Query the preferred readback config in CopyFromBackingStore

content/browser/frame_host/render_widget_host_view_child_frame.h

 // Copyright 2014 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_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/content_export.h"
@@ skipping 148 matching lines @@
   virtual GdkEventButton* GetLastMouseDown() OVERRIDE;
   virtual gfx::NativeView BuildInputMethodsGtkMenu() OVERRIDE;
 #endif  // defined(TOOLKIT_GTK)
 
 #if defined(OS_WIN)
   virtual void SetParentNativeViewAccessible(
       gfx::NativeViewAccessible accessible_parent) OVERRIDE;
   virtual gfx::NativeViewId GetParentForWindowlessPlugin() const OVERRIDE;
 #endif
 
+  virtual SkBitmap::Config PreferredReadbackFormat() OVERRIDE;
+
  protected:
   friend class RenderWidgetHostView;
 
   // Members will become private when RenderWidgetHostViewGuest is removed.
   // The model object.
   RenderWidgetHostImpl* host_;
 
   // frame_connector_ provides a platform abstraction. Messages
   // sent through it are routed to the embedding renderer process.
   CrossProcessFrameConnector* frame_connector_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewChildFrame);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_