Merging upstream version 127.0.

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

8 files changed, 762 insertions, 155 deletions

diff --git a/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs b/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs
index 56f6435e47..676f06ea68 100644
--- a/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs
+++ b/toolkit/components/resistfingerprinting/FingerprintingWebCompatService.sys.mjs
@@ -49,6 +49,8 @@ const SCHEMA = `{
 const COLLECTION_NAME = "fingerprinting-protection-overrides";
 const PREF_GRANULAR_OVERRIDES =
   "privacy.fingerprintingProtection.granularOverrides";
+const PREF_REMOTE_OVERRIDES_ENABLED =
+  "privacy.fingerprintingProtection.remoteOverrides.enabled";
 
 XPCOMUtils.defineLazyPreferenceGetter(
   lazy,
@@ -56,6 +58,12 @@ XPCOMUtils.defineLazyPreferenceGetter(
   PREF_GRANULAR_OVERRIDES
 );
 
+XPCOMUtils.defineLazyPreferenceGetter(
+  lazy,
+  "remoteOverridesEnabled",
+  PREF_REMOTE_OVERRIDES_ENABLED
+);
+
 /**
  * The object represents a fingerprinting override.
  */
@@ -195,6 +203,12 @@ export class FingerprintingWebCompatService {
 
   #onRemoteUpdate(entries) {
     lazy.logConsole.debug("onUpdateEntries", { entries });
+
+    if (!lazy.remoteOverridesEnabled) {
+      lazy.logConsole.debug("Abort remote overrides");
+      return;
+    }
+
     // Clear all overrides before we update the overrides.
     this.#remoteOverrides.clear();
 
diff --git a/toolkit/components/resistfingerprinting/metrics.yaml b/toolkit/components/resistfingerprinting/metrics.yaml
index 51b251508c..b5150defd3 100644
--- a/toolkit/components/resistfingerprinting/metrics.yaml
+++ b/toolkit/components/resistfingerprinting/metrics.yaml
@@ -528,3 +528,527 @@ characteristics:
     expires: never
     data_sensitivity:
       - interaction
+
+  prefs_browser_display_use_document_fonts: # browser.display.use_document_fonts
+    type: boolean
+    description: >
+      Allow pages to choose their own fonts.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_default_western: # font.default.x-western
+    type: string
+    description: >
+      The value of the font.default.x-western pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_default_default_group: # font.default.<default language group>
+    type: string
+    description: >
+      The value of the font.default.<default language group> pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_default_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of other modified font.default prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_serif_western: # font.name.serif.x-western
+    type: string
+    description: >
+      The value of the font.name.serif.x-western pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_serif_default_group: # font.name.serif.<default language group>
+    type: string
+    description: >
+      The value of the font.name.serif.<default language group> pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_serif_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of other modified font.name.serif prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_sans_serif_western: # font.name.sans-serif.x-western
+    type: string
+    description: >
+      The value of the font.name.sans-serif.x-western pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_sans_serif_default_group: # font.name.sans-serif.<default language group>
+    type: string
+    description: >
+      The value of the font.name.sans-serif.<default language group> pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_sans_serif_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of other modified font.name.sans-serif prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_monospace_western: # font.name.monospace.x-western
+    type: string
+    description: >
+      The value of the font.name.monospace.x-western pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_monospace_default_group: # font.name.monospace.<default language group>
+    type: string
+    description: >
+      The value of the font.name.monospace.<default language group> pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_monospace_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of other modified font.name.monospace prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_size_variable_western: # font.size.variable.x-western
+    type: string
+    description: >
+      The value of the font.size.variable.x-western pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_size_variable_default_group: # font.size.variable.<default language group>
+    type: string
+    description: >
+      The value of the font.size.variable.<default language group> pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_size_variable_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of other modified font.size.variable prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_size_monospace_western: # font.size.monospace.x-western
