Bug 1799435 - Make RFP checks faster. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D161447

dom/base/Document.cpp

@@ -1413,6 +1413,12 @@ Document::Document(const char* aContentType)
       mIsRunningExecCommand(false),
       mSetCompleteAfterDOMContentLoaded(false),
       mDidHitCompleteSheetCache(false),
+      mUseCountersInitialized(false),
+      mShouldReportUseCounters(false),
+      mShouldSendPageUseCounters(false),
+      mUserHasInteracted(false),
+      mHasUserInteractionTimerScheduled(false),
+      mShouldResistFingerprinting(false),
       mPendingFullscreenRequests(0),
       mXMLDeclarationBits(0),
       mOnloadBlockCount(0),
@@ -1441,11 +1447,6 @@ Document::Document(const char* aContentType)
       mBFCacheEntry(nullptr),
       mInSyncOperationCount(0),
       mBlockDOMContentLoaded(0),
-      mUseCountersInitialized(false),
-      mShouldReportUseCounters(false),
-      mShouldSendPageUseCounters(false),
-      mUserHasInteracted(false),
-      mHasUserInteractionTimerScheduled(false),
       mStackRefCnt(0),
       mUpdateNestLevel(0),
       mHttpsOnlyStatus(nsILoadInfo::HTTPS_ONLY_UNINITIALIZED),
@@ -2833,6 +2834,7 @@ void Document::Reset(nsIChannel* aChannel, nsILoadGroup* aLoadGroup) {
   }
 
   mChannel = aChannel;
+  RecomputeResistFingerprinting();
 }
 
 void Document::DisconnectNodeTree() {
@@ -3454,6 +3456,7 @@ nsresult Document::StartDocumentLoad(const char* aCommand, nsIChannel* aChannel,
   RetrieveRelevantHeaders(aChannel);
 
   mChannel = aChannel;
+  RecomputeResistFingerprinting();
   nsCOMPtr<nsIInputStreamChannel> inStrmChan = do_QueryInterface(mChannel);
   if (inStrmChan) {
     bool isSrcdocChannel;
@@ -11867,6 +11870,7 @@ nsresult Document::CloneDocHelper(Document* clone) const {
       uri = Document::GetDocumentURI();
     }
     clone->mChannel = channel;
+    clone->mShouldResistFingerprinting = mShouldResistFingerprinting;
     if (uri) {
       clone->ResetToURI(uri, loadGroup, NodePrincipal(), mPartitionedPrincipal);
     }
@@ -15687,6 +15691,12 @@ void Document::SendPageUseCounters() {
   wgc->SendAccumulatePageUseCounters(counters);
 }
 
+void Document::RecomputeResistFingerprinting() {
+  mShouldResistFingerprinting =
+      !nsContentUtils::IsChromeDoc(this) &&
+      nsContentUtils::ShouldResistFingerprinting(mChannel);
+}
+
 WindowContext* Document::GetWindowContextForPageUseCounters() const {
   if (mDisplayDocument) {
     // If we are a resource document, then go through it to find the
@@ -17842,8 +17852,7 @@ ColorScheme Document::DefaultColorScheme() const {
 }
 
 ColorScheme Document::PreferredColorScheme(IgnoreRFP aIgnoreRFP) const {
-  if (aIgnoreRFP == IgnoreRFP::No &&
+  if (ShouldResistFingerprinting() && aIgnoreRFP == IgnoreRFP::No) {
-      nsContentUtils::ShouldResistFingerprinting(this)) {
     return ColorScheme::Light;
   }
 

dom/base/Document.h

@@ -4087,6 +4087,12 @@ class Document : public nsINode,
 
   bool DidHitCompleteSheetCache() const { return mDidHitCompleteSheetCache; }
 
+  bool ShouldResistFingerprinting() const {
+    return mShouldResistFingerprinting;
+  }
+
+  void RecomputeResistFingerprinting();
+
  protected:
   // Returns the WindowContext for the document that we will contribute
   // page use counters to.
@@ -4827,6 +4833,29 @@ class Document : public nsINode,
   // Set the true if a completed cached stylesheet was created for the document.
   bool mDidHitCompleteSheetCache : 1;
 
+  // Whether we have initialized mShouldReportUseCounters and
+  // mShouldSendPageUseCounters, and sent any needed message to the parent
+  // process to indicate that use counter data will be sent at some later point.
+  bool mUseCountersInitialized : 1;
+
+  // Whether this document should report use counters.
+  bool mShouldReportUseCounters : 1;
+
+  // Whether this document should send page use counters.  Set to true after
+  // we've called SendExpectPageUseCounters on the top-level WindowGlobal.
+  bool mShouldSendPageUseCounters : 1;
+
+  // Whether the user has interacted with the document or not:
+  bool mUserHasInteracted : 1;
+
+  // We constantly update the user-interaction anti-tracking permission at any
+  // user-interaction using a timer. This boolean value is set to true when this
+  // timer is scheduled.
+  bool mHasUserInteractionTimerScheduled : 1;
+
+  // Whether we should resist fingerprinting.
+  bool mShouldResistFingerprinting : 1;
+
   uint8_t mPendingFullscreenRequests;
 
   uint8_t mXMLDeclarationBits;
@@ -5033,26 +5062,6 @@ class Document : public nsINode,
   // The CSS property use counters.
   UniquePtr<StyleUseCounters> mStyleUseCounters;
 
