Fixing flakiness of TextureLayerChangeInvisibleMailboxTest

cc/trees/single_thread_proxy.h

Index: cc/trees/single_thread_proxy.h
diff --git a/cc/trees/single_thread_proxy.h b/cc/trees/single_thread_proxy.h
index 4a091950a27cc9bb1c4a73695827c70a40ece935..78a3bc87362404f4744203621756735ea11dc13f 100644
--- a/cc/trees/single_thread_proxy.h
+++ b/cc/trees/single_thread_proxy.h
@@ -122,6 +122,8 @@ class CC_EXPORT SingleThreadProxy : public Proxy,
   bool ShouldComposite() const;
   void ScheduleRequestNewCompositorFrameSink();
 
+  void DidReceiveCompositorFrameAck();
+
   // Accessed on main thread only.
   LayerTreeHost* layer_tree_host_;
   LayerTreeHostSingleThreadClient* single_thread_client_;
@@ -158,6 +160,10 @@ class CC_EXPORT SingleThreadProxy : public Proxy,
   // This is the callback for the scheduled RequestNewCompositorFrameSink.
   base::CancelableClosure compositor_frame_sink_creation_callback_;
 
+  // WeakPtrs generated by this factory will be invalidated when
+  // CompositorFrameSink is released.
+  base::WeakPtrFactory<SingleThreadProxy> compositor_frame_sink_weak_factory_;
+
   base::WeakPtrFactory<SingleThreadProxy> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SingleThreadProxy);