Mac Overlays: Add sandwich strategy

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 127 matching lines @@
 
   // Notifies frame-rate smoothness preference. If true, all non-critical
   // processing should be stopped, or lowered in priority.
   virtual void UpdateSmoothnessTakesPriority(bool prefer_smoothness) {}
 
   bool HasClient() { return !!client_; }
 
   // Get the class capable of informing cc of hardware overlay capability.
   virtual OverlayCandidateValidator* GetOverlayCandidateValidator() const;
 
+  // Get the texture for the main image's overlay.
+  virtual unsigned GetOverlayTextureId() const;
+
   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.
   virtual void Invalidate() {}
 
   // Updates the worker context provider's visibility, freeing GPU resources if
@@ skipping 33 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_