+    type: string
+    description: >
+      The value of the font.size.monospace.x-western pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_size_monospace_default_group: # font.size.monospace.<default language group>
+    type: string
+    description: >
+      The value of the font.size.monospace.<default language group> pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_size_monospace_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of other modified font.size.monospace prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_minimum_size_western: # font.minimum-size.x-western
+    type: string
+    description: >
+      The value of the font.minimum-size.x-western pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_minimum_size_default_group: # font.minimum-size.<default language group>
+    type: string
+    description: >
+      The value of the font.minimum-size.<default language group> pref
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_minimum_size_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of other modified font.minimum-size prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_list_serif_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of modified font.name-list.serif. prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_list_sans_serif_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of modified font.name-list.sans-serif. prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_list_monospace_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of modified font.name-list.monospace. prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_list_cursive_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of modified font.name-list.cursive. prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_list_cursive_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of modified font.name-list.cursive. prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_list_emoji_modified:
+    type: quantity
+    unit: int
+    description: >
+      The number of modified font.name-list.cursive. prefs.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  font_name_list_emoji_modified:
+    type: boolean
+    description: >
+      Whether the pref font.name-list.emoji was modified.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1887658#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_network_cookie_cookiebehavior: # network.cookie.cookieBehavior
+    type: quantity
+    unit: int
+    description: >
+      Value of the network.cookie.cookieBehavior pref.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1892474
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1852340#c16
+    expires: never
+    data_sensitivity:
+      - interaction
diff --git a/toolkit/components/resistfingerprinting/nsRFPService.cpp b/toolkit/components/resistfingerprinting/nsRFPService.cpp
index f39deb3283..34c34a2496 100644
--- a/toolkit/components/resistfingerprinting/nsRFPService.cpp
+++ b/toolkit/components/resistfingerprinting/nsRFPService.cpp
@@ -100,6 +100,8 @@ static mozilla::LazyLogModule gResistFingerprintingLog(
 
 static mozilla::LazyLogModule gFingerprinterDetection("FingerprinterDetection");
 
+static mozilla::LazyLogModule gTimestamps("Timestamps");
+
 #define RESIST_FINGERPRINTINGPROTECTION_OVERRIDE_PREF \
   "privacy.fingerprintingProtection.overrides"
 #define GLEAN_DATA_SUBMISSION_PREF "datareporting.healthreport.uploadEnabled"
@@ -410,7 +412,7 @@ sec_per_extra_frame = 1 / (extra_frames_per_frame * 60) // 833.33
 min_per_extra_frame = sec_per_extra_frame / 60 // 13.89
 ```
 We expect an extra frame every ~14 minutes, which is enough to be smooth.
-16.67 would be ~1.4 minutes, which is OK, but is more noticable.
+16.67 would be ~1.4 minutes, which is OK, but is more noticeable.
 Put another way, if this is the only unacceptable hitch you have across 14
 minutes, I'm impressed, and we might revisit this.
 */
@@ -631,14 +633,13 @@ double nsRFPService::ReduceTimePrecisionImpl(double aTime, TimeScale aTimeScale,
     nsAutoCString type;
     TypeToText(aType, type);
     MOZ_LOG(
-        gResistFingerprintingLog, LogLevel::Error,
+        gTimestamps, LogLevel::Error,
         ("About to assert. aTime=%lli<%lli aContextMixin=%" PRId64 " aType=%s",
          timeAsInt, kFeb282008, aContextMixin, type.get()));
-    MOZ_ASSERT(
-        false,
-        "ReduceTimePrecisionImpl was given a relative time "
-        "with an empty context mix-in (or your clock is 10+ years off.) "
-        "Run this with MOZ_LOG=nsResistFingerprinting:1 to get more details.");
+    MOZ_ASSERT(false,
+               "ReduceTimePrecisionImpl was given a relative time "
+               "with an empty context mix-in (or your clock is 10+ years off.) "
+               "Run this with MOZ_LOG=Timestamps:1 to get more details.");
   }
 
   // Cast the resolution (in microseconds) to an int.
