.relatedTarget)) {
+        this._mouseenter();
+      }
     }
 
     on_mouseout(event) {
@@ -360,7 +373,11 @@
       if (event.target == this.overlayIcon) {
         this.setSecondaryTabTooltipLabel(null);
       }
-      this._mouseleave();
+
+      // If the new target is not part of this tab then this is a mouseleave event.
+      if (!this.contains(event.relatedTarget)) {
+        this._mouseleave();
+      }
     }
 
     on_dragstart(event) {
@@ -530,9 +547,6 @@
     }
 
     _mouseenter() {
-      if (this.hidden || this.closing) {
-        return;
-      }
       this._hover = true;
 
       if (this.selected) {
@@ -545,12 +559,6 @@
       // Prepare connection to host beforehand.
       SessionStore.speculativeConnectOnTabHover(this);
 
-      let tabToWarm = this;
-      if (this.mOverCloseButton) {
-        tabToWarm = gBrowser._findTabToBlurTo(this);
-      }
-      gBrowser.warmupTab(tabToWarm);
-
       this.dispatchEvent(new CustomEvent("TabHoverStart", { bubbles: true }));
     }
 
diff --git a/browser/base/content/tabbrowser-tabs.js b/browser/base/content/tabbrowser-tabs.js
index 4733e6d0b6..36b6aeb390 100644
--- a/browser/base/content/tabbrowser-tabs.js
+++ b/browser/base/content/tabbrowser-tabs.js
@@ -187,6 +187,26 @@
       this.updateTabIndicatorAttr(event.target);
     }
 
+    on_TabHoverStart(event) {
+      if (this._showCardPreviews) {
+        const previewContainer = document.getElementById(
+          "tabbrowser-tab-preview"
+        );
+        previewContainer.tab = event.target;
+      }
+    }
+
+    on_TabHoverEnd(event) {
+      if (this._showCardPreviews) {
+        const previewContainer = document.getElementById(
+          "tabbrowser-tab-preview"
+        );
+        if (previewContainer.tab === event.target) {
+          previewContainer.tab = null;
+        }
+      }
+    }
+
     on_transitionend(event) {
       if (event.propertyName != "max-width") {
         return;
@@ -1818,22 +1838,6 @@
 
     handleEvent(aEvent) {
       switch (aEvent.type) {
-        case "TabHoverStart":
-          if (this._showCardPreviews) {
-            const previewContainer = document.getElementById(
-              "tabbrowser-tab-preview"
-            );
-            previewContainer.tab = aEvent.target;
-          }
-          break;
-        case "TabHoverEnd":
-          if (this._showCardPreviews) {
-            const previewContainer = document.getElementById(
-              "tabbrowser-tab-preview"
-            );
-            previewContainer.tab = null;
-          }
-          break;
         case "mouseout":
           // If the "related target" (the node to which the pointer went) is not
           // a child of the current document, the mouse just left the window.
diff --git a/browser/base/content/tabbrowser.js b/browser/base/content/tabbrowser.js
index a9637ad262..54a801939a 100644
--- a/browser/base/content/tabbrowser.js
+++ b/browser/base/content/tabbrowser.js
@@ -119,8 +119,8 @@
 
       Services.obs.addObserver(this, "contextual-identity-updated");
 
-      Services.els.addSystemEventListener(document, "keydown", this, false);
-      Services.els.addSystemEventListener(document, "keypress", this, false);
+      document.addEventListener("keydown", this, { mozSystemGroup: true });
+      document.addEventListener("keypress", this, { mozSystemGroup: true });
       document.addEventListener("visibilitychange", this);
       window.addEventListener("framefocusrequested", this);
       window.addEventListener("activate", this);
@@ -5948,14 +5948,11 @@
         }
       }
 
-      Services.els.removeSystemEventListener(document, "keydown", this, false);
+      document.removeEventListener("keydown", this, { mozSystemGroup: true });
       if (AppConstants.platform == "macosx") {
-        Services.els.removeSystemEventListener(
-          document,
-          "keypress",
-          this,
-          false
-        );
+        document.removeEventListener("keypress", this, {
+          mozSystemGroup: true,
+        });
       }
       document.removeEventListener("visibilitychange", this);
       window.removeEventListener("framefocusrequested", this);
diff --git a/browser/base/content/test/about/browser.toml b/browser/base/content/test/about/browser.toml
index 900c6b7140..98961200a0 100644
--- a/browser/base/content/test/about/browser.toml
+++ b/browser/base/content/test/about/browser.toml
@@ -34,7 +34,8 @@ support-files = [
 ["browser_aboutHome_search_suggestion.js"]
 skip-if = [
   "os == 'mac'",
-  "os == 'linux' && (!debug || bits == 64)",
+  "os == 'linux' && os_version == '18.04' && !debug",
+  "os == 'linux' && os_version == '18.04' && bits == 64",
   "win10_2009 && bits == 64 && !debug", # Bug 1399648, bug 1402502
 ]
 
@@ -75,7 +76,7 @@ skip-if = ["tsan"] # Bug 1676326, highly frequent on TSan
 ["browser_aboutStopReload.js"]
 
 ["browser_aboutSupport.js"]
-skip-if = ["os == 'linux' && bits == 64 && asan && !debug"] # Bug 1713368
+skip-if = ["os == 'linux' && os_version == '18.04' && asan"] # Bug 1713368
 
 ["browser_aboutSupport_newtab_security_state.js"]
 
@@ -83,6 +84,9 @@ skip-if = ["os == 'linux' && bits == 64 && asan && !debug"] # Bug 1713368
 skip-if = ["os == 'android'"]
 
 ["browser_bug435325.js"]
-skip-if = ["verify && !debug && os == 'mac'"]
+skip-if = [
+  "apple_catalina && !debug && verify",
+  "apple_silicon && !debug && verify",
+]
 
 ["browser_bug633691.js"]
diff --git a/browser/base/content/test/about/browser_aboutNetError.js b/browser/base/content/test/about/browser_aboutNetError.js
index 8222a0f6e8..9131f5e696 100644
--- a/browser/base/content/test/about/browser_aboutNetError.js
+++ b/browser/base/content/test/about/browser_aboutNetError.js
@@ -25,6 +25,38 @@ function resetPrefs() {
   Services.prefs.clearUserPref("browser.fixup.alternate.enabled");
 }
 
+async function resetTelemetry() {
+  Services.telemetry.clearEvents();
+  await TestUtils.waitForCondition(() => {
+    let events = Services.telemetry.snapshotEvents(
+      Ci.nsITelemetry.DATASET_PRERELEASE_CHANNELS,
+      true
+    ).content;
+    return !events || !events.length;
+  });
+  Services.telemetry.setEventRecordingEnabled("security.ui.tlserror", true);
+}
+
+async function checkTelemetry(errorString) {
+  let loadEvent = await TestUtils.waitForCondition(() => {
+    let events = Services.telemetry.snapshotEvents(
+      Ci.nsITelemetry.DATASET_PRERELEASE_CHANNELS,
+      true
+    ).content;
+    return events?.find(e => e[1] == "security.ui.tlserror" && e[2] == "load");
+  }, "recorded telemetry for the load");
+  loadEvent.shift();
+  Assert.deepEqual(loadEvent, [
+    "security.ui.tlserror",
+    "load",
+    "abouttlserror",
+    errorString,
+    {
+      is_frame: "false",
+    },
+  ]);
+}
+
 add_task(async function resetToDefaultConfig() {
   info(
     "Change TLS config to cause page load to fail, check that reset button is shown and that it works"
@@ -34,6 +66,8 @@ add_task(async function resetToDefaultConfig() {
   Services.prefs.setIntPref("security.tls.version.min", 1); // TLS 1.0
   Services.prefs.setIntPref("security.tls.version.max", 1);
 
+  await resetTelemetry();
+
   let browser;
   let pageLoaded;
   await BrowserTestUtils.openNewForegroundTab(
@@ -49,6 +83,8 @@ add_task(async function resetToDefaultConfig() {
   info("Loading and waiting for the net error");
   await pageLoaded;
 
+  await checkTelemetry("SSL_ERROR_PROTOCOL_VERSION_ALERT");
+
   // Setup an observer for the target page.
   const finalLoadComplete = BrowserTestUtils.browserLoaded(
     browser,
@@ -92,6 +128,8 @@ add_task(async function checkLearnMoreLink() {
   Services.prefs.setIntPref("security.tls.version.min", 3);
   Services.prefs.setIntPref("security.tls.version.max", 4);
 
+  await resetTelemetry();
+
   let browser;
   let pageLoaded;
   await BrowserTestUtils.openNewForegroundTab(
@@ -107,6 +145,8 @@ add_task(async function checkLearnMoreLink() {
   info("Loading and waiting for the net error");
   await pageLoaded;
 
+  await checkTelemetry("SSL_ERROR_PROTOCOL_VERSION_ALERT");
+
   const baseURL = Services.urlFormatter.formatURLPref("app.support.baseURL");
 
   await SpecialPowers.spawn(browser, [baseURL], function (_baseURL) {
@@ -206,6 +246,8 @@ add_task(async function checkDomainCorrection() {
 // Test that ciphersuites that use 3DES (namely, TLS_RSA_WITH_3DES_EDE_CBC_SHA)
 // can only be enabled when deprecated TLS is enabled.
 add_task(async function onlyAllow3DESWithDeprecatedTLS() {
+  await resetTelemetry();
+
   // By default, connecting to a server that only uses 3DES should fail.
   await BrowserTestUtils.withNewTab(
     { gBrowser, url: "about:blank" },
@@ -215,6 +257,8 @@ add_task(async function onlyAllow3DESWithDeprecatedTLS() {
     }
   );
 
+  await checkTelemetry("SSL_ERROR_NO_CYPHER_OVERLAP");
+
   // Enabling deprecated TLS should also enable 3DES.
   Services.prefs.setBoolPref("security.tls.version.enable-deprecated", true);
   await BrowserTestUtils.withNewTab(
diff --git a/browser/base/content/test/contextMenu/browser_bug1798178.js b/browser/base/content/test/contextMenu/browser_bug1798178.js
index 529665a6f9..de8bab1820 100644
--- a/browser/base/content/test/contextMenu/browser_bug1798178.js
+++ b/browser/base/content/test/contextMenu/browser_bug1798178.js
@@ -15,7 +15,7 @@ const TEST_URL =
   ) + "file_bug1798178.html";
 
 let MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 function createTemporarySaveDirectory() {
   let saveDir = Services.dirsvc.get("TmpD", Ci.nsIFile);
diff --git a/browser/base/content/test/contextMenu/browser_contextmenu_save_blocked.js b/browser/base/content/test/contextMenu/browser_contextmenu_save_blocked.js
index 5064d9a316..062fbeac08 100644
--- a/browser/base/content/test/contextMenu/browser_contextmenu_save_blocked.js
+++ b/browser/base/content/test/contextMenu/browser_contextmenu_save_blocked.js
@@ -4,7 +4,7 @@
 "use strict";
 
 var MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 function mockPromptService() {
   let { prompt } = Services;
diff --git a/browser/base/content/test/forms/browser.toml b/browser/base/content/test/forms/browser.toml
index 33d73ba8bf..95b666369e 100644
--- a/browser/base/content/test/forms/browser.toml
+++ b/browser/base/content/test/forms/browser.toml
@@ -1,5 +1,5 @@
 [DEFAULT]
-prefs = ["gfx.font_loader.delay=0", "dom.select.showPicker.enabled=true"]
+prefs = ["gfx.font_loader.delay=0", "dom.select.showPicker.enabled=true", "font.minimum-size.x-western=9"]
 support-files = ["head.js"]
 
 ["browser_selectpopup.js"]
@@ -18,6 +18,8 @@ skip-if = ["os == 'linux'"] # Bug 1329991 - test fails intermittently on Linux b
 
 ["browser_selectpopup_large.js"]
 
+["browser_selectpopup_minFontSize.js"]
+
 ["browser_selectpopup_searchfocus.js"]
 fail-if = ["a11y_checks"] # Bug 1854233 input may not be labeled
 
diff --git a/browser/base/content/test/forms/browser_selectpopup_minFontSize.js b/browser/base/content/test/forms/browser_selectpopup_minFontSize.js
new file mode 100644
index 0000000000..d240c2d2d0
--- /dev/null
+++ b/browser/base/content/test/forms/browser_selectpopup_minFontSize.js
@@ -0,0 +1,38 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// NOTE that this test expects "font.minimum-size.x-western=9" to be set
+// in the manifest.
+
+const PAGE = `
+<!doctype html>
+<body lang="en-US">
+<select>
+  <option style="font-size:24px">A</option>
+  <option style="font-size:6px">BCD</option>
+</select>
+`;
+
+add_task(async function () {
+  const url = "data:text/html," + encodeURI(PAGE);
+  await BrowserTestUtils.withNewTab(
+    {
+      gBrowser,
+      url,
+    },
+    async function (browser) {
+      let popup = await openSelectPopup("click");
+      let menuitems = popup.querySelectorAll("menuitem");
+      is(
+        getComputedStyle(menuitems[0]).fontSize,
+        "24px",
+        "font-size should be honored"
+      );
+      is(
+        getComputedStyle(menuitems[1]).fontSize,
+        "9px",
+        "minimum font-size should be honored"
+      );
+    }
+  );
+});
diff --git a/browser/base/content/test/general/browser_beforeunload_duplicate_dialogs.js b/browser/base/content/test/general/browser_beforeunload_duplicate_dialogs.js
index 8a77f01ce4..8eb07a863a 100644
--- a/browser/base/content/test/general/browser_beforeunload_duplicate_dialogs.js
+++ b/browser/base/content/test/general/browser_beforeunload_duplicate_dialogs.js
@@ -1,36 +1,11 @@
 const TEST_PAGE =
   "http://mochi.test:8888/browser/browser/base/content/test/general/file_double_close_tab.html";
 
-const CONTENT_PROMPT_SUBDIALOG = Services.prefs.getBoolPref(
-  "prompts.contentPromptSubDialog",
-  false
-);
-
 var expectingDialog = false;
 var wantToClose = true;
 var resolveDialogPromise;
 
-function onTabModalDialogLoaded(node) {
-  ok(
-    !CONTENT_PROMPT_SUBDIALOG,
-    "Should not be using content prompt subdialogs."
-  );
-  ok(expectingDialog, "Should be expecting this dialog.");
-  expectingDialog = false;
-  if (wantToClose) {
-    // This accepts the dialog, closing it
-    node.querySelector(".tabmodalprompt-button0").click();
-  } else {
-    // This keeps the page open
-    node.querySelector(".tabmodalprompt-button1").click();
-  }
-  if (resolveDialogPromise) {
-    resolveDialogPromise();
-  }
-}
-
 function onCommonDialogLoaded(promptWindow) {
-  ok(CONTENT_PROMPT_SUBDIALOG, "Should be using content prompt subdialogs.");
   ok(expectingDialog, "Should be expecting this dialog.");
   expectingDialog = false;
   let dialog = promptWindow.Dialog;
@@ -51,11 +26,9 @@ SpecialPowers.pushPrefEnv({
 });
 
 // Listen for the dialog being created
-Services.obs.addObserver(onTabModalDialogLoaded, "tabmodal-dialog-loaded");
 Services.obs.addObserver(onCommonDialogLoaded, "common-dialog-loaded");
 registerCleanupFunction(() => {
   Services.prefs.clearUserPref("browser.tabs.warnOnClose");
-  Services.obs.removeObserver(onTabModalDialogLoaded, "tabmodal-dialog-loaded");
   Services.obs.removeObserver(onCommonDialogLoaded, "common-dialog-loaded");
 });
 
diff --git a/browser/base/content/test/general/browser_bug676619.js b/browser/base/content/test/general/browser_bug676619.js
index 24d8d88447..80bbce8cb0 100644
--- a/browser/base/content/test/general/browser_bug676619.js
+++ b/browser/base/content/test/general/browser_bug676619.js
@@ -1,5 +1,5 @@
 var MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 function waitForNewWindow() {
   return new Promise(resolve => {
diff --git a/browser/base/content/test/general/browser_double_close_tab.js b/browser/base/content/test/general/browser_double_close_tab.js
index 554aeb8077..f5f2f1b6c7 100644
--- a/browser/base/content/test/general/browser_double_close_tab.js
+++ b/browser/base/content/test/general/browser_double_close_tab.js
@@ -4,24 +4,15 @@ const TEST_PAGE =
   "http://mochi.test:8888/browser/browser/base/content/test/general/file_double_close_tab.html";
 var testTab;
 
-const CONTENT_PROMPT_SUBDIALOG = Services.prefs.getBoolPref(
-  "prompts.contentPromptSubDialog",
-  false
-);
-
 function waitForDialog(callback) {
   function onDialogLoaded(nodeOrDialogWindow) {
-    let node = CONTENT_PROMPT_SUBDIALOG
-      ? nodeOrDialogWindow.document.querySelector("dialog")
-      : nodeOrDialogWindow;
-    Services.obs.removeObserver(onDialogLoaded, "tabmodal-dialog-loaded");
+    let node = nodeOrDialogWindow.document.querySelector("dialog");
     Services.obs.removeObserver(onDialogLoaded, "common-dialog-loaded");
     // Allow dialog's onLoad call to run to completion
     Promise.resolve().then(() => callback(node));
   }
 
   // Listen for the dialog being created
-  Services.obs.addObserver(onDialogLoaded, "tabmodal-dialog-loaded");
   Services.obs.addObserver(onDialogLoaded, "common-dialog-loaded");
 }
 
@@ -35,9 +26,7 @@ function waitForDialogDestroyed(node, callback) {
   });
   observer.observe(node.parentNode, { childList: true });
 
-  if (CONTENT_PROMPT_SUBDIALOG) {
-    node.ownerGlobal.addEventListener("unload", done);
-  }
+  node.ownerGlobal.addEventListener("unload", done);
 
   let failureTimeout = setTimeout(function () {
     ok(false, "Dialog should have been destroyed");
@@ -49,12 +38,8 @@ function waitForDialogDestroyed(node, callback) {
     observer.disconnect();
     observer = null;
 
-    if (CONTENT_PROMPT_SUBDIALOG) {
-      node.ownerGlobal.removeEventListener("unload", done);
-      SimpleTest.executeSoon(callback);
-    } else {
-      callback();
-    }
+    node.ownerGlobal.removeEventListener("unload", done);
+    SimpleTest.executeSoon(callback);
   }
 }
 
@@ -76,23 +61,12 @@ add_task(async function () {
         let doCompletion = () => setTimeout(resolveOuter, 0);
         info("Now checking if dialog is destroyed");
 
-        if (CONTENT_PROMPT_SUBDIALOG) {
-          ok(
-            !dialogNode.ownerGlobal || dialogNode.ownerGlobal.closed,
-            "onbeforeunload dialog should be gone."
-          );
-          if (dialogNode.ownerGlobal && !dialogNode.ownerGlobal.closed) {
-            dialogNode.acceptDialog();
-          }
-        } else {
-          ok(!dialogNode.parentNode, "onbeforeunload dialog should be gone.");
-          if (dialogNode.parentNode) {
-            // Failed to remove onbeforeunload dialog, so do it ourselves:
-            let leaveBtn = dialogNode.querySelector(".tabmodalprompt-button0");
-            waitForDialogDestroyed(dialogNode, doCompletion);
-            EventUtils.synthesizeMouseAtCenter(leaveBtn, {});
-            return;
-          }
+        ok(
+          !dialogNode.ownerGlobal || dialogNode.ownerGlobal.closed,
+          "onbeforeunload dialog should be gone."
+        );
+        if (dialogNode.ownerGlobal && !dialogNode.ownerGlobal.closed) {
+          dialogNode.acceptDialog();
         }
 
         doCompletion();
diff --git a/browser/base/content/test/general/browser_minimize.js b/browser/base/content/test/general/browser_minimize.js
index a57fea079c..3919cd7d77 100644
--- a/browser/base/content/test/general/browser_minimize.js
+++ b/browser/base/content/test/general/browser_minimize.js
@@ -12,26 +12,57 @@ add_task(async function () {
   ok(isActive(), "Docshell should be active when starting the test");
   ok(!document.hidden, "Top level window should be visible");
 
+  // When we show or hide the window (including by minimization),
+  // there are 2 signifiers that the process is complete: the
+  // sizemodechange event, and the browsing context becoming active
+  // or inactive. There is another signifier, the
+  // occlusionstatechange event, but whether or not that event
+  // is sent is platform-dependent, so it's not very useful. The
+  // safest way to check for stable state is to build promises
+  // around sizemodechange and browsing context active and then
+  // wait for them all to complete, and that's what we do here.
   info("Calling window.minimize");
   let promiseSizeModeChange = BrowserTestUtils.waitForEvent(
     window,
     "sizemodechange"
+  ).then(
+    () => ok(true, "Got sizemodechange."),
+    () => ok(false, "Rejected sizemodechange.")
+  );
+  let promiseBrowserInactive = BrowserTestUtils.waitForCondition(
+    () => !isActive(),
+    "Docshell should be inactive."
+  ).then(
+    () => ok(true, "Got inactive."),
+    () => ok(false, "Rejected inactive.")
   );
   window.minimize();
-  await promiseSizeModeChange;
-  ok(!isActive(), "Docshell should be Inactive");
+  await Promise.all([promiseSizeModeChange, promiseBrowserInactive]);
   ok(document.hidden, "Top level window should be hidden");
 
