Forget about DesktopBackgroundWidget if it was deleted

ash/desktop_background/desktop_background_controller.h

Index: ash/desktop_background/desktop_background_controller.h
diff --git a/ash/desktop_background/desktop_background_controller.h b/ash/desktop_background/desktop_background_controller.h
index 3d2c919d41e95bbbc943ff29d933c80b05a262ae..2235f1331e1295c1cd691914f53f13148f5501a7 100644
--- a/ash/desktop_background/desktop_background_controller.h
+++ b/ash/desktop_background/desktop_background_controller.h
@@ -116,6 +116,10 @@ class ASH_EXPORT DesktopBackgroundController : public aura::WindowObserver {
   // Move all desktop widgets to unlocked container.
   void MoveDesktopToUnlockedContainer();
 
+  // Drop references to background view for |root_window|, because the view
+  // was deleted.
+  void CleanUpView(aura::RootWindow* root_window);

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

nit: Cleanup

+
   // WindowObserver implementation.
   virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;