aura: Draw drop shadows under browsers and menus.

ui/aura/window_observer.h

Index: ui/aura/window_observer.h
diff --git a/ui/aura/window_observer.h b/ui/aura/window_observer.h
index 5e1e9889321a20fed0e373de76dd8074e281288a..38a47efbfb9b78e6455d7771c95b66e5439f9a01 100644
--- a/ui/aura/window_observer.h
+++ b/ui/aura/window_observer.h
@@ -8,27 +8,42 @@
 
 #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) {}