+  // When we restore the window from minimization, we have the
+  // same concerns as above, so prepare our promises.
   info("Calling window.restore");
   promiseSizeModeChange = BrowserTestUtils.waitForEvent(
     window,
     "sizemodechange"
+  ).then(
+    () => ok(true, "Got sizemodechange."),
+    () => ok(false, "Rejected sizemodechange.")
+  );
+  let promiseBrowserActive = BrowserTestUtils.waitForCondition(
+    () => isActive(),
+    "Docshell should be active."
+  ).then(
+    () => ok(true, "Got active."),
+    () => ok(false, "Rejected active.")
   );
   window.restore();
+
   // On Ubuntu `window.restore` doesn't seem to work, use a timer to make the
   // test fail faster and more cleanly than with a test timeout.
   await Promise.race([
-    promiseSizeModeChange,
+    Promise.all([promiseSizeModeChange, promiseBrowserActive]),
     new Promise((resolve, reject) =>
       // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
       setTimeout(() => {
@@ -39,11 +70,5 @@ add_task(async function () {
       }, 5000)
     ),
   ]);
-  // The sizemodechange event can sometimes be fired before the
-  // occlusionstatechange event, especially in chaos mode.
-  if (window.isFullyOccluded) {
-    await BrowserTestUtils.waitForEvent(window, "occlusionstatechange");
-  }
-  ok(isActive(), "Docshell should be active again");
   ok(!document.hidden, "Top level window should be visible");
 });
diff --git a/browser/base/content/test/general/browser_save_link-perwindowpb.js b/browser/base/content/test/general/browser_save_link-perwindowpb.js
index b018212280..234813ca2c 100644
--- a/browser/base/content/test/general/browser_save_link-perwindowpb.js
+++ b/browser/base/content/test/general/browser_save_link-perwindowpb.js
@@ -2,7 +2,7 @@
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
 var MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 // Trigger a save of a link in public mode, then trigger an identical save
 // in private mode and ensure that the second request is differentiated from
@@ -14,7 +14,7 @@ function triggerSave(aWindow, aCallback) {
   let testBrowser = aWindow.gBrowser.selectedBrowser;
   // This page sets a cookie if and only if a cookie does not exist yet
   let testURI =
-    "http://mochi.test:8888/browser/browser/base/content/test/general/bug792517-2.html";
+    "https://example.com/browser/browser/base/content/test/general/bug792517-2.html";
   BrowserTestUtils.startLoadingURIString(testBrowser, testURI);
   BrowserTestUtils.browserLoaded(testBrowser, false, testURI).then(() => {
     waitForFocus(function () {
@@ -132,7 +132,7 @@ function test() {
     info("onExamineResponse with " + channel.URI.spec);
     if (
       channel.URI.spec !=
-      "http://mochi.test:8888/browser/browser/base/content/test/general/bug792517.sjs"
+      "https://example.com/browser/browser/base/content/test/general/bug792517.sjs"
     ) {
       info("returning");
       return;
@@ -158,7 +158,7 @@ function test() {
     info("onModifyRequest with " + channel.URI.spec);
     if (
       channel.URI.spec !=
-      "http://mochi.test:8888/browser/browser/base/content/test/general/bug792517.sjs"
+      "https://example.com/browser/browser/base/content/test/general/bug792517.sjs"
     ) {
       return;
     }
diff --git a/browser/base/content/test/general/browser_save_link_when_window_navigates.js b/browser/base/content/test/general/browser_save_link_when_window_navigates.js
index e7507fcbb0..65daef5f1b 100644
--- a/browser/base/content/test/general/browser_save_link_when_window_navigates.js
+++ b/browser/base/content/test/general/browser_save_link_when_window_navigates.js
@@ -2,7 +2,7 @@
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
 var MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 const SAVE_PER_SITE_PREF = "browser.download.lastDir.savePerSite";
 const ALWAYS_DOWNLOAD_DIR_PREF = "browser.download.useDownloadDir";
@@ -36,7 +36,7 @@ function triggerSave(aWindow, aCallback) {
   var fileName;
   let testBrowser = aWindow.gBrowser.selectedBrowser;
   let testURI =
-    "http://mochi.test:8888/browser/browser/base/content/test/general/navigating_window_with_download.html";
+    "https://example.com/browser/browser/base/content/test/general/navigating_window_with_download.html";
 
   // Only observe the UTC dialog if it's enabled by pref
   if (Services.prefs.getBoolPref(ALWAYS_ASK_PREF)) {
diff --git a/browser/base/content/test/general/browser_save_private_link_perwindowpb.js b/browser/base/content/test/general/browser_save_private_link_perwindowpb.js
index 8ede97e640..42632bdc5a 100644
--- a/browser/base/content/test/general/browser_save_private_link_perwindowpb.js
+++ b/browser/base/content/test/general/browser_save_private_link_perwindowpb.js
@@ -43,7 +43,7 @@ function promiseImageDownloaded() {
   return new Promise((resolve, reject) => {
     let fileName;
     let MockFilePicker = SpecialPowers.MockFilePicker;
-    MockFilePicker.init(window);
+    MockFilePicker.init(window.browsingContext);
 
     function onTransferComplete(downloadSuccess) {
       ok(
diff --git a/browser/base/content/test/general/browser_save_video.js b/browser/base/content/test/general/browser_save_video.js
index 276088fbb1..e9701d7023 100644
--- a/browser/base/content/test/general/browser_save_video.js
+++ b/browser/base/content/test/general/browser_save_video.js
@@ -2,7 +2,7 @@
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
 var MockFilePicker = SpecialPowers.MockFilePicker;
-MockFilePicker.init(window);
+MockFilePicker.init(window.browsingContext);
 
 /**
  * TestCase for bug 564387
@@ -14,7 +14,7 @@ add_task(async function () {
   let loadPromise = BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
   BrowserTestUtils.startLoadingURIString(
     gBrowser,
-    "http://mochi.test:8888/browser/browser/base/content/test/general/web_video.html"
+    "https://example.com/browser/browser/base/content/test/general/web_video.html"
   );
   await loadPromise;
 
diff --git a/browser/base/content/test/general/browser_save_video_frame.js b/browser/base/content/test/general/browser_save_video_frame.js
index 877c33bcd3..11fe3ac80e 100644
--- a/browser/base/content/test/general/browser_save_video_frame.js
+++ b/browser/base/content/test/general/browser_save_video_frame.js
@@ -49,7 +49,7 @@ function waitForTransferComplete() {
  */
 add_task(async function () {
   let MockFilePicker = SpecialPowers.MockFilePicker;
-  MockFilePicker.init(window);
+  MockFilePicker.init(window.browsingContext);
 
   // Create the folder the video will be saved into.
   let destDir = createTemporarySaveDirectory();
diff --git a/browser/base/content/test/general/browser_visibleTabs_bookmarkAllPages.js b/browser/base/content/test/general/browser_visibleTabs_bookmarkAllPages.js
index 2c0002fc44..2ec3b632f2 100644
--- a/browser/base/content/test/general/browser_visibleTabs_bookmarkAllPages.js
+++ b/browser/base/content/test/general/browser_visibleTabs_bookmarkAllPages.js
@@ -15,7 +15,9 @@ function test() {
 
     is(gBrowser.visibleTabs.length, 1, "Only one tab is visible");
 
-    let uris = PlacesCommandHook.uniqueCurrentPages;
+    let uris = PlacesCommandHook.getUniquePages(
+      gBrowser.visibleTabs.filter(tab => !tab.pinned)
+    );
     is(uris.length, 1, "Only one uri is returned");
 
     is(
diff --git a/browser/base/content/test/general/navigating_window_with_download.html b/browser/base/content/test/general/navigating_window_with_download.html
index 6b0918941f..8649168cf5 100644
--- a/browser/base/content/test/general/navigating_window_with_download.html
+++ b/browser/base/content/test/general/navigating_window_with_download.html
@@ -2,6 +2,6 @@
 <html>
   <head><title>This window will navigate while you're downloading something</title></head>
   <body>
-    <iframe src="http://mochi.test:8888/browser/browser/base/content/test/general/unknownContentType_file.pif"></iframe>
+    <iframe src="https://example.com/browser/browser/base/content/test/general/unknownContentType_file.pif"></iframe>
   </body>
 </html>
diff --git a/browser/base/content/test/outOfProcess/browser_controller.js b/browser/base/content/test/outOfProcess/browser_controller.js
index f9d9ca8c93..f3c0217b90 100644
--- a/browser/base/content/test/outOfProcess/browser_controller.js
+++ b/browser/base/content/test/outOfProcess/browser_controller.js
@@ -42,8 +42,19 @@ add_task(async function test_controllers_subframes() {
 
   gURLBar.focus();
 
+  let canTabMoveFocusToRootElement = !SpecialPowers.getBoolPref(
+    "dom.disable_tab_focus_to_root_element"
+  );
   for (let stepNum = 0; stepNum < browsingContexts.length; stepNum++) {
-    await keyAndUpdate(stepNum > 0 ? "VK_TAB" : "VK_F6", {}, 6);
+    let useTab = stepNum > 0;
+    // When canTabMoveFocusToRootElement is true, this kepress will move the
+    // focus to a root element, which will trigger an extra "select" command
+    // compare to the case when canTabMoveFocusToRootElement is false.
+    await keyAndUpdate(
+      useTab ? "VK_TAB" : "VK_F6",
+      {},
+      canTabMoveFocusToRootElement ? 6 : 4
+    );
 
     // Since focus may be switching into a separate process here,
     // need to wait for the focus to have been updated.
@@ -59,22 +70,35 @@ add_task(async function test_controllers_subframes() {
       goUpdateGlobalEditMenuItems(true);
     }
 
-    await SpecialPowers.spawn(browsingContexts[stepNum], [], () => {
-      // Both the tab key and document navigation with F6 will focus
-      // the root of the document within the frame.
-      let document = content.document;
-      Assert.equal(
-        document.activeElement,
-        document.documentElement,
-        "root focused"
+    await SpecialPowers.spawn(
+      browsingContexts[stepNum],
+      [{ canTabMoveFocusToRootElement, useTab }],
+      args => {
+        // Both the tab key and document navigation with F6 will focus
+        // the root of the document within the frame.
+        // When dom.disable_tab_focus_to_root_element is true, only F6 will do this.
+        let document = content.document;
+        let expectedElement =
+          args.canTabMoveFocusToRootElement || !args.useTab
+            ? document.documentElement
+            : document.getElementById("input");
+        Assert.equal(document.activeElement, expectedElement, "root focused");
+      }
+    );
+
+    if (canTabMoveFocusToRootElement || !useTab) {
+      // XXX Currently, Copy is always enabled when the root (not an editor element)
+      // is focused. Possibly that should only be true if a listener is present?
+      checkCommandState(
+        "step " + stepNum + " root focused",
+        false,
+        true,
+        false
       );
-    });
-    // XXX Currently, Copy is always enabled when the root (not an editor element)
-    // is focused. Possibly that should only be true if a listener is present?
-    checkCommandState("step " + stepNum + " root focused", false, true, false);
 
-    // Tab to the textbox.
-    await keyAndUpdate("VK_TAB", {}, 1);
+      // Tab to the textbox.
+      await keyAndUpdate("VK_TAB", {}, 1);
+    }
 
     if (AppConstants.platform != "macosx") {
       goUpdateGlobalEditMenuItems(true);
diff --git a/browser/base/content/test/performance/browser_appmenu.js b/browser/base/content/test/performance/browser_appmenu.js
index 37e7482c51..984d2b9fd8 100644
--- a/browser/base/content/test/performance/browser_appmenu.js
+++ b/browser/base/content/test/performance/browser_appmenu.js
@@ -21,15 +21,6 @@ const EXPECTED_APPMENU_OPEN_REFLOWS = [
       "openPopup/this._openPopupPromise<@resource:///modules/PanelMultiView.sys.mjs",
     ],
   },
-
-  {
-    stack: [
-      "_calculateMaxHeight@resource:///modules/PanelMultiView.sys.mjs",
-      "handleEvent@resource:///modules/PanelMultiView.sys.mjs",
-    ],
-
-    maxCount: 7, // This number should only ever go down - never up.
-  },
 ];
 
 add_task(async function () {
diff --git a/browser/base/content/test/performance/browser_startup_content_mainthreadio.js b/browser/base/content/test/performance/browser_startup_content_mainthreadio.js
index e60b95bb3c..e267363064 100644
--- a/browser/base/content/test/performance/browser_startup_content_mainthreadio.js
+++ b/browser/base/content/test/performance/browser_startup_content_mainthreadio.js
@@ -152,6 +152,13 @@ const processes = {
       condition: WIN,
       stat: 1,
     },
+    {
+      // We should remove this in bug 1882427
+      path: "*screenshots@mozilla.org.xpi",
+      condition: true,
+      ignoreIfUnused: true,
+      close: 1,
+    },
   ],
 };
 
diff --git a/browser/base/content/test/popupNotifications/browser_popupNotification_security_delay.js b/browser/base/content/test/popupNotifications/browser_popupNotification_security_delay.js
index 4a9276512c..3b027bc1ef 100644
--- a/browser/base/content/test/popupNotifications/browser_popupNotification_security_delay.js
+++ b/browser/base/content/test/popupNotifications/browser_popupNotification_security_delay.js
@@ -5,6 +5,8 @@
 
 const TEST_SECURITY_DELAY = 5000;
 
+SimpleTest.requestCompleteLog();
+
 /**
  * Shows a test PopupNotification.
  */
@@ -400,3 +402,166 @@ add_task(async function test_notificationWindowMove() {
   // Reset window position
   window.moveTo(screenX, screenY);
 });
+
+/**
+ * Tests that the security delay gets extended if a notification is shown during
+ * a full screen transition.
+ */
+add_task(async function test_notificationDuringFullScreenTransition() {
+  // Log full screen transition messages.
+  let loggingObserver = {
+    observe(subject, topic) {
+      info("Observed topic: " + topic);
+    },
+  };
+  Services.obs.addObserver(loggingObserver, "fullscreen-transition-start");
+  Services.obs.addObserver(loggingObserver, "fullscreen-transition-end");
+  // Unregister observers when the test ends:
+  registerCleanupFunction(() => {
+    Services.obs.removeObserver(loggingObserver, "fullscreen-transition-start");
+    Services.obs.removeObserver(loggingObserver, "fullscreen-transition-end");
+  });
+
+  if (Services.appinfo.OS == "Linux") {
+    ok(
+      "Skipping test on Linux because of disabled full screen transition in CI."
+    );
+    return;
+  }
+  // Bug 1882527: Intermittent failures on macOS.
+  if (Services.appinfo.OS == "Darwin") {
+    ok("Skipping test on macOS because of intermittent failures.");
+    return;
+  }
+
+  await BrowserTestUtils.withNewTab("https://example.com", async browser => {
+    await SpecialPowers.pushPrefEnv({
+      set: [
+        // Set a short security delay so we can observe it being extended.
+        ["security.notification_enable_delay", 1],
+        // Set a longer full screen exit transition so the test works on slow builds.
+        ["full-screen-api.transition-duration.leave", "1000 1000"],
+        // Waive the user activation requirement for full screen requests.
+        // The PoC this test is based on relies on spam clicking which grants
+        // user activation in the popup that requests full screen.
+        // This isn't reliable in automation.
+        ["full-screen-api.allow-trusted-requests-only", false],
+        // macOS native full screen is not affected by the full screen
+        // transition overlap. Test with the old full screen implementation.
+        ["full-screen-api.macos-native-full-screen", false],
+      ],
+    });
+
+    await ensureSecurityDelayReady();
+
+    ok(
+      !PopupNotifications.isPanelOpen,
+      "PopupNotification panel should not be open initially."
+    );
+
+    info("Open a notification.");
+    let popupShownPromise = waitForNotificationPanel();
+    showNotification();
+    await popupShownPromise;
+    ok(
+      PopupNotifications.isPanelOpen,
+      "PopupNotification should be open after show call."
+    );
+
+    let notification = PopupNotifications.getNotification("foo", browser);
+    is(notification?.id, "foo", "There should be a notification with id foo");
+
+    info(
+      "Open a new tab via window.open, enter full screen and remove the tab."
+    );
+
+    // There are two transitions, one for full screen entry and one for full screen exit.
+    let transitionStartCount = 0;
+    let transitionEndCount = 0;
+    let promiseFullScreenTransitionStart = TestUtils.topicObserved(
+      "fullscreen-transition-start",
+      () => {
+        transitionStartCount++;
+        return transitionStartCount == 2;
+      }
+    );
+    let promiseFullScreenTransitionEnd = TestUtils.topicObserved(
+      "fullscreen-transition-end",
+      () => {
+        transitionEndCount++;
+        return transitionEndCount == 2;
+      }
+    );
+    let notificationShownPromise = waitForNotificationPanel();
+
+    await SpecialPowers.spawn(browser, [], () => {
+      // Use eval to execute in the privilege context of the website.
+      content.eval(`
+           let button = document.createElement("button");
+           button.id = "triggerBtn";
+           button.innerText = "Open Popup";
+           button.addEventListener("click", () => {
+             let popup = window.open("about:blank");
+             popup.document.write(
+               "<script>setTimeout(() => document.documentElement.requestFullscreen(), 500)</script>"
+             );
+             popup.document.write(
+               "<script>setTimeout(() => window.close(), 1500)</script>"
+             );
+           });
+           // Insert button at the top so the synthesized click works. Otherwise
+           // the button may be outside of the viewport.
+           document.body.prepend(button);
+         `);
+    });
+
+    let timeClick = performance.now();
+    await BrowserTestUtils.synthesizeMouseAtCenter("#triggerBtn", {}, browser);
+
+    info("Wait for the exit transition to start. It's the second transition.");
+    await promiseFullScreenTransitionStart;
+    info("Full screen transition start");
+    ok(true, "Full screen transition started");
+    ok(
+      window.isInFullScreenTransition,
+      "Full screen transition is still running."
+    );
+
+    info(
+      "Wait for notification to re-show on tab switch, after the popup has been closed"
+    );
+    await notificationShownPromise;
+    ok(
+      window.isInFullScreenTransition,
+      "Full screen transition is still running."
+    );
+    info(
+      "about to trigger notification. time between btn click and notification show: " +
+        (performance.now() - timeClick)
+    );
+
+    info(
+      "Trigger main action via button click during the extended security delay."
+    );
+    triggerMainCommand(PopupNotifications.panel);
+
+    await new Promise(resolve => setTimeout(resolve, 0));
+
+    ok(
+      PopupNotifications.isPanelOpen,
+      "PopupNotification should still be open."
+    );
+    notification = PopupNotifications.getNotification(
+      "foo",
+      gBrowser.selectedBrowser
+    );
+    ok(
+      notification,
+      "Notification should still be open because we clicked during the security delay."
+    );
+
+    info("Wait for full screen transition end.");
+    await promiseFullScreenTransitionEnd;
+    info("Full screen transition end");
+  });
+});
diff --git a/browser/base/content/test/popups/browser_popup_blocker.js b/browser/base/content/test/popups/browser_popup_blocker.js
index bfda12331e..d2e182b366 100644
--- a/browser/base/content/test/popups/browser_popup_blocker.js
+++ b/browser/base/content/test/popups/browser_popup_blocker.js
@@ -34,9 +34,18 @@ add_task(async function test_maximum_reported_blocks() {
   );
 
   // Wait for the popup-blocked notification.
-  let notification = await TestUtils.waitForCondition(() =>
-    gBrowser.getNotificationBox().getNotificationWithValue("popup-blocked")
-  );
+  let notification = await TestUtils.waitForCondition(() => {
+    let tempNotif = gBrowser
+      .getNotificationBox()
+      .getNotificationWithValue("popup-blocked");
+
+    // The textContent in the notification object is contains
+    // blank spaces as placeholder if there is no value in it
+    if (tempNotif?.messageText.textContent.trim().length) {
+      return tempNotif;
+    }
+    return false;
+  });
 