-  // Whether we have initialized mShouldReportUseCounters and
-  // mShouldSendPageUseCounters, and sent any needed message to the parent
-  // process to indicate that use counter data will be sent at some later point.
-  bool mUseCountersInitialized : 1;
-
-  // Whether this document should report use counters.
-  bool mShouldReportUseCounters : 1;
-
-  // Whether this document should send page use counters.  Set to true after
-  // we've called SendExpectPageUseCounters on the top-level WindowGlobal.
-  bool mShouldSendPageUseCounters : 1;
-
-  // Whether the user has interacted with the document or not:
-  bool mUserHasInteracted;
-
-  // We constantly update the user-interaction anti-tracking permission at any
-  // user-interaction using a timer. This boolean value is set to true when this
-  // timer is scheduled.
-  bool mHasUserInteractionTimerScheduled;
-
   TimeStamp mPageUnloadingEventTimeStamp;
 
   RefPtr<DocGroup> mDocGroup;

dom/base/Element.cpp

@@ -278,7 +278,7 @@ nsDOMAttributeMap* Element::Attributes() {
 }
 
 void Element::SetPointerCapture(int32_t aPointerId, ErrorResult& aError) {
-  if (nsContentUtils::ShouldResistFingerprinting(GetComposedDoc()) &&
+  if (OwnerDoc()->ShouldResistFingerprinting() &&
       aPointerId != PointerEventHandler::GetSpoofedPointerIdForRFP()) {
     aError.ThrowNotFoundError("Invalid pointer id");
     return;
@@ -307,7 +307,7 @@ void Element::SetPointerCapture(int32_t aPointerId, ErrorResult& aError) {
 }
 
 void Element::ReleasePointerCapture(int32_t aPointerId, ErrorResult& aError) {
-  if (nsContentUtils::ShouldResistFingerprinting(GetComposedDoc()) &&
+  if (OwnerDoc()->ShouldResistFingerprinting() &&
       aPointerId != PointerEventHandler::GetSpoofedPointerIdForRFP()) {
     aError.ThrowNotFoundError("Invalid pointer id");
     return;

dom/base/Navigator.cpp

@@ -650,7 +650,7 @@ uint64_t Navigator::HardwareConcurrency() {
   }
 
   return rts->ClampedHardwareConcurrency(
-      nsContentUtils::ShouldResistFingerprinting(mWindow->GetExtantDoc()));
+      nsGlobalWindowInner::Cast(mWindow)->ShouldResistFingerprinting());
 }
 
 namespace {
@@ -1564,6 +1564,11 @@ void Navigator::ValidateShareData(const ShareData& aData, ErrorResult& aRv) {
   }
 }
 
+static bool ShouldResistFingerprinting(const Document* aDoc) {
+  return aDoc ? aDoc->ShouldResistFingerprinting()
+              : nsContentUtils::ShouldResistFingerprinting("Fallback");
+}
+
 already_AddRefed<LegacyMozTCPSocket> Navigator::MozTCPSocket() {
   RefPtr<LegacyMozTCPSocket> socket = new LegacyMozTCPSocket(GetWindow());
   return socket.forget();
@@ -1808,9 +1813,9 @@ network::Connection* Navigator::GetConnection(ErrorResult& aRv) {
       aRv.Throw(NS_ERROR_UNEXPECTED);
       return nullptr;
     }
-    nsCOMPtr<Document> doc = mWindow->GetExtantDoc();
     mConnection = network::Connection::CreateForWindow(
-        mWindow, nsContentUtils::ShouldResistFingerprinting(doc));
+        mWindow,
+        nsGlobalWindowInner::Cast(mWindow)->ShouldResistFingerprinting());
   }
 
   return mConnection;
@@ -1918,7 +1923,7 @@ nsresult Navigator::GetPlatform(nsAString& aPlatform, Document* aCallerDoc,
   if (aUsePrefOverriddenValue) {
     // If fingerprinting resistance is on, we will spoof this value. See
     // nsRFPService.h for details about spoofed values.
-    if (nsContentUtils::ShouldResistFingerprinting(aCallerDoc)) {
+    if (ShouldResistFingerprinting(aCallerDoc)) {
       aPlatform.AssignLiteral(SPOOFED_PLATFORM);
       return NS_OK;
     }
@@ -1961,7 +1966,7 @@ nsresult Navigator::GetAppVersion(nsAString& aAppVersion, Document* aCallerDoc,
   if (aUsePrefOverriddenValue) {
     // If fingerprinting resistance is on, we will spoof this value. See
     // nsRFPService.h for details about spoofed values.
-    if (nsContentUtils::ShouldResistFingerprinting(aCallerDoc)) {
+    if (ShouldResistFingerprinting(aCallerDoc)) {
       aAppVersion.AssignLiteral(SPOOFED_APPVERSION);
       return NS_OK;
     }
@@ -2005,7 +2010,7 @@ void Navigator::AppName(nsAString& aAppName, Document* aCallerDoc,
   if (aUsePrefOverriddenValue) {
     // If fingerprinting resistance is on, we will spoof this value. See
     // nsRFPService.h for details about spoofed values.
-    if (nsContentUtils::ShouldResistFingerprinting(aCallerDoc)) {
+    if (ShouldResistFingerprinting(aCallerDoc)) {
       aAppName.AssignLiteral(SPOOFED_APPNAME);
       return;
     }
@@ -2050,7 +2055,7 @@ nsresult Navigator::GetUserAgent(nsPIDOMWindowInner* aWindow,
   bool shouldResistFingerprinting =
       aShouldResistFingerprinting.isSome()
           ? aShouldResistFingerprinting.value()
-          : nsContentUtils::ShouldResistFingerprinting(aCallerDoc);
+          : ShouldResistFingerprinting(aCallerDoc);
 
