Tighter sync and faster ACK on SwapBuffers/PostSubBuffers

ui/compositor/compositor.h

 // Copyright (c) 2012 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 UI_COMPOSITOR_COMPOSITOR_H_
 #define UI_COMPOSITOR_COMPOSITOR_H_
 #pragma once
 
 #include "base/hash_tables.h"
 #include "base/memory/ref_counted.h"
@@ skipping 196 matching lines @@
   virtual void updateAnimations(double frameBeginTime);
   virtual void layout();
   virtual void applyScrollAndScale(const WebKit::WebSize& scrollDelta,
                                    float scaleFactor);
   virtual WebKit::WebGraphicsContext3D* createContext3D();
   virtual void didRebindGraphicsContext(bool success);
   virtual void didCommitAndDrawFrame();
   virtual void didCompleteSwapBuffers();
   virtual void scheduleComposite();
 
+  int last_started_id() { return last_started_id_; }
+  int last_will_end_id() { return last_will_end_id_; }
+  int last_ended_id() { return last_ended_id_; }
+
  private:
   friend class base::RefCounted<Compositor>;
 
   // When reading back pixel data we often get RGBA rather than BGRA pixels and
   // and the image often needs to be flipped vertically.
   static void SwizzleRGBAToBGRAAndFlip(unsigned char* pixels,
                                        const gfx::Size& image_size);
 
   // Notifies the compositor that compositing is complete.
   void NotifyEnd();
@@ skipping 10 matching lines @@
   WebKit::WebLayer root_web_layer_;
   WebKit::WebLayerTreeView host_;
 
   // This is set to true when the swap buffers has been posted and we're waiting
   // for completion.
   bool swap_posted_;
 
   // The device scale factor of the monitor that this compositor is compositing
   // layers on.
   float device_scale_factor_;
+
+  int last_started_id_;

[piman, 2012/06/04 18:20:39]

naming bikeshedding: mind calling these
last_started_frame_/last_will_end_frame_/last_ended_frame_ ? From outside the
class (e.g. in root_window.cc), it's very non-obvious what these "ids" refer to.

+  int last_will_end_id_;
+  int last_ended_id_;
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_H_