Merging upstream version 125.0.1.

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

9 files changed, 923 insertions, 1 deletions

diff --git a/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs b/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs
index a085aa492a..223c0259b7 100644
--- a/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs
+++ b/toolkit/components/resistfingerprinting/RFPHelper.sys.mjs
@@ -20,7 +20,7 @@ var logConsole;
 function log(msg) {
   if (!logConsole) {
     logConsole = console.createInstance({
-      prefix: "RFPHelper.jsm",
+      prefix: "RFPHelper",
       maxLogLevelPref: "privacy.resistFingerprinting.jsmloglevel",
     });
   }
diff --git a/toolkit/components/resistfingerprinting/metrics.yaml b/toolkit/components/resistfingerprinting/metrics.yaml
index 916c8c7871..3c706d20fa 100644
--- a/toolkit/components/resistfingerprinting/metrics.yaml
+++ b/toolkit/components/resistfingerprinting/metrics.yaml
@@ -25,3 +25,387 @@ fingerprinting.protection:
       - tschuster@mozilla.com
     expires: never
     telemetry_mirror: FINGERPRINTING_PROTECTION_CANVAS_NOISE_CALCULATE_TIME_MS
+
+
+characteristics:
+  client_identifier:
+    type: uuid
+    description: >
+      A unique identifier for a user, not the same as the normal Telemetry
+      client_id, but needed so we can deduplicate reports and only take the most
+      recent one per user.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+      - deletion-request
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879154
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879154#c8
+    expires: never
+    data_sensitivity:
+      - technical
+
+  submission_schema:
+    type: quantity
+    unit: versions
+    description: >
+      An incrementing constant that represents the current schema/source of the
+      data present in a ping. By referring to this value in a ping, one can know
+      for certain the provenance of other data present in the ping, and what
+      data may or may not be present.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879154
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879154#c8
+    expires: never
+
+  max_touch_points:
+    type: quantity
+    unit: Fingers
+    description: >
+      The number of touch points we will report to the web. On Android, this is
+      based on Android's FEATURE_TOUCHSCREEN* constants - Mozilla caps this at 5
+      as Android stops distinguishing between numbers greater than 5.  On
+      Windows this comes from the SM_MAXIMUMTOUCHES System Metric.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879156
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879156#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  video_dynamic_range:
+    type: boolean
+    description: >
+      What LookAndFeel(VideoDynamicRange) reports. Note that CSSVideoDynamicRange
+      has an additional dependency on Color Depth.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  prefers_reduced_transparency:
+    type: boolean
+    description: >
+      What LookAndFeel(PrefersReducedTransparency) reports.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  prefers_reduced_motion:
+    type: boolean
+    description: >
+      What LookAndFeel(PrefersReducedMotion) reports.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  prefers_contrast:
+    type: quantity
+    unit: enum StylePrefersContrast value
+    description: >
+      What Gecko_MediaFeatures_PrefersContrast reports for a ContentDocument
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  inverted_colors:
+    type: boolean
+    description: >
+      What LookAndFeel(InvertedColors) reports.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  color_scheme:
+    type: quantity
+    unit: enum mozilla::ColorScheme value
+    description: >
+      The Color Scheme used for Content, from ContentPrefs() Preference Sheet.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  color_gamut:
+    type: quantity
+    unit: enum dom::ScreenColorGamut value
+    description: >
+      The Color Gamut reported by CSS
