Fixing flakiness of TextureLayerChangeInvisibleMailboxTest

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index 0386145c7c55fea08e4f34362dd5f3536b1b1a02..469996e4b70d9ff09ffb09bf092f13b40031df94 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -425,7 +425,12 @@ void SingleThreadProxy::DidReceiveCompositorFrameAckOnImplThread() {
                "SingleThreadProxy::DidReceiveCompositorFrameAckOnImplThread");
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->DidReceiveCompositorFrameAck();
-  layer_tree_host_->DidReceiveCompositorFrameAck();
+  // We do a PostTask here because freeing resources in some cases (such as in
+  // TextureLayer) is PostTasked and we want to make sure ack is received after
+  // resources are returned.
+  task_runner_provider_->MainThreadTaskRunner()->PostTask(
+      FROM_HERE, base::Bind(&SingleThreadProxy::DidReceiveCompositorFrameAck,
+                            weak_factory_.GetWeakPtr()));
 }
 
 void SingleThreadProxy::OnDrawForCompositorFrameSink(
@@ -794,4 +799,8 @@ void SingleThreadProxy::DidFinishImplFrame() {
 #endif
 }
 
+void SingleThreadProxy::DidReceiveCompositorFrameAck() {
+  layer_tree_host_->DidReceiveCompositorFrameAck();
+}
+
 }  // namespace cc