   // Slightly hacky way to ensure we show the correct message in this case.
   ok(
diff --git a/browser/base/content/test/privateBrowsing/browser_private_browsing_simplified_ui.js b/browser/base/content/test/privateBrowsing/browser_private_browsing_simplified_ui.js
index 162bf7ab5a..c52ed4187a 100644
--- a/browser/base/content/test/privateBrowsing/browser_private_browsing_simplified_ui.js
+++ b/browser/base/content/test/privateBrowsing/browser_private_browsing_simplified_ui.js
@@ -30,19 +30,4 @@ add_task(async function check_for_simplified_pbm_ui() {
   );
 
   await BrowserTestUtils.closeWindow(pbmWindow);
-  await SpecialPowers.pushPrefEnv({
-    set: [["browser.toolbars.bookmarks.showInPrivateBrowsing", true]],
-  });
-  pbmWindow = await BrowserTestUtils.openNewBrowserWindow({
-    private: true,
-  });
-  bookmarksBar = pbmWindow.document.getElementById("PersonalToolbar");
-  console.info(bookmarksBar.getAttribute("collapsed"));
-  Assert.equal(
-    bookmarksBar.getAttribute("collapsed").toString(),
-    "false",
-    "Bookmarks bar is visible in PBM window when showInPrivateBrowsing pref is true"
-  );
-
-  await BrowserTestUtils.closeWindow(pbmWindow);
 });
diff --git a/browser/base/content/test/protectionsUI/browser.toml b/browser/base/content/test/protectionsUI/browser.toml
index 10611cbe8c..f3c64eb67f 100644
--- a/browser/base/content/test/protectionsUI/browser.toml
+++ b/browser/base/content/test/protectionsUI/browser.toml
@@ -59,13 +59,6 @@ https_first_disabled = true
 ["browser_protectionsUI_pbmode_exceptions.js"]
 https_first_disabled = true
 
-["browser_protectionsUI_report_breakage.js"]
-https_first_disabled = true
-skip-if = [
-  "debug", # Bug 1546797
-  "asan",
-]
-
 ["browser_protectionsUI_shield_visibility.js"]
 support-files = [
   "sandboxed.html",
diff --git a/browser/base/content/test/protectionsUI/browser_protectionsUI.js b/browser/base/content/test/protectionsUI/browser_protectionsUI.js
index 98698e087e..5dc6acebf7 100644
--- a/browser/base/content/test/protectionsUI/browser_protectionsUI.js
+++ b/browser/base/content/test/protectionsUI/browser_protectionsUI.js
@@ -73,85 +73,16 @@ add_task(async function testToggleSwitch() {
   console.log(buttonEvents);
   is(buttonEvents.length, 1, "recorded telemetry for opening the popup");
 
-  // Check the visibility of the "Site not working?" link.
-  ok(
-    BrowserTestUtils.isVisible(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageLink
-    ),
-    "The 'Site not working?' link should be visible."
-  );
-
-  // The 'Site Fixed?' link should be hidden.
-  ok(
-    BrowserTestUtils.isHidden(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageFixedLink
-    ),
-    "The 'Site Fixed?' link should be hidden."
-  );
-
-  // Navigate through the 'Site Not Working?' flow and back to the main view,
-  // checking for telemetry on the way.
-  let siteNotWorkingView = document.getElementById(
-    "protections-popup-siteNotWorkingView"
-  );
-  let viewShown = BrowserTestUtils.waitForEvent(
-    siteNotWorkingView,
-    "ViewShown"
-  );
-  gProtectionsHandler._protectionsPopupTPSwitchBreakageLink.click();
-  await viewShown;
-
-  checkClickTelemetry("sitenotworking_link");
-
-  let sendReportButton = document.getElementById(
-    "protections-popup-siteNotWorkingView-sendReport"
-  );
-  let sendReportView = document.getElementById(
-    "protections-popup-sendReportView"
-  );
-  viewShown = BrowserTestUtils.waitForEvent(sendReportView, "ViewShown");
-  sendReportButton.click();
-  await viewShown;
-
-  checkClickTelemetry("send_report_link");
-
-  viewShown = BrowserTestUtils.waitForEvent(siteNotWorkingView, "ViewShown");
-  sendReportView.querySelector(".subviewbutton-back").click();
-  await viewShown;
-
-  let mainView = document.getElementById("protections-popup-mainView");
-
-  viewShown = BrowserTestUtils.waitForEvent(mainView, "ViewShown");
-  siteNotWorkingView.querySelector(".subviewbutton-back").click();
-  await viewShown;
+  let browserLoadedPromise = BrowserTestUtils.browserLoaded(tab.linkedBrowser);
 
-  ok(
-    gProtectionsHandler._protectionsPopupTPSwitch.hasAttribute("pressed"),
-    "TP Switch should be on"
-  );
   let popuphiddenPromise = BrowserTestUtils.waitForEvent(
     gProtectionsHandler._protectionsPopup,
     "popuphidden"
   );
-  let browserLoadedPromise = BrowserTestUtils.browserLoaded(tab.linkedBrowser);
-  await clickToggle(gProtectionsHandler._protectionsPopupTPSwitch);
-
-  // The 'Site not working?' link should be hidden after clicking the TP switch.
-  ok(
-    BrowserTestUtils.isHidden(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageLink
-    ),
-    "The 'Site not working?' link should be hidden after TP switch turns to off."
-  );
-  // Same for the 'Site Fixed?' link
-  ok(
-    BrowserTestUtils.isHidden(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageFixedLink
-    ),
-    "The 'Site Fixed?' link should be hidden."
-  );
 
+  await clickToggle(gProtectionsHandler._protectionsPopupTPSwitch);
   await popuphiddenPromise;
+
   checkClickTelemetry("etp_toggle_off");
 
   // We need to wait toast's popup shown and popup hidden events. It won't fire
@@ -164,41 +95,13 @@ add_task(async function testToggleSwitch() {
   // Wait until the ETP state confirmation toast is shown and hides itself.
   await toastShown;
 
+  // Re-open the protections panel and confirm that the toggle is off, then toggle it back on.
   await openProtectionsPanel();
   ok(
     !gProtectionsHandler._protectionsPopupTPSwitch.hasAttribute("pressed"),
     "TP Switch should be off"
   );
 
-  // The 'Site not working?' link should be hidden if the TP is off.
-  ok(
-    BrowserTestUtils.isHidden(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageLink
-    ),
-    "The 'Site not working?' link should be hidden if TP is off."
-  );
-
-  // The 'Site Fixed?' link should be shown if TP is off.
-  ok(
-    BrowserTestUtils.isVisible(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageFixedLink
-    ),
-    "The 'Site Fixed?' link should be visible."
-  );
-
-  // Check telemetry for 'Site Fixed?' link.
-  viewShown = BrowserTestUtils.waitForEvent(sendReportView, "ViewShown");
-  gProtectionsHandler._protectionsPopupTPSwitchBreakageFixedLink.click();
-  await viewShown;
-
-  checkClickTelemetry("sitenotworking_link", "sitefixed");
-
-  viewShown = BrowserTestUtils.waitForEvent(mainView, "ViewShown");
-  sendReportView.querySelector(".subviewbutton-back").click();
-  await viewShown;
-
-  // Click the TP switch again and check the visibility of the 'Site not
-  // Working?'. It should be hidden after toggling the TP switch.
   browserLoadedPromise = BrowserTestUtils.browserLoaded(tab.linkedBrowser);
 
   popuphiddenPromise = BrowserTestUtils.waitForEvent(
@@ -208,20 +111,6 @@ add_task(async function testToggleSwitch() {
 
   await clickToggle(gProtectionsHandler._protectionsPopupTPSwitch);
 
-  ok(
-    BrowserTestUtils.isHidden(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageLink
-    ),
-    `The 'Site not working?' link should be still hidden after toggling TP
-     switch to on from off.`
-  );
-  ok(
-    BrowserTestUtils.isHidden(
-      gProtectionsHandler._protectionsPopupTPSwitchBreakageFixedLink
-    ),
-    "The 'Site Fixed?' link should be hidden."
-  );
-
   // Wait for the protections panel to be hidden as the result of the ETP toggle
   // on action.
   await popuphiddenPromise;
diff --git a/browser/base/content/test/protectionsUI/browser_protectionsUI_report_breakage.js b/browser/base/content/test/protectionsUI/browser_protectionsUI_report_breakage.js
deleted file mode 100644
index 2ae0d5c9d9..0000000000
--- a/browser/base/content/test/protectionsUI/browser_protectionsUI_report_breakage.js
+++ /dev/null
@@ -1,415 +0,0 @@
-/* Any copyright is dedicated to the Public Domain.
- * http://creativecommons.org/publicdomain/zero/1.0/ */
-
-"use strict";
-
-const TRACKING_PAGE =
-  // eslint-disable-next-line @microsoft/sdl/no-insecure-url
-  "http://tracking.example.org/browser/browser/base/content/test/protectionsUI/trackingPage.html";
-const BENIGN_PAGE =
-  // eslint-disable-next-line @microsoft/sdl/no-insecure-url
-  "http://tracking.example.org/browser/browser/base/content/test/protectionsUI/benignPage.html";
-const COOKIE_PAGE =
-  // eslint-disable-next-line @microsoft/sdl/no-insecure-url
-  "http://not-tracking.example.com/browser/browser/base/content/test/protectionsUI/cookiePage.html";
-
-const CM_PREF = "privacy.trackingprotection.cryptomining.enabled";
-const FP_PREF = "privacy.trackingprotection.fingerprinting.enabled";
-const TP_PREF = "privacy.trackingprotection.enabled";
-const CB_PREF = "network.cookie.cookieBehavior";
-const GPC_PREF = "privacy.globalprivacycontrol.enabled";
-
-const PREF_REPORT_BREAKAGE_URL = "browser.contentblocking.reportBreakage.url";
-
-let { HttpServer } = ChromeUtils.importESModule(
-  "resource://testing-common/httpd.sys.mjs"
-);
-let { CommonUtils } = ChromeUtils.importESModule(
-  "resource://services-common/utils.sys.mjs"
-);
-let { Preferences } = ChromeUtils.importESModule(
-  "resource://gre/modules/Preferences.sys.mjs"
-);
-
-add_setup(async function () {
-  await UrlClassifierTestUtils.addTestTrackers();
-
-  // Disable Report Broken Site, as it hides "Site not working?" when enabled.
-  await SpecialPowers.pushPrefEnv({
-    set: [["ui.new-webcompat-reporter.enabled", false]],
-  });
-
-  registerCleanupFunction(() => {
-    // Clear prefs that are touched in this test again for sanity.
-    Services.prefs.clearUserPref(TP_PREF);
-    Services.prefs.clearUserPref(CB_PREF);
-    Services.prefs.clearUserPref(FP_PREF);
-    Services.prefs.clearUserPref(CM_PREF);
-    Services.prefs.clearUserPref(GPC_PREF);
-    Services.prefs.clearUserPref(PREF_REPORT_BREAKAGE_URL);
-
-    UrlClassifierTestUtils.cleanupTestTrackers();
-  });
-
-  await SpecialPowers.pushPrefEnv({
-    set: [
-      [
-        "urlclassifier.features.fingerprinting.blacklistHosts",
-        "fingerprinting.example.com",
-      ],
-      [
-        "urlclassifier.features.fingerprinting.annotate.blacklistHosts",
-        "fingerprinting.example.com",
-      ],
-      ["privacy.trackingprotection.cryptomining.enabled", true],
-      [
-        "urlclassifier.features.cryptomining.blacklistHosts",
-        "cryptomining.example.com",
-      ],
-      [
-        "urlclassifier.features.cryptomining.annotate.blacklistHosts",
-        "cryptomining.example.com",
-      ],
-      ["privacy.globalprivacycontrol.enabled", true],
-    ],
-  });
-});
-
-add_task(async function testReportBreakageCancel() {
-  Services.prefs.setBoolPref(TP_PREF, true);
-
-  await BrowserTestUtils.withNewTab(TRACKING_PAGE, async function () {
-    await openProtectionsPanel();
-    await TestUtils.waitForCondition(() =>
-      gProtectionsHandler._protectionsPopup.hasAttribute("blocking")
-    );
-
-    let siteNotWorkingButton = document.getElementById(
-      "protections-popup-tp-switch-breakage-link"
-    );
-    ok(
-      BrowserTestUtils.isVisible(siteNotWorkingButton),
-      "site not working button is visible"
-    );
-    let siteNotWorkingView = document.getElementById(
-      "protections-popup-siteNotWorkingView"
-    );
-    let viewShown = BrowserTestUtils.waitForEvent(
-      siteNotWorkingView,
-      "ViewShown"
-    );
-    siteNotWorkingButton.click();
-    await viewShown;
-
-    let sendReportButton = document.getElementById(
-      "protections-popup-siteNotWorkingView-sendReport"
-    );
-    let sendReportView = document.getElementById(
-      "protections-popup-sendReportView"
-    );
-    viewShown = BrowserTestUtils.waitForEvent(sendReportView, "ViewShown");
-    sendReportButton.click();
-    await viewShown;
-
-    ok(true, "Report breakage view was shown");
-
-    viewShown = BrowserTestUtils.waitForEvent(siteNotWorkingView, "ViewShown");
-    let cancelButton = document.getElementById(
-      "protections-popup-sendReportView-cancel"
-    );
-    cancelButton.click();
-    await viewShown;
-
-    ok(true, "Main view was shown");
-  });
-
-  Services.prefs.clearUserPref(TP_PREF);
-});
-
-add_task(async function testReportBreakageSiteException() {
-  Services.prefs.setBoolPref(TP_PREF, true);
-
-  let url = TRACKING_PAGE + "?a=b&1=abc&unicode=🦊";
-
-  await BrowserTestUtils.withNewTab(url, async browser => {
-    let loaded = BrowserTestUtils.browserLoaded(browser, false);
-    gProtectionsHandler.disableForCurrentPage();
-    await loaded;
-
-    await openProtectionsPanel();
-
-    let siteFixedButton = document.getElementById(
-      "protections-popup-tp-switch-breakage-fixed-link"
-    );
-    ok(
-      BrowserTestUtils.isVisible(siteFixedButton),
-      "site fixed button is visible"
-    );
-    let sendReportView = document.getElementById(
-      "protections-popup-sendReportView"
-    );
-    let viewShown = BrowserTestUtils.waitForEvent(sendReportView, "ViewShown");
-    siteFixedButton.click();
-    await viewShown;
-
-    ok(true, "Report breakage view was shown");
-
-    await testReportBreakageSubmit(
-      TRACKING_PAGE,
-      "trackingprotection",
-      false,
-      true
-    );
-
-    // Pass false for shouldReload - there's no need since the tab is going away.
-    gProtectionsHandler.enableForCurrentPage(false);
-  });
-
-  Services.prefs.clearUserPref(TP_PREF);
-});
-
-add_task(async function testNoTracking() {
-  await BrowserTestUtils.withNewTab(BENIGN_PAGE, async function () {
-    await openProtectionsPanel();
-
-    let siteNotWorkingButton = document.getElementById(
-      "protections-popup-tp-switch-breakage-link"
-    );
-    ok(
-      BrowserTestUtils.isHidden(siteNotWorkingButton),
-      "site not working button is not visible"
-    );
-  });
-});
-
-add_task(async function testReportBreakageError() {
-  Services.prefs.setBoolPref(TP_PREF, true);
-  // Make sure that we correctly strip the query.
-  let url = TRACKING_PAGE + "?a=b&1=abc&unicode=🦊";
-  await BrowserTestUtils.withNewTab(url, async function () {
-    await openAndTestReportBreakage(TRACKING_PAGE, "trackingprotection", true);
-  });
-
-  Services.prefs.clearUserPref(TP_PREF);
-});
-
-add_task(async function testTP() {
-  Services.prefs.setBoolPref(TP_PREF, true);
-  // Make sure that we correctly strip the query.
-  let url = TRACKING_PAGE + "?a=b&1=abc&unicode=🦊";
-  await BrowserTestUtils.withNewTab(url, async function () {
-    await openAndTestReportBreakage(TRACKING_PAGE, "trackingprotection");
-  });
-
-  Services.prefs.clearUserPref(TP_PREF);
-});
-
-add_task(async function testCR() {
-  Services.prefs.setIntPref(
-    CB_PREF,
-    Ci.nsICookieService.BEHAVIOR_REJECT_TRACKER
-  );
-  // Make sure that we correctly strip the query.
-  let url = COOKIE_PAGE + "?a=b&1=abc&unicode=🦊";
-  await BrowserTestUtils.withNewTab(url, async function () {
-    await openAndTestReportBreakage(COOKIE_PAGE, "cookierestrictions");
-  });
-
-  Services.prefs.clearUserPref(CB_PREF);
-});
-
-add_task(async function testFP() {
-  Services.prefs.setIntPref(CB_PREF, Ci.nsICookieService.BEHAVIOR_ACCEPT);
-  Services.prefs.setBoolPref(FP_PREF, true);
-  // Make sure that we correctly strip the query.
-  let url = TRACKING_PAGE + "?a=b&1=abc&unicode=🦊";
-  await BrowserTestUtils.withNewTab(url, async function (browser) {
-    let promise = waitForContentBlockingEvent();
-    await SpecialPowers.spawn(browser, [], function () {
-      content.postMessage("fingerprinting", "*");
-    });
-    await promise;
-
-    await openAndTestReportBreakage(TRACKING_PAGE, "fingerprinting", true);
-  });
-
-  Services.prefs.clearUserPref(FP_PREF);
-  Services.prefs.clearUserPref(CB_PREF);
-});
-
-add_task(async function testCM() {
-  Services.prefs.setIntPref(CB_PREF, Ci.nsICookieService.BEHAVIOR_ACCEPT);
-  Services.prefs.setBoolPref(CM_PREF, true);
-  // Make sure that we correctly strip the query.
-  let url = TRACKING_PAGE + "?a=b&1=abc&unicode=🦊";
-  await BrowserTestUtils.withNewTab(url, async function (browser) {
-    let promise = waitForContentBlockingEvent();
-    await SpecialPowers.spawn(browser, [], function () {
-      content.postMessage("cryptomining", "*");
-    });
-    await promise;
-
-    await openAndTestReportBreakage(TRACKING_PAGE, "cryptomining", true);
-  });
-
-  Services.prefs.clearUserPref(CM_PREF);
-  Services.prefs.clearUserPref(CB_PREF);
-});
-
-async function openAndTestReportBreakage(url, tags, error = false) {
-  await openProtectionsPanel();
-
-  let siteNotWorkingButton = document.getElementById(
-    "protections-popup-tp-switch-breakage-link"
-  );
-  ok(
-    BrowserTestUtils.isVisible(siteNotWorkingButton),
-    "site not working button is visible"
-  );
-  let siteNotWorkingView = document.getElementById(
-    "protections-popup-siteNotWorkingView"
-  );
-  let viewShown = BrowserTestUtils.waitForEvent(
-    siteNotWorkingView,
-    "ViewShown"
-  );
-  siteNotWorkingButton.click();
-  await viewShown;
-
-  let sendReportButton = document.getElementById(
-    "protections-popup-siteNotWorkingView-sendReport"
-  );
-  let sendReportView = document.getElementById(
-    "protections-popup-sendReportView"
-  );
-  viewShown = BrowserTestUtils.waitForEvent(sendReportView, "ViewShown");
-  sendReportButton.click();
-  await viewShown;
-
-  ok(true, "Report breakage view was shown");
-
-  await testReportBreakageSubmit(url, tags, error, false);
-}
-
-// This function assumes that the breakage report view is ready.
-async function testReportBreakageSubmit(url, tags, error, hasException) {
-  // Setup a mock server for receiving breakage reports.
-  let server = new HttpServer();
-  server.start(-1);
-  let i = server.identity;
-  let path =
-    i.primaryScheme + "://" + i.primaryHost + ":" + i.primaryPort + "/";
-
-  Services.prefs.setStringPref(PREF_REPORT_BREAKAGE_URL, path);
-
-  let comments = document.getElementById(
-    "protections-popup-sendReportView-collection-comments"
-  );
-  is(comments.value, "", "Comments textarea should initially be empty");
-
-  let submitButton = document.getElementById(
-    "protections-popup-sendReportView-submit"
-  );
-  let reportURL = document.getElementById(
-    "protections-popup-sendReportView-collection-url"
-  ).value;
-
-  is(reportURL, url, "Shows the correct URL in the report UI.");
-
-  // Make sure that sending the report closes the identity popup.
-  let popuphidden = BrowserTestUtils.waitForEvent(
-    gProtectionsHandler._protectionsPopup,
-    "popuphidden"
-  );
-
-  // Check that we're receiving a good report.
-  await new Promise(resolve => {
-    server.registerPathHandler("/", async (request, response) => {
-      is(request.method, "POST", "request was a post");
-
-      // Extract and "parse" the form data in the request body.
-      let body = CommonUtils.readBytesFromInputStream(request.bodyInputStream);
-      let boundary = request
-        .getHeader("Content-Type")
-        .match(/boundary=-+([^-]*)/i)[1];
-      let regex = new RegExp("-+" + boundary + "-*\\s+");
-      let sections = body.split(regex);
-
-      let prefs = [
-        "privacy.trackingprotection.enabled",
-        "privacy.trackingprotection.pbmode.enabled",
-        "urlclassifier.trackingTable",
-        "network.http.referer.defaultPolicy",
-        "network.http.referer.defaultPolicy.pbmode",
-        "network.cookie.cookieBehavior",
-        "privacy.annotate_channels.strict_list.enabled",
-        "privacy.restrict3rdpartystorage.expiration",
-        "privacy.trackingprotection.fingerprinting.enabled",
-        "privacy.trackingprotection.cryptomining.enabled",
-        "privacy.globalprivacycontrol.enabled",
-      ];
-      let prefsBody = "";
-
-      for (let pref of prefs) {
-        prefsBody += `${pref}: ${Preferences.get(pref)}\r\n`;
-      }
-
-      Assert.deepEqual(
-        sections,
-        [
-          "",
-          `Content-Disposition: form-data; name=\"title\"\r\n\r\n${
-            Services.io.newURI(reportURL).host
-          }\r\n`,
-          'Content-Disposition: form-data; name="body"\r\n\r\n' +
-            `Full URL: ${reportURL + "?"}\r\n` +
-            `userAgent: ${navigator.userAgent}\r\n\r\n` +
-            "**Preferences**\r\n" +
-            `${prefsBody}\r\n` +
-            `hasException: ${hasException}\r\n\r\n` +
-            "**Comments**\r\n" +
-            "This is a comment\r\n",
-          'Content-Disposition: form-data; name="labels"\r\n\r\n' +
-            `${hasException ? "" : tags}\r\n`,
-          "",
-        ],
-        "Should send the correct form data"
-      );
-
-      if (error) {
-        response.setStatusLine(request.httpVersion, 500, "Request failed");
-      } else {
-        response.setStatusLine(request.httpVersion, 201, "Entry created");
-      }
-
-      resolve();
-    });
-
-    comments.value = "This is a comment";
-    submitButton.click();
-  });
-
-  let errorMessage = document.getElementById(
-    "protections-popup-sendReportView-report-error"
-  );
-  if (error) {
-    await TestUtils.waitForCondition(() =>
-      BrowserTestUtils.isVisible(errorMessage)
-    );
-    is(
-      comments.value,
-      "This is a comment",
-      "Comment not cleared in case of an error"
-    );
-    gProtectionsHandler._protectionsPopup.hidePopup();
-  } else {
-    ok(BrowserTestUtils.isHidden(errorMessage), "Error message not shown");
-  }
-
-  await popuphidden;
-
-  // Stop the server.
-  await new Promise(r => server.stop(r));
-
-  Services.prefs.clearUserPref(PREF_REPORT_BREAKAGE_URL);
-}
diff --git a/browser/base/content/test/sanitize/browser.toml b/browser/base/content/test/sanitize/browser.toml
index 814dc54c3d..3c53723833 100644
--- a/browser/base/content/test/sanitize/browser.toml
+++ b/browser/base/content/test/sanitize/browser.toml
@@ -36,4 +36,6 @@ support-files = [
 
