ui: Cleanup class/struct forward declarations

ui/aura/client/focus_client.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_CLIENT_FOCUS_CLIENT_H_
 #define UI_AURA_CLIENT_FOCUS_CLIENT_H_
 
 #include "ui/aura/aura_export.h"
 #include "ui/aura/window.h"
 
 namespace aura {
-class Window;
 namespace client {
 class FocusChangeObserver;
 
 // An interface implemented by an object that manages window focus.
 class AURA_EXPORT FocusClient {
  public:
   virtual ~FocusClient() {}
 
   virtual void AddObserver(FocusChangeObserver* observer) = 0;
   virtual void RemoveObserver(FocusChangeObserver* observer) = 0;
@@ skipping 14 matching lines @@
 AURA_EXPORT FocusClient* GetFocusClient(Window* window);
 AURA_EXPORT FocusClient* GetFocusClient(const Window* window);
 
 // The focus client is stored on the window using this property.
 AURA_EXPORT extern const WindowProperty<FocusClient*>* const kFocusClientKey;
 
 }  // namespace clients
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_FOCUS_CLIENT_H_