aura: Draw drop shadows under browsers and menus.

ui/aura/window_observer.h

 // Copyright (c) 2011 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"
 
+namespace gfx {
+class Rect;
+}  // namespace gfx
+
 namespace aura {
 
 class Window;
 
 class AURA_EXPORT WindowObserver {
  public:
-  // Invoked when the Window |new_window| has been added.
+  // Invoked when |new_window| has been added as a child of this window.
   virtual void OnWindowAdded(Window* new_window) {}
 
-  // Invoked prior to removing |window|.
+  // Invoked prior to removing |window| as a child of this window.
   virtual void OnWillRemoveWindow(Window* window) {}
 
-  // Invoked when |SetProperty| or |SetIntProperty| is called on |window|.
+  // Invoked when this window's parent window changes.  |parent| may be NULL.
+  virtual void OnWindowParentChanged(Window* window, Window* parent) {}
+
+  // Invoked when SetProperty() or SetIntProperty() is called on |window|.
   // |old| is the old property value.
   virtual void OnPropertyChanged(Window* window, const char* key, void* old) {}
 
-  // Invoked when the SetVisible() is invoked on a window. |visible| is the
+  // Invoked when SetVisible() is invoked on a window. |visible| is the
   // value supplied to SetVisible(). If |visible| is true, window->IsVisible()
   // may still return false. See description in Window::IsVisible() for details.
   virtual void OnWindowVisibilityChanged(Window* window, bool visible) {}
 
+  // Invoked when SetBounds() is invoked on |window|. |bounds| contains the
+  // window's new bounds.
+  virtual void OnWindowBoundsChanged(Window* window, const gfx::Rect& bounds) {}
+
+  // Invoked when |window|'s position among its siblings in the stacking order
+  // has changed.
+  virtual void OnWindowStackingChanged(Window* window) {}
+
   // Invoked when the Window has been destroyed (i.e. from its destructor).
   virtual void OnWindowDestroyed(Window* window) {}
 
  protected:
   virtual ~WindowObserver() {}
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_OBSERVER_H_