Adding upstream version 126.0.upstream/126.0

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

35 files changed, 930 insertions, 169 deletions

diff --git a/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs b/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs
index b6d5bed59c..56f6435e47 100644
--- a/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs
+++ b/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs
@@ -1,7 +1,7 @@
 // -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
 /* 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/. */
+ * You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 const lazy = {};
 
diff --git a/toolkit/components/resistfingerprinting/KeyCodeConsensus_En_US.h b/toolkit/components/resistfingerprinting/KeyCodeConsensus_En_US.h
index c8fafcf22e..6558bcdc29 100644
--- a/toolkit/components/resistfingerprinting/KeyCodeConsensus_En_US.h
+++ b/toolkit/components/resistfingerprinting/KeyCodeConsensus_En_US.h
@@ -1,7 +1,7 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 /**
  * This file contains the spoofed keycodes of en-US for fingerprinting
diff --git a/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs b/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs
index 223c0259b7..c586873a74 100644
--- a/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs
+++ b/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs
@@ -1,7 +1,7 @@
 // -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
 /* 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/. */
+ * You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
@@ -43,6 +43,8 @@ class _RFPHelper {
     this._initialized = true;
 
     // Add unconditional observers
+    Services.obs.addObserver(this, "user-characteristics-populating-data");
+    Services.obs.addObserver(this, "user-characteristics-populating-data-done");
     Services.prefs.addObserver(kPrefResistFingerprinting, this);
     Services.prefs.addObserver(kPrefLetterboxing, this);
     XPCOMUtils.defineLazyPreferenceGetter(
@@ -80,6 +82,12 @@ class _RFPHelper {
 
   observe(subject, topic, data) {
     switch (topic) {
+      case "user-characteristics-populating-data":
+        this._registerUserCharacteristicsActor();
+        break;
+      case "user-characteristics-populating-data-done":
+        this._unregisterUserCharacteristicsActor();
+        break;
       case "nsPref:changed":
         this._handlePrefChanged(data);
         break;
@@ -97,6 +105,28 @@ class _RFPHelper {
     }
   }
 
+  _registerUserCharacteristicsActor() {
+    log("_registerUserCharacteristicsActor()");
+    ChromeUtils.registerWindowActor("UserCharacteristics", {
+      parent: {
+        esModuleURI: "resource://gre/actors/UserCharacteristicsParent.sys.mjs",
+      },
+      child: {
+        esModuleURI: "resource://gre/actors/UserCharacteristicsChild.sys.mjs",
+        events: {
+          UserCharacteristicsDataDone: { wantUntrusted: true },
+        },
+      },
+      matches: ["about:fingerprinting"],
+      remoteTypes: ["privilegedabout"],
+    });
+  }
+
+  _unregisterUserCharacteristicsActor() {
+    log("_unregisterUserCharacteristicsActor()");
+    ChromeUtils.unregisterWindowActor("UserCharacteristics");
+  }
+
   handleEvent(aMessage) {
     switch (aMessage.type) {
       case "TabOpen": {
@@ -186,7 +216,7 @@ class _RFPHelper {
     );
   }
 
-  _handleHttpOnModifyRequest(subject, data) {
+  _handleHttpOnModifyRequest(subject) {
     // If we are loading an HTTP page from content, show the
     // "request English language web pages?" prompt.
     let httpChannel = subject.QueryInterface(Ci.nsIHttpChannel);
@@ -283,16 +313,16 @@ class _RFPHelper {
   _handleLetterboxingPrefChanged() {
     if (Services.prefs.getBoolPref(kPrefLetterboxing, false)) {
       Services.ww.registerNotification(this);
-      this._registerActor();
+      this._registerLetterboxingActor();
       this._attachAllWindows();
     } else {
-      this._unregisterActor();
+      this._unregisterLetterboxingActor();
       this._detachAllWindows();
       Services.ww.unregisterNotification(this);
     }
   }
 
-  _registerActor() {
+  _registerLetterboxingActor() {
     ChromeUtils.registerWindowActor("RFPHelper", {
       parent: {
         esModuleURI: "resource:///actors/RFPHelperParent.sys.mjs",
@@ -307,7 +337,7 @@ class _RFPHelper {
     });
   }
 
-  _unregisterActor() {
+  _unregisterLetterboxingActor() {
     ChromeUtils.unregisterWindowActor("RFPHelper");
   }
 
diff --git a/toolkit/components/resistfingerprinting/RFPTargetIPCUtils.h b/toolkit/components/resistfingerprinting/RFPTargetIPCUtils.h
index 198332e3f6..414aa94905 100644
--- a/toolkit/components/resistfingerprinting/RFPTargetIPCUtils.h
+++ b/toolkit/components/resistfingerprinting/RFPTargetIPCUtils.h
@@ -2,7 +2,7 @@
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* 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/. */
+ * You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #ifndef __RFPTargetIPCUtils_h__
 #define __RFPTargetIPCUtils_h__
diff --git a/toolkit/components/resistfingerprinting/RFPTargets.inc b/toolkit/components/resistfingerprinting/RFPTargets.inc
index d2327ffbfe..9bc9dcbb8e 100644
--- a/toolkit/components/resistfingerprinting/RFPTargets.inc
+++ b/toolkit/components/resistfingerprinting/RFPTargets.inc
@@ -1,7 +1,7 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // Names should not be re-used.
 
