Bug 1298254 - Ensure that the flush-apz-repaints codepath also waits for pending SetTargetAPZCNotification messages on the controller thread before returning. r=dvander

MozReview-Commit-ID: 5bY3TeJB4KN

--HG--
extra : rebase_source : 053dbbe4ac9f6e36bdb3b113eac44c7df29ba5c9

gfx/layers/ipc/CompositorBridgeParent.cpp

@@ -1660,7 +1660,9 @@ CompositorBridgeParent::FlushApzRepaints(const LayerTransactionParent* aLayerTre
     // use the compositor's root layer tree id.
     layersId = mRootLayerTreeID;
   }
-  mApzcTreeManager->FlushApzRepaints(layersId);
+  APZThreadUtils::RunOnControllerThread(NS_NewRunnableFunction([=] () {
+    mApzcTreeManager->FlushApzRepaints(layersId);
+  }));
 }
 
 void