cc: Introduce BeginFrame sequence numbers and acknowledgements.

ui/aura/mus/window_compositor_frame_sink.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/mus/window_compositor_frame_sink.h"
 
 #include "base/bind.h"
+#include "cc/output/begin_frame_args.h"
 #include "cc/output/compositor_frame_sink_client.h"
 #include "gpu/ipc/client/gpu_channel_host.h"
 
 namespace aura {
 
 // static
 std::unique_ptr<WindowCompositorFrameSink> WindowCompositorFrameSink::Create(
     scoped_refptr<cc::ContextProvider> context_provider,
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
     std::unique_ptr<WindowCompositorFrameSinkBinding>*
@@ skipping 95 matching lines @@
 
 void WindowCompositorFrameSink::WillDrawSurface() {
   // TODO(fsamuel, staraz): Implement this.
   NOTIMPLEMENTED();
 }
 
 void WindowCompositorFrameSink::OnNeedsBeginFrames(bool needs_begin_frames) {
   compositor_frame_sink_->SetNeedsBeginFrame(needs_begin_frames);
 }
 
+void WindowCompositorFrameSink::OnDidFinishFrame(const cc::BeginFrameAck& ack) {
+  // If there were updates, SubmitCompositorFrame serves as ack.
+  if (!ack.has_updates)
+    compositor_frame_sink_->BeginFrameDidNotDraw(ack);
+}
+
 WindowCompositorFrameSinkBinding::~WindowCompositorFrameSinkBinding() {}
 
 WindowCompositorFrameSinkBinding::WindowCompositorFrameSinkBinding(
     cc::mojom::MojoCompositorFrameSinkRequest compositor_frame_sink_request,
     mojo::InterfacePtrInfo<cc::mojom::MojoCompositorFrameSinkClient>
         compositor_frame_sink_client)
     : compositor_frame_sink_request_(std::move(compositor_frame_sink_request)),
       compositor_frame_sink_client_(std::move(compositor_frame_sink_client)) {}
 
 }  // namespace aura