diff --git a/toolkit/components/resistfingerprinting/RelativeTimeline.cpp b/toolkit/components/resistfingerprinting/RelativeTimeline.cpp
index dd2d304adb..84fdeb93f8 100644
--- a/toolkit/components/resistfingerprinting/RelativeTimeline.cpp
+++ b/toolkit/components/resistfingerprinting/RelativeTimeline.cpp
@@ -1,7 +1,7 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include "nsCOMPtr.h"
 #include "nsIRandomGenerator.h"
diff --git a/toolkit/components/resistfingerprinting/RelativeTimeline.h b/toolkit/components/resistfingerprinting/RelativeTimeline.h
index bf23de904d..c8ad1c7aad 100644
--- a/toolkit/components/resistfingerprinting/RelativeTimeline.h
+++ b/toolkit/components/resistfingerprinting/RelativeTimeline.h
@@ -1,7 +1,7 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #ifndef __RelativeTimeline_h__
 #define __RelativeTimeline_h__
diff --git a/toolkit/components/resistfingerprinting/UserCharacteristicsPageService.sys.mjs b/toolkit/components/resistfingerprinting/UserCharacteristicsPageService.sys.mjs
new file mode 100644
index 0000000000..d24a2eae33
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/UserCharacteristicsPageService.sys.mjs
@@ -0,0 +1,209 @@
+// -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  HiddenFrame: "resource://gre/modules/HiddenFrame.sys.mjs",
+});
+
+ChromeUtils.defineLazyGetter(lazy, "console", () => {
+  return console.createInstance({
+    prefix: "UserCharacteristicsPage",
+    maxLogLevelPref: "toolkit.telemetry.user_characteristics_ping.logLevel",
+  });
+});
+
+const BACKGROUND_WIDTH = 1024;
+const BACKGROUND_HEIGHT = 768;
+
+/**
+ * A manager for hidden browsers. Responsible for creating and destroying a
+ * hidden frame to hold them.
+ * All of this is copied from PageDataService.sys.mjs
+ */
+class HiddenBrowserManager {
+  /**
+   * The hidden frame if one has been created.
+   *
+   * @type {HiddenFrame | null}
+   */
+  #frame = null;
+  /**
+   * The number of hidden browser elements currently in use.
+   *
+   * @type {number}
+   */
+  #browsers = 0;
+
+  /**
+   * Creates and returns a new hidden browser.
+   *
+   * @returns {Browser}
+   */
+  async #acquireBrowser() {
+    this.#browsers++;
+    if (!this.#frame) {
+      this.#frame = new lazy.HiddenFrame();
+    }
+
+    let frame = await this.#frame.get();
+    let doc = frame.document;
+    let browser = doc.createXULElement("browser");
+    browser.setAttribute("remote", "true");
+    browser.setAttribute("type", "content");
+    browser.setAttribute(
+      "style",
+      `
+        width: ${BACKGROUND_WIDTH}px;
+        min-width: ${BACKGROUND_WIDTH}px;
+        height: ${BACKGROUND_HEIGHT}px;
+        min-height: ${BACKGROUND_HEIGHT}px;
+      `
+    );
+    browser.setAttribute("maychangeremoteness", "true");
+    doc.documentElement.appendChild(browser);
+
+    return browser;
+  }
+
+  /**
+   * Releases the given hidden browser.
+   *
+   * @param {Browser} browser
+   *   The hidden browser element.
+   */
+  #releaseBrowser(browser) {
+    browser.remove();
+
+    this.#browsers--;
+    if (this.#browsers == 0) {
+      this.#frame.destroy();
+      this.#frame = null;
+    }
+  }
+
+  /**
+   * Calls a callback function with a new hidden browser.
+   * This function will return whatever the callback function returns.
+   *
+   * @param {Callback} callback
+   *   The callback function will be called with the browser element and may
+   *   be asynchronous.
+   * @returns {T}
+   */
+  async withHiddenBrowser(callback) {
+    let browser = await this.#acquireBrowser();
+    try {
+      return await callback(browser);
+    } finally {
+      this.#releaseBrowser(browser);
+    }
+  }
+}
+
+export class UserCharacteristicsPageService {
+  classId = Components.ID("{ce3e9659-e311-49fb-b18b-7f27c6659b23}");
+  QueryInterface = ChromeUtils.generateQI([
+    "nsIUserCharacteristicsPageService",
+  ]);
+
+  _initialized = false;
+  _isParentProcess = false;
+
+  /**
+   * A manager for hidden browsers.
+   *
+   * @type {HiddenBrowserManager}
+   */
+  _browserManager = new HiddenBrowserManager();
+
+  /**
+   * A map of hidden browsers to a resolve function that should be passed the
+   * actor that was created for the browser.
+   *
+   * @type {WeakMap<Browser, function(PageDataParent): void>}
+   */
+  _backgroundBrowsers = new WeakMap();
+
+  constructor() {
+    lazy.console.debug("Init");
+
+    if (
+      Services.appinfo.processType !== Services.appinfo.PROCESS_TYPE_DEFAULT
+    ) {
+      throw new Error(
+        "Shouldn't init UserCharacteristicsPage in content processes."
+      );
+    }
+
+    // Return if we have initiated.
+    if (this._initialized) {
+      lazy.console.warn("preventing re-initilization...");
+      return;
+    }
+    this._initialized = true;
+  }
+
+  shutdown() {}
+
+  createContentPage() {
+    lazy.console.debug("called createContentPage");
+    return this._browserManager.withHiddenBrowser(async browser => {
+      lazy.console.debug(`In withHiddenBrowser`);
+      try {
+        let { promise, resolve } = Promise.withResolvers();
+        this._backgroundBrowsers.set(browser, resolve);
+
+        let principal = Services.scriptSecurityManager.getSystemPrincipal();
+        let loadURIOptions = {
+          triggeringPrincipal: principal,
+        };
+
+        let userCharacteristicsPageURI = Services.io.newURI(
+          "about:fingerprinting"
+        );
+
+        browser.loadURI(userCharacteristicsPageURI, loadURIOptions);
+
+        let data = await promise;
+        if (data.debug) {
+          lazy.console.debug(`Debugging Output:`);
+          for (let line of data.debug) {
+            lazy.console.debug(line);
+          }
+          lazy.console.debug(`(debugging output done)`);
+        }
+        lazy.console.debug(`Data:`, data.output);
+
+        lazy.console.debug("Populating Glean metrics...");
+        Glean.characteristics.timezone.set(data.output.foo);
+
+        lazy.console.debug("Unregistering actor");
+        Services.obs.notifyObservers(
+          null,
+          "user-characteristics-populating-data-done"
+        );
+      } finally {
+        this._backgroundBrowsers.delete(browser);
+      }
+    });
+  }
+
+  async pageLoaded(browsingContext, data) {
+    lazy.console.debug(
+      `pageLoaded browsingContext=${browsingContext} data=${data}`
+    );
+
+    let browser = browsingContext.embedderElement;
+
+    let backgroundResolve = this._backgroundBrowsers.get(browser);
+    if (backgroundResolve) {
+      backgroundResolve(data);
+      return;
+    }
+    throw new Error(`No backround resolve for ${browser} found`);
+  }
+}
diff --git a/toolkit/components/resistfingerprinting/components.conf b/toolkit/components/resistfingerprinting/components.conf
index aae29becf4..d7a5f71578 100644
--- a/toolkit/components/resistfingerprinting/components.conf
+++ b/toolkit/components/resistfingerprinting/components.conf
@@ -2,7 +2,7 @@
 # vim: set filetype=python:
 # 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/.
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 Classes = [
     {
@@ -34,4 +34,11 @@ Classes = [
         'constructor': 'FingerprintingWebCompatService',
         'processes': ProcessSelector.MAIN_PROCESS_ONLY,
     },
+    {
+        'cid': '{ce3e9659-e311-49fb-b18b-7f27c6659b23}',
+        'contract_ids': ['@mozilla.org/user-characteristics-page;1'],
+        'esModule': 'resource://gre/modules/UserCharacteristicsPageService.sys.mjs',
+        'constructor': 'UserCharacteristicsPageService',
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
 ]
diff --git a/toolkit/components/resistfingerprinting/content/usercharacteristics.html b/toolkit/components/resistfingerprinting/content/usercharacteristics.html
new file mode 100644
index 0000000000..50071bb21e
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/content/usercharacteristics.html
@@ -0,0 +1,18 @@
+<!-- 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 https://mozilla.org/MPL/2.0/. -->
+
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+    <meta
+      http-equiv="Content-Security-Policy"
+      content="default-src 'none'; object-src 'none'; script-src chrome:"
+    />
+    <title>about:fingerprinting</title>
+  </head>
+  <body>
+    <script src="chrome://global/content/usercharacteristics/usercharacteristics.js"></script>
+  </body>
+</html>
diff --git a/toolkit/components/resistfingerprinting/content/usercharacteristics.js b/toolkit/components/resistfingerprinting/content/usercharacteristics.js
new file mode 100644
index 0000000000..1f10ba9cbb
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/content/usercharacteristics.js
@@ -0,0 +1,41 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+var debugMsgs = [];
+function debug(...args) {
+  let msg = "";
+  if (!args.length) {
+    debugMsgs.push("");
+    return;
+  }
+
+  let stringify = o => {
+    if (typeof o == "string") {
+      return o;
+    }
+    return JSON.stringify(o);
+  };
+
+  let stringifiedArgs = args.map(stringify);
+  msg += stringifiedArgs.join(" ");
+  debugMsgs.push(msg);
+}
+
+debug("Debug Line");
+debug("Another debug line, with", { an: "object" });
+
+// The first time we put a real value in here, please update browser_usercharacteristics.js
+let output = {
+  foo: "Hello World",
+};
+
+document.dispatchEvent(
+  new CustomEvent("UserCharacteristicsDataDone", {
+    bubbles: true,
+    detail: {
+      debug: debugMsgs,
+      output,
+    },
+  })
+);
diff --git a/toolkit/components/resistfingerprinting/jar.mn b/toolkit/components/resistfingerprinting/jar.mn
new file mode 100644
index 0000000000..657797b6d0
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/jar.mn
@@ -0,0 +1,7 @@
+# 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 https://mozilla.org/MPL/2.0/.
+
+toolkit.jar:
+  content/global/usercharacteristics/usercharacteristics.html (content/usercharacteristics.html)
+  content/global/usercharacteristics/usercharacteristics.js (content/usercharacteristics.js)
diff --git a/toolkit/components/resistfingerprinting/metrics.yaml b/toolkit/components/resistfingerprinting/metrics.yaml
index 3c706d20fa..51b251508c 100644
--- a/toolkit/components/resistfingerprinting/metrics.yaml
+++ b/toolkit/components/resistfingerprinting/metrics.yaml
@@ -1,6 +1,6 @@
 # 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/.
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 # Adding a new metric? We have docs for that!
 # https://firefox-source-docs.mozilla.org/toolkit/components/glean/user/new_definitions_file.html
@@ -337,6 +337,23 @@ characteristics:
     data_sensitivity:
       - interaction
 
