Support browser side thumbnailing for GPU composited pages on Windows.

ui/gfx/surface/accelerated_surface_win.h

Index: ui/gfx/surface/accelerated_surface_win.h
diff --git a/ui/gfx/surface/accelerated_surface_win.h b/ui/gfx/surface/accelerated_surface_win.h
index cf59178742e1751fe64b851a47648ae930192ef3..1a50c00ca0fb6c1bbbfc1b952e09c9120b77030c 100644
--- a/ui/gfx/surface/accelerated_surface_win.h
+++ b/ui/gfx/surface/accelerated_surface_win.h
@@ -6,6 +6,8 @@
 #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"
@@ -30,6 +32,10 @@ class SURFACE_EXPORT AcceleratedSurface {
   // 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.