 ["browser_sanitizeDialog_v2.js"]
 
+["browser_sanitizeDialog_v2_dataSizes.js"]
+
 ["browser_sanitizeOnShutdown_migration.js"]
diff --git a/browser/base/content/test/sanitize/browser_sanitize-timespans.js b/browser/base/content/test/sanitize/browser_sanitize-timespans.js
index 30ccb90666..f9be12775b 100644
--- a/browser/base/content/test/sanitize/browser_sanitize-timespans.js
+++ b/browser/base/content/test/sanitize/browser_sanitize-timespans.js
@@ -8,9 +8,6 @@ const { PlacesTestUtils } = ChromeUtils.importESModule(
 var now_mSec = Date.now();
 var now_uSec = now_mSec * 1000;
 
-const kMsecPerMin = 60 * 1000;
-const kUsecPerMin = 60 * 1000000;
-
 function promiseFormHistoryRemoved() {
   return new Promise(resolve => {
     Services.obs.addObserver(function onfh() {
diff --git a/browser/base/content/test/sanitize/browser_sanitizeDialog.js b/browser/base/content/test/sanitize/browser_sanitizeDialog.js
index 2df7d83c6e..a1e8a5dc85 100644
--- a/browser/base/content/test/sanitize/browser_sanitizeDialog.js
+++ b/browser/base/content/test/sanitize/browser_sanitizeDialog.js
@@ -22,9 +22,6 @@ ChromeUtils.defineESModuleGetters(this, {
   Timer: "resource://gre/modules/Timer.sys.mjs",
 });
 
-const kMsecPerMin = 60 * 1000;
-const kUsecPerMin = 60 * 1000000;
-
 /**
  * Ensures that the specified URIs are either cleared or not.
  *
@@ -694,10 +691,6 @@ DialogHelper.prototype = {
   },
 };
 
-function promiseSanitizationComplete() {
-  return TestUtils.topicObserved("sanitizer-sanitization-complete");
-}
-
 /**
  * Adds a download to history.
  *
@@ -752,21 +745,6 @@ async function formNameExists(name) {
 }
 
 /**
- * Removes all history visits, downloads, and form entries.
- */
-async function blankSlate() {
-  let publicList = await Downloads.getList(Downloads.PUBLIC);
-  let downloads = await publicList.getAll();
-  for (let download of downloads) {
-    await publicList.remove(download);
-    await download.finalize(true);
-  }
-
-  await FormHistory.update({ op: "remove" });
-  await PlacesUtils.history.clear();
-}
-
-/**
  * Ensures that the given pref is the expected value.
  *
  * @param aPrefName
diff --git a/browser/base/content/test/sanitize/browser_sanitizeDialog_v2.js b/browser/base/content/test/sanitize/browser_sanitizeDialog_v2.js
index 29f760f57f..8ae0263c82 100644
--- a/browser/base/content/test/sanitize/browser_sanitizeDialog_v2.js
+++ b/browser/base/content/test/sanitize/browser_sanitizeDialog_v2.js
@@ -20,33 +20,9 @@ ChromeUtils.defineESModuleGetters(this, {
   PlacesTestUtils: "resource://testing-common/PlacesTestUtils.sys.mjs",
   Timer: "resource://gre/modules/Timer.sys.mjs",
   PermissionTestUtils: "resource://testing-common/PermissionTestUtils.sys.mjs",
-  FileTestUtils: "resource://testing-common/FileTestUtils.sys.mjs",
   Downloads: "resource://gre/modules/Downloads.sys.mjs",
 });
 
-const kMsecPerMin = 60 * 1000;
-const kUsecPerMin = 60 * 1000000;
-let today = Date.now() - new Date().setHours(0, 0, 0, 0);
-let nowMSec = Date.now();
-let nowUSec = nowMSec * 1000;
-let fileURL;
-
-const TEST_TARGET_FILE_NAME = "test-download.txt";
-const TEST_QUOTA_USAGE_HOST = "example.com";
-const TEST_QUOTA_USAGE_ORIGIN = "https://" + TEST_QUOTA_USAGE_HOST;
-const TEST_QUOTA_USAGE_URL =
-  getRootDirectory(gTestPath).replace(
-    "chrome://mochitests/content",
-    TEST_QUOTA_USAGE_ORIGIN
-  ) + "site_data_test.html";
-
-const siteOrigins = [
-  "https://www.example.com",
-  "https://example.org",
-  "http://localhost:8000",
-  "http://localhost:3000",
-];
-
 /**
  * Ensures that the specified URIs are either cleared or not.
  *
@@ -167,90 +143,6 @@ async function addDownloadWithMinutesAgo(aExpectedPathList, aMinutesAgo) {
   aExpectedPathList.push(name);
 }
 
-/**
- * Adds multiple downloads to the PUBLIC download list
- */
-async function addToDownloadList() {
-  const url = createFileURL();
-  const downloadsList = await Downloads.getList(Downloads.PUBLIC);
-  let timeOptions = [1, 2, 4, 24, 128, 128];
-  let buffer = 100000;
-
-  for (let i = 0; i < timeOptions.length; i++) {
-    let timeDownloaded = 60 * kMsecPerMin * timeOptions[i];
-    if (timeOptions[i] === 24) {
-      timeDownloaded = today;
-    }
-
-    let download = await Downloads.createDownload({
-      source: { url: url.spec, isPrivate: false },
-      target: { path: FileTestUtils.getTempFile(TEST_TARGET_FILE_NAME).path },
-      startTime: {
-        getTime: _ => {
-          return nowMSec - timeDownloaded + buffer;
-        },
-      },
-    });
-
-    Assert.ok(!!download);
-    downloadsList.add(download);
-  }
-  let items = await downloadsList.getAll();
-  Assert.equal(items.length, 6, "Items were added to the list");
-}
-
-async function addToSiteUsage() {
-  // Fill indexedDB with test data.
-  // Don't wait for the page to load, to register the content event handler as quickly as possible.
-  // If this test goes intermittent, we might have to tell the page to wait longer before
-  // firing the event.
-  BrowserTestUtils.openNewForegroundTab(gBrowser, TEST_QUOTA_USAGE_URL, false);
-  await BrowserTestUtils.waitForContentEvent(
-    gBrowser.selectedBrowser,
-    "test-indexedDB-done",
-    false,
-    null,
-    true
-  );
-  BrowserTestUtils.removeTab(gBrowser.selectedTab);
-
-  let siteLastAccessed = [1, 2, 4, 24];
-
-  let staticUsage = 4096 * 6;
-  // Add a time buffer so the site access falls within the time range
-  const buffer = 10000;
-
-  // Change lastAccessed of sites
-  for (let index = 0; index < siteLastAccessed.length; index++) {
-    let lastAccessedTime = 60 * kMsecPerMin * siteLastAccessed[index];
-    if (siteLastAccessed[index] === 24) {
-      lastAccessedTime = today;
-    }
-
-    let site = SiteDataManager._testInsertSite(siteOrigins[index], {
-      quotaUsage: staticUsage,
-      lastAccessed: (nowMSec - lastAccessedTime + buffer) * 1000,
-    });
-    Assert.ok(site, "Site added successfully");
-  }
-}
-
-/**
- * Helper function to create file URL to open
- *
- * @returns {Object} a file URL
- */
-function createFileURL() {
-  if (!fileURL) {
-    let file = Services.dirsvc.get("TmpD", Ci.nsIFile);
-    file.append("foo.txt");
-    file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o600);
-
-    fileURL = Services.io.newFileURI(file);
-  }
-  return fileURL;
-}
-
 add_setup(async function () {
   requestLongerTimeout(3);
   await blankSlate();
@@ -268,248 +160,6 @@ add_setup(async function () {
 });
 
 /**
- * Removes all history visits, downloads, and form entries.
- */
-async function blankSlate() {
-  let publicList = await Downloads.getList(Downloads.PUBLIC);
-  let downloads = await publicList.getAll();
-  for (let download of downloads) {
-    await publicList.remove(download);
-    await download.finalize(true);
-  }
-
-  await FormHistory.update({ op: "remove" });
-  await PlacesUtils.history.clear();
-}
-
-/**
- * This wraps the dialog and provides some convenience methods for interacting
- * with it.
- *
- * @param browserWin (optional)
- *        The browser window that the dialog is expected to open in. If not
- *        supplied, the initial browser window of the test run is used.
- * @param mode (optional)
- *        One of
- *          clear on shutdown settings context ("clearOnShutdown"),
- *          clear site data settings context ("clearSiteData"),
- *          clear history context ("clearHistory"),
- *          browser context ("browser")
- *        "browser" by default
- */
-function DialogHelper(openContext = "browser") {
-  this._browserWin = window;
-  this.win = null;
-  this._mode = openContext;
-  this.promiseClosed = new Promise(resolve => {
-    this._resolveClosed = resolve;
-  });
-}
-
-DialogHelper.prototype = {
-  /**
-   * "Presses" the dialog's OK button.
-   */
-  acceptDialog() {
-    let dialogEl = this.win.document.querySelector("dialog");
-    is(
-      dialogEl.getButton("accept").disabled,
-      false,
-      "Dialog's OK button should not be disabled"
-    );
-    dialogEl.acceptDialog();
-  },
-
-  /**
-   * "Presses" the dialog's Cancel button.
-   */
-  cancelDialog() {
-    this.win.document.querySelector("dialog").cancelDialog();
-  },
-
-  /**
-   * (Un)checks a history scope checkbox (browser & download history,
-   * form history, etc.).
-   *
-   * @param aPrefName
-   *        The final portion of the checkbox's privacy.cpd.* preference name
-   * @param aCheckState
-   *        True if the checkbox should be checked, false otherwise
-   */
-  checkPrefCheckbox(aPrefName, aCheckState) {
-    var cb = this.win.document.querySelectorAll(
-      "checkbox[id='" + aPrefName + "']"
-    );
-    is(cb.length, 1, "found checkbox for " + aPrefName + " id");
-    if (cb[0].checked != aCheckState) {
-      cb[0].click();
-    }
-  },
-
-  /**
-   * @param {String} aCheckboxId
-   *        The checkbox id name
-   * @param {Boolean} aCheckState
-   *        True if the checkbox should be checked, false otherwise
-   */
-  validateCheckbox(aCheckboxId, aCheckState) {
-    let cb = this.win.document.querySelectorAll(
-      "checkbox[id='" + aCheckboxId + "']"
-    );
-    is(cb.length, 1, `found checkbox for id=${aCheckboxId}`);
-    is(
-      cb[0].checked,
-      aCheckState,
-      `checkbox for ${aCheckboxId} is ${aCheckState}`
-    );
-  },
-
-  /**
-   * Makes sure all the checkboxes are checked.
-   */
-  _checkAllCheckboxesCustom(check) {
-    var cb = this.win.document.querySelectorAll(".clearingItemCheckbox");
-    ok(cb.length, "found checkboxes for ids");
-    for (var i = 0; i < cb.length; ++i) {
-      if (cb[i].checked != check) {
-        cb[i].click();
-      }
-    }
-  },
-
-  checkAllCheckboxes() {
-    this._checkAllCheckboxesCustom(true);
-  },
-
-  uncheckAllCheckboxes() {
-    this._checkAllCheckboxesCustom(false);
-  },
-
-  /**
-   * @return The dialog's duration dropdown
-   */
-  getDurationDropdown() {
-    return this.win.document.getElementById("sanitizeDurationChoice");
-  },
-
-  /**
-   * @return The clear-everything warning box
-   */
-  getWarningPanel() {
-    return this.win.document.getElementById("sanitizeEverythingWarningBox");
-  },
-
-  /**
-   * @return True if the "Everything" warning panel is visible (as opposed to
-   *         the tree)
-   */
-  isWarningPanelVisible() {
-    return !this.getWarningPanel().hidden;
-  },
-
-  /**
-   * Opens the clear recent history dialog.  Before calling this, set
-   * this.onload to a function to execute onload.  It should close the dialog
-   * when done so that the tests may continue.  Set this.onunload to a function
-   * to execute onunload.  this.onunload is optional. If it returns true, the
-   * caller is expected to call promiseAsyncUpdates at some point; if false is
-   * returned, promiseAsyncUpdates is called automatically.
-   */
-  async open() {
-    let dialogPromise = BrowserTestUtils.promiseAlertDialogOpen(
-      null,
-      "chrome://browser/content/sanitize_v2.xhtml",
-      {
-        isSubDialog: true,
-      }
-    );
-
-    // We want to simulate opening the dialog inside preferences for clear history
-    // and clear site data
-    if (this._mode != "browser") {
-      await openPreferencesViaOpenPreferencesAPI("privacy", {
-        leaveOpen: true,
-      });
-      let tabWindow = gBrowser.selectedBrowser.contentWindow;
-      let clearDialogOpenButtonId = this._mode + "Button";
-      // the id for clear on shutdown is of a different format
-      if (this._mode == "clearOnShutdown") {
-        // set always clear to true to enable the clear on shutdown dialog
-        let enableSettingsCheckbox =
-          tabWindow.document.getElementById("alwaysClear");
-        if (!enableSettingsCheckbox.checked) {
-          enableSettingsCheckbox.click();
-        }
-        clearDialogOpenButtonId = "clearDataSettings";
-      }
-      // open dialog
-      tabWindow.document.getElementById(clearDialogOpenButtonId).click();
-    }
-    // We open the dialog in the chrome context in other cases
-    else {
-      executeSoon(() => {
-        Sanitizer.showUI(this._browserWin, this._mode);
-      });
-    }
-
-    this.win = await dialogPromise;
-    this.win.addEventListener(
-      "load",
-      () => {
-        // Run onload on next tick so that gSanitizePromptDialog.init can run first.
-        executeSoon(async () => {
-          await this.win.gSanitizePromptDialog.dataSizesFinishedUpdatingPromise;
-          this.onload();
-        });
-      },
-      { once: true }
-    );
-    this.win.addEventListener(
-      "unload",
-      () => {
-        // Some exceptions that reach here don't reach the test harness, but
-        // ok()/is() do...
-        (async () => {
-          if (this.onunload) {
-            await this.onunload();
-          }
-          if (this._mode != "browser") {
-            BrowserTestUtils.removeTab(gBrowser.selectedTab);
-          }
-          await PlacesTestUtils.promiseAsyncUpdates();
-          this._resolveClosed();
-          this.win = null;
-        })();
-      },
-      { once: true }
-    );
-  },
-
-  /**
-   * Selects a duration in the duration dropdown.
-   *
-   * @param aDurVal
-   *        One of the Sanitizer.TIMESPAN_* values
-   */
-  selectDuration(aDurVal) {
-    this.getDurationDropdown().value = aDurVal;
-    if (aDurVal === Sanitizer.TIMESPAN_EVERYTHING) {
-      is(
-        this.isWarningPanelVisible(),
-        true,
-        "Warning panel should be visible for TIMESPAN_EVERYTHING"
-      );
-    } else {
-      is(
-        this.isWarningPanelVisible(),
-        false,
-        "Warning panel should not be visible for non-TIMESPAN_EVERYTHING"
-      );
-    }
-  },
-};
-
-/**
  * Ensures that the given pref is the expected value.
  *
  * @param aPrefName
@@ -533,58 +183,6 @@ function visitTimeForMinutesAgo(aMinutesAgo) {
   return nowUSec - aMinutesAgo * kUsecPerMin;
 }
 
-function promiseSanitizationComplete() {
-  return TestUtils.topicObserved("sanitizer-sanitization-complete");
-}
-
-/**
- * Helper function to validate the data sizes shown for each time selection
- *
- * @param {DialogHelper} dh - dialog object to access window and timespan
- */
-async function validateDataSizes(dialogHelper) {
-  let timespans = [
-    "TIMESPAN_HOUR",
-    "TIMESPAN_2HOURS",
-    "TIMESPAN_4HOURS",
-    "TIMESPAN_TODAY",
-    "TIMESPAN_EVERYTHING",
-  ];
-
-  // get current data sizes from siteDataManager
-  let cacheUsage = await SiteDataManager.getCacheSize();
-  let quotaUsage = await SiteDataManager.getQuotaUsageForTimeRanges(timespans);
-
-  for (let i = 0; i < timespans.length; i++) {
-    // select timespan to check
-    dialogHelper.selectDuration(Sanitizer[timespans[i]]);
-
-    // get the elements
-    let clearCookiesAndSiteDataCheckbox =
-      dialogHelper.win.document.getElementById("cookiesAndStorage");
-    let clearCacheCheckbox = dialogHelper.win.document.getElementById("cache");
-
-    let [convertedQuotaUsage] = DownloadUtils.convertByteUnits(
-      quotaUsage[timespans[i]]
-    );
-    let [, convertedCacheUnit] = DownloadUtils.convertByteUnits(cacheUsage);
-
-    // Ensure l10n is finished before inspecting the category labels.
-    await dialogHelper.win.document.l10n.translateElements([
-      clearCookiesAndSiteDataCheckbox,
-      clearCacheCheckbox,
-    ]);
-    ok(
-      clearCacheCheckbox.label.includes(convertedCacheUnit),
-      "Should show the cache usage"
-    );
-    ok(
-      clearCookiesAndSiteDataCheckbox.label.includes(convertedQuotaUsage),
-      `Should show the quota usage as ${convertedQuotaUsage}`
-    );
-  }
-}
-
 /**
  *
  * Opens dialog in the provided context and selects the checkboxes
@@ -602,7 +200,7 @@ async function performActionsOnDialog({
   cache = false,
   siteSettings = false,
 }) {
-  let dh = new DialogHelper(context);
+  let dh = new ClearHistoryDialogHelper({ mode: context });
   dh.onload = function () {
     this.selectDuration(timespan);
     this.checkPrefCheckbox(
@@ -622,7 +220,7 @@ async function performActionsOnDialog({
  * Initializes the dialog to its default state.
  */
 add_task(async function default_state() {
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     // Select "Last Hour"
     this.selectDuration(Sanitizer.TIMESPAN_HOUR);
@@ -647,7 +245,7 @@ add_task(async function test_cancel() {
   }
   await PlacesTestUtils.addVisits(places);
 