+  system_locale:
+    type: string
+    description: >
+      The locale used by the host OS for localization.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881744
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881744#c7
+    expires: never
+    data_sensitivity:
+      - technical
+
   target_frame_rate:
     type: quantity
     unit: int
@@ -409,3 +426,105 @@ characteristics:
     expires: never
     data_sensitivity:
       - interaction
+
+  prefs_privacy_donottrackheader_enabled:
+    type: boolean
+    description: >
+      Sending "do not track" HTTP header
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693#c5
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_privacy_globalprivacycontrol_enabled:
+    type: boolean
+    description: >
+      Sending "global privacy control" HTTP header
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693#c5
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_general_autoscroll: # general.autoScroll
+    type: boolean
+    description: >
+      Use autoscrolling
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693#c5
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_general_smoothscroll: # general.smoothScroll
+    type: boolean
+    description: >
+      Use smooth scrolling
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693#c5
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_overlay_scrollbars: # widget.gtk.overlay-scrollbars.enabled
+    type: boolean
+    description: >
+      Use overlay scrollbars (or otherwise "Always show scrollbars")
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693#c5
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_block_popups: # dom.disable_open_during_load
+    type: boolean
+    description: >
+      Block pop-up windows (The dom.disable_open_during_load pref)
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1884693#c5
+    expires: never
+    data_sensitivity:
+      - interaction
diff --git a/toolkit/components/resistfingerprinting/moz.build b/toolkit/components/resistfingerprinting/moz.build
index 9b4e9cc8ed..4b71617b9b 100644
--- a/toolkit/components/resistfingerprinting/moz.build
+++ b/toolkit/components/resistfingerprinting/moz.build
@@ -2,13 +2,15 @@
 # vim: set filetype=python:
 # 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/.
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 with Files("**"):
     BUG_COMPONENT = ("Core", "Privacy: Anti-Tracking")
 
 TEST_DIRS += ["tests"]
 
+JAR_MANIFESTS += ["jar.mn"]
+
 UNIFIED_SOURCES += [
     "nsRFPService.cpp",
     "RelativeTimeline.cpp",
@@ -39,6 +41,7 @@ EXPORTS.mozilla.gtest += ["nsUserCharacteristics.h"]
 EXTRA_JS_MODULES += [
     "FingerprintingWebCompatService.sys.mjs",
     "RFPHelper.sys.mjs",
+    "UserCharacteristicsPageService.sys.mjs",
 ]
 
 XPIDL_MODULE = "toolkit_resistfingerprinting"
@@ -50,6 +53,7 @@ XPCOM_MANIFESTS += [
 XPIDL_SOURCES += [
     "nsIFingerprintingWebCompatService.idl",
     "nsIRFPService.idl",
+    "nsIUserCharacteristicsPageService.idl",
 ]
 
 include("/ipc/chromium/chromium-config.mozbuild")
diff --git a/toolkit/components/resistfingerprinting/nsIFingerprintingWebCompatService.idl b/toolkit/components/resistfingerprinting/nsIFingerprintingWebCompatService.idl
index 01b1379e44..e8c7195a0e 100644
--- a/toolkit/components/resistfingerprinting/nsIFingerprintingWebCompatService.idl
+++ b/toolkit/components/resistfingerprinting/nsIFingerprintingWebCompatService.idl
@@ -1,6 +1,6 @@
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include "nsISupports.idl"
 
diff --git a/toolkit/components/resistfingerprinting/nsIRFPService.idl b/toolkit/components/resistfingerprinting/nsIRFPService.idl
index b81868d202..8c83cc7e6e 100644
--- a/toolkit/components/resistfingerprinting/nsIRFPService.idl
+++ b/toolkit/components/resistfingerprinting/nsIRFPService.idl
@@ -1,6 +1,6 @@
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include "nsISupports.idl"
 #include "nsIFingerprintingWebCompatService.idl"
diff --git a/toolkit/components/resistfingerprinting/nsIUserCharacteristicsPageService.idl b/toolkit/components/resistfingerprinting/nsIUserCharacteristicsPageService.idl
new file mode 100644
index 0000000000..ce58c1a14a
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/nsIUserCharacteristicsPageService.idl
@@ -0,0 +1,23 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+webidl BrowsingContext;
+
+[scriptable, uuid(ce3e9659-e311-49fb-b18b-7f27c6659b23)]
+interface nsIUserCharacteristicsPageService : nsISupports {
+
+    /*
+     * Create the UserCharacteristics about: page as a HiddenFrame
+     * and begin the data collection.
+     */
+    Promise createContentPage();
+
+    /*
+     * Called when the UserCharacteristics about: page has been loaded
+     * and supplied data back to the actor, which is passed as `data`
+     */
+    void pageLoaded(in BrowsingContext browsingContext, in jsval data);
+};
diff --git a/toolkit/components/resistfingerprinting/nsRFPService.cpp b/toolkit/components/resistfingerprinting/nsRFPService.cpp
index 643cc2cb7a..f39deb3283 100644
--- a/toolkit/components/resistfingerprinting/nsRFPService.cpp
+++ b/toolkit/components/resistfingerprinting/nsRFPService.cpp
@@ -1,7 +1,7 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include "nsRFPService.h"
 
@@ -19,6 +19,7 @@
 #include "MainThreadUtils.h"
 #include "ScopedNSSTypes.h"
 
+#include "mozilla/AntiTrackingUtils.h"
 #include "mozilla/ArrayIterator.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/Atomics.h"
@@ -109,6 +110,8 @@ static mozilla::LazyLogModule gFingerprinterDetection("FingerprinterDetection");
 #define LAST_PB_SESSION_EXITED_TOPIC "last-pb-context-exited"
 #define IDLE_TOPIC "browser-idle-startup-tasks-finished"
 #define GFX_FEATURES "gfx-features-ready"
+#define USER_CHARACTERISTICS_TEST_REQUEST \
+  "user-characteristics-testing-please-populate-data"
 
 static constexpr uint32_t kVideoFramesPerSec = 30;
 static constexpr uint32_t kVideoDroppedRatio = 5;
@@ -190,6 +193,9 @@ nsresult nsRFPService::Init() {
 
     rv = obs->AddObserver(this, GFX_FEATURES, false);
     NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = obs->AddObserver(this, USER_CHARACTERISTICS_TEST_REQUEST, false);
+    NS_ENSURE_SUCCESS(rv, rv);
   }
 
   Preferences::RegisterCallbacks(nsRFPService::PrefChanged, gCallbackPrefs,
@@ -289,6 +295,7 @@ void nsRFPService::StartShutdown() {
       obs->RemoveObserver(this, OBSERVER_TOPIC_IDLE_DAILY);
       obs->RemoveObserver(this, IDLE_TOPIC);
       obs->RemoveObserver(this, GFX_FEATURES);
+      obs->RemoveObserver(this, USER_CHARACTERISTICS_TEST_REQUEST);
     }
   }
 
@@ -350,6 +357,12 @@ nsRFPService::Observe(nsISupports* aObject, const char* aTopic,
     }
   }
 
+  if (!strcmp(USER_CHARACTERISTICS_TEST_REQUEST, aTopic) &&
+      xpc::IsInAutomation()) {
+    nsUserCharacteristics::PopulateDataAndEventuallySubmit(
+        /* aUpdatePref = */ false, /* aTesting = */ true);
+  }
+
   if (!strcmp(OBSERVER_TOPIC_IDLE_DAILY, aTopic)) {
     if (StaticPrefs::
             privacy_resistFingerprinting_randomization_daily_reset_enabled()) {
@@ -1267,7 +1280,10 @@ Maybe<nsTArray<uint8_t>> nsRFPService::GenerateKey(nsIChannel* aChannel) {
 
   // Set the partitionKey using the top level URI to ensure that the key is
   // specific to the top level site.
-  attrs.SetPartitionKey(topLevelURI);
+  bool foreignByAncestorContext =
+      AntiTrackingUtils::IsThirdPartyChannel(aChannel) &&
+      loadInfo->GetIsThirdPartyContextToTopWindow();
+  attrs.SetPartitionKey(topLevelURI, foreignByAncestorContext);
 
   nsAutoCString oaSuffix;
   attrs.CreateSuffix(oaSuffix);
@@ -1337,8 +1353,14 @@ nsRFPService::CleanRandomKeyByPrincipal(nsIPrincipal* aPrincipal) {
 
   OriginAttributes attrs = aPrincipal->OriginAttributesRef();
   nsCOMPtr<nsIURI> uri = aPrincipal->GetURI();
-  attrs.SetPartitionKey(uri);
 