@@ -673,7 +674,7 @@ double nsRFPService::ReduceTimePrecisionImpl(double aTime, TimeScale aTimeScale,
   double ret = double(clampedAndJittered) / (1000000.0 / double(aTimeScale));
 
   MOZ_LOG(
-      gResistFingerprintingLog, LogLevel::Verbose,
+      gTimestamps, LogLevel::Verbose,
       ("Given: (%.*f, Scaled: %.*f, Converted: %lli), Rounding %s with (%lli, "
        "Originally %.*f), "
        "Intermediate: (%lli), Clamped: (%lli) Jitter: (%i Context: %" PRId64
diff --git a/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp b/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
index 86de7d61a7..9e3c6c1aaf 100644
--- a/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
+++ b/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
@@ -18,9 +18,11 @@
 #include "mozilla/Components.h"
 #include "mozilla/dom/Promise-inl.h"
 
+#include "mozilla/StaticPrefs_browser.h"
 #include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/StaticPrefs_general.h"
 #include "mozilla/StaticPrefs_media.h"
+#include "mozilla/StaticPrefs_network.h"
 #include "mozilla/StaticPrefs_widget.h"
 
 #include "mozilla/LookAndFeel.h"
@@ -171,6 +173,122 @@ void PopulatePrefs() {
 
   glean::characteristics::prefs_block_popups.Set(
       StaticPrefs::dom_disable_open_during_load());
+
+  glean::characteristics::prefs_browser_display_use_document_fonts.Set(
+      mozilla::StaticPrefs::browser_display_use_document_fonts());
+
+  glean::characteristics::prefs_network_cookie_cookiebehavior.Set(
+      StaticPrefs::network_cookie_cookieBehavior());
+}
+
+template <typename StringMetric, typename QuantityMetric>
+static void CollectFontPrefValue(nsIPrefBranch* aPrefBranch,
+                                 const nsACString& aDefaultLanguageGroup,
+                                 const char* aStartingAt,
+                                 StringMetric& aWesternMetric,
+                                 StringMetric& aDefaultGroupMetric,
+                                 QuantityMetric& aModifiedMetric) {
+  nsTArray<nsCString> prefNames;
+  if (NS_WARN_IF(
+          NS_FAILED(aPrefBranch->GetChildList(aStartingAt, prefNames)))) {
+    return;
+  }
+
+  nsCString westernPref(aStartingAt);
+  westernPref.Append("x-western");
+  nsCString defaultGroupPref(aStartingAt);
+  defaultGroupPref.Append(aDefaultLanguageGroup);
+
+  nsAutoCString westernPrefValue;
+  Preferences::GetCString(westernPref.get(), westernPrefValue);
+  aWesternMetric.Set(westernPrefValue);
+
+  nsAutoCString defaultGroupPrefValue;
+  if (!westernPref.Equals(defaultGroupPref)) {
+    Preferences::GetCString(defaultGroupPref.get(), defaultGroupPrefValue);
+  }
+  aDefaultGroupMetric.Set(defaultGroupPrefValue);
+
+  uint32_t modifiedCount = 0;
+  for (const auto& prefName : prefNames) {
+    if (!prefName.Equals(westernPref) && !prefName.Equals(defaultGroupPref)) {
+      if (Preferences::HasUserValue(prefName.get())) {
+        modifiedCount++;
+      }
+    }
+  }
+  aModifiedMetric.Set(modifiedCount);
+}
+
+template <typename QuantityMetric>
+static void CollectFontPrefModified(nsIPrefBranch* aPrefBranch,
+                                    const char* aStartingAt,
+                                    QuantityMetric& aModifiedMetric) {
+  nsTArray<nsCString> prefNames;
+  if (NS_WARN_IF(
+          NS_FAILED(aPrefBranch->GetChildList(aStartingAt, prefNames)))) {
+    return;
+  }
+
+  uint32_t modifiedCount = 0;
+  for (const auto& prefName : prefNames) {
+    if (Preferences::HasUserValue(prefName.get())) {
+      modifiedCount++;
+    }
+  }
+  aModifiedMetric.Set(modifiedCount);
+}
+
+void PopulateFontPrefs() {
+  nsIPrefBranch* prefRootBranch = Preferences::GetRootBranch();
+  if (!prefRootBranch) {
+    return;
+  }
+
+  nsCString defaultLanguageGroup;
+  Preferences::GetLocalizedCString("font.language.group", defaultLanguageGroup);
+
+#define FONT_PREF(PREF_NAME, METRIC_NAME)                                   \
+  CollectFontPrefValue(prefRootBranch, defaultLanguageGroup, PREF_NAME,     \
+                       glean::characteristics::METRIC_NAME##_western,       \
+                       glean::characteristics::METRIC_NAME##_default_group, \
+                       glean::characteristics::METRIC_NAME##_modified)
+
+  // The following preferences can be modified using the advanced font options
+  // on the about:preferences page. Every preference has a sub-branch per
+  // script, so for example font.default.x-western or font.default.x-cyrillic
+  // etc. For all of the 7 main preferences, we collect:
+  // - The value for the x-western branch (if user modified)
+  // - The value for the current default language group (~ script) based
+  //   on the localized version of Firefox being used. (Only when not x-western)
+  // - How many /other/ script that are not x-western or the default have been
+  //   modified.
