Fix VsyncBridgeParent leaking on GPU process shutdown. (bug 1308398 part 2, r=mattwoodrow)

gfx/ipc/GPUParent.cpp

@@ -169,7 +169,7 @@ GPUParent::RecvInit(nsTArray<GfxPrefSetting>&& prefs,
 bool
 GPUParent::RecvInitVsyncBridge(Endpoint<PVsyncBridgeParent>&& aVsyncEndpoint)
 {
-  VsyncBridgeParent::Start(Move(aVsyncEndpoint));
+  mVsyncBridge = VsyncBridgeParent::Start(Move(aVsyncEndpoint));
   return true;
 }
 
@@ -325,6 +325,7 @@ GPUParent::ActorDestroy(ActorDestroyReason aWhy)
 
   if (mVsyncBridge) {
     mVsyncBridge->Shutdown();
+    mVsyncBridge = nullptr;
   }
   CompositorThreadHolder::Shutdown();
 #if defined(XP_WIN)

gfx/ipc/VsyncBridgeParent.cpp

@@ -55,10 +55,16 @@ VsyncBridgeParent::Shutdown()
 {
   MessageLoop* ccloop = CompositorThreadHolder::Loop();
   if (MessageLoop::current() != ccloop) {
-    ccloop->PostTask(NewRunnableMethod(this, &VsyncBridgeParent::Shutdown));
+    ccloop->PostTask(NewRunnableMethod(this, &VsyncBridgeParent::ShutdownImpl));
     return;
   }
 
+  ShutdownImpl();
+}
+
+void
+VsyncBridgeParent::ShutdownImpl()
+{
   if (mOpen) {
     Close();
     mOpen = false;

gfx/ipc/VsyncBridgeParent.h

@@ -30,6 +30,7 @@ private:
   ~VsyncBridgeParent();
 
   void Open(Endpoint<PVsyncBridgeParent>&& aEndpoint);
+  void ShutdownImpl();
 
 private:
   bool mOpen;