+  attrs.SetPartitionKey(uri, false);
+  ClearBrowsingSessionKey(attrs);
+
+  // We must also include the cross-site embeds of this principal that end up
+  // re-embedded back into the same principal's top level, otherwise state will
+  // persist for this target
+  attrs.SetPartitionKey(uri, true);
   ClearBrowsingSessionKey(attrs);
   return NS_OK;
 }
@@ -1354,14 +1376,21 @@ nsRFPService::CleanRandomKeyByDomain(const nsACString& aDomain) {
 
   // Use the originAttributes to get the partitionKey.
   OriginAttributes attrs;
-  attrs.SetPartitionKey(httpURI);
+  attrs.SetPartitionKey(httpURI, false);
 
   // Create a originAttributesPattern and set the http partitionKey to the
   // pattern.
   OriginAttributesPattern pattern;
   pattern.mPartitionKey.Reset();
   pattern.mPartitionKey.Construct(attrs.mPartitionKey);
+  ClearBrowsingSessionKey(pattern);
 
+  // We must also include the cross-site embeds of this principal that end up
+  // re-embedded back into the same principal's top level, otherwise state will
+  // persist for this target
+  attrs.SetPartitionKey(httpURI, true);
+  pattern.mPartitionKey.Reset();
+  pattern.mPartitionKey.Construct(attrs.mPartitionKey);
   ClearBrowsingSessionKey(pattern);
 
   // Get https URI from the domain.
@@ -1370,10 +1399,17 @@ nsRFPService::CleanRandomKeyByDomain(const nsACString& aDomain) {
   NS_ENSURE_SUCCESS(rv, rv);
 
   // Use the originAttributes to get the partitionKey and set to the pattern.
-  attrs.SetPartitionKey(httpsURI);
+  attrs.SetPartitionKey(httpsURI, false);
   pattern.mPartitionKey.Reset();
   pattern.mPartitionKey.Construct(attrs.mPartitionKey);
+  ClearBrowsingSessionKey(pattern);
 
+  // We must also include the cross-site embeds of this principal that end up
+  // re-embedded back into the same principal's top level, otherwise state will
+  // persist for this target
+  attrs.SetPartitionKey(httpsURI, true);
+  pattern.mPartitionKey.Reset();
+  pattern.mPartitionKey.Construct(attrs.mPartitionKey);
   ClearBrowsingSessionKey(pattern);
   return NS_OK;
 }
@@ -1395,7 +1431,7 @@ nsRFPService::CleanRandomKeyByHost(const nsACString& aHost,
 
   // Use the originAttributes to get the partitionKey.
   OriginAttributes attrs;
-  attrs.SetPartitionKey(httpURI);
+  attrs.SetPartitionKey(httpURI, false);
 
   // Set the partitionKey to the pattern.
   pattern.mPartitionKey.Reset();
@@ -1403,16 +1439,31 @@ nsRFPService::CleanRandomKeyByHost(const nsACString& aHost,
 
   ClearBrowsingSessionKey(pattern);
 
+  // We must also include the cross-site embeds of this principal that end up
+  // re-embedded back into the same principal's top level, otherwise state will
+  // persist for this target
+  attrs.SetPartitionKey(httpURI, true);
+  pattern.mPartitionKey.Reset();
+  pattern.mPartitionKey.Construct(attrs.mPartitionKey);
+  ClearBrowsingSessionKey(pattern);
+
   // Get https URI from the host.
   nsCOMPtr<nsIURI> httpsURI;
   rv = NS_NewURI(getter_AddRefs(httpsURI), "https://"_ns + aHost);
   NS_ENSURE_SUCCESS(rv, rv);
 
   // Use the originAttributes to get the partitionKey and set to the pattern.
-  attrs.SetPartitionKey(httpsURI);
+  attrs.SetPartitionKey(httpsURI, false);
   pattern.mPartitionKey.Reset();
   pattern.mPartitionKey.Construct(attrs.mPartitionKey);
+  ClearBrowsingSessionKey(pattern);
 
+  // We must also include the cross-site embeds of this principal that end up
+  // re-embedded back into the same principal's top level, otherwise state will
+  // persist for this target
+  attrs.SetPartitionKey(httpsURI, true);
+  pattern.mPartitionKey.Reset();
+  pattern.mPartitionKey.Construct(attrs.mPartitionKey);
   ClearBrowsingSessionKey(pattern);
   return NS_OK;
 }
@@ -2011,19 +2062,63 @@ Maybe<RFPTarget> nsRFPService::GetOverriddenFingerprintingSettingsForChannel(
   }
 
   // The channel is for the first-party load.
-  if (!loadInfo->GetIsThirdPartyContextToTopWindow()) {
+  if (!AntiTrackingUtils::IsThirdPartyChannel(aChannel)) {
     return GetOverriddenFingerprintingSettingsForURI(uri, nullptr);
   }
 
   // The channel is for the third-party load. We get the first-party URI from
   // the top-level window global parent.
-  RefPtr<dom::WindowGlobalParent> topWGP =
-      bc->Top()->Canonical()->GetCurrentWindowGlobal();
+  RefPtr<dom::CanonicalBrowsingContext> topBC = bc->Top()->Canonical();
+  RefPtr<dom::WindowGlobalParent> topWGP = topBC->GetCurrentWindowGlobal();
 
   if (NS_WARN_IF(!topWGP)) {
     return Nothing();
   }
 
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
+  DebugOnly<nsresult> rv =
+      loadInfo->GetCookieJarSettings(getter_AddRefs(cookieJarSettings));
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  MOZ_ASSERT(cookieJarSettings);
+
+  uint64_t topWindowContextIdFromCJS =
+      net::CookieJarSettings::Cast(cookieJarSettings)
+          ->GetTopLevelWindowContextId();
+
+  // The top-level window could be navigated away when we get the fingerprinting
+  // override here. For example, the beacon requests. In this case, the
+  // top-level windowContext id won't match the inner window id of the top-level
+  // windowGlobalParent. So, we cannot rely on the URI from the top-level
+  // windowGlobalParent because it could be different from the one that creates
+  // the channel. Instead, we fallback to use the partitionKey in the
+  // cookieJarSettings to get the top-level URI.
+  if (topWGP->InnerWindowId() != topWindowContextIdFromCJS) {
+    nsAutoString partitionKey;
+    rv = cookieJarSettings->GetPartitionKey(partitionKey);
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+    // Bail out early if the partitionKey is empty.
+    if (partitionKey.IsEmpty()) {
+      return Nothing();
+    }
+
+    nsAutoString scheme;
+    nsAutoString domain;
+    int32_t unused;
+    bool unused2;
+    if (!OriginAttributes::ParsePartitionKey(partitionKey, scheme, domain,
+                                             unused, unused2)) {
+      MOZ_ASSERT(false);
+      return Nothing();
+    }
+
+    nsCOMPtr<nsIURI> topURI;
+    rv = NS_NewURI(getter_AddRefs(topURI), scheme + u"://"_ns + domain);
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+    return GetOverriddenFingerprintingSettingsForURI(topURI, uri);
+  }
+
   nsCOMPtr<nsIPrincipal> topPrincipal = topWGP->DocumentPrincipal();
   if (NS_WARN_IF(!topPrincipal)) {
     return Nothing();
@@ -2049,19 +2144,20 @@ Maybe<RFPTarget> nsRFPService::GetOverriddenFingerprintingSettingsForChannel(
 
 #ifdef DEBUG
   // Verify if the top URI matches the partitionKey of the channel.
-  nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
-  Unused << loadInfo->GetCookieJarSettings(getter_AddRefs(cookieJarSettings));
-
   nsAutoString partitionKey;
   cookieJarSettings->GetPartitionKey(partitionKey);
 
   OriginAttributes attrs;
-  attrs.SetPartitionKey(topURI);
+  attrs.SetPartitionKey(topURI, false);
+
+  OriginAttributes attrsForeignByAncestor;
+  attrsForeignByAncestor.SetPartitionKey(topURI, true);
 
   // The partitionKey of the channel could haven't been set here if the loading
   // channel is top-level.
   MOZ_ASSERT_IF(!partitionKey.IsEmpty(),
-                attrs.mPartitionKey.Equals(partitionKey));
+                attrs.mPartitionKey.Equals(partitionKey) ||
+                    attrsForeignByAncestor.mPartitionKey.Equals(partitionKey));
 #endif
 
   return GetOverriddenFingerprintingSettingsForURI(topURI, uri);
diff --git a/toolkit/components/resistfingerprinting/nsRFPService.h b/toolkit/components/resistfingerprinting/nsRFPService.h
index 9e0ae9b6af..d45f4172c9 100644
--- a/toolkit/components/resistfingerprinting/nsRFPService.h
+++ b/toolkit/components/resistfingerprinting/nsRFPService.h
@@ -1,7 +1,7 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #ifndef __nsRFPService_h__
 #define __nsRFPService_h__
diff --git a/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp b/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
index 9bce616f81..86de7d61a7 100644
--- a/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
+++ b/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
@@ -1,25 +1,34 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include "nsUserCharacteristics.h"
 
