Implement WebCompositorOutputSurface

content/browser/renderer_host/render_widget_host_impl.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 CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <deque>
 #include <string>
 #include <vector>
@@ skipping 340 matching lines @@
   void ScrollFocusedEditableNodeIntoRect(const gfx::Rect& rect);
 
   // Requests the renderer to select the region between two points.
   void SelectRange(const gfx::Point& start, const gfx::Point& end);
 
   // Called when the reponse to a pending mouse lock request has arrived.
   // Returns true if |allowed| is true and the mouse has been successfully
   // locked.
   bool GotResponseToLockMouseRequest(bool allowed);
 
+  // Tells the RenderWidget about the latest vsync parameters.
+  virtual void UpdateVSyncParameters(base::TimeTicks timebase,
+                                     base::TimeDelta interval);

[jbates, 2012/07/27 18:42:26]

If the interval is TimeDelta, it's limited to microsecond precision, which
equates to a dropped frame every ~5 minutes. I guess the timebase will give the
scheduler a chance to correct that drift though, but it's unclear whether all
platforms can get a timebase and how often we will update it. The DWM API gives
a numerator and denominator for the interval (for example: 60000 and 1001 on my
z600 box). How about changing the interval to uint32 numerator and uint32
denominator? That way the CC scheduler can have the best chance at maintaining
an accurate tick rate.

+
   // Called by the view in response to AcceleratedSurfaceBuffersSwapped or
   // AcceleratedSurfacePostSubBuffer.
   static void AcknowledgeBufferPresent(
       int32 route_id,
       int gpu_host_id,
       uint32 sync_point);
 
   // Called by the view in response to AcceleratedSurfaceBuffersSwapped for
   // platforms that support deferred GPU process descheduling. This does
   // nothing if the compositor thread is enabled.
@@ skipping 397 matching lines @@
   scoped_ptr<TapSuppressionController> tap_suppression_controller_;
 
   scoped_ptr<SmoothScrollGesture> active_smooth_scroll_gesture_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_