Send vsync timebase updates to the browser compositor

ui/gl/gl_surface.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_GL_GL_SURFACE_H_
 #define UI_GL_GL_SURFACE_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 84 matching lines @@
   // Get the platform specific display on which this surface resides, if
   // available.
   virtual void* GetDisplay();
 
   // Get the platfrom specific configuration for this surface, if available.
   virtual void* GetConfig();
 
   // Get the GL pixel format of the surface, if available.
   virtual unsigned GetFormat();
 
+  // Get the CLOCK_MONOTONIC time (in microseconds) for the most recent screen

[piman, 2012/10/24 16:56:54]

CLOCK_MONOTONIC is a linux-only concept. Maybe the best here is to pass
base::TimeTicks which is a platform independent representation.

At the same time, exposing "media stream counter" and "swap buffer counter"
isn't meaningful in the cross-platform interface if it's not available and not
used anywhere.
We should make this expose the last tick time and the tick rate (or interval),
because that's exactly what we need, and what we may be able to provide on all
platforms.

[ajuma, 2012/10/26 20:12:39]

Done.

+  // refresh, along with the values of the Media Stream Counter (which counts
+  // screen refreshes) and the Swap Buffer Counter. Returns false on error,
+  // including when these values are unavailable.
+  virtual bool GetSyncValues(int64* monotonicTime,

[piman, 2012/10/24 16:56:54]

nit: chrome style for parameters

[ajuma, 2012/10/26 20:12:39]

Done.

+                             int64* mediaStreamCounter,
+                             int64* swapBufferCounter);
+
   // Create a GL surface that renders directly to a view.
   static scoped_refptr<GLSurface> CreateViewGLSurface(
       bool software,
       gfx::AcceleratedWidget window);
 
   // Create a GL surface used for offscreen rendering.
   static scoped_refptr<GLSurface> CreateOffscreenGLSurface(
       bool software,
       const gfx::Size& size);
 
@@ skipping 31 matching lines @@
   virtual gfx::Size GetSize() OVERRIDE;
   virtual void* GetHandle() OVERRIDE;
   virtual unsigned int GetBackingFrameBufferObject() OVERRIDE;
   virtual bool OnMakeCurrent(GLContext* context) OVERRIDE;
   virtual void SetBackbufferAllocation(bool allocated) OVERRIDE;
   virtual void SetFrontbufferAllocation(bool allocated) OVERRIDE;
   virtual void* GetShareHandle() OVERRIDE;
   virtual void* GetDisplay() OVERRIDE;
   virtual void* GetConfig() OVERRIDE;
   virtual unsigned GetFormat() OVERRIDE;
+  virtual bool GetSyncValues(int64* monotonicTime,
+                             int64* mediaStreamCounter,
+                             int64* swapBufferCounter) OVERRIDE;
 
   GLSurface* surface() const { return surface_.get(); }
 
  protected:
   virtual ~GLSurfaceAdapter();
 
  private:
   scoped_refptr<GLSurface> surface_;
 
   DISALLOW_COPY_AND_ASSIGN(GLSurfaceAdapter);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_SURFACE_H_