 #include "nsID.h"
 #include "nsIUUIDGenerator.h"
+#include "nsIUserCharacteristicsPageService.h"
 #include "nsServiceManagerUtils.h"
 
 #include "mozilla/Logging.h"
 #include "mozilla/glean/GleanPings.h"
 #include "mozilla/glean/GleanMetrics.h"
 
+#include "jsapi.h"
+#include "mozilla/Components.h"
+#include "mozilla/dom/Promise-inl.h"
+
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPrefs_general.h"
 #include "mozilla/StaticPrefs_media.h"
+#include "mozilla/StaticPrefs_widget.h"
 
 #include "mozilla/LookAndFeel.h"
 #include "mozilla/PreferenceSheet.h"
 #include "mozilla/RelativeLuminanceUtils.h"
 #include "mozilla/ServoStyleConsts.h"
 #include "mozilla/dom/ScreenBinding.h"
+#include "mozilla/intl/OSPreferences.h"
 #include "mozilla/intl/TimeZone.h"
 #include "mozilla/widget/ScreenManager.h"
 
@@ -33,7 +42,9 @@
 #  include "nsMacUtilsImpl.h"
 #endif
 
-static mozilla::LazyLogModule gUserCharacteristicsLog("UserCharacteristics");
+using namespace mozilla;
+
+static LazyLogModule gUserCharacteristicsLog("UserCharacteristics");
 
 // ==================================================================
 namespace testing {
@@ -41,9 +52,9 @@ extern "C" {
 
 int MaxTouchPoints() {
 #if defined(XP_WIN)
-  return mozilla::widget::WinUtils::GetMaxTouchPoints();
+  return widget::WinUtils::GetMaxTouchPoints();
 #elif defined(MOZ_WIDGET_ANDROID)
-  return mozilla::java::GeckoAppShell::GetMaxTouchPoints();
+  return java::GeckoAppShell::GetMaxTouchPoints();
 #else
   return 0;
 #endif
@@ -53,84 +64,113 @@ int MaxTouchPoints() {
 };  // namespace testing
 
 // ==================================================================
+// ==================================================================
+already_AddRefed<mozilla::dom::Promise> ContentPageStuff() {
+  nsCOMPtr<nsIUserCharacteristicsPageService> ucp =
+      do_GetService("@mozilla.org/user-characteristics-page;1");
+  MOZ_ASSERT(ucp);
+
+  RefPtr<mozilla::dom::Promise> promise;
+  nsresult rv = ucp->CreateContentPage(getter_AddRefs(promise));
+  if (NS_FAILED(rv)) {
+    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Error,
+            ("Could not create Content Page"));
+    return nullptr;
+  }
+  MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+          ("Created Content Page"));
+
+  return promise.forget();
+}
+
 void PopulateCSSProperties() {
-  mozilla::glean::characteristics::video_dynamic_range.Set(
-      mozilla::LookAndFeel::GetInt(
-          mozilla::LookAndFeel::IntID::VideoDynamicRange));
-  mozilla::glean::characteristics::prefers_reduced_transparency.Set(
-      mozilla::LookAndFeel::GetInt(
-          mozilla::LookAndFeel::IntID::PrefersReducedTransparency));
-  mozilla::glean::characteristics::prefers_reduced_motion.Set(
-      mozilla::LookAndFeel::GetInt(
-          mozilla::LookAndFeel::IntID::PrefersReducedMotion));
-  mozilla::glean::characteristics::inverted_colors.Set(
-      mozilla::LookAndFeel::GetInt(
-          mozilla::LookAndFeel::IntID::InvertedColors));
-  mozilla::glean::characteristics::color_scheme.Set(
-      (int)mozilla::PreferenceSheet::ContentPrefs().mColorScheme);
-
-  mozilla::StylePrefersContrast prefersContrast = [] {
+  glean::characteristics::prefers_reduced_transparency.Set(
+      LookAndFeel::GetInt(LookAndFeel::IntID::PrefersReducedTransparency));
+  glean::characteristics::prefers_reduced_motion.Set(
+      LookAndFeel::GetInt(LookAndFeel::IntID::PrefersReducedMotion));
+  glean::characteristics::inverted_colors.Set(
+      LookAndFeel::GetInt(LookAndFeel::IntID::InvertedColors));
+  glean::characteristics::color_scheme.Set(
+      (int)PreferenceSheet::ContentPrefs().mColorScheme);
+
+  StylePrefersContrast prefersContrast = [] {
     // Replicates Gecko_MediaFeatures_PrefersContrast but without a Document
-    if (!mozilla::PreferenceSheet::ContentPrefs().mUseAccessibilityTheme &&
-        mozilla::PreferenceSheet::ContentPrefs().mUseDocumentColors) {
-      return mozilla::StylePrefersContrast::NoPreference;
+    if (!PreferenceSheet::ContentPrefs().mUseAccessibilityTheme &&
+        PreferenceSheet::ContentPrefs().mUseDocumentColors) {
+      return StylePrefersContrast::NoPreference;
     }
 
-    const auto& colors = mozilla::PreferenceSheet::ContentPrefs().ColorsFor(
-        mozilla::ColorScheme::Light);
-    float ratio = mozilla::RelativeLuminanceUtils::ContrastRatio(
+    const auto& colors =
+        PreferenceSheet::ContentPrefs().ColorsFor(ColorScheme::Light);
+    float ratio = RelativeLuminanceUtils::ContrastRatio(
         colors.mDefaultBackground, colors.mDefault);
     // https://www.w3.org/TR/WCAG21/#contrast-minimum
     if (ratio < 4.5f) {
-      return mozilla::StylePrefersContrast::Less;
+      return StylePrefersContrast::Less;
     }
     // https://www.w3.org/TR/WCAG21/#contrast-enhanced
     if (ratio >= 7.0f) {
-      return mozilla::StylePrefersContrast::More;
+      return StylePrefersContrast::More;
     }
-    return mozilla::StylePrefersContrast::Custom;
+    return StylePrefersContrast::Custom;
   }();
-  mozilla::glean::characteristics::prefers_contrast.Set((int)prefersContrast);
+  glean::characteristics::prefers_contrast.Set((int)prefersContrast);
 }
 
 void PopulateScreenProperties() {
-  auto& screenManager = mozilla::widget::ScreenManager::GetSingleton();
-  RefPtr<mozilla::widget::Screen> screen = screenManager.GetPrimaryScreen();
+  auto& screenManager = widget::ScreenManager::GetSingleton();
+  RefPtr<widget::Screen> screen = screenManager.GetPrimaryScreen();
   MOZ_ASSERT(screen);
 
-  mozilla::dom::ScreenColorGamut colorGamut;
+  dom::ScreenColorGamut colorGamut;
   screen->GetColorGamut(&colorGamut);
-  mozilla::glean::characteristics::color_gamut.Set((int)colorGamut);
+  glean::characteristics::color_gamut.Set((int)colorGamut);
 
   int32_t colorDepth;
   screen->GetColorDepth(&colorDepth);
-  mozilla::glean::characteristics::color_depth.Set(colorDepth);
+  glean::characteristics::color_depth.Set(colorDepth);
+
+  glean::characteristics::color_gamut.Set((int)colorGamut);
+  glean::characteristics::color_depth.Set(colorDepth);
+  const LayoutDeviceIntRect rect = screen->GetRect();
+  glean::characteristics::screen_height.Set(rect.Height());
+  glean::characteristics::screen_width.Set(rect.Width());
 
-  mozilla::glean::characteristics::color_gamut.Set((int)colorGamut);
-  mozilla::glean::characteristics::color_depth.Set(colorDepth);
-  const mozilla::LayoutDeviceIntRect rect = screen->GetRect();
-  mozilla::glean::characteristics::screen_height.Set(rect.Height());
-  mozilla::glean::characteristics::screen_width.Set(rect.Width());
+  glean::characteristics::video_dynamic_range.Set(screen->GetIsHDR());
 }
 
 void PopulateMissingFonts() {
   nsCString aMissingFonts;
   gfxPlatformFontList::PlatformFontList()->GetMissingFonts(aMissingFonts);
 
