Bug 1076915 - Ensure that PostDelayedTask is always called on the controller thread. r=botond

gfx/layers/apz/public/GeckoContentController.h

@@ -87,6 +87,7 @@ public:
   /**
    * Schedules a runnable to run on the controller/UI thread at some time
    * in the future.
+   * This method must always be called on the controller thread.
    */
   virtual void PostDelayedTask(Task* aTask, int aDelayMs) = 0;
 

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -3138,6 +3138,7 @@ AsyncPanZoomController::GetZoomConstraints() const
 
 
 void AsyncPanZoomController::PostDelayedTask(Task* aTask, int aDelayMs) {
+  AssertOnControllerThread();
   nsRefPtr<GeckoContentController> controller = GetGeckoContentController();
   if (controller) {
     controller->PostDelayedTask(aTask, aDelayMs);