aura: Draw drop shadows under browsers and menus.

ui/aura/desktop_observer.h

Index: ui/aura/desktop_observer.h
diff --git a/ui/aura/desktop_observer.h b/ui/aura/desktop_observer.h
index 3d5e775dd271b3ea7a132258b0fb1663afa60dca..dba7e5c646cb31e793c8ac276b63ec72780d35b0 100644
--- a/ui/aura/desktop_observer.h
+++ b/ui/aura/desktop_observer.h
@@ -21,6 +21,9 @@ class AURA_EXPORT DesktopObserver {
   // Invoked after the desktop is resized.
   virtual void OnDesktopResized(const gfx::Size& new_size) {}
 
+  // Invoked when a new window is initialized.
+  virtual void OnWindowInitialized(Window* window) {}
+
   // Invoked when the active window is changed. |active| may be NULL if there is
   // not active window.
   virtual void OnActiveWindowChanged(Window* active) {}