   // We will skip the override and pass to httpHandler to get spoofed userAgent
   // when 'privacy.resistFingerprinting' is true.

dom/base/nsContentUtils.cpp

@@ -97,6 +97,7 @@
 #include "mozilla/MacroForEach.h"
 #include "mozilla/ManualNAC.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/MediaFeatureChange.h"
 #include "mozilla/MouseEvents.h"
 #include "mozilla/NotNull.h"
 #include "mozilla/NullPrincipal.h"
@@ -731,6 +732,33 @@ class nsContentUtils::UserInteractionObserver final
   ~UserInteractionObserver() = default;
 };
 
+static constexpr nsLiteralCString kRfpPrefs[] = {
+    "privacy.resistFingerprinting"_ns,
+    "privacy.resistFingerprinting.testGranularityMask"_ns,
+};
+
+static void RecomputeResistFingerprintingAllDocs(const char*, void*) {
+  AutoTArray<RefPtr<BrowsingContextGroup>, 5> bcGroups;
+  BrowsingContextGroup::GetAllGroups(bcGroups);
+  for (auto& bcGroup : bcGroups) {
+    AutoTArray<DocGroup*, 5> docGroups;
+    bcGroup->GetDocGroups(docGroups);
+    for (auto* docGroup : docGroups) {
+      for (Document* doc : *docGroup) {
+        const bool old = doc->ShouldResistFingerprinting();
+        doc->RecomputeResistFingerprinting();
+        if (old != doc->ShouldResistFingerprinting()) {
+          if (auto* pc = doc->GetPresContext()) {
+            pc->MediaFeatureValuesChanged(
+                {MediaFeatureChangeReason::PreferenceChange},
+                MediaFeatureChangePropagation::JustThisDocument);
+          }
+        }
+      }
+    }
+  }
+}
+
 // static
 nsresult nsContentUtils::Init() {
   if (sInitialized) {
@@ -804,6 +832,10 @@ nsresult nsContentUtils::Init() {
   uio->Init();
   uio.forget(&sUserInteractionObserver);
 
+  for (const auto& pref : kRfpPrefs) {
+    Preferences::RegisterCallback(RecomputeResistFingerprintingAllDocs, pref);
+  }
+
   sInitialized = true;
 
   return NS_OK;
@@ -1932,6 +1964,10 @@ void nsContentUtils::Shutdown() {
     NS_RELEASE(sUserInteractionObserver);
   }
 
+  for (const auto& pref : kRfpPrefs) {
+    Preferences::UnregisterCallback(RecomputeResistFingerprintingAllDocs, pref);
+  }
+
   TextControlState::Shutdown();
   nsMappedAttributes::Shutdown();
 }
@@ -2179,27 +2215,18 @@ bool nsContentUtils::ShouldResistFingerprinting(const char* aJustification) {
 bool nsContentUtils::ShouldResistFingerprinting(nsIDocShell* aDocShell) {
   if (!aDocShell) {
     MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
-            ("Called nsContentUtils::ShouldResistFingerprinting(const "
+            ("Called nsContentUtils::ShouldResistFingerprinting(nsIDocShell*) "
-             "nsIDocShell* aDocShell) with NULL docshell"));
+             "with NULL docshell"));
     return ShouldResistFingerprinting();
   }
-  return ShouldResistFingerprinting(aDocShell->GetDocument());
+  Document* doc = aDocShell->GetDocument();
-}
+  if (!doc) {
-
-// --------------------------------------------------------------------
-/* static */
-bool nsContentUtils::ShouldResistFingerprinting(const Document* aDoc) {
-  if (!aDoc) {
     MOZ_LOG(nsContentUtils::ResistFingerprintingLog(), LogLevel::Info,
-            ("Called nsContentUtils::ShouldResistFingerprinting(const "
+            ("Called nsContentUtils::ShouldResistFingerprinting(nsIDocShell*) "
-             "Document* aDoc) with NULL document"));
+             "with NULL doc"));
     return ShouldResistFingerprinting();
   }
-  bool isChrome = nsContentUtils::IsChromeDoc(aDoc);
+  return doc->ShouldResistFingerprinting();
-  if (isChrome) {
-    return false;
-  }
-  return ShouldResistFingerprinting(aDoc->GetChannel());
 }
 