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  color_depth:
+    type: quantity
+    unit: bits
+    description: >
+      The Color Depth reported by CSS
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879624#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  missing_fonts:
+    type: text
+    description: >
+      If a Font List is available for the user's platform, this
+      string_list contains the fonts that are missing from the user's
+      computer.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1880561
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1880561#c6
+    expires: never
+    data_sensitivity:
+      # Text metrics are _required_ to be web_activity or highly_sensitive, so even though this
+      # is more like 'technical' (per the Data Review), I'm marking highly sensitive.
+      - highly_sensitive
+
+  screen_width:
+    type: quantity
+    unit: pixels
+    description: >
+      Width of the primary screen in pixels.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881749
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881749#c5
+    expires: never
+    data_sensitivity:
+      - technical
+
+  screen_height:
+    type: quantity
+    unit: pixels
+    description: >
+      Height of the primary screen in pixels.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881749
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881749#c5
+    expires: never
+    data_sensitivity:
+      - technical
+
+  processor_count:
+    type: quantity
+    unit: int
+    description: >
+      Number of processors.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881759
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881759#c4
+    expires: never
+    data_sensitivity:
+      - technical
+
+  timezone:
+    type: string
+    description: >
+      The the current timezone of the system
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881773
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1881773#c4
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  target_frame_rate:
+    type: quantity
+    unit: int
+    description: >
+      The target frame rate in frames-per-second.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882054
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882054#c3
+    expires: never
+    data_sensitivity:
+      - technical
+
+  prefs_intl_accept_languages:
+    type: string
+    description: >
+      Value of the intl.accept_languages pref.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882482
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882482#c6
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_media_eme_enabled:
+    type: boolean
+    description: >
+      Value of the media.eme.enabled pref.
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882482
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882482#c6
+    expires: never
+    data_sensitivity:
+      - interaction
+
+  prefs_zoom_text_only:
+    type: boolean
+    description: >
+      Text-only zoom enabled (vs. full-zoom)
+    lifetime: application
+    send_in_pings:
+      - user-characteristics
+    notification_emails:
+      - tom@mozilla.com
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882482
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1882482#c6
+    expires: never
+    data_sensitivity:
+      - interaction
diff --git a/toolkit/components/resistfingerprinting/moz.build b/toolkit/components/resistfingerprinting/moz.build
index 6ac25d3b76..9b4e9cc8ed 100644
--- a/toolkit/components/resistfingerprinting/moz.build
+++ b/toolkit/components/resistfingerprinting/moz.build
@@ -13,6 +13,17 @@ UNIFIED_SOURCES += [
     "nsRFPService.cpp",
     "RelativeTimeline.cpp",
 ]
+# Because nsUserCharacteristics doesn't `use namespace mozilla` (because we're going to wind
+# up with a million includes on this file and pollution will get confusing), unified build
+# will mask a lot of errors that would cause backouts. This exposes them locally.
+SOURCES += [
+    "nsUserCharacteristics.cpp",
+]
+
+if CONFIG["MOZ_WIDGET_TOOLKIT"] == "cocoa":
+    LOCAL_INCLUDES += [
+        "/xpcom/base",
+    ]
 