+
+  FONT_PREF("font.default.", font_default);
+  FONT_PREF("font.name.serif.", font_name_serif);
+  FONT_PREF("font.name.sans-serif.", font_name_sans_serif);
+  FONT_PREF("font.name.monospace.", font_name_monospace);
+  FONT_PREF("font.size.variable.", font_size_variable);
+  FONT_PREF("font.size.monospace.", font_size_monospace);
+  FONT_PREF("font.minimum-size.", font_minimum_size);
+
+#undef FONT_PREF
+
+  CollectFontPrefModified(
+      prefRootBranch, "font.name-list.serif.",
+      glean::characteristics::font_name_list_serif_modified);
+  CollectFontPrefModified(
+      prefRootBranch, "font.name-list.sans-serif.",
+      glean::characteristics::font_name_list_sans_serif_modified);
+  CollectFontPrefModified(
+      prefRootBranch, "font.name-list.monospace.",
+      glean::characteristics::font_name_list_monospace_modified);
+  CollectFontPrefModified(
+      prefRootBranch, "font.name-list.cursive.",
+      glean::characteristics::font_name_list_cursive_modified);
+  // Exceptionally this pref has no variants per-script.
+  glean::characteristics::font_name_list_emoji_modified.Set(
+      Preferences::HasUserValue("font.name-list.emoji"));
 }
 
 // ==================================================================
@@ -178,7 +296,7 @@ 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 = 1;
+const int kSubmissionSchema = 2;
 
 const auto* const kLastVersionPref =
     "toolkit.telemetry.user_characteristics_ping.last_version_sent";
@@ -304,6 +422,7 @@ void nsUserCharacteristics::PopulateDataAndEventuallySubmit(
     PopulateCSSProperties();
     PopulateScreenProperties();
     PopulatePrefs();
+    PopulateFontPrefs();
 
     glean::characteristics::target_frame_rate.Set(
         gfxPlatform::TargetFrameRate());
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js
index e526f7fff1..8d78fb29eb 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization.js
@@ -39,29 +39,7 @@ var TEST_CASES = [
 
       return [imageData.data, imageDataSecond.data];
     },
-    isDataRandomized(name, data1, data2, isCompareOriginal) {
-      let diffCnt = countDifferencesInUint8Arrays(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-
-      // The Canvas randomization adds at most 512 bits noise to the image data.
-      // We compare the image data arrays to see if they are different and the
-      // difference is within the range.
-
-      // If we are compare two randomized arrays, the difference can be doubled.
-      let expected = isCompareOriginal
-        ? NUM_RANDOMIZED_CANVAS_BITS
-        : NUM_RANDOMIZED_CANVAS_BITS * 2;
-
-      // The number of difference bits should never bigger than the expected
-      // number. It could be zero if the randomization is disabled.
-      Assert.lessOrEqual(
-        diffCnt,
-        expected,
-        "The number of noise bits is expected."
-      );
-
-      return diffCnt <= expected && diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedFuzzy,
   },
   {
     name: "CanvasRenderingContext2D.getImageData().",
@@ -88,29 +66,7 @@ var TEST_CASES = [
 
       return [imageData.data, imageDataSecond.data];
     },
-    isDataRandomized(name, data1, data2, isCompareOriginal) {
-      let diffCnt = countDifferencesInUint8Arrays(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-
-      // The Canvas randomization adds at most 512 bits noise to the image data.
-      // We compare the image data arrays to see if they are different and the
-      // difference is within the range.
-
-      // If we are compare two randomized arrays, the difference can be doubled.
-      let expected = isCompareOriginal
-        ? NUM_RANDOMIZED_CANVAS_BITS
-        : NUM_RANDOMIZED_CANVAS_BITS * 2;
-
-      // The number of difference bits should never bigger than the expected
-      // number. It could be zero if the randomization is disabled.