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     this.selectDuration(Sanitizer.TIMESPAN_HOUR);
     this.checkPrefCheckbox("historyFormDataAndDownloads", false);
@@ -662,6 +260,72 @@ add_task(async function test_cancel() {
   await dh.promiseClosed;
 });
 
+// test remembering user options for various entry points
+add_task(async function test_pref_remembering() {
+  let dh = new ClearHistoryDialogHelper({ mode: "clearSiteData" });
+  dh.onload = function () {
+    this.checkPrefCheckbox("cookiesAndStorage", false);
+    this.checkPrefCheckbox("siteSettings", true);
+
+    this.acceptDialog();
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  // validate if prefs are remembered
+  dh = new ClearHistoryDialogHelper({ mode: "clearSiteData" });
+  dh.onload = function () {
+    this.validateCheckbox("cookiesAndStorage", false);
+    this.validateCheckbox("siteSettings", true);
+
+    this.checkPrefCheckbox("cookiesAndStorage", true);
+    this.checkPrefCheckbox("siteSettings", false);
+
+    // we will test cancelling the dialog, to make sure it doesn't remember
+    // the prefs when cancelled
+    this.cancelDialog();
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  // validate if prefs did not change since we cancelled the dialog
+  dh = new ClearHistoryDialogHelper({ mode: "clearSiteData" });
+  dh.onload = function () {
+    this.validateCheckbox("cookiesAndStorage", false);
+    this.validateCheckbox("siteSettings", true);
+
+    this.cancelDialog();
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  // test rememebering prefs from the clear history context
+  // since clear history and clear site data have seperate remembering
+  // of prefs
+  dh = new ClearHistoryDialogHelper({ mode: "clearHistory" });
+  dh.onload = function () {
+    this.checkPrefCheckbox("cookiesAndStorage", true);
+    this.checkPrefCheckbox("siteSettings", false);
+    this.checkPrefCheckbox("cache", false);
+
+    this.acceptDialog();
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  // validate if prefs are remembered across both clear history and browser
+  dh = new ClearHistoryDialogHelper({ mode: "browser" });
+  dh.onload = function () {
+    this.validateCheckbox("cookiesAndStorage", true);
+    this.validateCheckbox("siteSettings", false);
+    this.validateCheckbox("cache", false);
+
+    this.cancelDialog();
+  };
+  dh.open();
+  await dh.promiseClosed;
+});
+
 /**
  * Ensures that the "Everything" duration option works.
  */
@@ -681,7 +345,7 @@ add_task(async function test_everything() {
   let promiseSanitized = promiseSanitizationComplete();
 
   await PlacesTestUtils.addVisits(places);
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     is(
       this.isWarningPanelVisible(),
@@ -728,7 +392,7 @@ add_task(async function test_everything_warning() {
   let promiseSanitized = promiseSanitizationComplete();
 
   await PlacesTestUtils.addVisits(places);
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     is(
       this.isWarningPanelVisible(),
@@ -761,7 +425,7 @@ add_task(async function test_everything_warning() {
  * and enabled when at least one checkbox is checked
  */
 add_task(async function testAcceptButtonDisabled() {
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = async function () {
     let clearButton = this.win.document
       .querySelector("dialog")
@@ -769,12 +433,6 @@ add_task(async function testAcceptButtonDisabled() {
     this.uncheckAllCheckboxes();
     await new Promise(resolve => SimpleTest.executeSoon(resolve));
     is(clearButton.disabled, true, "Clear button should be disabled");
-    // await BrowserTestUtils.waitForMutationCondition(
-    //   clearButton,
-    //   { attributes: true },
-    //   () => clearButton.disabled,
-    //   "Clear button should be disabled"
-    // );
 
     this.checkPrefCheckbox("cache", true);
     await new Promise(resolve => SimpleTest.executeSoon(resolve));
@@ -790,7 +448,7 @@ add_task(async function testAcceptButtonDisabled() {
  * Tests to see if the warning box is hidden when opened in the clear on shutdown context
  */
 add_task(async function testWarningBoxInClearOnShutdown() {
-  let dh = new DialogHelper("clearSiteData");
+  let dh = new ClearHistoryDialogHelper({ mode: "clearSiteData" });
   dh.onload = function () {
     this.selectDuration(Sanitizer.TIMESPAN_EVERYTHING);
     is(
@@ -803,7 +461,7 @@ add_task(async function testWarningBoxInClearOnShutdown() {
   dh.open();
   await dh.promiseClosed;
 
-  dh = new DialogHelper("clearOnShutdown");
+  dh = new ClearHistoryDialogHelper({ mode: "clearOnShutdown" });
   dh.onload = function () {
     is(
       BrowserTestUtils.isVisible(this.getWarningPanel()),
@@ -853,7 +511,7 @@ add_task(async function test_history_downloads_checked() {
 
   await PlacesTestUtils.addVisits(places);
 
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     this.selectDuration(Sanitizer.TIMESPAN_HOUR);
     this.checkPrefCheckbox("historyFormDataAndDownloads", true);
@@ -905,7 +563,7 @@ add_task(async function test_cannot_clear_history() {
   });
   let uris = [pURI];
 
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     var cb = this.win.document.querySelectorAll(
       "checkbox[id='historyFormDataAndDownloads']"
@@ -932,7 +590,7 @@ add_task(async function test_cannot_clear_history() {
 
 add_task(async function test_no_formdata_history_to_clear() {
   let promiseSanitized = promiseSanitizationComplete();
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     var cb = this.win.document.querySelectorAll(
       "checkbox[id='historyFormDataAndDownloads']"
@@ -955,7 +613,7 @@ add_task(async function test_form_entries() {
 
   let promiseSanitized = promiseSanitizationComplete();
 
-  let dh = new DialogHelper();
+  let dh = new ClearHistoryDialogHelper();
   dh.onload = function () {
     var cb = this.win.document.querySelectorAll(
       "checkbox[id='historyFormDataAndDownloads']"
@@ -975,97 +633,13 @@ add_task(async function test_form_entries() {
   await dh.promiseClosed;
 });
 
-add_task(async function test_cookie_sizes() {
-  await clearAndValidateDataSizes({
-    clearCookies: true,
-    clearCache: false,
-    clearDownloads: false,
-    timespan: Sanitizer.TIMESPAN_HOUR,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: true,
-    clearCache: false,
-    clearDownloads: false,
-    timespan: Sanitizer.TIMESPAN_4HOURS,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: true,
-    clearCache: false,
-    clearDownloads: false,
-    timespan: Sanitizer.TIMESPAN_EVERYTHING,
-  });
-});
-
-add_task(async function test_cache_sizes() {
-  await clearAndValidateDataSizes({
-    clearCookies: false,
-    clearCache: true,
-    clearDownloads: false,
-    timespan: Sanitizer.TIMESPAN_HOUR,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: false,
-    clearCache: true,
-    clearDownloads: false,
-    timespan: Sanitizer.TIMESPAN_4HOURS,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: false,
-    clearCache: true,
-    clearDownloads: false,
-    timespan: Sanitizer.TIMESPAN_EVERYTHING,
-  });
-});
-
-add_task(async function test_downloads_sizes() {
-  await clearAndValidateDataSizes({
-    clearCookies: false,
-    clearCache: false,
-    clearDownloads: true,
-    timespan: Sanitizer.TIMESPAN_HOUR,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: false,
-    clearCache: false,
-    clearDownloads: true,
-    timespan: Sanitizer.TIMESPAN_4HOURS,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: false,
-    clearCache: false,
-    clearDownloads: true,
-    timespan: Sanitizer.TIMESPAN_EVERYTHING,
-  });
-});
-
-add_task(async function test_all_data_sizes() {
-  await clearAndValidateDataSizes({
-    clearCookies: true,
-    clearCache: true,
-    clearDownloads: true,
-    timespan: Sanitizer.TIMESPAN_HOUR,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: true,
-    clearCache: true,
-    clearDownloads: true,
-    timespan: Sanitizer.TIMESPAN_4HOURS,
-  });
-  await clearAndValidateDataSizes({
-    clearCookies: true,
-    clearCache: true,
-    clearDownloads: true,
-    timespan: Sanitizer.TIMESPAN_EVERYTHING,
-  });
-});
-
 // test the case when we open the dialog through the clear on shutdown settings
 add_task(async function test_clear_on_shutdown() {
   await SpecialPowers.pushPrefEnv({
     set: [["privacy.sanitize.sanitizeOnShutdown", true]],
   });
 
-  let dh = new DialogHelper("clearOnShutdown");
+  let dh = new ClearHistoryDialogHelper({ mode: "clearOnShutdown" });
   dh.onload = async function () {
     this.uncheckAllCheckboxes();
     this.checkPrefCheckbox("historyFormDataAndDownloads", false);
@@ -1134,7 +708,7 @@ add_task(async function test_clear_on_shutdown() {
   await ensureDownloadsClearedState(downloadIDs, false);
   await ensureDownloadsClearedState(olderDownloadIDs, false);
 
-  dh = new DialogHelper("clearOnShutdown");
+  dh = new ClearHistoryDialogHelper({ mode: "clearOnShutdown" });
   dh.onload = async function () {
     this.uncheckAllCheckboxes();
     this.checkPrefCheckbox("historyFormDataAndDownloads", true);
@@ -1192,89 +766,6 @@ add_task(async function test_clear_on_shutdown() {
   await SiteDataTestUtils.clear();
 });
 
-// test default prefs for entry points
-add_task(async function test_defaults_prefs() {
-  let dh = new DialogHelper("clearSiteData");
-  dh.onload = function () {
-    this.validateCheckbox("historyFormDataAndDownloads", false);
-    this.validateCheckbox("cache", true);
-    this.validateCheckbox("cookiesAndStorage", true);
-    this.validateCheckbox("siteSettings", false);
-
-    this.cancelDialog();
-  };
-  dh.open();
-  await dh.promiseClosed;
-
-  // We don't need to specify the mode again,
-  // as the default mode is taken (browser, clear history)
-
-  dh = new DialogHelper();
-  dh.onload = function () {
-    // Default checked for browser and clear history mode
-    this.validateCheckbox("historyFormDataAndDownloads", true);
-    this.validateCheckbox("cache", true);
-    this.validateCheckbox("cookiesAndStorage", true);
-    this.validateCheckbox("siteSettings", false);
-
-    this.cancelDialog();
-  };
-  dh.open();
-  await dh.promiseClosed;
-});
-
-/**
- * Helper function to simulate switching timespan selections and
- * validate data sizes before and after clearing
- *
- * @param {Object}
- *    clearCookies - boolean
- *    clearDownloads - boolean
- *    clearCaches - boolean
- *    timespan - one of Sanitizer.TIMESPAN_*
- */
-async function clearAndValidateDataSizes({
-  clearCache,
-  clearDownloads,
-  clearCookies,
-  timespan,
-}) {
-  await blankSlate();
-
-  await addToDownloadList();
-  await addToSiteUsage();
-  let promiseSanitized = promiseSanitizationComplete();
-
-  await openPreferencesViaOpenPreferencesAPI("privacy", { leaveOpen: true });
-
-  let dh = new DialogHelper();
-  dh.onload = async function () {
-    await validateDataSizes(this);
-    this.checkPrefCheckbox("cache", clearCache);
-    this.checkPrefCheckbox("cookiesAndStorage", clearCookies);
-    this.checkPrefCheckbox("historyFormDataAndDownloads", clearDownloads);
-    this.selectDuration(timespan);
-    this.acceptDialog();
-  };
-  dh.onunload = async function () {
-    await promiseSanitized;
-  };
-  dh.open();
-  await dh.promiseClosed;
-
-  let dh2 = new DialogHelper();
-  // Check if the newly cleared values are reflected
-  dh2.onload = async function () {
-    await validateDataSizes(this);
-    this.acceptDialog();
-  };
-  dh2.open();
-  await dh2.promiseClosed;
-
-  await SiteDataTestUtils.clear();
-  BrowserTestUtils.removeTab(gBrowser.selectedTab);
-}
-
 add_task(async function testEntryPointTelemetry() {
   Services.fog.testResetFOG();
 
@@ -1401,27 +892,47 @@ add_task(async function testClearingOptionsTelemetry() {
   );
 });
 
-add_task(async function testCheckboxStatesAfterMigration() {
+add_task(async function testClearHistoryCheckboxStatesAfterMigration() {
   await SpecialPowers.pushPrefEnv({
     set: [
-      ["privacy.clearOnShutdown.history", false],
-      ["privacy.clearOnShutdown.formdata", true],
-      ["privacy.clearOnShutdown.cookies", true],
-      ["privacy.clearOnShutdown.offlineApps", false],
-      ["privacy.clearOnShutdown.sessions", false],
-      ["privacy.clearOnShutdown.siteSettings", false],
-      ["privacy.clearOnShutdown.cache", true],
-      ["privacy.clearOnShutdown_v2.cookiesAndStorage", false],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", false],
+      ["privacy.cpd.history", false],
+      ["privacy.cpd.formdata", true],
+      ["privacy.cpd.cookies", true],
+      ["privacy.cpd.offlineApps", false],
+      ["privacy.cpd.sessions", false],
+      ["privacy.cpd.siteSettings", false],
+      ["privacy.cpd.cache", true],
+      // Set cookiesAndStorage to verify that the pref is flipped in the test
+      ["privacy.clearHistory.cookiesAndStorage", false],
+      ["privacy.sanitize.cpd.hasMigratedToNewPrefs", false],
     ],
   });
 
-  let dh = new DialogHelper("clearOnShutdown");
+  let dh = new ClearHistoryDialogHelper({ mode: "clearHistory" });
   dh.onload = function () {
     this.validateCheckbox("cookiesAndStorage", true);
     this.validateCheckbox("historyFormDataAndDownloads", false);
     this.validateCheckbox("cache", true);
     this.validateCheckbox("siteSettings", false);
+
+    this.checkPrefCheckbox("siteSettings", true);
+    this.checkPrefCheckbox("cookiesAndStorage", false);
+    this.acceptDialog();
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  is(
+    Services.prefs.getBoolPref("privacy.sanitize.cpd.hasMigratedToNewPrefs"),
+    true,
+    "Migration is complete for cpd branch"
+  );
+
+  // make sure the migration doesn't run again
+  dh = new ClearHistoryDialogHelper({ mode: "clearHistory" });
+  dh.onload = function () {
+    this.validateCheckbox("siteSettings", true);
+    this.validateCheckbox("cookiesAndStorage", false);
     this.cancelDialog();
   };
   dh.open();
diff --git a/browser/base/content/test/sanitize/browser_sanitizeDialog_v2_dataSizes.js b/browser/base/content/test/sanitize/browser_sanitizeDialog_v2_dataSizes.js
new file mode 100644
index 0000000000..ccb3c7d519
--- /dev/null
+++ b/browser/base/content/test/sanitize/browser_sanitizeDialog_v2_dataSizes.js
@@ -0,0 +1,310 @@
+/* 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/. */
+
+/**
+ * This tests the new clear history dialog's data size display functionality
+ */
+ChromeUtils.defineESModuleGetters(this, {
+  sinon: "resource://testing-common/Sinon.sys.mjs",
+  Sanitizer: "resource:///modules/Sanitizer.sys.mjs",
+});
+
+add_setup(async function () {
+  await blankSlate();
+  registerCleanupFunction(async function () {
+    await blankSlate();
+    await PlacesTestUtils.promiseAsyncUpdates();
+  });
+  await SpecialPowers.pushPrefEnv({
+    set: [["privacy.sanitize.useOldClearHistoryDialog", false]],
+  });
+});
+
+/**
+ * Helper function to validate the data sizes shown for each time selection
+ *
+ * @param {ClearHistoryDialogHelper} dh - dialog object to access window and timespan
+ */
+async function validateDataSizes(ClearHistoryDialogHelper) {
+  let timespans = [
+    "TIMESPAN_HOUR",
+    "TIMESPAN_2HOURS",
+    "TIMESPAN_4HOURS",
+    "TIMESPAN_TODAY",
+    "TIMESPAN_EVERYTHING",
+  ];
+
+  // get current data sizes from siteDataManager
+  let cacheUsage = await SiteDataManager.getCacheSize();
+  let quotaUsage = await SiteDataManager.getQuotaUsageForTimeRanges(timespans);
+
+  for (let i = 0; i < timespans.length; i++) {
+    // select timespan to check
+    ClearHistoryDialogHelper.selectDuration(Sanitizer[timespans[i]]);
+
+    // get the elements
+    let clearCookiesAndSiteDataCheckbox =
+      ClearHistoryDialogHelper.win.document.getElementById("cookiesAndStorage");
+    let clearCacheCheckbox =
+      ClearHistoryDialogHelper.win.document.getElementById("cache");
+
+    let [convertedQuotaUsage] = DownloadUtils.convertByteUnits(
+      quotaUsage[timespans[i]]
+    );
+    let [, convertedCacheUnit] = DownloadUtils.convertByteUnits(cacheUsage);
+
+    // Ensure l10n is finished before inspecting the category labels.
+    await ClearHistoryDialogHelper.win.document.l10n.translateElements([
+      clearCookiesAndSiteDataCheckbox,
+      clearCacheCheckbox,
+    ]);
+    ok(
+      clearCacheCheckbox.label.includes(convertedCacheUnit),
+      "Should show the cache usage"
+    );
+    ok(
+      clearCookiesAndSiteDataCheckbox.label.includes(convertedQuotaUsage),
+      `Should show the quota usage as ${convertedQuotaUsage}`
+    );
+  }
+}
+
+/**
+ * Helper function to simulate switching timespan selections and
+ * validate data sizes before and after clearing
+ *
+ * @param {Object}
+ *    clearCookies - boolean
+ *    clearDownloads - boolean
+ *    clearCaches - boolean
+ *    timespan - one of Sanitizer.TIMESPAN_*
+ */
+async function clearAndValidateDataSizes({
+  clearCache,
+  clearDownloads,
+  clearCookies,
+  timespan,
+}) {
+  await blankSlate();
+
+  await addToSiteUsage();
+  let promiseSanitized = promiseSanitizationComplete();
+
+  await openPreferencesViaOpenPreferencesAPI("privacy", { leaveOpen: true });
+
+  let dh = new ClearHistoryDialogHelper({ checkingDataSizes: true });
+  dh.onload = async function () {
+    await validateDataSizes(this);
+    this.checkPrefCheckbox("cache", clearCache);
+    this.checkPrefCheckbox("cookiesAndStorage", clearCookies);
+    this.checkPrefCheckbox("historyFormDataAndDownloads", clearDownloads);
+    this.selectDuration(timespan);
+    this.acceptDialog();
+  };
+  dh.onunload = async function () {
+    await promiseSanitized;
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  let dh2 = new ClearHistoryDialogHelper({ checkingDataSizes: true });
+  // Check if the newly cleared values are reflected
+  dh2.onload = async function () {
+    await validateDataSizes(this);
+    this.acceptDialog();
+  };
+  dh2.open();
+  await dh2.promiseClosed;
+
+  await SiteDataTestUtils.clear();
+  BrowserTestUtils.removeTab(gBrowser.selectedTab);
+}
+
+add_task(async function test_cookie_sizes() {
+  await clearAndValidateDataSizes({
+    clearCookies: true,
+    clearCache: false,
+    clearDownloads: false,
+    timespan: Sanitizer.TIMESPAN_HOUR,
+  });
+  await clearAndValidateDataSizes({
+    clearCookies: true,
+    clearCache: false,
+    clearDownloads: false,
+    timespan: Sanitizer.TIMESPAN_4HOURS,
+  });
+  await clearAndValidateDataSizes({
+    clearCookies: true,
+    clearCache: false,
+    clearDownloads: false,
+    timespan: Sanitizer.TIMESPAN_EVERYTHING,
+  });
+});
+
+add_task(async function test_cache_sizes() {
+  await clearAndValidateDataSizes({
+    clearCookies: false,
+    clearCache: true,
+    clearDownloads: false,
+    timespan: Sanitizer.TIMESPAN_HOUR,
+  });
+  await clearAndValidateDataSizes({
+    clearCookies: false,
+    clearCache: true,
+    clearDownloads: false,
+    timespan: Sanitizer.TIMESPAN_4HOURS,
+  });
+  await clearAndValidateDataSizes({
+    clearCookies: false,
+    clearCache: true,
+    clearDownloads: false,
+    timespan: Sanitizer.TIMESPAN_EVERYTHING,
+  });
+});
+
+add_task(async function test_all_data_sizes() {
+  await clearAndValidateDataSizes({
+    clearCookies: true,
+    clearCache: true,
+    clearDownloads: true,
+    timespan: Sanitizer.TIMESPAN_HOUR,
+  });
+  await clearAndValidateDataSizes({
+    clearCookies: true,
+    clearCache: true,
+    clearDownloads: true,
+    timespan: Sanitizer.TIMESPAN_4HOURS,
+  });
+  await clearAndValidateDataSizes({
+    clearCookies: true,
+    clearCache: true,
+    clearDownloads: true,
+    timespan: Sanitizer.TIMESPAN_EVERYTHING,
+  });
+});
+
+// This test makes sure that the user can change their timerange option
+// even if the data sizes are not loaded yet.
+add_task(async function testUIWithDataSizesLoading() {
+  await blankSlate();
+  await addToSiteUsage();
+
+  let origGetQuotaUsageForTimeRanges =
+    SiteDataManager.getQuotaUsageForTimeRanges.bind(SiteDataManager);
+  let resolveStubFn;
+  let resolverAssigned = false;
+
+  let dh = new ClearHistoryDialogHelper();
+  // Create a sandbox for isolated stubbing within the test
+  let sandbox = sinon.createSandbox();
+  sandbox
+    .stub(SiteDataManager, "getQuotaUsageForTimeRanges")
+    .callsFake(async (...args) => {
+      info("stub called");
+
+      let dataSizesReadyToLoadPromise = new Promise(resolve => {
+        resolveStubFn = resolve;
+        info("Sending message to notify dialog that the resolver is assigned");
+        window.postMessage("resolver-assigned", "*");
+        resolverAssigned = true;
+      });
+      await dataSizesReadyToLoadPromise;
+      return origGetQuotaUsageForTimeRanges(...args);
+    });
+  dh.onload = async function () {
+    // we add this event listener in the case where init finishes before the resolver is assigned
+    if (!resolverAssigned) {
+      await new Promise(resolve => {
+        let listener = event => {
+          if (event.data === "resolver-assigned") {
+            window.removeEventListener("message", listener);
+            // we are ready to test the dialog without any data sizes loaded
+            resolve();
+          }
+        };
+        window.addEventListener("message", listener);
+      });
+    }
+
+    ok(
+      !this.win.gSanitizePromptDialog._dataSizesUpdated,
+      "Data sizes should not have loaded yet"
+    );
+    this.selectDuration(Sanitizer.TIMESPAN_2HOURS);
+
+    info("triggering loading state end");
+    resolveStubFn();
+
+    await this.win.gSanitizePromptDialog.dataSizesFinishedUpdatingPromise;
+
+    validateDataSizes(this);
+    this.cancelDialog();
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  // Restore the sandbox after the test is complete
+  sandbox.restore();
+});
+
+add_task(async function testClearingBeforeDataSizesLoad() {
+  await blankSlate();
+  await addToSiteUsage();
+
+  // add site data that we can verify if it gets cleared
+  await createDummyDataForHost("example.org");
+  await createDummyDataForHost("example.com");
+
+  ok(
+    await SiteDataTestUtils.hasIndexedDB("https://example.org"),
+    "We have indexedDB data for example.org"
+  );
+  ok(
+    await SiteDataTestUtils.hasIndexedDB("https://example.com"),
+    "We have indexedDB data for example.com"
+  );
+
+  let dh = new ClearHistoryDialogHelper();
+  let promiseSanitized = promiseSanitizationComplete();
+  // Create a sandbox for isolated stubbing within the test
+  let sandbox = sinon.createSandbox();
+  sandbox
+    .stub(SiteDataManager, "getQuotaUsageForTimeRanges")
+    .callsFake(async () => {
+      info("stub called");
+
+      info("This promise should never resolve");
+      await new Promise(resolve => {});
+    });
+  dh.onload = async function () {
+    // we don't need to initiate a event listener to wait for the resolver to be assigned for this
+    // test since we do not want the data sizes to load
+    ok(
+      !this.win.gSanitizePromptDialog._dataSizesUpdated,
+      "Data sizes should not be loaded yet"
+    );
+    this.selectDuration(Sanitizer.TIMESPAN_2HOURS);
+    this.checkPrefCheckbox("cookiesAndStorage", true);
+    this.acceptDialog();
+  };
+  dh.onunload = async () => {
+    await promiseSanitized;
+  };
+  dh.open();
+  await dh.promiseClosed;
+
+  // Data for example.org should be cleared
+  ok(
+    !(await SiteDataTestUtils.hasIndexedDB("https://example.org")),
+    "We don't have indexedDB data for example.org"
+  );
+  // Data for example.com should be cleared
+  ok(
+    !(await SiteDataTestUtils.hasIndexedDB("https://example.com")),
+    "We don't have indexedDB data for example.com"
+  );
+
+  // Restore the sandbox after the test is complete
+  sandbox.restore();
+});
diff --git a/browser/base/content/test/sanitize/browser_sanitizeOnShutdown_migration.js b/browser/base/content/test/sanitize/browser_sanitizeOnShutdown_migration.js
index 3c2af1d513..bc5c925702 100644
--- a/browser/base/content/test/sanitize/browser_sanitizeOnShutdown_migration.js
+++ b/browser/base/content/test/sanitize/browser_sanitizeOnShutdown_migration.js
@@ -17,7 +17,7 @@ add_task(async function testMigrationOfCacheAndSiteSettings() {
       ["privacy.clearOnShutdown.siteSettings", true],
       ["privacy.clearOnShutdown_v2.cache", false],
       ["privacy.clearOnShutdown_v2.siteSettings", false],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", false],
+      ["privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs", false],
     ],
   });
 