 // ----------------------------------------------------------------------

dom/base/nsContentUtils.h

@@ -350,7 +350,6 @@ class nsContentUtils {
   static bool ShouldResistFingerprinting(nsIGlobalObject* aGlobalObject);
   static bool ShouldResistFingerprinting(nsIDocShell* aDocShell);
   // These functions are the new, nuanced functions
-  static bool ShouldResistFingerprinting(const Document* aDoc);
   static bool ShouldResistFingerprinting(nsIChannel* aChannel);
   static bool ShouldResistFingerprinting(nsILoadInfo* aPrincipal);
   // These functions are labeled as dangerous because they will do the wrong

dom/base/nsGlobalWindowInner.cpp

@@ -1625,7 +1625,7 @@ bool nsGlobalWindowInner::IsBlackForCC(bool aTracingNeeded) {
 
 bool nsGlobalWindowInner::ShouldResistFingerprinting() const {
   if (mDoc) {
-    return nsContentUtils::ShouldResistFingerprinting(mDoc);
+    return mDoc->ShouldResistFingerprinting();
   }
   return nsIScriptGlobalObject::ShouldResistFingerprinting();
 }
@@ -4982,10 +4982,8 @@ Storage* nsGlobalWindowInner::GetLocalStorage(ErrorResult& aError) {
   if (mDoc) {
     cookieJarSettings = mDoc->CookieJarSettings();
   } else {
-    bool shouldResistFingerprinting =
-        nsContentUtils::ShouldResistFingerprinting(this->GetExtantDoc());
     cookieJarSettings =
-        net::CookieJarSettings::GetBlockingAll(shouldResistFingerprinting);
+        net::CookieJarSettings::GetBlockingAll(ShouldResistFingerprinting());
   }
 
   // Note that this behavior is observable: if we grant storage permission to a
@@ -6584,7 +6582,7 @@ void nsGlobalWindowInner::DisableDeviceSensor(uint32_t aType) {
 
 #if defined(MOZ_WIDGET_ANDROID)
 void nsGlobalWindowInner::EnableOrientationChangeListener() {
-  if (!nsContentUtils::ShouldResistFingerprinting(GetDocShell())) {
+  if (!ShouldResistFingerprinting()) {
     mHasOrientationChangeListeners = true;
     mOrientationAngle = Orientation(CallerType::System);
   }
@@ -6911,7 +6909,7 @@ void nsGlobalWindowInner::GetGamepads(nsTArray<RefPtr<Gamepad>>& aGamepads) {
 
   // navigator.getGamepads() always returns an empty array when
   // privacy.resistFingerprinting is true.
-  if (nsContentUtils::ShouldResistFingerprinting(GetDocShell())) {
+  if (ShouldResistFingerprinting()) {
     return;
   }
 
@@ -7559,7 +7557,7 @@ void nsGlobalWindowInner::SetReplaceableWindowCoord(
     return;
   }
 
-  if (nsContentUtils::ShouldResistFingerprinting(GetDocShell())) {
+  if (ShouldResistFingerprinting()) {
     bool innerWidthSpecified = false;
     bool innerHeightSpecified = false;
     bool outerWidthSpecified = false;

dom/base/nsGlobalWindowOuter.cpp

@@ -1668,7 +1668,7 @@ bool nsGlobalWindowOuter::IsBlackForCC(bool aTracingNeeded) {
 
 bool nsGlobalWindowOuter::ShouldResistFingerprinting() const {
   if (mDoc) {
-    return nsContentUtils::ShouldResistFingerprinting(mDoc);
+    return mDoc->ShouldResistFingerprinting();
   }
   return nsIScriptGlobalObject::ShouldResistFingerprinting();
 }

dom/base/nsMimeTypeArray.cpp

@@ -8,6 +8,7 @@
 
 #include "mozilla/dom/MimeTypeArrayBinding.h"
 #include "mozilla/dom/MimeTypeBinding.h"
+#include "nsGlobalWindowInner.h"
 #include "nsPluginArray.h"
 #include "mozilla/StaticPrefs_pdfjs.h"
 #include "nsContentUtils.h"
@@ -81,7 +82,7 @@ void nsMimeTypeArray::GetSupportedNames(nsTArray<nsString>& retval) {
 
 bool nsMimeTypeArray::ForceNoPlugins() {
   return StaticPrefs::pdfjs_disabled() &&
-         !nsContentUtils::ShouldResistFingerprinting(mWindow->GetExtantDoc());
+         !nsGlobalWindowInner::Cast(mWindow)->ShouldResistFingerprinting();
 }
 
 NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(nsMimeType, AddRef)

dom/base/nsPluginArray.cpp

@@ -12,6 +12,7 @@
 
 #include "nsMimeTypeArray.h"
 #include "nsPIDOMWindow.h"
+#include "nsGlobalWindowInner.h"
 #include "nsContentUtils.h"
 
 using namespace mozilla;
@@ -99,7 +100,7 @@ void nsPluginArray::GetSupportedNames(nsTArray<nsString>& aRetval) {
 
 bool nsPluginArray::ForceNoPlugins() {
   return StaticPrefs::pdfjs_disabled() &&
-         !nsContentUtils::ShouldResistFingerprinting(mWindow->GetExtantDoc());
+         !nsGlobalWindowInner::Cast(mWindow)->ShouldResistFingerprinting();
 }
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(nsPluginArray)

dom/canvas/CanvasUtils.cpp

@@ -53,12 +53,20 @@ namespace mozilla::CanvasUtils {
 bool IsImageExtractionAllowed(dom::Document* aDocument, JSContext* aCx,
                               Maybe<nsIPrincipal*> aPrincipal) {
   // Do the rest of the checks only if privacy.resistFingerprinting is on.
-  if (!nsContentUtils::ShouldResistFingerprinting(aDocument)) {
+  if (!nsContentUtils::ShouldResistFingerprinting()) {
+    return true;
+  }
+
+  if (!aDocument) {
+    return false;
+  }
+
+  if (!aDocument->ShouldResistFingerprinting()) {
     return true;
   }
 
