cc: Introduce BeginFrame sequence numbers and acknowledgements.

cc/output/output_surface_frame.h

 // Copyright 2016 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.
 
 #ifndef CC_OUTPUT_OUTPUT_SURFACE_FRAME_H_
 #define CC_OUTPUT_OUTPUT_SURFACE_FRAME_H_
 
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 11 matching lines @@
   OutputSurfaceFrame();
   OutputSurfaceFrame(OutputSurfaceFrame&& other);
   ~OutputSurfaceFrame();
 
   OutputSurfaceFrame& operator=(OutputSurfaceFrame&& other);
 
   gfx::Size size;
   gfx::Rect sub_buffer_rect;
   std::vector<ui::LatencyInfo> latency_info;
 
+  // See corresponding fields in CompositorFrameMetadata.
+  uint64_t begin_frame_source_id = 0;
+  uint64_t begin_frame_number = 0;
+  uint64_t latest_confirmed_frame = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(OutputSurfaceFrame);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_OUTPUT_SURFACE_FRAME_H_