Support browser side thumbnailing for GPU composited pages on Windows.

content/public/browser/render_widget_host.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 CONTENT_PUBLIC_BROWSER_RENDER_WIDGET_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_RENDER_WIDGET_HOST_H_
 #pragma once
 
 #include "content/common/content_export.h"
 #include "content/public/browser/keyboard_listener.h"
@@ skipping 173 matching lines @@
 #if defined(TOOLKIT_GTK)
   // Paint the backing store into the target's |dest_rect|.
   virtual bool CopyFromBackingStoreToGtkWindow(const gfx::Rect& dest_rect,
                                                GdkWindow* target) = 0;
 #elif defined(OS_MACOSX)
   virtual gfx::Size GetBackingStoreSize() = 0;
   virtual bool CopyFromBackingStoreToCGContext(const CGRect& dest_rect,
                                                CGContextRef target) = 0;
 #endif
 
+  // Copies the contents of the compositing surface into the given
+  // (uninitialized) PlatformCanvas if any. Returns true on success, false
+  // otherwise.
+  virtual bool CopyFromCompositingSurface(const gfx::Size& size,
+                                          skia::PlatformCanvas* output) = 0;
+
   // Enable renderer accessibility. This should only be called when a
   // screenreader is detected.
   virtual void EnableRendererAccessibility() = 0;
 
   // Forwards the given message to the renderer. These are called by
   // the view when it has received a message.
   virtual void ForwardMouseEvent(
       const WebKit::WebMouseEvent& mouse_event) = 0;
   virtual void ForwardWheelEvent(
       const WebKit::WebMouseWheelEvent& wheel_event) = 0;
@@ skipping 85 matching lines @@
 
   // Retrieves the implementation class.  Intended only for code
   // within content/.  This method is necessary because
   // RenderWidgetHost is the root of a diamond inheritance pattern, so
   // subclasses inherit it virtually, which removes our ability to
   // static_cast to the subclass.
   virtual RenderWidgetHostImpl* AsRenderWidgetHostImpl() = 0;
 };
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_WIDGET_HOST_H_