   // Don't proceed if we don't have a document or JavaScript context.
-  if (!aDocument || !aCx || !aPrincipal) {
+  if (!aCx || !aPrincipal) {
     return false;
   }
 

dom/canvas/ClientWebGLContext.cpp

@@ -5653,8 +5653,8 @@ void ClientWebGLContext::GetSupportedProfilesASTC(
 
 bool ClientWebGLContext::ShouldResistFingerprinting() const {
   if (mCanvasElement) {
-    // If we're constructed from a canvas element
+    // If we're constructed from a canvas element.
-    return nsContentUtils::ShouldResistFingerprinting(GetOwnerDoc());
+    return mCanvasElement->OwnerDoc()->ShouldResistFingerprinting();
   }
   if (mOffscreenCanvas) {
     // If we're constructed from an offscreen canvas

dom/events/KeyboardEvent.cpp

@@ -360,23 +360,22 @@ void KeyboardEvent::InitKeyboardEventJS(
 
 bool KeyboardEvent::ShouldResistFingerprinting(CallerType aCallerType) {
   // There are five situations we don't need to spoof this keyboard event.
-  //   1. This event is initialized by scripts.
+  //   1. The pref privcy.resistFingerprinting' is false, we fast return here
-  //   2. This event is from Numpad.
-  //   3. This event is in the system group.
-  //   4. The caller type is system.
-  //   5. The pref privcy.resistFingerprinting' is false, we fast return here
   //      since we don't need to do any QI of following codes.
-  if (mInitializedByJS || aCallerType == CallerType::System ||
+  //   2. This event is initialized by scripts.
-      mEvent->mFlags.mInSystemGroup ||
+  //   3. This event is from Numpad.
-      !nsContentUtils::ShouldResistFingerprinting() ||
+  //   4. This event is in the system group.
+  //   5. The caller type is system.
+  if (!nsContentUtils::ShouldResistFingerprinting() || mInitializedByJS ||
+      aCallerType == CallerType::System || mEvent->mFlags.mInSystemGroup ||
       mEvent->AsKeyboardEvent()->mLocation ==
           KeyboardEvent_Binding::DOM_KEY_LOCATION_NUMPAD) {
     return false;
   }
 
   nsCOMPtr<Document> doc = GetDocument();
-
+  // We've checked the pref above, so use true as fallback if doc is null.
-  return nsContentUtils::ShouldResistFingerprinting(doc);
+  return doc ? doc->ShouldResistFingerprinting() : true;
 }
 
 bool KeyboardEvent::GetSpoofedModifierStates(const Modifiers aModifierKey,

dom/events/PointerEvent.cpp

@@ -278,23 +278,23 @@ void PointerEvent::GetPredictedEvents(
 
 bool PointerEvent::ShouldResistFingerprinting(CallerType aCallerType) {
   // There are four situations we don't need to spoof this pointer event.
-  //   1. This event is generated by scripts.
+  //   1. The pref privcy.resistFingerprinting' is false, we fast return here
-  //   2. This event is a mouse pointer event.
-  //   3. The caller type is system.
-  //   4. The pref privcy.resistFingerprinting' is false, we fast return here
   //      since we don't need to do any QI of following codes.
+  //   2. This event is generated by scripts.
+  //   3. This event is a mouse pointer event.
+  //   4. The caller type is system.
   //  We don't need to check for the system group since pointer events won't be
   //  dispatched to the system group.
-  if (!mEvent->IsTrusted() || aCallerType == CallerType::System ||
+  if (!nsContentUtils::ShouldResistFingerprinting() || !mEvent->IsTrusted() ||
-      !nsContentUtils::ShouldResistFingerprinting() ||
+      aCallerType == CallerType::System ||
       mEvent->AsPointerEvent()->mInputSource ==
           MouseEvent_Binding::MOZ_SOURCE_MOUSE) {
     return false;
   }
 
+  // Pref is checked above, so use true as fallback.
   nsCOMPtr<Document> doc = GetDocument();
-
+  return doc ? doc->ShouldResistFingerprinting() : true;
-  return nsContentUtils::ShouldResistFingerprinting(doc);
 }
 
 }  // namespace mozilla::dom

dom/gamepad/GamepadManager.cpp

@@ -144,8 +144,7 @@ void GamepadManager::AddListener(nsGlobalWindowInner* aWindow) {
     }
   }
 
-  if (!mEnabled || mShuttingDown ||
+  if (!mEnabled || mShuttingDown || aWindow->ShouldResistFingerprinting()) {
-      nsContentUtils::ShouldResistFingerprinting(aWindow->GetExtantDoc())) {
     return;
   }
 
@@ -280,8 +279,7 @@ void GamepadManager::NewConnectionEvent(GamepadHandle aHandle,
 
