ash: Cleanup class/struct forward declarations

ash/common/wm/window_cycle_controller.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_COMMON_WM_WINDOW_CYCLE_CONTROLLER_H_
 #define ASH_COMMON_WM_WINDOW_CYCLE_CONTROLLER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
 #include "base/time/time.h"
 
-namespace ui {
-class EventHandler;
-}
-
 namespace ash {
 
 class WindowCycleEventFilter;
 class WindowCycleList;
 class WmWindow;
 
 // Controls cycling through windows with the keyboard via alt-tab.
 // Windows are sorted primarily by most recently used, and then by screen order.
 // We activate windows as you cycle through them, so the order on the screen
 // may change during the gesture, but the most recently used list isn't updated
@@ skipping 43 matching lines @@
   std::unique_ptr<WindowCycleEventFilter> event_filter_;
 
   base::Time cycle_start_time_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowCycleController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_WINDOW_CYCLE_CONTROLLER_H_