 SPHINX_TREES["resistfingerprinting"] = "docs"
 
@@ -23,6 +34,7 @@ EXPORTS.mozilla += [
     "RelativeTimeline.h",
     "RFPTargetIPCUtils.h",
 ]
+EXPORTS.mozilla.gtest += ["nsUserCharacteristics.h"]
 
 EXTRA_JS_MODULES += [
     "FingerprintingWebCompatService.sys.mjs",
diff --git a/toolkit/components/resistfingerprinting/nsRFPService.cpp b/toolkit/components/resistfingerprinting/nsRFPService.cpp
index 8579fe2a3b..643cc2cb7a 100644
--- a/toolkit/components/resistfingerprinting/nsRFPService.cpp
+++ b/toolkit/components/resistfingerprinting/nsRFPService.cpp
@@ -71,6 +71,7 @@
 #include "nsTLiteralString.h"
 #include "nsTPromiseFlatString.h"
 #include "nsTStringRepr.h"
+#include "nsUserCharacteristics.h"
 #include "nsXPCOM.h"
 
 #include "nsICookieJarSettings.h"
@@ -100,8 +101,14 @@ static mozilla::LazyLogModule gFingerprinterDetection("FingerprinterDetection");
 
 #define RESIST_FINGERPRINTINGPROTECTION_OVERRIDE_PREF \
   "privacy.fingerprintingProtection.overrides"
+#define GLEAN_DATA_SUBMISSION_PREF "datareporting.healthreport.uploadEnabled"
+#define USER_CHARACTERISTICS_UUID_PREF \
+  "toolkit.telemetry.user_characteristics_ping.uuid"
+
 #define RFP_TIMER_UNCONDITIONAL_VALUE 20
 #define LAST_PB_SESSION_EXITED_TOPIC "last-pb-context-exited"
+#define IDLE_TOPIC "browser-idle-startup-tasks-finished"
+#define GFX_FEATURES "gfx-features-ready"
 
 static constexpr uint32_t kVideoFramesPerSec = 30;
 static constexpr uint32_t kVideoDroppedRatio = 5;
@@ -156,6 +163,7 @@ already_AddRefed<nsRFPService> nsRFPService::GetOrCreate() {
 
 static const char* gCallbackPrefs[] = {
     RESIST_FINGERPRINTINGPROTECTION_OVERRIDE_PREF,
+    GLEAN_DATA_SUBMISSION_PREF,
     nullptr,
 };
 
@@ -176,6 +184,12 @@ nsresult nsRFPService::Init() {
 
     rv = obs->AddObserver(this, OBSERVER_TOPIC_IDLE_DAILY, false);
     NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = obs->AddObserver(this, IDLE_TOPIC, false);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = obs->AddObserver(this, GFX_FEATURES, false);
+    NS_ENSURE_SUCCESS(rv, rv);
   }
 
   Preferences::RegisterCallbacks(nsRFPService::PrefChanged, gCallbackPrefs,
@@ -273,6 +287,8 @@ void nsRFPService::StartShutdown() {
     if (XRE_IsParentProcess()) {
       obs->RemoveObserver(this, LAST_PB_SESSION_EXITED_TOPIC);
       obs->RemoveObserver(this, OBSERVER_TOPIC_IDLE_DAILY);
+      obs->RemoveObserver(this, IDLE_TOPIC);
+      obs->RemoveObserver(this, GFX_FEATURES);
     }
   }
 
@@ -290,16 +306,30 @@ void nsRFPService::PrefChanged(const char* aPref, void* aSelf) {
 }
 
 void nsRFPService::PrefChanged(const char* aPref) {
+  MOZ_LOG(gResistFingerprintingLog, LogLevel::Info,
+          ("Pref Changed: %s", aPref));
   nsDependentCString pref(aPref);
 
   if (pref.EqualsLiteral(RESIST_FINGERPRINTINGPROTECTION_OVERRIDE_PREF)) {
     UpdateFPPOverrideList();
+  } else if (pref.EqualsLiteral(GLEAN_DATA_SUBMISSION_PREF)) {
+    if (XRE_IsParentProcess() &&
+        !Preferences::GetBool(GLEAN_DATA_SUBMISSION_PREF, false)) {
+      MOZ_LOG(gResistFingerprintingLog, LogLevel::Info, ("Clearing UUID"));
+      // If the user has unset the telemetry pref, wipe out the UUID pref value
+      // (The data will also be erased server-side via the "deletion-request"
+      // ping)
+      Preferences::SetCString(USER_CHARACTERISTICS_UUID_PREF, ""_ns);
+    }
   }
 }
 
 NS_IMETHODIMP
 nsRFPService::Observe(nsISupports* aObject, const char* aTopic,
                       const char16_t* aMessage) {
+  const int kNumTopicsForUserCharacteristics = 2;
+  static int seenTopicsForUserCharacteristics = 0;
+
   if (strcmp(NS_XPCOM_SHUTDOWN_OBSERVER_ID, aTopic) == 0) {
     StartShutdown();
   }
@@ -312,6 +342,14 @@ nsRFPService::Observe(nsISupports* aObject, const char* aTopic,
     ClearBrowsingSessionKey(pattern);
   }
 
