ash: Clean up system background layer.

ui/aura/root_window_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 UI_AURA_ROOT_WINDOW_HOST_H_
 #define UI_AURA_ROOT_WINDOW_HOST_H_
 
 #include <vector>
 
 #include "base/message_loop.h"
 #include "ui/aura/aura_export.h"
 #include "ui/base/cursor/cursor.h"
 #include "ui/gfx/native_widget_types.h"
 
+class SkCanvas;
+
 namespace gfx {
 class Point;
 class Rect;
 class Size;
 }
 
 namespace aura {
 
 class RootWindow;
 class RootWindowHostDelegate;
@@ skipping 55 matching lines @@
   // Clips the cursor to the bounds of the root window until UnConfineCursor().
   virtual bool ConfineCursorToRootWindow() = 0;
   virtual void UnConfineCursor() = 0;
 
   // Moves the cursor to the specified location relative to the root window.
   virtual void MoveCursorTo(const gfx::Point& location) = 0;
 
   // Sets if the window should be focused when shown.
   virtual void SetFocusWhenShown(bool focus_when_shown) = 0;
 
+  // Copies |source_bounds| from the root window (as displayed on the host
+  // machine) to |canvas| at offset |dest_offset|.  The bounds need to be in
+  // physical pixels.
+  virtual bool CopyAreaToSkCanvas(const gfx::Rect& source_bounds,
+                                  const gfx::Point& dest_offset,
+                                  SkCanvas* canvas) = 0;
+
   // Grabs the snapshot of the root window by using the platform-dependent APIs.
   // The bounds need to be in physical pixels.
   virtual bool GrabSnapshot(
       const gfx::Rect& snapshot_bounds,
       std::vector<unsigned char>* png_representation) = 0;
 
   // Posts |native_event| to the platform's event queue.
 #if !defined(OS_MACOSX)
   virtual void PostNativeEvent(const base::NativeEvent& native_event) = 0;
 #endif
 
   // Called when the device scale factor of the root window has chagned.
   virtual void OnDeviceScaleFactorChanged(float device_scale_factor) = 0;
 
   // Stop listening events in preparation for shutdown.
   virtual void PrepareForShutdown() = 0;
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_HOST_H_