ash: Cleanup class/struct forward declarations

ash/display/display_util.h

 // Copyright 2014 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_UTIL_H_
 #define ASH_DISPLAY_DISPLAY_UTIL_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "base/strings/string16.h"
 
 namespace aura {
 class Window;
 }
 
 namespace display {
 class DisplayManager;
-class ManagedDisplayInfo;
 }
 
 namespace gfx {
 class Point;
 class Rect;
 }
 
 namespace ash {
 class AshWindowTreeHost;
 class MouseWarpController;
@@ skipping 21 matching lines @@
 #if defined(OS_CHROMEOS)
 // Shows the notification message for display related issues.
 void ShowDisplayErrorNotification(int message_id);
 #endif
 
 ASH_EXPORT base::string16 GetDisplayErrorNotificationMessageForTest();
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_DISPLAY_UTIL_H_