cc: Introduce BeginFrame sequence numbers and acknowledgements.

cc/trees/layer_tree_host_impl.h

 // Copyright 2011 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_TREES_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <stddef.h>
 
 #include <bitset>
@@ skipping 205 matching lines @@
     ~FrameData() override;
     void AsValueInto(base::trace_event::TracedValue* value) const;
 
     std::vector<gfx::Rect> occluding_screen_space_rects;
     std::vector<gfx::Rect> non_occluding_screen_space_rects;
     RenderPassList render_passes;
     const LayerImplList* render_surface_layer_list;
     LayerImplList will_draw_layers;
     bool has_no_damage;
     bool may_contain_video;
+    uint64_t begin_frame_source_id;
+    uint64_t begin_frame_number;
+    uint64_t oldest_incorporated_frame;
 
     // RenderPassSink implementation.
     void AppendRenderPass(std::unique_ptr<RenderPass> render_pass) override;
 
    private:
     DISALLOW_COPY_AND_ASSIGN(FrameData);
   };
 
   virtual void BeginMainFrameAborted(
       CommitEarlyOutReason reason,
@@ skipping 582 matching lines @@
 
   std::unique_ptr<PendingTreeDurationHistogramTimer>
       pending_tree_duration_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_