Bug 1415762 - Cancel VRListener task when CompositorVsyncScheduler is going to destroy; r=dvander

MozReview-Commit-ID: CB5JrDGZTu1

--HG--
extra : rebase_source : 4a6f65f4aaf2c11f2dad1a471f0cb219470f1dbe

gfx/layers/ipc/CompositorVsyncScheduler.cpp

@@ -117,6 +117,7 @@ CompositorVsyncScheduler::Destroy()
 
   CancelCurrentSetNeedsCompositeTask();
   CancelCurrentCompositeTask();
+  CancelCurrentVRTask();
 }
 
 void
@@ -133,6 +134,7 @@ CompositorVsyncScheduler::PostCompositeTask(TimeStamp aCompositeTimestamp)
     mCurrentCompositeTask = task;
     ScheduleTask(task.forget(), 0);
   }
+  MonitorAutoLock lockVR(mCurrentVRListenerTaskMonitor);
   if (mCurrentVRListenerTask == nullptr && VRListenerThreadHolder::Loop()) {
     RefPtr<CancelableRunnable> task = NewCancelableRunnableMethod<TimeStamp>(
       "layers::CompositorVsyncScheduler::DispatchVREvents",
@@ -242,6 +244,18 @@ CompositorVsyncScheduler::CancelCurrentCompositeTask()
   }
 }
 
+void
+CompositorVsyncScheduler::CancelCurrentVRTask()
+{
+  // This function is only called by CompositorVsyncScheduler::Destroy().
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  MonitorAutoLock lockVR(mCurrentVRListenerTaskMonitor);
+  if (mCurrentVRListenerTask) {
+    mCurrentVRListenerTask->Cancel();
+    mCurrentVRListenerTask = nullptr;
+  }
+}
+
 void
 CompositorVsyncScheduler::Composite(TimeStamp aVsyncTimestamp)
 {

gfx/layers/ipc/CompositorVsyncScheduler.h

@@ -83,6 +83,7 @@ private:
   void DispatchTouchEvents(TimeStamp aVsyncTimestamp);
   void DispatchVREvents(TimeStamp aVsyncTimestamp);
   void CancelCurrentSetNeedsCompositeTask();
+  void CancelCurrentVRTask();
 
   class Observer final : public VsyncObserver
   {

gfx/vr/VRThread.h

@@ -27,7 +27,7 @@ public:
   static VRListenerThreadHolder* GetSingleton();
 
   static bool IsActive() {
-    return !!GetSingleton();
+    return GetSingleton() && Loop();
   }
 
   static void Start();