+  if (!strcmp(IDLE_TOPIC, aTopic) || !strcmp(GFX_FEATURES, aTopic)) {
+    seenTopicsForUserCharacteristics++;
+
+    if (seenTopicsForUserCharacteristics == kNumTopicsForUserCharacteristics) {
+      nsUserCharacteristics::MaybeSubmitPing();
+    }
+  }
+
   if (!strcmp(OBSERVER_TOPIC_IDLE_DAILY, aTopic)) {
     if (StaticPrefs::
             privacy_resistFingerprinting_randomization_daily_reset_enabled()) {
diff --git a/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp b/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
new file mode 100644
index 0000000000..9bce616f81
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/nsUserCharacteristics.cpp
@@ -0,0 +1,297 @@
+/* -*- 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/. */
+
+#include "nsUserCharacteristics.h"
+
+#include "nsID.h"
+#include "nsIUUIDGenerator.h"
+#include "nsServiceManagerUtils.h"
+
+#include "mozilla/Logging.h"
+#include "mozilla/glean/GleanPings.h"
+#include "mozilla/glean/GleanMetrics.h"
+
+#include "mozilla/StaticPrefs_media.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/TimeZone.h"
+#include "mozilla/widget/ScreenManager.h"
+
+#include "gfxPlatformFontList.h"
+#include "prsystem.h"
+#if defined(XP_WIN)
+#  include "WinUtils.h"
+#elif defined(MOZ_WIDGET_ANDROID)
+#  include "mozilla/java/GeckoAppShellWrappers.h"
+#elif defined(XP_MACOSX)
+#  include "nsMacUtilsImpl.h"
+#endif
+
+static mozilla::LazyLogModule gUserCharacteristicsLog("UserCharacteristics");
+
+// ==================================================================
+namespace testing {
+extern "C" {
+
+int MaxTouchPoints() {
+#if defined(XP_WIN)
+  return mozilla::widget::WinUtils::GetMaxTouchPoints();
+#elif defined(MOZ_WIDGET_ANDROID)
+  return mozilla::java::GeckoAppShell::GetMaxTouchPoints();
+#else
+  return 0;
+#endif
+}
+
+}  // extern "C"
+};  // namespace testing
+
+// ==================================================================
+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 = [] {
+    // Replicates Gecko_MediaFeatures_PrefersContrast but without a Document
+    if (!mozilla::PreferenceSheet::ContentPrefs().mUseAccessibilityTheme &&
+        mozilla::PreferenceSheet::ContentPrefs().mUseDocumentColors) {
+      return mozilla::StylePrefersContrast::NoPreference;
+    }
+
+    const auto& colors = mozilla::PreferenceSheet::ContentPrefs().ColorsFor(
+        mozilla::ColorScheme::Light);
+    float ratio = mozilla::RelativeLuminanceUtils::ContrastRatio(
+        colors.mDefaultBackground, colors.mDefault);
+    // https://www.w3.org/TR/WCAG21/#contrast-minimum
+    if (ratio < 4.5f) {
+      return mozilla::StylePrefersContrast::Less;
+    }
+    // https://www.w3.org/TR/WCAG21/#contrast-enhanced
+    if (ratio >= 7.0f) {
+      return mozilla::StylePrefersContrast::More;
+    }
+    return mozilla::StylePrefersContrast::Custom;
+  }();
+  mozilla::glean::characteristics::prefers_contrast.Set((int)prefersContrast);
+}
+
+void PopulateScreenProperties() {
+  auto& screenManager = mozilla::widget::ScreenManager::GetSingleton();
+  RefPtr<mozilla::widget::Screen> screen = screenManager.GetPrimaryScreen();
+  MOZ_ASSERT(screen);
+
+  mozilla::dom::ScreenColorGamut colorGamut;
+  screen->GetColorGamut(&colorGamut);
+  mozilla::glean::characteristics::color_gamut.Set((int)colorGamut);
+
+  int32_t colorDepth;
+  screen->GetColorDepth(&colorDepth);
