Removed unnecessary declaration in ash::DisplayManager

ash/display/display_manager.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 ASH_DISPLAY_DISPLAY_MANAGER_H_
 #define ASH_DISPLAY_DISPLAY_MANAGER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 10 matching lines @@
 #include "base/observer_list.h"
 #include "ui/display/display.h"
 #include "ui/display/display_observer.h"
 #include "ui/display/manager/display_layout.h"
 #include "ui/display/manager/managed_display_info.h"
 
 #if defined(OS_CHROMEOS)
 #include "ui/display/chromeos/display_configurator.h"
 #endif
 
-namespace aura {
-class Window;
-}
-
 namespace chromeos {
 class DisplayNotificationsTest;
 }
 
 namespace display {
 class DisplayLayoutStore;
 class DisplayObserver;
 class Screen;
 }
 
@@ skipping 437 matching lines @@
   base::ObserverList<display::DisplayObserver> observers_;
 
   base::WeakPtrFactory<DisplayManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_DISPLAY_MANAGER_H_