Bug 1752907: Cut over Hardware Concurrency to finer-grained RFP Check r=tjr

Differential Revision: https://phabricator.services.mozilla.com/D137481

dom/base/Navigator.cpp

@@ -649,7 +649,8 @@ uint64_t Navigator::HardwareConcurrency() {
     return 1;
   }
 
-  return rts->ClampedHardwareConcurrency();
+  return rts->ClampedHardwareConcurrency(
+      nsContentUtils::ShouldResistFingerprinting(mWindow->GetExtantDoc()));
 }
 
 namespace {

dom/workers/RuntimeService.cpp

@@ -1847,11 +1847,12 @@ void RuntimeService::MemoryPressureAllWorkers() {
   BroadcastAllWorkers([](auto& worker) { worker.MemoryPressure(); });
 }
 
-uint32_t RuntimeService::ClampedHardwareConcurrency() const {
+uint32_t RuntimeService::ClampedHardwareConcurrency(
+    bool aShouldResistFingerprinting) const {
   // The Firefox Hardware Report says 70% of Firefox users have exactly 2 cores.
   // When the resistFingerprinting pref is set, we want to blend into the crowd
   // so spoof navigator.hardwareConcurrency = 2 to reduce user uniqueness.
-  if (MOZ_UNLIKELY(nsContentUtils::ShouldResistFingerprinting())) {
+  if (MOZ_UNLIKELY(aShouldResistFingerprinting)) {
     return 2;
   }
 

dom/workers/RuntimeService.h

@@ -164,7 +164,7 @@ class RuntimeService final : public nsIObserver {
 
   void MemoryPressureAllWorkers();
 
-  uint32_t ClampedHardwareConcurrency() const;
+  uint32_t ClampedHardwareConcurrency(bool aShouldResistFingerprinting) const;
 
   void CrashIfHanging();
 

dom/workers/WorkerNavigator.cpp

@@ -176,7 +176,10 @@ uint64_t WorkerNavigator::HardwareConcurrency() const {
   RuntimeService* rts = RuntimeService::GetService();
   MOZ_ASSERT(rts);
 
-  return rts->ClampedHardwareConcurrency();
+  WorkerPrivate* aWorkerPrivate = GetCurrentThreadWorkerPrivate();
+  bool rfp = aWorkerPrivate->ShouldResistFingerprinting();
+
+  return rts->ClampedHardwareConcurrency(rfp);
 }
 
 StorageManager* WorkerNavigator::Storage() {