       // Do not fire gamepadconnected and gamepaddisconnected events when
       // privacy.resistFingerprinting is true.
-      if (nsContentUtils::ShouldResistFingerprinting(
+      if (listeners[i]->ShouldResistFingerprinting()) {
-              listeners[i]->GetExtantDoc())) {
         continue;
       }
 
@@ -314,8 +312,7 @@ void GamepadManager::NewConnectionEvent(GamepadHandle aHandle,
 
       // Do not fire gamepadconnected and gamepaddisconnected events when
       // privacy.resistFingerprinting is true.
-      if (nsContentUtils::ShouldResistFingerprinting(
+      if (listeners[i]->ShouldResistFingerprinting()) {
-              listeners[i]->GetExtantDoc())) {
         continue;
       }
 
@@ -350,8 +347,7 @@ void GamepadManager::FireConnectionEvent(EventTarget* aTarget,
 void GamepadManager::SyncGamepadState(GamepadHandle aHandle,
                                       nsGlobalWindowInner* aWindow,
                                       Gamepad* aGamepad) {
-  if (mShuttingDown || !mEnabled ||
+  if (mShuttingDown || !mEnabled || aWindow->ShouldResistFingerprinting()) {
-      nsContentUtils::ShouldResistFingerprinting(aWindow->GetExtantDoc())) {
     return;
   }
 

dom/html/HTMLVideoElement.cpp

@@ -259,7 +259,7 @@ uint32_t HTMLVideoElement::MozParsedFrames() const {
     return 0;
   }
 
-  if (nsContentUtils::ShouldResistFingerprinting(OwnerDoc())) {
+  if (OwnerDoc()->ShouldResistFingerprinting()) {
     return nsRFPService::GetSpoofedTotalFrames(TotalPlayTime());
   }
 
@@ -272,7 +272,7 @@ uint32_t HTMLVideoElement::MozDecodedFrames() const {
     return 0;
   }
 
-  if (nsContentUtils::ShouldResistFingerprinting(OwnerDoc())) {
+  if (OwnerDoc()->ShouldResistFingerprinting()) {
     return nsRFPService::GetSpoofedTotalFrames(TotalPlayTime());
   }
 
@@ -285,7 +285,7 @@ uint32_t HTMLVideoElement::MozPresentedFrames() {
     return 0;
   }
 
-  if (nsContentUtils::ShouldResistFingerprinting(OwnerDoc())) {
+  if (OwnerDoc()->ShouldResistFingerprinting()) {
     return nsRFPService::GetSpoofedPresentedFrames(TotalPlayTime(),
                                                    VideoWidth(), VideoHeight());
   }
@@ -299,7 +299,7 @@ uint32_t HTMLVideoElement::MozPaintedFrames() {
     return 0;
   }
 
-  if (nsContentUtils::ShouldResistFingerprinting(OwnerDoc())) {
+  if (OwnerDoc()->ShouldResistFingerprinting()) {
     return nsRFPService::GetSpoofedPresentedFrames(TotalPlayTime(),
                                                    VideoWidth(), VideoHeight());
   }
@@ -311,8 +311,7 @@ uint32_t HTMLVideoElement::MozPaintedFrames() {
 double HTMLVideoElement::MozFrameDelay() {
   MOZ_ASSERT(NS_IsMainThread(), "Should be on main thread.");
 
-  if (!IsVideoStatsEnabled() ||
+  if (!IsVideoStatsEnabled() || OwnerDoc()->ShouldResistFingerprinting()) {
-      nsContentUtils::ShouldResistFingerprinting(OwnerDoc())) {
     return 0.0;
   }
 
@@ -349,7 +348,7 @@ HTMLVideoElement::GetVideoPlaybackQuality() {
     }
 
     if (mDecoder) {
-      if (nsContentUtils::ShouldResistFingerprinting(OwnerDoc())) {
+      if (OwnerDoc()->ShouldResistFingerprinting()) {
         totalFrames = nsRFPService::GetSpoofedTotalFrames(TotalPlayTime());
         droppedFrames = nsRFPService::GetSpoofedDroppedFrames(
             TotalPlayTime(), VideoWidth(), VideoHeight());

dom/html/MediaError.cpp

@@ -34,12 +34,13 @@ MediaError::MediaError(HTMLMediaElement* aParent, uint16_t aCode,
 void MediaError::GetMessage(nsAString& aResult) const {
   // When fingerprinting resistance is enabled, only messages in this list
   // can be returned to content script.
+  // FIXME: An unordered_set seems overkill for this.
   static const std::unordered_set<std::string> whitelist = {
       "404: Not Found"
       // TODO
   };
 
-  bool shouldBlank = (whitelist.find(mMessage.get()) == whitelist.end());
+  const bool shouldBlank = whitelist.find(mMessage.get()) == whitelist.end();
 
   if (shouldBlank) {
     // Print a warning message to JavaScript console to alert developers of
@@ -65,14 +66,13 @@ void MediaError::GetMessage(nsAString& aResult) const {
           NS_ConvertASCIItoUTF16(message), nsIScriptError::warningFlag,
           "MediaError"_ns, ownerDoc);
     }
-  }
 
     if (!nsContentUtils::IsCallerChrome() &&
-      nsContentUtils::ShouldResistFingerprinting(mParent->OwnerDoc()) &&
+        ownerDoc->ShouldResistFingerprinting()) {
-      shouldBlank) {
       aResult.Truncate();
       return;
     }
+  }
 