-      Assert.lessOrEqual(
-        diffCnt,
-        expected,
-        "The number of noise bits is expected."
-      );
-
-      return diffCnt <= expected && diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedFuzzy,
   },
   {
     name: "HTMLCanvasElement.toDataURL() with a 2d context",
@@ -137,9 +93,7 @@ var TEST_CASES = [
 
       return [dataURL, dataURLSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      return data1 !== data2;
-    },
+    isDataRandomized: isDataRandomizedNotEqual,
   },
   {
     name: "HTMLCanvasElement.toDataURL() with a webgl context",
@@ -170,9 +124,7 @@ var TEST_CASES = [
 
       return [dataURL, dataURLSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      return data1 !== data2;
-    },
+    isDataRandomized: isDataRandomizedNotEqual,
   },
   {
     name: "HTMLCanvasElement.toDataURL() with a bitmaprenderer context",
@@ -208,9 +160,7 @@ var TEST_CASES = [
 
       return [dataURL, dataURLSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      return data1 !== data2;
-    },
+    isDataRandomized: isDataRandomizedNotEqual,
   },
   {
     name: "HTMLCanvasElement.toBlob() with a 2d context",
@@ -253,11 +203,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "HTMLCanvasElement.toBlob() with a webgl context",
@@ -298,11 +244,7 @@ var TEST_CASES = [
 
       return [data, data];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "HTMLCanvasElement.toBlob() with a bitmaprenderer context",
@@ -354,11 +296,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "OffscreenCanvas.convertToBlob() with a 2d context",
@@ -382,11 +320,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "OffscreenCanvas.convertToBlob() with a webgl context",
@@ -416,11 +350,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "OffscreenCanvas.convertToBlob() with a bitmaprenderer context",
@@ -450,11 +380,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "CanvasRenderingContext2D.getImageData() with a offscreen canvas",
@@ -477,29 +403,7 @@ var TEST_CASES = [
 
       return [imageData.data, imageDataSecond.data];
     },
-    isDataRandomized(name, data1, data2, isCompareOriginal) {
-      let diffCnt = countDifferencesInUint8Arrays(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-
-      // The Canvas randomization adds at most 512 bits noise to the image data.
-      // We compare the image data arrays to see if they are different and the
-      // difference is within the range.
-
-      // If we are compare two randomized arrays, the difference can be doubled.
-      let expected = isCompareOriginal
-        ? NUM_RANDOMIZED_CANVAS_BITS
-        : NUM_RANDOMIZED_CANVAS_BITS * 2;
-
-      // The number of difference bits should never bigger than the expected
-      // number. It could be zero if the randomization is disabled.
-      Assert.lessOrEqual(
-        diffCnt,
-        expected,
-        "The number of noise bits is expected."
-      );
-
-      return diffCnt <= expected && diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedFuzzy,
   },
 ];
 
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 723d7382f8..4bf0f34811 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization_worker.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_canvas_randomization_worker.js
@@ -35,29 +35,7 @@ var TEST_CASES = [
 
       return [imageData.data, imageDataSecond.data];
     },
-    isDataRandomized(name, data1, data2, isCompareOriginal) {
-      let diffCnt = countDifferencesInUint8Arrays(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-
-      // The Canvas randomization adds at most 512 bits noise to the image data.
-      // We compare the image data arrays to see if they are different and the
-      // difference is within the range.
-
-      // If we are compare two randomized arrays, the difference can be doubled.
-      let expected = isCompareOriginal
-        ? NUM_RANDOMIZED_CANVAS_BITS
-        : NUM_RANDOMIZED_CANVAS_BITS * 2;
-
-      // The number of difference bits should never bigger than the expected
-      // number. It could be zero if the randomization is disabled.
-      Assert.lessOrEqual(
-        diffCnt,
-        expected,
-        "The number of noise bits is expected."
