Wires keeping the launcher up to date with the browser.

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 aura {
 
 class Window;
 
 class AURA_EXPORT WindowObserver {
  public:
   // Invoked when the Window |new_window| has been added.
   virtual void OnWindowAdded(Window* new_window) {}
 
   // Invoked prior to removing |window|.
   virtual void OnWillRemoveWindow(Window* window) {}
 
+  // Invoked when the 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 visibile) {}
+
  protected:
   virtual ~WindowObserver() {}
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_OBSERVER_H_