@@ -46,7 +46,7 @@ add_task(async function testMigrationOfCacheAndSiteSettings() {
 
   Assert.equal(
     Services.prefs.getBoolPref(
-      "privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs"
+      "privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs"
     ),
     true,
     "migration pref has been flipped"
@@ -59,7 +59,7 @@ add_task(async function testHistoryAndFormData_historyTrue() {
       ["privacy.clearOnShutdown.history", true],
       ["privacy.clearOnShutdown.formdata", false],
       ["privacy.clearOnShutdown_v2.historyFormDataAndDownloads", false],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", false],
+      ["privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs", false],
     ],
   });
 
@@ -85,7 +85,7 @@ add_task(async function testHistoryAndFormData_historyTrue() {
 
   Assert.equal(
     Services.prefs.getBoolPref(
-      "privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs"
+      "privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs"
     ),
     true,
     "migration pref has been flipped"
@@ -98,7 +98,7 @@ add_task(async function testHistoryAndFormData_historyFalse() {
       ["privacy.clearOnShutdown.history", false],
       ["privacy.clearOnShutdown.formdata", true],
       ["privacy.clearOnShutdown_v2.historyFormDataAndDownloads", true],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", false],
+      ["privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs", false],
     ],
   });
 
@@ -124,7 +124,7 @@ add_task(async function testHistoryAndFormData_historyFalse() {
 
   Assert.equal(
     Services.prefs.getBoolPref(
-      "privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs"
+      "privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs"
     ),
     true,
     "migration pref has been flipped"
@@ -138,7 +138,7 @@ add_task(async function testCookiesAndStorage_cookiesFalse() {
       ["privacy.clearOnShutdown.offlineApps", true],
       ["privacy.clearOnShutdown.sessions", true],
       ["privacy.clearOnShutdown_v2.cookiesAndStorage", true],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", false],
+      ["privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs", false],
     ],
   });
 
@@ -168,7 +168,7 @@ add_task(async function testCookiesAndStorage_cookiesFalse() {
 
   Assert.equal(
     Services.prefs.getBoolPref(
-      "privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs"
+      "privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs"
     ),
     true,
     "migration pref has been flipped"
@@ -182,7 +182,7 @@ add_task(async function testCookiesAndStorage_cookiesTrue() {
       ["privacy.clearOnShutdown.offlineApps", false],
       ["privacy.clearOnShutdown.sessions", false],
       ["privacy.clearOnShutdown_v2.cookiesAndStorage", false],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", false],
+      ["privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs", false],
     ],
   });
 
@@ -211,7 +211,7 @@ add_task(async function testCookiesAndStorage_cookiesTrue() {
 
   Assert.equal(
     Services.prefs.getBoolPref(
-      "privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs"
+      "privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs"
     ),
     true,
     "migration pref has been flipped"
@@ -225,7 +225,7 @@ add_task(async function testMigrationDoesNotRepeat() {
       ["privacy.clearOnShutdown.offlineApps", false],
       ["privacy.clearOnShutdown.sessions", false],
       ["privacy.clearOnShutdown_v2.cookiesAndStorage", false],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", true],
+      ["privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs", true],
     ],
   });
 
@@ -255,7 +255,7 @@ add_task(async function testMigrationDoesNotRepeat() {
 
   Assert.equal(
     Services.prefs.getBoolPref(
-      "privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs"
+      "privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs"
     ),
     true,
     "migration pref has been flipped"
@@ -273,7 +273,7 @@ add_task(async function ensureNoOldPrefsAreEffectedByMigration() {
       ["privacy.clearOnShutdown.siteSettings", true],
       ["privacy.clearOnShutdown.cache", true],
       ["privacy.clearOnShutdown_v2.cookiesAndStorage", false],
-      ["privacy.sanitize.sanitizeOnShutdown.hasMigratedToNewPrefs", false],
+      ["privacy.sanitize.clearOnShutdown.hasMigratedToNewPrefs", false],
     ],
   });
 
diff --git a/browser/base/content/test/sanitize/head.js b/browser/base/content/test/sanitize/head.js
index f5a6031b84..30d96c69f6 100644
--- a/browser/base/content/test/sanitize/head.js
+++ b/browser/base/content/test/sanitize/head.js
@@ -3,10 +3,34 @@ ChromeUtils.defineESModuleGetters(this, {
   FormHistory: "resource://gre/modules/FormHistory.sys.mjs",
   PermissionTestUtils: "resource://testing-common/PermissionTestUtils.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+  PlacesTestUtils: "resource://testing-common/PlacesTestUtils.sys.mjs",
+  FileTestUtils: "resource://testing-common/FileTestUtils.sys.mjs",
   Sanitizer: "resource:///modules/Sanitizer.sys.mjs",
   SiteDataTestUtils: "resource://testing-common/SiteDataTestUtils.sys.mjs",
 });
 
+const kMsecPerMin = 60 * 1000;
+const kUsecPerMin = kMsecPerMin * 1000;
+let today = Date.now() - new Date().setHours(0, 0, 0, 0);
+let nowMSec = Date.now();
+let nowUSec = nowMSec * 1000;
+const TEST_TARGET_FILE_NAME = "test-download.txt";
+const TEST_QUOTA_USAGE_HOST = "example.com";
+const TEST_QUOTA_USAGE_ORIGIN = "https://" + TEST_QUOTA_USAGE_HOST;
+const TEST_QUOTA_USAGE_URL =
+  getRootDirectory(gTestPath).replace(
+    "chrome://mochitests/content",
+    TEST_QUOTA_USAGE_ORIGIN
+  ) + "site_data_test.html";
+const SITE_ORIGINS = [
+  "https://www.example.com",
+  "https://example.org",
+  "http://localhost:8000",
+  "http://localhost:3000",
+];
+
+let fileURL;
+
 function createIndexedDB(host, originAttributes) {
   let uri = Services.io.newURI("https://" + host);
   let principal = Services.scriptSecurityManager.createContentPrincipal(
@@ -369,3 +393,345 @@ async function createDummyDataForHost(host) {
   await SiteDataTestUtils.addToIndexedDB(origin);
   await SiteDataTestUtils.addServiceWorker(dummySWURL);
 }
+
+/**
+ * Helper function to create file URL to open
+ *
+ * @returns {Object} a file URL
+ */
+function createFileURL() {
+  if (!fileURL) {
+    let file = Services.dirsvc.get("TmpD", Ci.nsIFile);
+    file.append("foo.txt");
+    file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o600);
+
+    fileURL = Services.io.newFileURI(file);
+  }
+  return fileURL;
+}
+
+/**
+ * Removes all history visits, downloads, and form entries.
+ */
+async function blankSlate() {
+  let publicList = await Downloads.getList(Downloads.PUBLIC);
+  let downloads = await publicList.getAll();
+  for (let download of downloads) {
+    await publicList.remove(download);
+    await download.finalize(true);
+  }
+
+  await FormHistory.update({ op: "remove" });
+  await PlacesUtils.history.clear();
+}
+
+/**
+ * Adds multiple downloads to the PUBLIC download list
+ */
+async function addToDownloadList() {
+  const url = createFileURL();
+  const downloadsList = await Downloads.getList(Downloads.PUBLIC);
+  let timeOptions = [1, 2, 4, 24, 128, 128];
+  let buffer = 100000;
+
+  for (let i = 0; i < timeOptions.length; i++) {
+    let timeDownloaded = 60 * kMsecPerMin * timeOptions[i];
+    if (timeOptions[i] === 24) {
+      timeDownloaded = today;
+    }
+
+    let download = await Downloads.createDownload({
+      source: { url: url.spec, isPrivate: false },
+      target: { path: FileTestUtils.getTempFile(TEST_TARGET_FILE_NAME).path },
+      startTime: {
+        getTime: _ => {
+          return nowMSec - timeDownloaded + buffer;
+        },
+      },
+    });
+
+    Assert.ok(!!download);
+    downloadsList.add(download);
+  }
+  let items = await downloadsList.getAll();
+  Assert.equal(items.length, 6, "Items were added to the list");
+}
+
+async function addToSiteUsage() {
+  // Fill indexedDB with test data.
+  // Don't wait for the page to load, to register the content event handler as quickly as possible.
+  // If this test goes intermittent, we might have to tell the page to wait longer before
+  // firing the event.
+  BrowserTestUtils.openNewForegroundTab(gBrowser, TEST_QUOTA_USAGE_URL, false);
+  await BrowserTestUtils.waitForContentEvent(
+    gBrowser.selectedBrowser,
+    "test-indexedDB-done",
+    false,
+    null,
+    true
+  );
+  BrowserTestUtils.removeTab(gBrowser.selectedTab);
+
+  let siteLastAccessed = [1, 2, 4, 24];
+
+  let staticUsage = 4096 * 6;
+  // Add a time buffer so the site access falls within the time range
+  const buffer = 10000;
+
+  // Change lastAccessed of sites
+  for (let index = 0; index < siteLastAccessed.length; index++) {
+    let lastAccessedTime = 60 * kMsecPerMin * siteLastAccessed[index];
+    if (siteLastAccessed[index] === 24) {
+      lastAccessedTime = today;
+    }
+
+    let site = SiteDataManager._testInsertSite(SITE_ORIGINS[index], {
+      quotaUsage: staticUsage,
+      lastAccessed: (nowMSec - lastAccessedTime + buffer) * 1000,
+    });
+    Assert.ok(site, "Site added successfully");
+  }
+}
+
+function promiseSanitizationComplete() {
+  return TestUtils.topicObserved("sanitizer-sanitization-complete");
+}
+
+/**
+ * This wraps the dialog and provides some convenience methods for interacting
+ * with it.
+ *
+ * @param {Window} browserWin (optional)
+ *        The browser window that the dialog is expected to open in. If not
+ *        supplied, the initial browser window of the test run is used.
+ * @param {Object} {mode, checkingDataSizes}
+ *        mode: context to open the dialog in
+ *          One of
+ *            clear on shutdown settings context ("clearOnShutdown"),
+ *            clear site data settings context ("clearSiteData"),
+ *            clear history context ("clearHistory"),
+ *            browser context ("browser")
+ *          "browser" by default
+ *        checkingDataSizes: boolean check if we should wait for the data sizes
+ *          to load
+ *
+ */
+function ClearHistoryDialogHelper({
+  mode = "browser",
+  checkingDataSizes = false,
+} = {}) {
+  this._browserWin = window;
+  this.win = null;
+  this._mode = mode;
+  this._checkingDataSizes = checkingDataSizes;
+  this.promiseClosed = new Promise(resolve => {
+    this._resolveClosed = resolve;
+  });
+}
+
+ClearHistoryDialogHelper.prototype = {
+  /**
+   * "Presses" the dialog's OK button.
+   */
+  acceptDialog() {
+    let dialogEl = this.win.document.querySelector("dialog");
+    is(
+      dialogEl.getButton("accept").disabled,
+      false,
+      "Dialog's OK button should not be disabled"
+    );
+    dialogEl.acceptDialog();
+  },
+
+  /**
+   * "Presses" the dialog's Cancel button.
+   */
+  cancelDialog() {
+    this.win.document.querySelector("dialog").cancelDialog();
+  },
+
+  /**
+   * (Un)checks a history scope checkbox (browser & download history,
+   * form history, etc.).
+   *
+   * @param aPrefName
+   *        The final portion of the checkbox's privacy.cpd.* preference name
+   * @param aCheckState
+   *        True if the checkbox should be checked, false otherwise
+   */
+  checkPrefCheckbox(aPrefName, aCheckState) {
+    var cb = this.win.document.querySelectorAll(
+      "checkbox[id='" + aPrefName + "']"
+    );
+    is(cb.length, 1, "found checkbox for " + aPrefName + " id");
+    if (cb[0].checked != aCheckState) {
+      cb[0].click();
+    }
+  },
+
+  /**
+   * @param {String} aCheckboxId
+   *        The checkbox id name
+   * @param {Boolean} aCheckState
+   *        True if the checkbox should be checked, false otherwise
+   */
+  validateCheckbox(aCheckboxId, aCheckState) {
+    let cb = this.win.document.querySelectorAll(
+      "checkbox[id='" + aCheckboxId + "']"
+    );
+    is(cb.length, 1, `found checkbox for id=${aCheckboxId}`);
+    is(
+      cb[0].checked,
+      aCheckState,
+      `checkbox for ${aCheckboxId} is ${aCheckState}`
+    );
+  },
+
+  /**
+   * Makes sure all the checkboxes are checked.
+   */
+  _checkAllCheckboxesCustom(check) {
+    var cb = this.win.document.querySelectorAll(".clearingItemCheckbox");
+    ok(cb.length, "found checkboxes for ids");
+    for (var i = 0; i < cb.length; ++i) {
+      if (cb[i].checked != check) {
+        cb[i].click();
+      }
+    }
+  },
+
+  checkAllCheckboxes() {
+    this._checkAllCheckboxesCustom(true);
+  },
+
+  uncheckAllCheckboxes() {
+    this._checkAllCheckboxesCustom(false);
+  },
+
+  /**
+   * @return The dialog's duration dropdown
+   */
+  getDurationDropdown() {
+    return this.win.document.getElementById("sanitizeDurationChoice");
+  },
+
+  /**
+   * @return The clear-everything warning box
+   */
+  getWarningPanel() {
+    return this.win.document.getElementById("sanitizeEverythingWarningBox");
+  },
+
+  /**
+   * @return True if the "Everything" warning panel is visible (as opposed to
+   *         the tree)
+   */
+  isWarningPanelVisible() {
+    return !this.getWarningPanel().hidden;
+  },
+
+  /**
+   * Opens the clear recent history dialog.  Before calling this, set
+   * this.onload to a function to execute onload.  It should close the dialog
+   * when done so that the tests may continue.  Set this.onunload to a function
+   * to execute onunload.  this.onunload is optional. If it returns true, the
+   * caller is expected to call promiseAsyncUpdates at some point; if false is
+   * returned, promiseAsyncUpdates is called automatically.
+   */
+  async open() {
+    let dialogPromise = BrowserTestUtils.promiseAlertDialogOpen(
+      null,
+      "chrome://browser/content/sanitize_v2.xhtml",
+      {
+        isSubDialog: true,
+      }
+    );
+
+    // We want to simulate opening the dialog inside preferences for clear history
+    // and clear site data
+    if (this._mode != "browser") {
+      await openPreferencesViaOpenPreferencesAPI("privacy", {
+        leaveOpen: true,
+      });
+      let tabWindow = gBrowser.selectedBrowser.contentWindow;
+      let clearDialogOpenButtonId = this._mode + "Button";
+      // the id for clear on shutdown is of a different format
+      if (this._mode == "clearOnShutdown") {
+        // set always clear to true to enable the clear on shutdown dialog
+        let enableSettingsCheckbox =
+          tabWindow.document.getElementById("alwaysClear");
+        if (!enableSettingsCheckbox.checked) {
+          enableSettingsCheckbox.click();
+        }
+        clearDialogOpenButtonId = "clearDataSettings";
+      }
+      // open dialog
+      tabWindow.document.getElementById(clearDialogOpenButtonId).click();
+    }
+    // We open the dialog in the chrome context in other cases
+    else {
+      executeSoon(() => {
+        Sanitizer.showUI(this._browserWin, this._mode);
+      });
+    }
+
+    this.win = await dialogPromise;
+    this.win.addEventListener(
+      "load",
+      () => {
+        // Run onload on next tick so that gSanitizePromptDialog.init can run first.
+        executeSoon(async () => {
+          if (this._checkingDataSizes) {
+            // we wait for the data sizes to load to avoid async errors when validating sizes
+            await this.win.gSanitizePromptDialog
+              .dataSizesFinishedUpdatingPromise;
+          }
+          this.onload();
+        });
+      },
+      { once: true }
+    );
+    this.win.addEventListener(
+      "unload",
+      () => {
+        // Some exceptions that reach here don't reach the test harness, but
+        // ok()/is() do...
+        (async () => {
+          if (this.onunload) {
+            await this.onunload();
+          }
+          if (this._mode != "browser") {
+            BrowserTestUtils.removeTab(gBrowser.selectedTab);
+          }
+          await PlacesTestUtils.promiseAsyncUpdates();
+          this._resolveClosed();
+          this.win = null;
+        })();
+      },
+      { once: true }
+    );
+  },
+
+  /**
+   * Selects a duration in the duration dropdown.
+   *
+   * @param aDurVal
+   *        One of the Sanitizer.TIMESPAN_* values
+   */
+  selectDuration(aDurVal) {
+    this.getDurationDropdown().value = aDurVal;
+    if (aDurVal === Sanitizer.TIMESPAN_EVERYTHING) {
+      is(
+        this.isWarningPanelVisible(),
+        true,
+        "Warning panel should be visible for TIMESPAN_EVERYTHING"
+      );
+    } else {
+      is(
+        this.isWarningPanelVisible(),
+        false,
+        "Warning panel should not be visible for non-TIMESPAN_EVERYTHING"
+      );
+    }
+  },
+};
diff --git a/browser/base/content/test/siteIdentity/browser.toml b/browser/base/content/test/siteIdentity/browser.toml
index f0b6191302..c075052fa5 100644
--- a/browser/base/content/test/siteIdentity/browser.toml
+++ b/browser/base/content/test/siteIdentity/browser.toml
@@ -106,6 +106,12 @@ skip-if = [
 ["browser_identity_UI.js"]
 https_first_disabled = true
 
