Support browser side thumbnailing for GPU composited pages on Windows.

ui/gfx/surface/accelerated_surface_win.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_GFX_SURFACE_ACCELERATED_SURFACE_WIN_H_
 #define UI_GFX_SURFACE_ACCELERATED_SURFACE_WIN_H_
 #pragma once
 
+#include <vector>
+
 #include "base/callback_forward.h"
 #include "base/memory/linked_ptr.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/size.h"
 #include "ui/gfx/surface/surface_export.h"
 
 class AcceleratedPresenter;
 
 class SURFACE_EXPORT AcceleratedSurface {
  public:
   AcceleratedSurface();
   ~AcceleratedSurface();
 
   // Schedule a frame to be presented. The completion callback will be invoked
   // when it is safe to write to the surface on another thread. The lock for
   // this surface will be held while the completion callback runs.
   void AsyncPresentAndAcknowledge(HWND window,
                                   const gfx::Size& size,
                                   int64 surface_id,
                                   const base::Closure& completion_task);
 
   // Synchronously present a frame with no acknowledgement.
   bool Present(HWND window);
 
+  // Copies the surface data to |buf|. The image data is transformed so that it
+  // fits in |size|.
+  bool CopyTo(const gfx::Size& size, std::vector<unsigned char>* buf);
+
   // Temporarily release resources until a new surface is asynchronously
   // presented. Present will not be able to represent the last surface after
   // calling this and will return false.
   void Suspend();
 
  private:
   linked_ptr<AcceleratedPresenter> presenter_;
   DISALLOW_COPY_AND_ASSIGN(AcceleratedSurface);
 };
 
 #endif  // UI_GFX_SURFACE_ACCELERATED_SURFACE_WIN_H_