Allow CopyFromBackingStore to fallback to copying from the renderer side if the accelerated surface…

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_
 
 #include "base/callback.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/keyboard_listener.h"
@@ skipping 266 matching lines @@
   // Add a keyboard listener that can handle key presses without requiring
   // focus.
   virtual void AddKeyboardListener(KeyboardListener* listener) = 0;
 
   // Remove a keyboard listener.
   virtual void RemoveKeyboardListener(KeyboardListener* listener) = 0;
 
   // Get the screen info corresponding to this render widget.
   virtual void GetWebScreenInfo(WebKit::WebScreenInfo* result) = 0;
 
+  // Grabs snapshot from renderer side and returns the bitmap to a callback.
+  // If |src_rect| is empty, the whole contents is copied. This is an expensive
+  // operation due to the IPC, but it can be used as a fallback method when
+  // CopyFromBackingStore fails due to the backing store not being available or,
+  // in composited mode, when the accelerated surface is not available to the
+  // browser side.
+  virtual void GetSnapshotFromRenderer(
+      const gfx::Rect& src_subrect,
+      const base::Callback<void(bool, const SkBitmap&)>& callback) = 0;
+
  protected:
   friend class RenderWidgetHostImpl;
 
   // 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;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_WIDGET_HOST_H_