+["browser_identity_web_controlled_blank.js"]
+support-files = [
+  "test_web_controlled_blank.html",
+  "dummy_page.html",
+]
+
 ["browser_iframe_navigation.js"]
 https_first_disabled = true
 support-files = ["iframe_navigation.html"]
diff --git a/browser/base/content/test/siteIdentity/browser_identity_web_controlled_blank.js b/browser/base/content/test/siteIdentity/browser_identity_web_controlled_blank.js
new file mode 100644
index 0000000000..01eca12178
--- /dev/null
+++ b/browser/base/content/test/siteIdentity/browser_identity_web_controlled_blank.js
@@ -0,0 +1,128 @@
+/*
+ * This work is marked with CC0 1.0. To view a copy of this license,
+ * visit http://creativecommons.org/publicdomain/zero/1.0
+ *
+ *
+ * Tests for correct behaviour of web-controlled about:blank pages in identity panel.
+ * Getting into a testable state is different enough that we test all the behaviors here
+ * separately, rather than with the usual (secure, insecure, etc.) cases
+ */
+
+const TEST_HOST = "example.com";
+const TEST_ORIGIN = "https://" + TEST_HOST;
+const TEST_PATH = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  TEST_ORIGIN
+);
+const LOCALHOST_PATH = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "http://127.0.0.1:8888"
+);
+const TEST_URI = TEST_PATH + "test_web_controlled_blank.html";
+const DUMMY_URI = LOCALHOST_PATH + "dummy_page.html";
+
+// Open a new tab of `test_web_controlled_blank.html` and click
+// an element with a particular ID to open an about:blank popup
+// that is controlled by that first tab.
+//
+// Then test that the UI elements are all correct. And make sure
+// we don't have anything odd going on after navigating away in the
+// popup.
+async function web_controlled_about_blank_helper(id_to_click) {
+  // Open a new tab that will control about:blank pages
+  await BrowserTestUtils.withNewTab(TEST_URI, async browser => {
+    // Open a new popup by clicking the provided id_to_click from the content
+    let popupWindowPromise = BrowserTestUtils.waitForNewWindow();
+    await SpecialPowers.spawn(browser, [id_to_click], async function (id) {
+      content.document.getElementById(id).click();
+    });
+    let popupWindow = await popupWindowPromise;
+
+    // Validate the icon in the urlbar
+    let identityIcon = popupWindow.document.querySelector("#identity-icon");
+    let identityIconImageURL = popupWindow
+      .getComputedStyle(identityIcon)
+      .getPropertyValue("list-style-image");
+    is(
+      identityIconImageURL,
+      `url("chrome://global/skin/icons/info.svg")`,
+      "The identity icon has a correct image url."
+    );
+
+    // Open the identity panel
+    let popupShown = BrowserTestUtils.waitForEvent(
+      popupWindow,
+      "popupshown",
+      true,
+      event => event.target == popupWindow.gIdentityHandler._identityPopup
+    );
+    popupWindow.gIdentityHandler._identityIconBox.click();
+    info("Waiting for the Control Center to be shown");
+    await popupShown;
+    ok(
+      !popupWindow.gIdentityHandler._identityPopup.hidden,
+      "Control Center is visible"
+    );
+
+    // Validate that the predecessor is shown in the identity panel
+    ok(
+      popupWindow.gIdentityHandler._identityPopupMainViewHeaderLabel.textContent.includes(
+        TEST_HOST
+      ),
+      "Identity UI header shows the host of the predecessor"
+    );
+
+    // Validate that the correct message is displayed
+    is(
+      popupWindow.gIdentityHandler._identityPopup.getAttribute("connection"),
+      "associated",
+      "Identity UI shows associated message."
+    );
+
+    // Validate that there is no additional security info
+    let securityButton = popupWindow.gBrowser.ownerDocument.querySelector(
+      "#identity-popup-security-button"
+    );
+    is(
+      securityButton.disabled,
+      true,
+      "Security button has correct disabled state"
+    );
+
+    // Navigate away to a localhost page and make sure the identity icon changes
+    let loaded = BrowserTestUtils.browserLoaded(
+      popupWindow.gBrowser.selectedBrowser,
+      false,
+      DUMMY_URI
+    );
+    await SpecialPowers.spawn(
+      popupWindow.gBrowser.selectedBrowser,
+      [DUMMY_URI],
+      async function (uri) {
+        content.location = uri;
+      }
+    );
+    info("Waiting for the navigation to a dummy page to complete.");
+    await loaded;
+
+    identityIconImageURL = popupWindow.gBrowser.ownerGlobal
+      .getComputedStyle(identityIcon)
+      .getPropertyValue("list-style-image");
+    is(
+      identityIconImageURL,
+      `url("chrome://global/skin/icons/page-portrait.svg")`,
+      "The identity icon has a correct image url after navigating away."
+    );
+
+    // Exit this test, cleaning up as we go.
+    await BrowserTestUtils.closeWindow(popupWindow);
+  });
+}
+
+add_task(async function test_document_write() {
+  await web_controlled_about_blank_helper("document_write");
+});
+
+add_task(async function test_innerHTML() {
+  await web_controlled_about_blank_helper("innerhtml");
+});
diff --git a/browser/base/content/test/siteIdentity/test_web_controlled_blank.html b/browser/base/content/test/siteIdentity/test_web_controlled_blank.html
new file mode 100644
index 0000000000..35c1fd4ca2
--- /dev/null
+++ b/browser/base/content/test/siteIdentity/test_web_controlled_blank.html
@@ -0,0 +1,36 @@
+<!doctype html>
+<html>
+    <head>
+        <title>Bug 1813463: Web controlled about:blank</title>
+    </head>
+    <!--
+      This work is marked with CC0 1.0. To view a copy of this license,
+      visit http://creativecommons.org/publicdomain/zero/1.0
+    -->
+    <body>
+        <p><a href="#" id="document_write">document.write example</a></p>
+        <p><a href="#" id="innerhtml">innerHTML example</a></p>
+
+        <script>
+            document.getElementById("document_write").addEventListener("click", function (aEvent) {
+                aEvent.preventDefault();
+                let popup = window.open("about:blank", "_blank", "width=800,height=600,popup");
+                popup.document.write(`
+                    <h1>check security info</h1>
+                    <p>initial window.location = ${popup.location}</p>
+                    <script>
+                        document.write("<p>new window.location = " + window.location + "</p>")
+                    <${"/"}script>
+                    `);
+            });
+            document.getElementById("innerhtml").addEventListener("click", function (aEvent) {
+                aEvent.preventDefault();
+                let popup = window.open("about:blank", "_blank", "width=800,height=600,popup");
+                popup.stop();
+                popup.document.body.innerHTML = `
+                    <h1>check security info</h1>
+                    <p>window.location = ${popup.location}</p>`;
+            });
+        </script>
+    </body>
+</html>
diff --git a/browser/base/content/test/static/browser_all_files_referenced.js b/browser/base/content/test/static/browser_all_files_referenced.js
index 6389e59e00..5e83443ec7 100644
--- a/browser/base/content/test/static/browser_all_files_referenced.js
+++ b/browser/base/content/test/static/browser_all_files_referenced.js
@@ -76,6 +76,9 @@ var gExceptionPaths = [
   // Localization file added programatically in FeatureCallout.sys.mjs
   "resource://app/localization/en-US/browser/featureCallout.ftl",
 
+  // Localization file added programatically in ContentAnalysis.sys.mjs
+  "resource://gre/localization/en-US/toolkit/contentanalysis/",
+
   // CSS files are referenced inside JS in an html template
   "chrome://browser/content/aboutlogins/components/",
 ];
@@ -277,6 +280,9 @@ var allowlist = [
   // find the references)
   { file: "chrome://browser/content/screenshots/copied-notification.svg" },
 
+  // Bug 1875361
+  { file: "chrome://global/content/ml/SummarizerModel.sys.mjs" },
+
   // toolkit/xre/MacRunFromDmgUtils.mm
   { file: "resource://gre/localization/en-US/toolkit/global/run-from-dmg.ftl" },
 
@@ -871,9 +877,6 @@ add_task(async function checkAllTheFiles() {
   // Wait for all manifest to be parsed
   await PerfTestHelpers.throttledMapPromises(manifestURIs, parseManifest);
 
-  for (let jsm of Components.manager.getComponentJSMs()) {
-    gReferencesFromCode.set(jsm, null);
-  }
   for (let esModule of Components.manager.getComponentESModules()) {
     gReferencesFromCode.set(esModule, null);
   }
diff --git a/browser/base/content/test/static/browser_misused_characters_in_strings.js b/browser/base/content/test/static/browser_misused_characters_in_strings.js
index 4191cc966e..c234f8107e 100644
--- a/browser/base/content/test/static/browser_misused_characters_in_strings.js
+++ b/browser/base/content/test/static/browser_misused_characters_in_strings.js
@@ -68,6 +68,28 @@ let gExceptionsList = [
     key: "MathML_DeprecatedMathVariantWarning",
     type: "single-quote",
   },
+  // These error messages contain references to the CSP keywords 'unsafe-eval'/'wasm-unsafe-eval',
+  // and those keywords contain actual single-quotes: https://w3c.github.io/webappsec-csp/#grammardef-keyword-source
+  {
+    file: "csp.properties",
+    key: "CSPEvalScriptViolation",
+    type: "single-quote",
+  },
+  {
+    file: "csp.properties",
+    key: "CSPROEvalScriptViolation",
+    type: "single-quote",
+  },
+  {
+    file: "csp.properties",
+    key: "CSPWasmEvalScriptViolation",
+    type: "single-quote",
+  },
+  {
+    file: "csp.properties",
+    key: "CSPROWasmEvalScriptViolation",
+    type: "single-quote",
+  },
 ];
 
 /**
diff --git a/browser/base/content/test/static/browser_parsable_css.js b/browser/base/content/test/static/browser_parsable_css.js
index b34ae7d9c1..602cc5a7e2 100644
--- a/browser/base/content/test/static/browser_parsable_css.js
+++ b/browser/base/content/test/static/browser_parsable_css.js
@@ -68,24 +68,6 @@ if (!Services.prefs.getBoolPref("layout.css.zoom.enabled")) {
   });
 }
 
-if (!Services.prefs.getBoolPref("layout.css.math-depth.enabled")) {
-  // mathml.css UA sheet rule for math-depth.
-  ignoreList.push({
-    sourceName: /\b(scrollbars|mathml)\.css$/i,
-    errorMessage: /Unknown property .*\bmath-depth\b/i,
-    isFromDevTools: false,
-  });
-}
-
-if (!Services.prefs.getBoolPref("layout.css.math-style.enabled")) {
-  // mathml.css UA sheet rule for math-style.
-  ignoreList.push({
-    sourceName: /(?:res|gre-resources)\/mathml\.css$/i,
-    errorMessage: /Unknown property .*\bmath-style\b/i,
-    isFromDevTools: false,
-  });
-}
-
 if (!Services.prefs.getBoolPref("layout.css.scroll-anchoring.enabled")) {
   ignoreList.push({
     sourceName: /webconsole\.css$/i,
diff --git a/browser/base/content/test/tabPrompts/browser_beforeunload_urlbar.js b/browser/base/content/test/tabPrompts/browser_beforeunload_urlbar.js
index 52044b5874..1466e9ca86 100644
--- a/browser/base/content/test/tabPrompts/browser_beforeunload_urlbar.js
+++ b/browser/base/content/test/tabPrompts/browser_beforeunload_urlbar.js
@@ -9,11 +9,6 @@ const TEST_ROOT = getRootDirectory(gTestPath).replace(
   "http://example.com"
 );
 
-const CONTENT_PROMPT_SUBDIALOG = Services.prefs.getBoolPref(
-  "prompts.contentPromptSubDialog",
-  false
-);
-
 add_task(async function test_beforeunload_stay_clears_urlbar() {
   await SpecialPowers.pushPrefEnv({
     set: [["dom.require_user_interaction_for_beforeunload", false]],
@@ -27,27 +22,10 @@ add_task(async function test_beforeunload_stay_clears_urlbar() {
     gURLBar.value = inputValue.slice(0, -1);
     EventUtils.sendString(inputValue.slice(-1));
 
-    if (CONTENT_PROMPT_SUBDIALOG) {
-      let promptOpenedPromise =
-        BrowserTestUtils.promiseAlertDialogOpen("cancel");
-      EventUtils.synthesizeKey("VK_RETURN");
-      await promptOpenedPromise;
-      await TestUtils.waitForTick();
-    } else {
-      let promptOpenedPromise = TestUtils.topicObserved(
-        "tabmodal-dialog-loaded"
-      );
-      EventUtils.synthesizeKey("VK_RETURN");
-      await promptOpenedPromise;
-      let promptElement = browser.parentNode.querySelector("tabmodalprompt");
-
-      // Click the cancel button
-      promptElement.querySelector(".tabmodalprompt-button1").click();
-      await TestUtils.waitForCondition(
-        () => promptElement.parentNode == null,
-        "tabprompt should be removed"
-      );
-    }
+    let promptOpenedPromise = BrowserTestUtils.promiseAlertDialogOpen("cancel");
+    EventUtils.synthesizeKey("VK_RETURN");
+    await promptOpenedPromise;
+    await TestUtils.waitForTick();
 
     // Can't just compare directly with TEST_URL because the URL may be trimmed.
     // Just need it to not be the example.org thing we typed in.
diff --git a/browser/base/content/test/tabPrompts/browser_confirmFolderUpload.js b/browser/base/content/test/tabPrompts/browser_confirmFolderUpload.js
index 62b0ed4f2b..52596095c4 100644
--- a/browser/base/content/test/tabPrompts/browser_confirmFolderUpload.js
+++ b/browser/base/content/test/tabPrompts/browser_confirmFolderUpload.js
@@ -88,7 +88,7 @@ async function testUploadPrompt(confirmUpload) {
     await ContentTask.spawn(browser, { path }, args => {
       let MockFilePicker = content.SpecialPowers.MockFilePicker;
       MockFilePicker.init(
-        content,
+        content.browsingContext,
         "A Mock File Picker",
         content.SpecialPowers.Ci.nsIFilePicker.modeGetFolder
       );
diff --git a/browser/base/content/test/tabPrompts/browser_contentOrigins.js b/browser/base/content/test/tabPrompts/browser_contentOrigins.js
index 10c8809490..2bf4ba6039 100644
--- a/browser/base/content/test/tabPrompts/browser_contentOrigins.js
+++ b/browser/base/content/test/tabPrompts/browser_contentOrigins.js
@@ -129,11 +129,7 @@ async function checkDialog(
 
 add_setup(async function () {
   await SpecialPowers.pushPrefEnv({
-    set: [
-      ["prompts.contentPromptSubDialog", true],
-      ["prompts.modalType.httpAuth", Ci.nsIPrompt.MODAL_TYPE_TAB],
-      ["prompts.tabChromePromptSubDialog", true],
-    ],
+    set: [["prompts.modalType.httpAuth", Ci.nsIPrompt.MODAL_TYPE_TAB]],
   });
 });
 
diff --git a/browser/base/content/test/tabPrompts/browser_multiplePrompts.js b/browser/base/content/test/tabPrompts/browser_multiplePrompts.js
index 597b7dfd6f..65c8b3eff4 100644
--- a/browser/base/content/test/tabPrompts/browser_multiplePrompts.js
+++ b/browser/base/content/test/tabPrompts/browser_multiplePrompts.js
@@ -1,13 +1,7 @@
 "use strict";
 
-const CONTENT_PROMPT_SUBDIALOG = Services.prefs.getBoolPref(
-  "prompts.contentPromptSubDialog",
-  false
-);
-
 /**
- * Goes through a stacked series of dialogs opened with
- * CONTENT_PROMPT_SUBDIALOG set to true, and ensures that
+ * Goes through a stacked series of dialogs  and ensures that
  * the oldest one is front-most and has the right type. It
  * then closes the oldest to newest dialog.
  *
@@ -58,64 +52,6 @@ async function closeDialogs(tab, dialogCount) {
   is(dialogs.length, 0, "Dialogs should all be dismissed.");
 }
 
-/**
- * Goes through a stacked series of tabprompt modals opened with
- * CONTENT_PROMPT_SUBDIALOG set to false, and ensures that
- * the oldest one is front-most and has the right type. It also
- * ensures that the other tabprompt modals are hidden. It
- * then closes the oldest to newest dialog.
- *
- * @param {Element} tab The <tab> that has had tabprompt modals opened
- * for it.
- * @param {Number} promptCount How many modals we expected to have been
- * opened.
- *
- * @return {Promise}
- * @resolves {undefined} Once the modals have all been closed.
- */
-async function closeTabModals(tab, promptCount) {
-  let promptElementsCount = promptCount;
-  while (promptElementsCount--) {
-    let promptElements =
-      tab.linkedBrowser.parentNode.querySelectorAll("tabmodalprompt");
-    is(
-      promptElements.length,
-      promptElementsCount + 1,
-      "There should be " + (promptElementsCount + 1) + " prompt(s)."
-    );
-    // The oldest should be the first.
-    let i = 0;
-
-    for (let promptElement of promptElements) {
-      let prompt = tab.linkedBrowser.tabModalPromptBox.getPrompt(promptElement);
-      let expectedType = ["alert", "prompt", "confirm"][i % 3];
-      is(
-        prompt.Dialog.args.text,
-        expectedType + " countdown #" + i,
-        "The #" + i + " alert should be labelled as such."
-      );
-      if (i !== promptElementsCount) {
-        is(prompt.element.hidden, true, "This prompt should be hidden.");
-        i++;
-        continue;
-      }
-
-      is(prompt.element.hidden, false, "The last prompt should not be hidden.");
-      prompt.onButtonClick(0);
-
-      // The click is handled async; wait for an event loop turn for that to
-      // happen.
-      await new Promise(function (resolve) {
-        Services.tm.dispatchToMainThread(resolve);
-      });
-    }
-  }
-
-  let promptElements =
-    tab.linkedBrowser.parentNode.querySelectorAll("tabmodalprompt");
-  is(promptElements.length, 0, "Prompts should all be dismissed.");
-}
-
 /*
  * This test triggers multiple alerts on one single tab, because it"s possible
  * for web content to do so. The behavior is described in bug 1266353.
@@ -161,11 +97,7 @@ add_task(async function () {
 
   await promptsOpenedPromise;
 
-  if (CONTENT_PROMPT_SUBDIALOG) {
-    await closeDialogs(tab, PROMPTCOUNT);
-  } else {
-    await closeTabModals(tab, PROMPTCOUNT);
-  }
+  await closeDialogs(tab, PROMPTCOUNT);
 
