ash: Cleanup class/struct forward declarations

ash/common/wm/maximize_mode/maximize_mode_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_MAXIMIZE_MODE_MAXIMIZE_MODE_CONTROLLER_H_
 #define ASH_COMMON_WM_MAXIMIZE_MODE_MAXIMIZE_MODE_CONTROLLER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 10 matching lines @@
 #endif  // OS_CHROMEOS
 
 namespace base {
 class TickClock;
 }
 
 namespace gfx {
 class Vector3dF;
 }
 
-namespace ui {
-class EventHandler;
-}
-
 namespace ash {
 
 class MaximizeModeControllerTest;
 class ScopedDisableInternalMouseAndKeyboard;
 class MaximizeModeWindowManager;
 class MaximizeModeWindowManagerTest;
 class WmWindow;
 namespace test {
 class MultiUserWindowManagerChromeOSTest;
 class VirtualKeyboardControllerTest;
@@ skipping 136 matching lines @@
   // incorrect calculations of hinge angles.
   gfx::Vector3dF base_smoothed_;
   gfx::Vector3dF lid_smoothed_;
 
   DISALLOW_COPY_AND_ASSIGN(MaximizeModeController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_MAXIMIZE_MODE_MAXIMIZE_MODE_CONTROLLER_H_