cc: Make scheduling be driven by vsync for android webview.

cc/output/output_surface.h

 // Copyright 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 CC_OUTPUT_OUTPUT_SURFACE_H_
 #define CC_OUTPUT_OUTPUT_SURFACE_H_
 
 #include <deque>
 
 #include "base/basictypes.h"
@@ skipping 117 matching lines @@
   bool HasClient() { return !!client_; }
 
   // Get the class capable of informing cc of hardware overlay capability.
   OverlayCandidateValidator* overlay_candidate_validator() const {
     return overlay_candidate_validator_.get();
   }
 
   void DidLoseOutputSurface();
   void SetMemoryPolicy(const ManagedMemoryPolicy& policy);
 
+  // Support for a pull-model where draws are requested by the output surface.
+  //
+  // OutputSurface::Invalidate is called by the compositor to notify that 
+  // there's new content.
+  //
+  // OutputSurfaceClient::RequestDraw is called by the output surface later to
+  // notify that the output surface is ready for a draw.
+  virtual void Invalidate() {}
+
  protected:
   OutputSurfaceClient* client_;
 
   // Synchronously initialize context3d and enter hardware mode.
   // This can only supported in threaded compositing mode.
   bool InitializeAndSetContext3d(
       scoped_refptr<ContextProvider> context_provider);
   void ReleaseGL();
 
   void PostSwapBuffersComplete();
@@ skipping 26 matching lines @@
   bool external_stencil_test_enabled_;
 
   base::WeakPtrFactory<OutputSurface> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OutputSurface);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_OUTPUT_SURFACE_H_