Forget about DesktopBackgroundWidget if it was deleted

ash/desktop_background/desktop_background_widget_controller.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 ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_WIDGET_CONTROLLER_H_
 #define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_WIDGET_CONTROLLER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/aura/window_property.h"
 #include "ui/compositor/layer.h"
@@ skipping 10 matching lines @@
 // (kComponentWrapper). When the animation completes the old
 // DesktopBackgroundWidgetController is destroyed.
 class DesktopBackgroundWidgetController {
  public:
   // Create
   explicit DesktopBackgroundWidgetController(views::Widget* widget);
   explicit DesktopBackgroundWidgetController(ui::Layer* layer);
 
   ~DesktopBackgroundWidgetController();
 
+  // Drop ownership of widget.

[Nikita (slow), 2012/08/28 17:42:38]

nit: Drop widget reference.

widget is not owned.

+  void CleanUpWidget();

[Nikita (slow), 2012/08/28 17:42:38]

nit: CleanupWidget()

+
   // Set bounds of component that draws background.
   void SetBounds(gfx::Rect bounds);
 
   // Move component from |src_container| in |root_window| to |dest_container|.
   // It is required for lock screen, when we need to move background so that
   // it hides user's windows.
   void Reparent(aura::RootWindow* root_window,
                 int src_container,
                 int dest_container);
 
@@ skipping 32 matching lines @@
 // to root windows.
 extern const aura::WindowProperty<DesktopBackgroundWidgetController*>* const
     kWindowDesktopComponent;
 
 extern const aura::WindowProperty<ComponentWrapper*>* const kComponentWrapper;
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_WIDGET_CONTROLLER_H_