+  mozilla::glean::characteristics::color_depth.Set(colorDepth);
+
+  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());
+}
+
+void PopulateMissingFonts() {
+  nsCString aMissingFonts;
+  gfxPlatformFontList::PlatformFontList()->GetMissingFonts(aMissingFonts);
+
+  mozilla::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);
+
+  mozilla::glean::characteristics::prefs_media_eme_enabled.Set(
+      mozilla::StaticPrefs::media_eme_enabled());
+
+  mozilla::glean::characteristics::prefs_zoom_text_only.Set(
+      !mozilla::Preferences::GetBool("browser.zoom.full"));
+}
+
+// ==================================================================
+// The current schema of the data. Anytime you add a metric, or change how a
+// 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;
+
+/* static */
+void nsUserCharacteristics::MaybeSubmitPing() {
+  MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+          ("In MaybeSubmitPing()"));
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  /**
+   * There are two preferences at play here:
+   *  - Last Version Sent - preference containing the last version sent by the
+   * user to Mozilla
+   *  - Current Version - preference containing the version Mozilla would like
+   * the user to send
+   *
+   * A point of complexity arises in that these two values _may_ be changed
+   * by the user, even though neither is intended to be.
+   *
+   * When Current Version > Last Version Sent, we intend for the user to submit
+   * a new ping, which will include the schema version. Then update Last Version
+   * 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);
+
+  MOZ_ASSERT(currentVersion == -1 || lastSubmissionVersion <= currentVersion,
+             "lastSubmissionVersion is somehow greater than currentVersion "
+             "- did you edit prefs improperly?");
+
+  if (lastSubmissionVersion < 0) {
+    // This is a way for users to opt out of this ping specifically.
+    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Debug,
+            ("Returning, User Opt-out"));
+    return;
+  }
+  if (currentVersion == 0) {
+    // Do nothing. We do not want any pings.
+    MOZ_LOG(gUserCharacteristicsLog, mozilla::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,
+            ("Force-Submitting Ping"));
+    if (NS_SUCCEEDED(PopulateData())) {
+      SubmitPing();
+    }
+    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,
+            ("Returning, lastSubmissionVersion > currentVersion"));
+    return;
+  }
+  if (lastSubmissionVersion == currentVersion) {
+    // We are okay, we've already submitted the most recent ping
+    MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Warning,
+            ("Returning, lastSubmissionVersion == currentVersion"));
+    return;
+  }
+  if (lastSubmissionVersion < currentVersion) {
+    if (NS_SUCCEEDED(PopulateData())) {
+      if (NS_SUCCEEDED(SubmitPing())) {
+        mozilla::Preferences::SetInt(kLastVersionPref, currentVersion);
+      }
+    }
+  } else {
+    MOZ_ASSERT_UNREACHABLE("Should never reach here");
+  }
+}
+
+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"));
+  MOZ_ASSERT(XRE_IsParentProcess());
+  mozilla::glean::characteristics::submission_schema.Set(kSubmissionSchema);
+
+  nsAutoCString uuidString;
+  nsresult rv = mozilla::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);