-  mozilla::glean::characteristics::missing_fonts.Set(aMissingFonts);
+  glean::characteristics::missing_fonts.Set(aMissingFonts);
 }
 
 void PopulatePrefs() {
   nsAutoCString acceptLang;
-  mozilla::Preferences::GetLocalizedCString("intl.accept_languages",
-                                            acceptLang);
-  mozilla::glean::characteristics::prefs_intl_accept_languages.Set(acceptLang);
+  Preferences::GetLocalizedCString("intl.accept_languages", acceptLang);
+  glean::characteristics::prefs_intl_accept_languages.Set(acceptLang);
+
+  glean::characteristics::prefs_media_eme_enabled.Set(
+      StaticPrefs::media_eme_enabled());
+
+  glean::characteristics::prefs_zoom_text_only.Set(
+      !Preferences::GetBool("browser.zoom.full"));
+
+  glean::characteristics::prefs_privacy_donottrackheader_enabled.Set(
+      StaticPrefs::privacy_donottrackheader_enabled());
+  glean::characteristics::prefs_privacy_globalprivacycontrol_enabled.Set(
+      StaticPrefs::privacy_globalprivacycontrol_enabled());
 
-  mozilla::glean::characteristics::prefs_media_eme_enabled.Set(
-      mozilla::StaticPrefs::media_eme_enabled());
+  glean::characteristics::prefs_general_autoscroll.Set(
+      Preferences::GetBool("general.autoScroll"));
+  glean::characteristics::prefs_general_smoothscroll.Set(
+      StaticPrefs::general_smoothScroll());
+  glean::characteristics::prefs_overlay_scrollbars.Set(
+      StaticPrefs::widget_gtk_overlay_scrollbars_enabled());
 
-  mozilla::glean::characteristics::prefs_zoom_text_only.Set(
-      !mozilla::Preferences::GetBool("browser.zoom.full"));
+  glean::characteristics::prefs_block_popups.Set(
+      StaticPrefs::dom_disable_open_during_load());
 }
 
 // ==================================================================
@@ -138,12 +178,16 @@ void PopulatePrefs() {
 // metric is set, this variable should be incremented. It'll be a lot. It's
 // okay. We're going to need it to know (including during development) what is
 // the source of the data we are looking at.
-const int kSubmissionSchema = 0;
+const int kSubmissionSchema = 1;
+
+const auto* const kLastVersionPref =
+    "toolkit.telemetry.user_characteristics_ping.last_version_sent";
+const auto* const kCurrentVersionPref =
+    "toolkit.telemetry.user_characteristics_ping.current_version";
 
 /* static */
 void nsUserCharacteristics::MaybeSubmitPing() {
-  MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
-          ("In MaybeSubmitPing()"));
+  MOZ_LOG(gUserCharacteristicsLog, LogLevel::Debug, ("In MaybeSubmitPing()"));
   MOZ_ASSERT(XRE_IsParentProcess());
 
   /**
@@ -161,14 +205,8 @@ void nsUserCharacteristics::MaybeSubmitPing() {
    * Sent = Current Version.
    *
    */
-  const auto* const kLastVersionPref =
-      "toolkit.telemetry.user_characteristics_ping.last_version_sent";
-  const auto* const kCurrentVersionPref =
-      "toolkit.telemetry.user_characteristics_ping.current_version";
-
-  auto lastSubmissionVersion =
-      mozilla::Preferences::GetInt(kLastVersionPref, 0);
-  auto currentVersion = mozilla::Preferences::GetInt(kCurrentVersionPref, 0);
+  auto lastSubmissionVersion = Preferences::GetInt(kLastVersionPref, 0);
+  auto currentVersion = Preferences::GetInt(kCurrentVersionPref, 0);
 
   MOZ_ASSERT(currentVersion == -1 || lastSubmissionVersion <= currentVersion,
              "lastSubmissionVersion is somehow greater than currentVersion "
@@ -176,46 +214,40 @@ void nsUserCharacteristics::MaybeSubmitPing() {
 
   if (lastSubmissionVersion < 0) {
     // This is a way for users to opt out of this ping specifically.
-    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+    MOZ_LOG(gUserCharacteristicsLog, LogLevel::Debug,
             ("Returning, User Opt-out"));
     return;
   }
   if (currentVersion == 0) {
     // Do nothing. We do not want any pings.
-    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+    MOZ_LOG(gUserCharacteristicsLog, LogLevel::Debug,
             ("Returning, currentVersion == 0"));
     return;
   }
   if (currentVersion == -1) {
     // currentVersion = -1 is a development value to force a ping submission
-    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+    MOZ_LOG(gUserCharacteristicsLog, LogLevel::Debug,
             ("Force-Submitting Ping"));
-    if (NS_SUCCEEDED(PopulateData())) {
-      SubmitPing();
-    }
+    PopulateDataAndEventuallySubmit(false);
     return;
   }
   if (lastSubmissionVersion > currentVersion) {
     // This is an unexpected scneario that indicates something is wrong. We
     // asserted against it (in debug, above) We will try to sanity-correct
     // ourselves by setting it to the current version.
-    mozilla::Preferences::SetInt(kLastVersionPref, currentVersion);
-    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Warning,
+    Preferences::SetInt(kLastVersionPref, currentVersion);
+    MOZ_LOG(gUserCharacteristicsLog, LogLevel::Warning,
             ("Returning, lastSubmissionVersion > currentVersion"));
     return;
   }
   if (lastSubmissionVersion == currentVersion) {
     // We are okay, we've already submitted the most recent ping
-    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Warning,
+    MOZ_LOG(gUserCharacteristicsLog, LogLevel::Warning,
             ("Returning, lastSubmissionVersion == currentVersion"));
     return;
   }
   if (lastSubmissionVersion < currentVersion) {
-    if (NS_SUCCEEDED(PopulateData())) {
-      if (NS_SUCCEEDED(SubmitPing())) {
-        mozilla::Preferences::SetInt(kLastVersionPref, currentVersion);
-      }
-    }
+    PopulateDataAndEventuallySubmit(false);
   } else {
     MOZ_ASSERT_UNREACHABLE("Should never reach here");
   }
@@ -225,73 +257,128 @@ const auto* const kUUIDPref =
     "toolkit.telemetry.user_characteristics_ping.uuid";
 
 /* static */
-nsresult nsUserCharacteristics::PopulateData(bool aTesting /* = false */) {
-  MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Warning,
-          ("Populating Data"));
+void nsUserCharacteristics::PopulateDataAndEventuallySubmit(
+    bool aUpdatePref /* = true */, bool aTesting /* = false */
+) {
+  MOZ_LOG(gUserCharacteristicsLog, LogLevel::Warning, ("Populating Data"));
   MOZ_ASSERT(XRE_IsParentProcess());
-  mozilla::glean::characteristics::submission_schema.Set(kSubmissionSchema);
+
+  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+  if (!obs) {
+    return;
+  }
+
+  // This notification tells us to register the actor
+  obs->NotifyObservers(nullptr, "user-characteristics-populating-data",
+                       nullptr);
+
+  glean::characteristics::submission_schema.Set(kSubmissionSchema);
 
   nsAutoCString uuidString;
-  nsresult rv = mozilla::Preferences::GetCString(kUUIDPref, uuidString);
+  nsresult rv = Preferences::GetCString(kUUIDPref, uuidString);
   if (NS_FAILED(rv) || uuidString.Length() == 0) {
     nsCOMPtr<nsIUUIDGenerator> uuidgen =
         do_GetService("@mozilla.org/uuid-generator;1", &rv);
-    NS_ENSURE_SUCCESS(rv, rv);
+    if (NS_FAILED(rv)) {
+      return;
+    }
 
     nsIDToCString id(nsID::GenerateUUID());
     uuidString = id.get();
-    mozilla::Preferences::SetCString(kUUIDPref, uuidString);
+    Preferences::SetCString(kUUIDPref, uuidString);
   }
-  mozilla::glean::characteristics::client_identifier.Set(uuidString);
 
-  mozilla::glean::characteristics::max_touch_points.Set(
-      testing::MaxTouchPoints());
+  glean::characteristics::client_identifier.Set(uuidString);
+
+  glean::characteristics::max_touch_points.Set(testing::MaxTouchPoints());
+
+  // ------------------------------------------------------------------------
 