   CopyUTF8toUTF16(mMessage, aResult);
 }

dom/media/MediaDevices.cpp

@@ -24,6 +24,7 @@
 #include "nsINamed.h"
 #include "nsIScriptGlobalObject.h"
 #include "nsPIDOMWindow.h"
+#include "nsGlobalWindowInner.h"
 #include "nsQueryObject.h"
 
 namespace mozilla::dom {
@@ -226,8 +227,7 @@ RefPtr<MediaDeviceSetRefCnt> MediaDevices::FilterExposedDevices(
       !Preferences::GetBool("media.setsinkid.enabled") ||
       !FeaturePolicyUtils::IsFeatureAllowed(doc, u"speaker-selection"_ns);
 
-  bool resistFingerprinting = nsContentUtils::ShouldResistFingerprinting(doc);
+  if (doc->ShouldResistFingerprinting()) {
-  if (resistFingerprinting) {
     RefPtr fakeEngine = new MediaEngineFake();
     fakeEngine->EnumerateDevices(MediaSourceEnum::Microphone,
                                  MediaSinkEnum::Other, exposed);
@@ -731,8 +731,7 @@ void MediaDevices::OnDeviceChange() {
       return;
     }
 
-    Document* doc = window->GetExtantDoc();
+    if (nsGlobalWindowInner::Cast(window)->ShouldResistFingerprinting()) {
-    if (nsContentUtils::ShouldResistFingerprinting(doc)) {
       return;
     }
   }

dom/system/nsDeviceSensors.cpp

@@ -10,6 +10,7 @@
 #include "nsContentUtils.h"
 #include "nsDeviceSensors.h"
 
+#include "nsGlobalWindowInner.h"
 #include "nsPIDOMWindow.h"
 #include "nsIScriptObjectPrincipal.h"
 #include "mozilla/Preferences.h"
@@ -509,7 +510,8 @@ bool nsDeviceSensors::IsSensorAllowedByPref(uint32_t aType,
       // checks "device.sensors.motion.enabled" pref
       if (!StaticPrefs::device_sensors_motion_enabled()) {
         return false;
-      } else if (doc) {
+      }
+      if (doc) {
         doc->WarnOnceAbout(DeprecatedOperations::eMotionEvent);
       }
       break;
@@ -519,7 +521,8 @@ bool nsDeviceSensors::IsSensorAllowedByPref(uint32_t aType,
       // checks "device.sensors.orientation.enabled" pref
       if (!StaticPrefs::device_sensors_orientation_enabled()) {
         return false;
-      } else if (doc) {
+      }
+      if (doc) {
         doc->WarnOnceAbout(DeprecatedOperations::eOrientationEvent);
       }
       break;
@@ -527,7 +530,8 @@ bool nsDeviceSensors::IsSensorAllowedByPref(uint32_t aType,
       // checks "device.sensors.proximity.enabled" pref
       if (!StaticPrefs::device_sensors_proximity_enabled()) {
         return false;
-      } else if (doc) {
+      }
+      if (doc) {
         doc->WarnOnceAbout(DeprecatedOperations::eProximityEvent, true);
       }
       break;
@@ -535,7 +539,8 @@ bool nsDeviceSensors::IsSensorAllowedByPref(uint32_t aType,
       // checks "device.sensors.ambientLight.enabled" pref
       if (!StaticPrefs::device_sensors_ambientLight_enabled()) {
         return false;
-      } else if (doc) {
+      }
+      if (doc) {
         doc->WarnOnceAbout(DeprecatedOperations::eAmbientLightEvent, true);
       }
       break;
@@ -547,6 +552,5 @@ bool nsDeviceSensors::IsSensorAllowedByPref(uint32_t aType,
   if (!window) {
     return true;
   }
-
+  return !nsGlobalWindowInner::Cast(window)->ShouldResistFingerprinting();
-  return !nsContentUtils::ShouldResistFingerprinting(doc);
 }

dom/workers/WorkerPrivate.cpp

@@ -2887,7 +2887,7 @@ nsresult WorkerPrivate::GetLoadInfo(JSContext* aCx, nsPIDOMWindowInner* aWindow,
       loadInfo.mHasStorageAccessPermissionGranted =
           document->HasStorageAccessPermissionGranted();
       loadInfo.mShouldResistFingerprinting =
-          nsContentUtils::ShouldResistFingerprinting(document);
+          document->ShouldResistFingerprinting();
 
       // This is an hack to deny the storage-access-permission for workers of
       // sub-iframes.

layout/base/nsPresContext.cpp

@@ -331,7 +331,6 @@ static const char* gExactCallbackPrefs[] = {
     "intl.accept_languages",
     "layout.css.devPixelsPerPx",
     "layout.css.dpi",
-    "privacy.resistFingerprinting",
     "privacy.trackingprotection.enabled",
     "ui.use_standins_for_native_colors",
     nullptr,
@@ -577,7 +576,6 @@ void nsPresContext::PreferenceChanged(const char* aPrefName) {
   // because that pref doesn't just affect the "live" value of the media query;
   // it affects whether it is parsed at all.
   if (prefName.EqualsLiteral("browser.display.document_color_use") ||
-      prefName.EqualsLiteral("privacy.resistFingerprinting") ||
       prefName.EqualsLiteral("browser.display.foreground_color") ||
       prefName.EqualsLiteral("browser.display.background_color")) {
     MediaFeatureValuesChanged({MediaFeatureChangeReason::PreferenceChange},

layout/style/nsMediaFeatures.cpp

@@ -37,8 +37,8 @@ using mozilla::dom::DisplayMode;
 using mozilla::dom::Document;
 
