Bug 1563871 - Pass the result of apz.test.logging_enabled pref value to APZPaintLogHelper. r=botond

APZCTreeManager::UpdateHitTestingTree runs on the updater thread, so it's
possible that querying StaticPrefs::apz_test_logging_enabled() at different
places will return different results.

Differential Revision: https://phabricator.services.mozilla.com/D201180

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -83,10 +83,10 @@ typedef CompositorBridgeParent::LayerTreeState LayerTreeState;
 struct APZCTreeManager::TreeBuildingState {
   TreeBuildingState(LayersId aRootLayersId, bool aIsFirstPaint,
                     LayersId aOriginatingLayersId, APZTestData* aTestData,
-                    uint32_t aPaintSequence)
+                    uint32_t aPaintSequence, bool aIsTestLoggingEnabled)
       : mIsFirstPaint(aIsFirstPaint),
         mOriginatingLayersId(aOriginatingLayersId),
-        mPaintLogger(aTestData, aPaintSequence) {
+        mPaintLogger(aTestData, aPaintSequence, aIsTestLoggingEnabled) {
     CompositorBridgeParent::CallWithIndirectShadowTree(
         aRootLayersId, [this](LayerTreeState& aState) -> void {
           mCompositorController = aState.GetCompositorController();
@@ -430,7 +430,8 @@ void APZCTreeManager::UpdateHitTestingTree(
   // For testing purposes, we log some data to the APZTestData associated with
   // the layers id that originated this update.
   APZTestData* testData = nullptr;
-  if (StaticPrefs::apz_test_logging_enabled()) {
+  const bool testLoggingEnabled = StaticPrefs::apz_test_logging_enabled();
+  if (testLoggingEnabled) {
     MutexAutoLock lock(mTestDataLock);
     UniquePtr<APZTestData> ptr = MakeUnique<APZTestData>();
     auto result =
@@ -440,7 +441,7 @@ void APZCTreeManager::UpdateHitTestingTree(
   }
 
   TreeBuildingState state(mRootLayersId, aIsFirstPaint, aOriginatingLayersId,
-                          testData, aPaintSequenceNumber);
+                          testData, aPaintSequenceNumber, testLoggingEnabled);
 
   // We do this business with collecting the entire tree into an array because
   // otherwise it's very hard to determine which APZC instances need to be

gfx/layers/apz/testutil/APZTestData.h

@@ -144,10 +144,10 @@ class APZTestData {
 // A helper class for logging data for a paint.
 class APZPaintLogHelper {
  public:
-  APZPaintLogHelper(APZTestData* aTestData, SequenceNumber aPaintSequenceNumber)
+  APZPaintLogHelper(APZTestData* aTestData, SequenceNumber aPaintSequenceNumber,
+                    bool aIsTestLoggingEnabled)
       : mTestData(aTestData), mPaintSequenceNumber(aPaintSequenceNumber) {
-    MOZ_ASSERT(!aTestData || StaticPrefs::apz_test_logging_enabled(),
-               "don't call me");
+    MOZ_ASSERT(!aTestData || aIsTestLoggingEnabled, "don't call me");
   }
 
   template <typename Value>