   BrowserTestUtils.removeTab(tab);
 });
diff --git a/browser/base/content/test/tabPrompts/browser_openPromptInBackgroundTab.js b/browser/base/content/test/tabPrompts/browser_openPromptInBackgroundTab.js
index 6b116b71f9..2fa3752881 100644
--- a/browser/base/content/test/tabPrompts/browser_openPromptInBackgroundTab.js
+++ b/browser/base/content/test/tabPrompts/browser_openPromptInBackgroundTab.js
@@ -22,118 +22,7 @@ registerCleanupFunction(function () {
  * the user to enable this automatically re-selecting. We then check that
  * checking the checkbox does actually enable that behaviour.
  */
-add_task(async function test_old_modal_ui() {
-  // We're intentionally testing the old modal mechanism, so disable the new one.
-  await SpecialPowers.pushPrefEnv({
-    set: [["prompts.contentPromptSubDialog", false]],
-  });
-
-  let firstTab = gBrowser.selectedTab;
-  // load page that opens prompt when page is hidden
-  let openedTab = await BrowserTestUtils.openNewForegroundTab(
-    gBrowser,
-    pageWithAlert,
-    true
-  );
-  let openedTabGotAttentionPromise = BrowserTestUtils.waitForAttribute(
-    "attention",
-    openedTab
-  );
-  // switch away from that tab again - this triggers the alert.
-  await BrowserTestUtils.switchTab(gBrowser, firstTab);
-  // ... but that's async on e10s...
-  await openedTabGotAttentionPromise;
-  // check for attention attribute
-  is(
-    openedTab.hasAttribute("attention"),
-    true,
-    "Tab with alert should have 'attention' attribute."
-  );
-  ok(!openedTab.selected, "Tab with alert should not be selected");
-
-  // switch tab back, and check the checkbox is displayed:
-  await BrowserTestUtils.switchTab(gBrowser, openedTab);
-  // check the prompt is there, and the extra row is present
-  let promptElements =
-    openedTab.linkedBrowser.parentNode.querySelectorAll("tabmodalprompt");
-  is(promptElements.length, 1, "There should be 1 prompt");
-  let ourPromptElement = promptElements[0];
-  let checkbox = ourPromptElement.querySelector(
-    "checkbox[label*='example.com']"
-  );
-  ok(checkbox, "The checkbox should be there");
-  ok(!checkbox.checked, "Checkbox shouldn't be checked");
-  // tick box and accept dialog
-  checkbox.checked = true;
-  let ourPrompt =
-    openedTab.linkedBrowser.tabModalPromptBox.getPrompt(ourPromptElement);
-  ourPrompt.onButtonClick(0);
-  // Wait for that click to actually be handled completely.
-  await new Promise(function (resolve) {
-    Services.tm.dispatchToMainThread(resolve);
-  });
-  // check permission is set
-  is(
-    Services.perms.ALLOW_ACTION,
-    PermissionTestUtils.testPermission(pageWithAlert, "focus-tab-by-prompt"),
-    "Tab switching should now be allowed"
-  );
-
-  // Check if the control center shows the correct permission.
-  let shown = BrowserTestUtils.waitForEvent(
-    window,
-    "popupshown",
-    true,
-    event => event.target == gPermissionPanel._permissionPopup
-  );
-  gPermissionPanel._identityPermissionBox.click();
-  await shown;
-  let labelText = SitePermissions.getPermissionLabel("focus-tab-by-prompt");
-  let permissionsList = document.getElementById(
-    "permission-popup-permission-list"
-  );
-  let label = permissionsList.querySelector(
-    ".permission-popup-permission-label"
-  );
-  is(label.textContent, labelText);
-  gPermissionPanel._permissionPopup.hidePopup();
-
-  // Check if the identity icon signals granted permission.
-  ok(
-    gPermissionPanel._identityPermissionBox.hasAttribute("hasPermissions"),
-    "identity-box signals granted permissions"
-  );
-
-  let openedTabSelectedPromise = BrowserTestUtils.waitForAttribute(
-    "selected",
-    openedTab,
-    "true"
-  );
-  // switch to other tab again
-  await BrowserTestUtils.switchTab(gBrowser, firstTab);
-
-  // This is sync in non-e10s, but in e10s we need to wait for this, so yield anyway.
-  // Note that the switchTab promise doesn't actually guarantee anything about *which*
-  // tab ends up as selected when its event fires, so using that here wouldn't work.
-  await openedTabSelectedPromise;
-  // should be switched back
-  ok(openedTab.selected, "Ta-dah, the other tab should now be selected again!");
-
-  // In e10s, with the conformant promise scheduling, we have to wait for next tick
-  // to ensure that the prompt is open before removing the opened tab, because the
-  // promise callback of 'openedTabSelectedPromise' could be done at the middle of
-  // RemotePrompt.openTabPrompt() while 'DOMModalDialogClosed' event is fired.
-  await TestUtils.waitForTick();
-
-  BrowserTestUtils.removeTab(openedTab);
-});
-
-add_task(async function test_new_modal_ui() {
-  // We're intentionally testing the new modal mechanism, so make sure it's enabled.
-  await SpecialPowers.pushPrefEnv({
-    set: [["prompts.contentPromptSubDialog", true]],
-  });
-
+add_task(async function test_modal_ui() {
   // Make sure we clear the focus tab permission set in the previous test
   PermissionTestUtils.remove(pageWithAlert, "focus-tab-by-prompt");
 
diff --git a/browser/base/content/test/tabdialogs/browser_tabdialogbox_content_prompts.js b/browser/base/content/test/tabdialogs/browser_tabdialogbox_content_prompts.js
index 50b94e1a36..5cac19f6af 100644
--- a/browser/base/content/test/tabdialogs/browser_tabdialogbox_content_prompts.js
+++ b/browser/base/content/test/tabdialogs/browser_tabdialogbox_content_prompts.js
@@ -3,7 +3,6 @@
 
 "use strict";
 
-const CONTENT_PROMPT_PREF = "prompts.contentPromptSubDialog";
 const TEST_ROOT_CHROME = getRootDirectory(gTestPath);
 const TEST_DIALOG_PATH = TEST_ROOT_CHROME + "subdialog.xhtml";
 
@@ -41,13 +40,6 @@ var commonDialogsBundle = Services.strings.createBundle(
   "chrome://global/locale/commonDialogs.properties"
 );
 
-// Setup.
-add_setup(async function () {
-  await SpecialPowers.pushPrefEnv({
-    set: [[CONTENT_PROMPT_PREF, true]],
-  });
-});
-
 /**
  * Test that a manager for content prompts is added to tab dialog box.
  */
diff --git a/browser/base/content/test/tabs/browser.toml b/browser/base/content/test/tabs/browser.toml
index 8008d70f0c..1b4a6900bf 100644
--- a/browser/base/content/test/tabs/browser.toml
+++ b/browser/base/content/test/tabs/browser.toml
@@ -236,7 +236,6 @@ support-files = [
 ]
 
 ["browser_overflowScroll.js"]
-fail-if = ["a11y_checks"] # Bugs 1854233 and 1873049 scrollbutton-down/up are not labeled
 skip-if = [
   "win11_2009", # Bug 1797751
 ]
diff --git a/browser/base/content/test/tabs/browser_close_during_beforeunload.js b/browser/base/content/test/tabs/browser_close_during_beforeunload.js
index 32bbb65b62..035884d713 100644
--- a/browser/base/content/test/tabs/browser_close_during_beforeunload.js
+++ b/browser/base/content/test/tabs/browser_close_during_beforeunload.js
@@ -4,14 +4,7 @@
 // beforeunload confirmation ignores the beforeunload listener and
 // unblocks the original close call.
 
-const CONTENT_PROMPT_SUBDIALOG = Services.prefs.getBoolPref(
-  "prompts.contentPromptSubDialog",
-  false
-);
-
-const DIALOG_TOPIC = CONTENT_PROMPT_SUBDIALOG
-  ? "common-dialog-loaded"
-  : "tabmodal-dialog-loaded";
+const DIALOG_TOPIC = "common-dialog-loaded";
 
 add_task(async function () {
   await SpecialPowers.pushPrefEnv({
diff --git a/browser/base/content/test/tabs/browser_multiselect_tabs_bookmark.js b/browser/base/content/test/tabs/browser_multiselect_tabs_bookmark.js
index a24e72c0bb..cd3728edcd 100644
--- a/browser/base/content/test/tabs/browser_multiselect_tabs_bookmark.js
+++ b/browser/base/content/test/tabs/browser_multiselect_tabs_bookmark.js
@@ -48,11 +48,6 @@ add_task(async function test() {
     false,
     "Bookmark Selected Tabs is hidden"
   );
-  is(
-    PlacesCommandHook.uniqueSelectedPages.length,
-    1,
-    "No more than one unique selected page"
-  );
 
   info("Add a different page to selection");
   let tab4 = await addTab_example_com();
@@ -69,11 +64,6 @@ add_task(async function test() {
     false,
     "Bookmark Selected Tabs is hidden"
   );
-  is(
-    PlacesCommandHook.uniqueSelectedPages.length,
-    2,
-    "More than one unique selected page"
-  );
 
   for (let tab of [tab1, tab2, tab3, tab4]) {
     BrowserTestUtils.removeTab(tab);
diff --git a/browser/base/content/test/tabs/browser_tab_preview.js b/browser/base/content/test/tabs/browser_tab_preview.js
index e3dd1b6842..718afbb940 100644
--- a/browser/base/content/test/tabs/browser_tab_preview.js
+++ b/browser/base/content/test/tabs/browser_tab_preview.js
@@ -34,7 +34,7 @@ add_setup(async function () {
     set: [
       ["browser.tabs.cardPreview.enabled", true],
       ["browser.tabs.cardPreview.showThumbnails", false],
-      ["browser.tabs.cardPreview.delayMs", 0],
+      ["ui.tooltip.delay_ms", 0],
     ],
   });
 });
@@ -46,7 +46,7 @@ add_setup(async function () {
  * 2. Tab preview card shows the correct preview for the tab being hovered
  * 3. Tab preview card is dismissed when the mouse leaves the tab bar
  */
-add_task(async () => {
+add_task(async function hoverTests() {
   const tabUrl1 =
     "data:text/html,<html><head><title>First New Tab</title></head><body>Hello</body></html>";
   const tab1 = await BrowserTestUtils.openNewForegroundTab(gBrowser, tabUrl1);
@@ -85,6 +85,11 @@ add_task(async () => {
 
   BrowserTestUtils.removeTab(tab1);
   BrowserTestUtils.removeTab(tab2);
+
+  // Move the mouse outside of the tab strip.
+  EventUtils.synthesizeMouseAtCenter(document.documentElement, {
+    type: "mouseover",
+  });
 });
 
 /**
@@ -92,7 +97,7 @@ add_task(async () => {
  * when browser.tabs.cardPreview.showThumbnails is set to true,
  * while the currently selected tab never displays a thumbnail in its preview.
  */
-add_task(async () => {
+add_task(async function thumbnailTests() {
   await SpecialPowers.pushPrefEnv({
     set: [["browser.tabs.cardPreview.showThumbnails", true]],
   });
@@ -120,15 +125,28 @@ add_task(async () => {
     "Tab2 (selected) does not contain thumbnail"
   );
 
+  const previewHidden = BrowserTestUtils.waitForEvent(
+    document.getElementById("tabbrowser-tab-preview"),
+    "previewhidden"
+  );
+
   BrowserTestUtils.removeTab(tab1);
   BrowserTestUtils.removeTab(tab2);
   await SpecialPowers.popPrefEnv();
+
+  // Removing the tab should close the preview.
+  await previewHidden;
+
+  // Move the mouse outside of the tab strip.
+  EventUtils.synthesizeMouseAtCenter(document.documentElement, {
+    type: "mouseover",
+  });
 });
 
 /**
  * Wheel events at the document-level of the window should hide the preview.
  */
-add_task(async () => {
+add_task(async function wheelTests() {
   const tabUrl1 = "about:blank";
   const tab1 = await BrowserTestUtils.openNewForegroundTab(gBrowser, tabUrl1);
   const tabUrl2 = "about:blank";
@@ -141,14 +159,49 @@ add_task(async () => {
     document.getElementById("tabbrowser-tab-preview"),
     "previewhidden"
   );
-  EventUtils.synthesizeMouse(tabs, 0, tabs.outerHeight + 1, {
-    wheel: true,
-    deltaY: -1,
-    deltaMode: WheelEvent.DOM_DELTA_LINE,
-  });
+
+  // Copied from apz_test_native_event_utils.js
+  let message = 0;
+  switch (AppConstants.platform) {
+    case "win":
+      message = 0x020a;
+      break;
+    case "linux":
+      message = 4;
+      break;
+    case "macosx":
+      message = 1;
+      break;
+  }
+
+  let rect = tabs.getBoundingClientRect();
+  let screenRect = window.windowUtils.toScreenRect(
+    rect.x,
+    rect.y,
+    rect.width,
+    rect.height
+  );
+  window.windowUtils.sendNativeMouseScrollEvent(
+    screenRect.left,
+    screenRect.bottom,
+    message,
+    0,
+    3,
+    0,
+    0,
+    Ci.nsIDOMWindowUtils.MOUSESCROLL_SCROLL_LINES,
+    tabs,
+    null
+  );
+
   await previewHidden;
 
   BrowserTestUtils.removeTab(tab1);
   BrowserTestUtils.removeTab(tab2);
   await SpecialPowers.popPrefEnv();
+
+  // Move the mouse outside of the tab strip.
+  EventUtils.synthesizeMouseAtCenter(document.documentElement, {
+    type: "mouseover",
+  });
 });
diff --git a/browser/base/content/test/webextensions/browser_permissions_local_file.js b/browser/base/content/test/webextensions/browser_permissions_local_file.js
index a2fdc34db3..7f8f256e14 100644
--- a/browser/base/content/test/webextensions/browser_permissions_local_file.js
+++ b/browser/base/content/test/webextensions/browser_permissions_local_file.js
@@ -10,7 +10,7 @@ async function installFile(filename) {
   file.leafName = filename;
 
   let MockFilePicker = SpecialPowers.MockFilePicker;
-  MockFilePicker.init(window);
+  MockFilePicker.init(window.browsingContext);
   MockFilePicker.setFiles([file]);
   MockFilePicker.afterOpenCallback = MockFilePicker.cleanup;
 
diff --git a/browser/base/content/utilityOverlay.js b/browser/base/content/utilityOverlay.js
index ae9c1d0a9a..5967c878b3 100644
--- a/browser/base/content/utilityOverlay.js
+++ b/browser/base/content/utilityOverlay.js
@@ -431,8 +431,7 @@ async function openPreferences(paneID, extraArgs) {
       }
     }
   }
-  let preferencesURL =
-    "about:preferences" +
+  let preferencesURLSuffix =
     (params ? "?" + params : "") +
     (friendlyCategoryName ? "#" + friendlyCategoryName : "");
   let newLoad = true;
@@ -444,7 +443,7 @@ async function openPreferences(paneID, extraArgs) {
     let supportsStringPrefURL = Cc[
       "@mozilla.org/supports-string;1"
     ].createInstance(Ci.nsISupportsString);
-    supportsStringPrefURL.data = preferencesURL;
+    supportsStringPrefURL.data = "about:preferences" + preferencesURLSuffix;
     windowArguments.appendElement(supportsStringPrefURL);
 
     win = Services.ww.openWindow(
@@ -458,11 +457,28 @@ async function openPreferences(paneID, extraArgs) {
     let shouldReplaceFragment = friendlyCategoryName
       ? "whenComparingAndReplace"
       : "whenComparing";
-    newLoad = !win.switchToTabHavingURI(preferencesURL, true, {
-      ignoreFragment: shouldReplaceFragment,
-      replaceQueryString: true,
-      triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
-    });
+    newLoad = !win.switchToTabHavingURI(
+      "about:settings" + preferencesURLSuffix,
+      false,
+      {
+        ignoreFragment: shouldReplaceFragment,
+        replaceQueryString: true,
+        triggeringPrincipal:
+          Services.scriptSecurityManager.getSystemPrincipal(),
+      }
+    );
+    if (newLoad) {
+      newLoad = !win.switchToTabHavingURI(
+        "about:preferences" + preferencesURLSuffix,
+        true,
+        {
+          ignoreFragment: shouldReplaceFragment,
+          replaceQueryString: true,
+          triggeringPrincipal:
+            Services.scriptSecurityManager.getSystemPrincipal(),
+        }
+      );
+    }
     browser = win.gBrowser.selectedBrowser;
   }
 
@@ -533,11 +549,6 @@ function buildHelpMenu() {
   if (typeof gSafeBrowsing != "undefined") {
     gSafeBrowsing.setReportPhishingMenu();
   }
-
-  if (NimbusFeatures.deviceMigration.getVariable("helpMenuHidden")) {
-    let helpMenuItem = document.getElementById("helpSwitchDevice");
-    helpMenuItem.hidden = true;
-  }
 }
 
 function isElementVisible(aElement) {
diff --git a/browser/base/content/webext-panels.xhtml b/browser/base/content/webext-panels.xhtml
index 902fa7e7b3..f421d9bf80 100644
--- a/browser/base/content/webext-panels.xhtml
+++ b/browser/base/content/webext-panels.xhtml
@@ -28,6 +28,7 @@
     <html:link rel="localization" href="toolkit/branding/brandings.ftl"/>
     <html:link rel="localization" href="toolkit/global/textActions.ftl"/>
     <html:link rel="localization" href="browser/browserContext.ftl"/>
+    <html:link rel="localization" href="preview/select-translations.ftl"/>
   </linkset>
 
   <commandset id="mainCommandset">
diff --git a/browser/base/jar.mn b/browser/base/jar.mn
index e3eb0e6e5f..1342630d54 100644
--- a/browser/base/jar.mn
+++ b/browser/base/jar.mn
@@ -52,6 +52,7 @@ browser.jar:
         content/browser/browser-pageActions.js              (content/browser-pageActions.js)
         content/browser/browser-pagestyle.js                (content/browser-pagestyle.js)
         content/browser/browser-places.js                   (content/browser-places.js)
+        content/browser/browser-profiles.js                 (content/browser-profiles.js)
         content/browser/browser-safebrowsing.js             (content/browser-safebrowsing.js)
         content/browser/browser-sidebar.js                  (content/browser-sidebar.js)
         content/browser/browser-siteIdentity.js             (content/browser-siteIdentity.js)
diff --git a/browser/base/moz.build b/browser/base/moz.build
index 98c3992a5d..9813d68058 100644
--- a/browser/base/moz.build
+++ b/browser/base/moz.build
@@ -85,8 +85,4 @@ if CONFIG["MOZ_WIDGET_TOOLKIT"] in ("windows", "gtk", "cocoa"):
 if CONFIG["MOZ_WIDGET_TOOLKIT"] in ("windows", "gtk"):
     DEFINES["MENUBAR_CAN_AUTOHIDE"] = 1
 
-if CONFIG["OS_ARCH"] == "WINNT" and CONFIG["MOZ_DEFAULT_BROWSER_AGENT"]:
-    # Impacts `/toolkit/content/license.html`.
-    DEFINES["MOZ_DEFAULT_BROWSER_AGENT"] = True
-
 JAR_MANIFESTS += ["jar.mn"]
diff --git a/browser/base/triage-tabbrowser.json b/browser/base/triage-tabbrowser.json
new file mode 100644
index 0000000000..237be342e3
--- /dev/null
+++ b/browser/base/triage-tabbrowser.json
@@ -0,0 +1,51 @@
+{
+  "triagers": {
+    "Dão Gottwald": {
+      "bzmail": "dao+bmo@mozilla.com"
+    },
+    "DJ Walker": {
+      "bzmail": "dwalker@mozilla.com"
+    },
+    "Marco Bonardo": {
+      "bzmail": "mak@mozilla.com"
+    },
+    "Mike Conley": {
+      "bzmail": "mconley@mozilla.com"
+    },
+    "Niklas Baumgardner": {
+      "bzmail": "nbaumgardner@mozilla.com"
+    }
+  },
+  "duty-start-dates": {
+    "2024-03-01": "Marco Bonardo",
+    "2024-03-16": "Dão Gottwald",
+    "2024-04-01": "Mike Conley",
+    "2024-04-16": "Dão Gottwald",
+    "2024-05-01": "Marco Bonardo",
+    "2024-05-16": "Mike Conley",
+    "2024-06-01": "Niklas Baumgardner",
+    "2024-06-16": "Dão Gottwald",
+    "2024-07-01": "DJ Walker",
+    "2024-07-16": "Marco Bonardo",
+    "2024-08-01": "Mike Conley",
+    "2024-08-16": "Niklas Baumgardner",
+    "2024-09-01": "Dão Gottwald",
+    "2024-09-16": "DJ Walker",
+    "2024-10-01": "Marco Bonardo",
+    "2024-10-16": "Mike Conley",
+    "2024-11-01": "Niklas Baumgardner",
+    "2024-11-16": "Dão Gottwald",
+    "2024-12-01": "DJ Walker",
+    "2024-12-16": "Marco Bonardo",
+    "2025-01-01": "Mike Conley",
+    "2025-01-16": "Niklas Baumgardner",
+    "2025-02-01": "Dão Gottwald",
+    "2025-02-16": "DJ Walker",
+    "2025-03-01": "Marco Bonardo",
+    "2025-03-16": "Mike Conley",
+    "2025-04-01": "Niklas Baumgardner",
+    "2025-04-16": "Dão Gottwald",
+    "2025-05-01": "DJ Walker",
+    "2025-05-16": "Marco Bonardo"
+  }
+}