 // A helper for four features below
-static nsSize GetSize(const Document* aDocument) {
+static nsSize GetSize(const Document& aDocument) {
-  nsPresContext* pc = aDocument->GetPresContext();
+  nsPresContext* pc = aDocument.GetPresContext();
 
   // Per spec, return a 0x0 viewport if we're not being rendered. See:
   //
@@ -60,20 +60,20 @@ static nsSize GetSize(const Document* aDocument) {
 }
 
 // A helper for three features below.
-static nsSize GetDeviceSize(const Document* aDocument) {
+static nsSize GetDeviceSize(const Document& aDocument) {
-  if (nsContentUtils::ShouldResistFingerprinting(aDocument)) {
+  if (aDocument.ShouldResistFingerprinting()) {
     return GetSize(aDocument);
   }
 
   // Media queries in documents in an RDM pane should use the simulated
   // device size.
   Maybe<CSSIntSize> deviceSize =
-      nsGlobalWindowOuter::GetRDMDeviceSize(*aDocument);
+      nsGlobalWindowOuter::GetRDMDeviceSize(aDocument);
   if (deviceSize.isSome()) {
     return CSSPixel::ToAppUnits(deviceSize.value());
   }
 
-  nsPresContext* pc = aDocument->GetPresContext();
+  nsPresContext* pc = aDocument.GetPresContext();
   // NOTE(emilio): We should probably figure out how to return an appropriate
   // device size here, though in a multi-screen world that makes no sense
   // really.
@@ -124,7 +124,7 @@ static nsDeviceContext* GetDeviceContextFor(const Document* aDocument) {
 
 void Gecko_MediaFeatures_GetDeviceSize(const Document* aDocument,
                                        nscoord* aWidth, nscoord* aHeight) {
-  nsSize size = GetDeviceSize(aDocument);
+  nsSize size = GetDeviceSize(*aDocument);
   *aWidth = size.width;
   *aHeight = size.height;
 }
@@ -159,7 +159,7 @@ uint32_t Gecko_MediaFeatures_GetColorDepth(const Document* aDocument) {
   // rendered.
   uint32_t depth = 24;
 
-  if (!nsContentUtils::ShouldResistFingerprinting(aDocument)) {
+  if (!aDocument->ShouldResistFingerprinting()) {
     if (nsDeviceContext* dx = GetDeviceContextFor(aDocument)) {
       depth = dx->GetDepth();
     }
@@ -185,7 +185,7 @@ float Gecko_MediaFeatures_GetResolution(const Document* aDocument) {
     return pc->GetOverrideDPPX();
   }
 
-  if (nsContentUtils::ShouldResistFingerprinting(aDocument)) {
+  if (aDocument->ShouldResistFingerprinting()) {
     return pc->DeviceContext()->GetFullZoom();
   }
   // Get the actual device pixel ratio, which also takes zoom into account.
@@ -264,7 +264,7 @@ bool Gecko_MediaFeatures_MatchesPlatform(StylePlatform aPlatform) {
 }
 
 bool Gecko_MediaFeatures_PrefersReducedMotion(const Document* aDocument) {
-  if (nsContentUtils::ShouldResistFingerprinting(aDocument)) {
+  if (aDocument->ShouldResistFingerprinting()) {
     return false;
   }
   return LookAndFeel::GetInt(LookAndFeel::IntID::PrefersReducedMotion, 0) == 1;
@@ -283,7 +283,7 @@ StylePrefersColorScheme Gecko_MediaFeatures_PrefersColorScheme(
 // as a signal.
 StylePrefersContrast Gecko_MediaFeatures_PrefersContrast(
     const Document* aDocument) {
-  if (nsContentUtils::ShouldResistFingerprinting(aDocument)) {
+  if (aDocument->ShouldResistFingerprinting()) {
     return StylePrefersContrast::NoPreference;
   }
   const auto& prefs = PreferenceSheet::PrefsFor(*aDocument);
@@ -313,7 +313,7 @@ StyleDynamicRange Gecko_MediaFeatures_DynamicRange(const Document* aDocument) {
 
 StyleDynamicRange Gecko_MediaFeatures_VideoDynamicRange(
     const Document* aDocument) {
-  if (nsContentUtils::ShouldResistFingerprinting(aDocument)) {
+  if (aDocument->ShouldResistFingerprinting()) {
     return StyleDynamicRange::Standard;
   }
   // video-dynamic-range: high has 3 requirements:
@@ -354,8 +354,7 @@ static PointerCapabilities GetPointerCapabilities(const Document* aDocument,
 #else
       PointerCapabilities::Fine | PointerCapabilities::Hover;
 #endif
-
+  if (aDocument->ShouldResistFingerprinting()) {
-  if (nsContentUtils::ShouldResistFingerprinting(aDocument)) {
     return kDefaultCapabilities;
   }