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 <d3d9.h>
+#include <vector>
 
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/lock.h"
 #include "base/win/scoped_comptr.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/size.h"
 #include "ui/gfx/surface/surface_export.h"
 
 class PresentThread;
 
 class AcceleratedPresenter : public base::RefCounted<AcceleratedPresenter> {
  public:
   AcceleratedPresenter();
 
   // The public member functions are called on the main thread.
   void AsyncPresentAndAcknowledge(gfx::NativeWindow window,
                                   const gfx::Size& size,
                                   int64 surface_id,
                                   const base::Closure& completion_task);
   bool Present(gfx::NativeWindow window);
+  bool CopyTo(const gfx::Size& size, std::vector<unsigned char>* buf);
   void Suspend();
   void WaitForPendingTasks();
 
  private:
   friend class base::RefCounted<AcceleratedPresenter>;
 
   ~AcceleratedPresenter();
 
   // These member functions are called on the PresentThread with which the
   // presenter has affinity.
@@ skipping 31 matching lines @@
   // 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:
   scoped_refptr<AcceleratedPresenter> presenter_;
   DISALLOW_COPY_AND_ASSIGN(AcceleratedSurface);
 };
 
 #endif  // UI_GFX_SURFACE_ACCELERATED_SURFACE_WIN_H_