+
+    nsIDToCString id(nsID::GenerateUUID());
+    uuidString = id.get();
+    mozilla::Preferences::SetCString(kUUIDPref, uuidString);
+  }
+  mozilla::glean::characteristics::client_identifier.Set(uuidString);
+
+  mozilla::glean::characteristics::max_touch_points.Set(
+      testing::MaxTouchPoints());
+
+  if (aTesting) {
+    // Many of the later peices of data do not work in a gtest
+    // so just populate something, and return
+    return NS_OK;
+  }
+
+  PopulateMissingFonts();
+  PopulateCSSProperties();
+  PopulateScreenProperties();
+  PopulatePrefs();
+
+  mozilla::glean::characteristics::target_frame_rate.Set(
+      gfxPlatform::TargetFrameRate());
+
+  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();
+  }
+#endif
+  if (processorCount == 0) {
+    processorCount = PR_GetNumberOfProcessors();
+  }
+  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);
+  } else {
+    mozilla::glean::characteristics::timezone.Set("<error>"_ns);
+  }
+
+  return NS_OK;
+}
+
+/* static */
+nsresult nsUserCharacteristics::SubmitPing() {
+  MOZ_LOG(gUserCharacteristicsLog, mozilla::LogLevel::Warning,
+          ("Submitting Ping"));
+  mozilla::glean_pings::UserCharacteristics.Submit();
+
+  return NS_OK;
+}
diff --git a/toolkit/components/resistfingerprinting/nsUserCharacteristics.h b/toolkit/components/resistfingerprinting/nsUserCharacteristics.h
new file mode 100644
index 0000000000..a52bc9aea7
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/nsUserCharacteristics.h
@@ -0,0 +1,28 @@
+/* -*- 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/. */
+
+#ifndef __nsUserCharacteristics_h__
+#define __nsUserCharacteristics_h__
+
+#include "ErrorList.h"
+
+class nsUserCharacteristics {
+ public:
+  static void MaybeSubmitPing();
+
+  // Public For testing
+  static nsresult PopulateData(bool aTesting = false);
+  static nsresult SubmitPing();
+};
+
+namespace testing {
+extern "C" {  // Needed to call these in the gtest
+
+int MaxTouchPoints();
+
+}  // extern "C"
+};  // namespace testing
+
+#endif /*  __nsUserCharacteristics_h__ */
diff --git a/toolkit/components/resistfingerprinting/pings.yaml b/toolkit/components/resistfingerprinting/pings.yaml
new file mode 100644
index 0000000000..46a4b2da19
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/pings.yaml
@@ -0,0 +1,19 @@
+# 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/.
+
+---
+$schema: moz://mozilla.org/schemas/glean/pings/2-0-0
+
+user-characteristics:
+  description: |
+    A ping representing user hardware and software settings.  Note that this
+    ping does not include client_id.  More details are available in Bug 1879151
+  include_client_id: false
+  bugs:
+    - https://bugzilla.mozilla.org/show_bug.cgi?id=1879151
+    - https://bugzilla.mozilla.org/show_bug.cgi?id=1879154
+  data_reviews:
+    - https://bugzilla.mozilla.org/show_bug.cgi?id=1879154#c8
+  notification_emails:
+    - tritter@mozilla.com
diff --git a/toolkit/components/resistfingerprinting/tests/gtest/moz.build b/toolkit/components/resistfingerprinting/tests/gtest/moz.build
index dcc6a7e12e..a677def009 100644
--- a/toolkit/components/resistfingerprinting/tests/gtest/moz.build
+++ b/toolkit/components/resistfingerprinting/tests/gtest/moz.build
@@ -1,5 +1,6 @@
 UNIFIED_SOURCES += [
     "test_reduceprecision.cpp",
+    "test_usercharping.cpp",
 ]
 
