Moves transient window observer methods out of WindowObserver

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_
 
 #include "base/basictypes.h"
 #include "ui/aura/aura_export.h"
 
@@ skipping 85 matching lines @@
   //    window->RemoveObserver(this);
   // }
   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) {}
 
-  // Called when a transient child is added to |window|.
-  virtual void OnAddTransientChild(Window* window, Window* transient) {}
-
-  // Called when a transient child is removed from |window|.
-  virtual void OnRemoveTransientChild(Window* window, Window* transient) {}
-
  protected:
   virtual ~WindowObserver() {}
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_OBSERVER_H_