ash: Cleanup class/struct forward declarations

ash/display/mirror_window_controller.h

 // Copyright (c) 2013 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_MIRROR_WINDOW_CONTROLLER_H_
 #define ASH_DISPLAY_MIRROR_WINDOW_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 21 matching lines @@
 class Display;
 class ManagedDisplayInfo;
 }
 
 namespace ui {
 class Reflector;
 }
 
 namespace ash {
 class AshWindowTreeHost;
-class RootWindowTransformer;
 
 namespace test {
 class MirrorWindowTestApi;
 }
 
 // An object that copies the content of the primary root window to a
 // mirror window. This also draws a mouse cursor as the mouse cursor
 // is typically drawn by the window system.
 class ASH_EXPORT MirrorWindowController : public aura::WindowTreeHostObserver {
  public:
@@ skipping 49 matching lines @@
   std::unique_ptr<aura::client::ScreenPositionClient> screen_position_client_;
 
   std::unique_ptr<ui::Reflector> reflector_;
 
   DISALLOW_COPY_AND_ASSIGN(MirrorWindowController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_MIRROR_WINDOW_CONTROLLER_H_