 FINAL_LIBRARY = "xul-gtest"
diff --git a/toolkit/components/resistfingerprinting/tests/gtest/test_usercharping.cpp b/toolkit/components/resistfingerprinting/tests/gtest/test_usercharping.cpp
new file mode 100644
index 0000000000..dd1cbe7d46
--- /dev/null
+++ b/toolkit/components/resistfingerprinting/tests/gtest/test_usercharping.cpp
@@ -0,0 +1,143 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * 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/. */
+
+#include "gtest/gtest.h"
+#include "mozilla/gtest/nsUserCharacteristics.h"
+
+#include "mozilla/glean/GleanPings.h"
+#include "mozilla/glean/GleanMetrics.h"
+
+using namespace mozilla;
+
+const auto* const kUUIDPref =
+    "toolkit.telemetry.user_characteristics_ping.uuid";
+
+TEST(ResistFingerprinting, UserCharacteristics_Simple)
+{
+  mozilla::glean::characteristics::max_touch_points.Set(7);
+
+  bool submitted = false;
+  mozilla::glean_pings::UserCharacteristics.TestBeforeNextSubmit(
+      [&submitted](const nsACString& aReason) {
+        submitted = true;
+
+        ASSERT_EQ(
+            7, mozilla::glean::characteristics::max_touch_points.TestGetValue()
+                   .unwrap()
+                   .ref());
+      });
+  mozilla::glean_pings::UserCharacteristics.Submit();
+  ASSERT_TRUE(submitted);
+}
+
+TEST(ResistFingerprinting, UserCharacteristics_Complex)
+{
+  nsUserCharacteristics::PopulateData(true);
+
+  bool submitted = false;
+  mozilla::glean_pings::UserCharacteristics.TestBeforeNextSubmit(
+      [&submitted](const nsACString& aReason) {
+        submitted = true;
+
+        ASSERT_STRNE("", mozilla::glean::characteristics::client_identifier
+                             .TestGetValue()
+                             .unwrap()
+                             .value()
+                             .get());
+
+        nsCString fullUuidStr;
+        Preferences::GetCString(kUUIDPref, fullUuidStr);
+
+        // Remove the '{' and '}'
+        nsAutoCString uuidString;
+        uuidString = Substring(fullUuidStr, 1, NSID_LENGTH - 3);
+
+        ASSERT_STREQ(
+            uuidString.get(),
+            mozilla::glean::characteristics::client_identifier.TestGetValue()
+                .unwrap()
+                .value()
+                .get());
+        ASSERT_EQ(
+            testing::MaxTouchPoints(),
+            mozilla::glean::characteristics::max_touch_points.TestGetValue()
+                .unwrap()
+                .ref());
+      });
+  nsUserCharacteristics::SubmitPing();
+  ASSERT_TRUE(submitted);
+}
+
+TEST(ResistFingerprinting, UserCharacteristics_ClearPref)
+{
+  nsCString originalUUID;
+
+  mozilla::glean_pings::UserCharacteristics.TestBeforeNextSubmit(
+      [&originalUUID](const nsACString& aReason) {
+        originalUUID =
+            mozilla::glean::characteristics::client_identifier.TestGetValue()
+                .unwrap()
+                .value()
+                .get();
+        ASSERT_STRNE("", mozilla::glean::characteristics::client_identifier
+                             .TestGetValue()
+                             .unwrap()
+                             .value()
+                             .get());
+
+        nsCString fullUuidStr;
+        Preferences::GetCString(kUUIDPref, fullUuidStr);
+
+        // Remove the '{' and '}'
+        nsAutoCString uuidString;
+        uuidString = Substring(fullUuidStr, 1, NSID_LENGTH - 3);
+
+        ASSERT_STREQ(
+            uuidString.get(),
+            mozilla::glean::characteristics::client_identifier.TestGetValue()
+                .unwrap()
+                .value()
+                .get());
+      });
+  nsUserCharacteristics::PopulateData(true);
+  nsUserCharacteristics::SubmitPing();
+
+  auto original_value =
+      Preferences::GetBool("datareporting.healthreport.uploadEnabled");
+  Preferences::SetBool("datareporting.healthreport.uploadEnabled", true);
+  Preferences::SetBool("datareporting.healthreport.uploadEnabled", false);
+
+  mozilla::glean_pings::UserCharacteristics.TestBeforeNextSubmit(
+      [](const nsACString& aReason) {
+        // Assert that the pref is blank
+        nsAutoCString uuidValue;
+        Preferences::GetCString(kUUIDPref, uuidValue);
+        ASSERT_STREQ("", uuidValue.get());
+      });
+  nsUserCharacteristics::SubmitPing();
+
+  Preferences::SetBool("datareporting.healthreport.uploadEnabled", true);
+  mozilla::glean_pings::UserCharacteristics.TestBeforeNextSubmit(
+      [&originalUUID](const nsACString& aReason) {
+        // Assert that the new UUID is different from the old one
+        ASSERT_STRNE(
+            originalUUID.get(),
+            mozilla::glean::characteristics::client_identifier.TestGetValue()
+                .unwrap()
+                .value()
+                .get());
+
+        // Assert that the pref is not blank
+        nsAutoCString uuidValue;
+        Preferences::GetCString(kUUIDPref, uuidValue);
+        ASSERT_STRNE("", uuidValue.get());
+      });
+  nsUserCharacteristics::PopulateData(true);
+  nsUserCharacteristics::SubmitPing();
+
+  Preferences::SetBool("datareporting.healthreport.uploadEnabled",
+                       original_value);
+}