Adds two new observer methods to allow code to be notified when a Window is added/removed from a ...

ui/aura/window_observer.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_WINDOW_OBSERVER_H_
 #define UI_AURA_WINDOW_OBSERVER_H_
 #pragma once
 
 #include "ui/aura/aura_export.h"
 
@@ skipping 40 matching lines @@
                                       const gfx::Rect& region) {}
 
   // Invoked when the Window is being destroyed (i.e. from the start of its
   // destructor). This is called before the window is removed from its parent.
   virtual void OnWindowDestroying(Window* window) {}
 
   // Invoked when the Window has been destroyed (i.e. at the end of its
   // destructor). This is called after the window is removed from its parent.
   virtual void OnWindowDestroyed(Window* window) {}
 
+  // Called when a Window has been added to a RootWindow.
+  virtual void OnWindowAddedToRootWindow(Window* window) {}
+
+  // Called when a Window is about to be removed from a RootWindow.
+  virtual void OnWindowRemovingFromRootWindow(Window* window) {}
+
  protected:
   virtual ~WindowObserver() {}
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_OBSERVER_H_