-      );
-
-      return diffCnt <= expected && diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedFuzzy,
   },
   {
     name: "OffscreenCanvas.convertToBlob() with a 2d context",
@@ -94,11 +72,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "OffscreenCanvas.convertToBlob() with a webgl context",
@@ -140,11 +114,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
   {
     name: "OffscreenCanvas.convertToBlob() with a bitmaprenderer context",
@@ -187,11 +157,7 @@ var TEST_CASES = [
 
       return [data, dataSecond];
     },
-    isDataRandomized(name, data1, data2) {
-      let diffCnt = countDifferencesInArrayBuffers(data1, data2);
-      info(`For ${name} there are ${diffCnt} bits are different.`);
-      return diffCnt > 0;
-    },
+    isDataRandomized: isDataRandomizedGreaterThanZero,
   },
 ];
 
diff --git a/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js b/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js
index ac4722fd84..64efa270d7 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/browser_fingerprintingRemoteOverrides.js
@@ -323,6 +323,51 @@ add_task(async function test_remote_settings() {
   db.clear();
 });
 
+add_task(async function test_remote_settings_pref() {
+  // Add initial empty record.
+  let db = RemoteSettings(COLLECTION_NAME).db;
+  await db.importChanges({}, Date.now(), []);
+
+  for (let test of TEST_CASES) {
+    info(`Testing with entry ${JSON.stringify(test.entires)}`);
+
+    // Disable remote overrides
+    await SpecialPowers.pushPrefEnv({
+      set: [
+        ["privacy.fingerprintingProtection.remoteOverrides.enabled", false],
+      ],
+    });
+
+    // Create a promise for waiting the overrides get updated.
+    let promise = promiseObserver("fpp-test:set-overrides-finishes");
+
+    // Trigger the fingerprinting overrides update by a remote settings sync.
+    await RemoteSettings(COLLECTION_NAME).emit("sync", {
+      data: {
+        current: test.entires,
+      },
+    });
+    await promise;
+
+    ok(true, "Got overrides update");
+
+    for (let expect of test.expects) {
+      try {
+        // Check for the existance of RFP overrides
+        Services.rfp.getFingerprintingOverrides(expect.domain);
+        ok(
+          false,
+          "This line should never run as the override should not exist and the previous line would throw an exception"
+        );
+      } catch (e) {
+        ok(true, "Received an exception as expected");
+      }
+    }
+  }
+
+  db.clear();
+});
+
 add_task(async function test_pref() {
   for (let test of TEST_CASES) {
     info(`Testing with entry ${JSON.stringify(test.entires)}`);
diff --git a/toolkit/components/resistfingerprinting/tests/browser/head.js b/toolkit/components/resistfingerprinting/tests/browser/head.js
index e2fddaecc6..2a1b52f1c0 100644
--- a/toolkit/components/resistfingerprinting/tests/browser/head.js
+++ b/toolkit/components/resistfingerprinting/tests/browser/head.js
@@ -52,6 +52,40 @@ function countDifferencesInArrayBuffers(buffer1, buffer2) {
   return differences;
 }
 
+function isDataRandomizedFuzzy(name, data1, data2, isCompareOriginal) {
+  let diffCnt = countDifferencesInUint8Arrays(data1, data2);
+  info(`For ${name} there are ${diffCnt} bits are different.`);
+
+  // The Canvas randomization adds at most 512 bits noise to the image data.
+  // We compare the image data arrays to see if they are different and the
+  // difference is within the range.
+
+  // If we are compare two randomized arrays, the difference can be doubled.
+  let expected = isCompareOriginal
+    ? NUM_RANDOMIZED_CANVAS_BITS
+    : NUM_RANDOMIZED_CANVAS_BITS * 2;
+
+  // The number of difference bits should never bigger than the expected
+  // number. It could be zero if the randomization is disabled.
+  Assert.lessOrEqual(
+    diffCnt,
+    expected,
+    "The number of noise bits is expected."
+  );
+
+  return diffCnt <= expected && diffCnt > 0;
+}
+
+function isDataRandomizedNotEqual(name, data1, data2) {
+  return data1 !== data2;
+}
+
+function isDataRandomizedGreaterThanZero(name, data1, data2) {
+  let diffCnt = countDifferencesInArrayBuffers(data1, data2);
+  info(`For ${name} there are ${diffCnt} bits are different.`);
+  return diffCnt > 0;
+}
+
 function promiseObserver(topic) {
   return new Promise(resolve => {
     let obs = (aSubject, aTopic) => {