-  if (aTesting) {
+  if (!aTesting) {
     // Many of the later peices of data do not work in a gtest
-    // so just populate something, and return
-    return NS_OK;
-  }
+    // so skip populating them
+
+    // ------------------------------------------------------------------------
 
-  PopulateMissingFonts();
-  PopulateCSSProperties();
-  PopulateScreenProperties();
-  PopulatePrefs();
+    PopulateMissingFonts();
+    PopulateCSSProperties();
+    PopulateScreenProperties();
+    PopulatePrefs();
 
-  mozilla::glean::characteristics::target_frame_rate.Set(
-      gfxPlatform::TargetFrameRate());
+    glean::characteristics::target_frame_rate.Set(
+        gfxPlatform::TargetFrameRate());
 
-  int32_t processorCount = 0;
+    int32_t processorCount = 0;
 #if defined(XP_MACOSX)
-  if (nsMacUtilsImpl::IsTCSMAvailable()) {
-    // On failure, zero is returned from GetPhysicalCPUCount()
-    // and we fallback to PR_GetNumberOfProcessors below.
-    processorCount = nsMacUtilsImpl::GetPhysicalCPUCount();
-  }
+    if (nsMacUtilsImpl::IsTCSMAvailable()) {
+      // On failure, zero is returned from GetPhysicalCPUCount()
+      // and we fallback to PR_GetNumberOfProcessors below.
+      processorCount = nsMacUtilsImpl::GetPhysicalCPUCount();
+    }
 #endif
-  if (processorCount == 0) {
-    processorCount = PR_GetNumberOfProcessors();
+    if (processorCount == 0) {
+      processorCount = PR_GetNumberOfProcessors();
+    }
+    glean::characteristics::processor_count.Set(processorCount);
+
+    AutoTArray<char16_t, 128> tzBuffer;
+    auto result = intl::TimeZone::GetDefaultTimeZone(tzBuffer);
+    if (result.isOk()) {
+      NS_ConvertUTF16toUTF8 timeZone(
+          nsDependentString(tzBuffer.Elements(), tzBuffer.Length()));
+      glean::characteristics::timezone.Set(timeZone);
+    } else {
+      glean::characteristics::timezone.Set("<error>"_ns);
+    }
+
+    nsAutoCString locale;
+    intl::OSPreferences::GetInstance()->GetSystemLocale(locale);
+    glean::characteristics::system_locale.Set(locale);
   }
-  mozilla::glean::characteristics::processor_count.Set(processorCount);
-
-  AutoTArray<char16_t, 128> tzBuffer;
-  auto result = mozilla::intl::TimeZone::GetDefaultTimeZone(tzBuffer);
-  if (result.isOk()) {
-    NS_ConvertUTF16toUTF8 timeZone(
-        nsDependentString(tzBuffer.Elements(), tzBuffer.Length()));
-    mozilla::glean::characteristics::timezone.Set(timeZone);
+
+  // When this promise resolves, everything succeeded and we can submit.
+  RefPtr<mozilla::dom::Promise> promise = ContentPageStuff();
+
+  // ------------------------------------------------------------------------
+
+  auto fulfillSteps = [aUpdatePref, aTesting](
+                          JSContext* aCx, JS::Handle<JS::Value> aPromiseResult,
+                          mozilla::ErrorResult& aRv) {
+    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+            ("ContentPageStuff Promise Resolved"));
+
+    if (!aTesting) {
+      nsUserCharacteristics::SubmitPing();
+    }
+
+    if (aUpdatePref) {
+      MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+              ("Updating preference"));
+      auto current_version =
+          mozilla::Preferences::GetInt(kCurrentVersionPref, 0);
+      mozilla::Preferences::SetInt(kLastVersionPref, current_version);
+    }
+  };
+
+  // Something failed in the Content Page...
+  auto rejectSteps = [](JSContext* aCx, JS::Handle<JS::Value> aReason,
+                        mozilla::ErrorResult& aRv) {
+    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Error,
+            ("ContentPageStuff Promise Rejected"));
+  };
+
+  if (promise) {
+    promise->AddCallbacksWithCycleCollectedArgs(std::move(fulfillSteps),
+                                                std::move(rejectSteps));
   } else {
-    mozilla::glean::characteristics::timezone.Set("<error>"_ns);
+    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Error,
+            ("Did not get a Promise back from ContentPageStuff"));
   }
-
-  return NS_OK;
 }
 
 /* static */
-nsresult nsUserCharacteristics::SubmitPing() {
+void nsUserCharacteristics::SubmitPing() {
   MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Warning,
           ("Submitting Ping"));
-  mozilla::glean_pings::UserCharacteristics.Submit();
-
-  return NS_OK;
+  glean_pings::UserCharacteristics.Submit();
 }
diff --git a/toolkit/components/resistfingerprinting/nsUserCharacteristics.h b/toolkit/components/resistfingerprinting/nsUserCharacteristics.h
index a52bc9aea7..7d78dcd965 100644
--- a/toolkit/components/resistfingerprinting/nsUserCharacteristics.h
+++ b/toolkit/components/resistfingerprinting/nsUserCharacteristics.h
@@ -1,7 +1,7 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #ifndef __nsUserCharacteristics_h__
 #define __nsUserCharacteristics_h__
@@ -12,9 +12,15 @@ class nsUserCharacteristics {
  public:
   static void MaybeSubmitPing();
 
-  // Public For testing
-  static nsresult PopulateData(bool aTesting = false);
-  static nsresult SubmitPing();
+  /*
+   * These APIs are public only for testing using the gtest
+   * When PopulateDataAndEventuallySubmit is called with aTesting = true
+   *   it will not submit the data, and SubmitPing must be called explicitly.
+   *   This is perfect because that's what we want for the gtest.
+   */
+  static void PopulateDataAndEventuallySubmit(bool aUpdatePref = true,
+                                              bool aTesting = false);
+  static void SubmitPing();
 };
 
 namespace testing {
diff --git a/toolkit/components/resistfingerprinting/pings.yaml b/toolkit/components/resistfingerprinting/pings.yaml
index 46a4b2da19..ddbd48d1d1 100644
--- a/toolkit/components/resistfingerprinting/pings.yaml
+++ b/toolkit/components/resistfingerprinting/pings.yaml
@@ -1,6 +1,6 @@
 # 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/.
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 ---
 $schema: moz://mozilla.org/schemas/glean/pings/2-0-0
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser.toml b/toolkit/components/resistfingerprinting/tests/browser/browser.toml
index 213d6d4287..527e39ad89 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser.toml
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser.toml
@@ -31,3 +31,5 @@ support-files = [
 support-files = ["file_pdf.pdf"]
 
 ["browser_serviceWorker_fingerprinting_webcompat.js"]
+
+["browser_usercharacteristics.js"]
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_fingerprinter_telemetry.js b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_fingerprinter_telemetry.js
index d2a33a4347..1098d91138 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_fingerprinter_telemetry.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_fingerprinter_telemetry.js
@@ -1,7 +1,7 @@
 /* vim: set ts=2 et sw=2 tw=80: */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js
index 8b4be78d53..e526f7fff1 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js
@@ -1,6 +1,6 @@
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 /**
  * Bug 1816189 - Testing canvas randomization on canvas data extraction.
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization_worker.js b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization_worker.js
index dd7c292fa4..723d7382f8 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization_worker.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization_worker.js
@@ -1,6 +1,6 @@
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 const emptyPage =
   getRootDirectory(gTestPath).replace(
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js b/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js
index 29c7c9170b..ac4722fd84 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js
@@ -1,6 +1,6 @@
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
@@ -20,6 +20,18 @@ const TARGET_CanvasRandomization = 0x000000100;
 const TARGET_WindowOuterSize = 0x002000000;
 const TARGET_Gamepad = 0x00800000;
 
+const TEST_PAGE =
+  getRootDirectory(gTestPath).replace(
+    "chrome://mochitests/content",
+    "https://example.com"
+  ) + "empty.html";
+
+const TEST_ANOTHER_PAGE =
+  getRootDirectory(gTestPath).replace(
+    "chrome://mochitests/content",
+    "https://example.net"
+  ) + "empty.html";
+
 // A helper function to filter high 32 bits.
 function extractLow32Bits(value) {
   return value & 0xffffffff;
@@ -404,3 +416,49 @@ add_task(async function test_pref_override_remote_settings() {
 
   db.clear();
 });
+
+// Bug 1873682 - Verify that a third-party beacon request won't hit the
+// assertion in nsRFPService::GetOverriddenFingerprintingSettingsForChannel().
+add_task(async function test_beacon_request() {
+  // Open an empty page.
+  let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, TEST_PAGE);
+
+  await SpecialPowers.spawn(
+    tab.linkedBrowser,
+    [TEST_ANOTHER_PAGE],
+    async url => {
+      // Create a third-party iframe
+      let ifr = content.document.createElement("iframe");
+
+      await new content.Promise(resolve => {
+        ifr.onload = resolve;
+        content.document.body.appendChild(ifr);
+        ifr.src = url;
+      });
+
+      await SpecialPowers.spawn(ifr, [url], url => {
+        // Sending the beacon request right before the tab navigates away.
+        content.addEventListener("unload", _ => {
+          let value = ["text"];
+          let blob = new Blob(value, {
+            type: "application/x-www-form-urlencoded",
+          });
+          content.navigator.sendBeacon(url, blob);
+        });
+      });
+
+      // Navigate the tab to another page.
+      content.location = url;
+    }
+  );
+
+  await BrowserTestUtils.browserLoaded(
+    tab.linkedBrowser,
+    false,
+    TEST_ANOTHER_PAGE
+  );
+
+  ok(true, "Successfully navigates away.");
+
+  BrowserTestUtils.removeTab(tab);
+});
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingWebCompat.js b/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingWebCompat.js
index 1a882fc63d..62335b2fe7 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingWebCompat.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingWebCompat.js
@@ -1,6 +1,6 @@
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_font_fingerprinter_telemetry.js b/toolkit/components/resistfingerprinting/tests/browser/browser_font_fingerprinter_telemetry.js
index 2231197eed..0cccf0c5f3 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_font_fingerprinter_telemetry.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_font_fingerprinter_telemetry.js
@@ -1,7 +1,7 @@
 /* vim: set ts=2 et sw=2 tw=80: */
 /* 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_fpiServiceWorkers_fingerprinting.js b/toolkit/components/resistfingerprinting/tests/browser/browser_fpiServiceWorkers_fingerprinting.js
index 64279ae442..aaa40a7928 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_fpiServiceWorkers_fingerprinting.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_fpiServiceWorkers_fingerprinting.js
@@ -68,7 +68,7 @@ runTestInFirstAndThirdPartyContexts(
   },
   async _ => {
     await new Promise(resolve => {
-      Services.clearData.deleteData(Ci.nsIClearDataService.CLEAR_ALL, value =>
+      Services.clearData.deleteData(Ci.nsIClearDataService.CLEAR_ALL, () =>
         resolve()
       );
     });
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_serviceWorker_fingerprinting_webcompat.js b/toolkit/components/resistfingerprinting/tests/browser/browser_serviceWorker_fingerprinting_webcompat.js
index a9bab38e61..eb1ab8d795 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_serviceWorker_fingerprinting_webcompat.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_serviceWorker_fingerprinting_webcompat.js
@@ -59,7 +59,7 @@ runTestInFirstAndThirdPartyContexts(
 
   async _ => {
     await new Promise(resolve => {
-      Services.clearData.deleteData(Ci.nsIClearDataService.CLEAR_ALL, value =>
+      Services.clearData.deleteData(Ci.nsIClearDataService.CLEAR_ALL, () =>
         resolve()
       );
     });
@@ -142,7 +142,7 @@ runTestInFirstAndThirdPartyContexts(
 
   async _ => {
     await new Promise(resolve => {
-      Services.clearData.deleteData(Ci.nsIClearDataService.CLEAR_ALL, value =>
+      Services.clearData.deleteData(Ci.nsIClearDataService.CLEAR_ALL, () =>
         resolve()
       );
     });
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_usercharacteristics.js b/toolkit/components/resistfingerprinting/tests/browser/browser_usercharacteristics.js
new file mode 100644
index 0000000000..9896948311
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_usercharacteristics.js
@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+const emptyPage =
+  getRootDirectory(gTestPath).replace(
+    "chrome://mochitests/content",
+    "https://example.com"
+  ) + "empty.html";
+
+function promiseObserverNotification() {
+  return TestUtils.topicObserved(
+    "user-characteristics-populating-data-done",
+    _ => {
+      var submitted = false;
+      GleanPings.userCharacteristics.testBeforeNextSubmit(_ => {
+        submitted = true;
+
+        // Did we assign a value we got out of about:fingerprinting?
+        // For now, we are sticking the test value in a random telemetry
+        // metric, but once we have a real metric, we'll update this
+        Assert.equal(
+          "Hello World",
+          Glean.characteristics.timezone.testGetValue()
+        );
+      });
+      GleanPings.userCharacteristics.submit();
+
+      return submitted;
+    }
+  );
+}
+
+add_task(async function run_test() {
+  info("Starting test...");
+
+  await BrowserTestUtils.withNewTab(
+    { gBrowser, url: emptyPage },
+    async function tabTask(_) {
+      let promise = promiseObserverNotification();
+
+      Services.obs.notifyObservers(
+        null,
+        "user-characteristics-testing-please-populate-data"
+      );
+
+      let submitted = await promise;
+      Assert.ok(submitted);
+    }
+  );
+});
diff --git a/toolkit/components/resistfingerprinting/tests/browser/head.js b/toolkit/components/resistfingerprinting/tests/browser/head.js
index 9d8ec19956..e2fddaecc6 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/head.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/head.js
@@ -54,7 +54,7 @@ function countDifferencesInArrayBuffers(buffer1, buffer2) {
 
 function promiseObserver(topic) {
   return new Promise(resolve => {
-    let obs = (aSubject, aTopic, aData) => {
+    let obs = (aSubject, aTopic) => {
       Services.obs.removeObserver(obs, aTopic);
       resolve(aSubject);
     };
diff --git a/toolkit/components/resistfingerprinting/tests/gtest/test_reduceprecision.cpp b/toolkit/components/resistfingerprinting/tests/gtest/test_reduceprecision.cpp
index 5d8b598ff0..a36b819d8f 100644
--- a/toolkit/components/resistfingerprinting/tests/gtest/test_reduceprecision.cpp
+++ b/toolkit/components/resistfingerprinting/tests/gtest/test_reduceprecision.cpp
@@ -2,7 +2,7 @@
  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
  * 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include <math.h>
 
diff --git a/toolkit/components/resistfingerprinting/tests/gtest/test_usercharping.cpp b/toolkit/components/resistfingerprinting/tests/gtest/test_usercharping.cpp
index dd1cbe7d46..2eefa8e7fe 100644
--- a/toolkit/components/resistfingerprinting/tests/gtest/test_usercharping.cpp
+++ b/toolkit/components/resistfingerprinting/tests/gtest/test_usercharping.cpp
@@ -2,7 +2,7 @@
  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
  * 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/. */
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include "gtest/gtest.h"
 #include "mozilla/gtest/nsUserCharacteristics.h"
@@ -35,7 +35,8 @@ TEST(ResistFingerprinting, UserCharacteristics_Simple)
 
 TEST(ResistFingerprinting, UserCharacteristics_Complex)
 {
-  nsUserCharacteristics::PopulateData(true);
+  nsUserCharacteristics::PopulateDataAndEventuallySubmit(
+      /* aUpdatePref = */ false, /* aTesting = */ true);
 
   bool submitted = false;
   mozilla::glean_pings::UserCharacteristics.TestBeforeNextSubmit(
@@ -102,7 +103,8 @@ TEST(ResistFingerprinting, UserCharacteristics_ClearPref)
                 .value()
                 .get());
       });
-  nsUserCharacteristics::PopulateData(true);
+  nsUserCharacteristics::PopulateDataAndEventuallySubmit(
+      /* aUpdatePref = */ false, /* aTesting = */ true);
   nsUserCharacteristics::SubmitPing();
 
   auto original_value =
@@ -135,7 +137,8 @@ TEST(ResistFingerprinting, UserCharacteristics_ClearPref)
         Preferences::GetCString(kUUIDPref, uuidValue);
         ASSERT_STRNE("", uuidValue.get());
       });
-  nsUserCharacteristics::PopulateData(true);
+  nsUserCharacteristics::PopulateDataAndEventuallySubmit(
+      /* aUpdatePref = */ false, /* aTesting = */ true);
   nsUserCharacteristics::SubmitPing();
 
   Preferences::SetBool("datareporting.healthreport.uploadEnabled",