ash: Cleanup class/struct forward declarations

ash/sticky_keys/sticky_keys_controller.h

 // Copyright 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_STICKY_KEYS_STICKY_KEYS_CONTROLLER_H_
 #define ASH_STICKY_KEYS_STICKY_KEYS_CONTROLLER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/sticky_keys/sticky_keys_state.h"
 #include "base/macros.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/event_handler.h"
 #include "ui/events/event_rewriter.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 
 namespace ui {
 class Event;
 class KeyEvent;
 class MouseEvent;
 }  // namespace ui
 
-namespace aura {
-class Window;
-}  // namespace aura
-
 namespace ash {
 
 class StickyKeysOverlay;
 class StickyKeysHandler;
 
 // StickyKeysController is an accessibility feature for users to be able to
 // compose key and mouse event with modifier keys without simultaneous key
 // press event. Instead they can compose events separately pressing each of the
 // modifier keys involved.
 // e.g. Composing Ctrl + T
@@ skipping 236 matching lines @@
 
   // The modifier up key event to be sent on non modifier key on ENABLED state.
   std::unique_ptr<ui::KeyEvent> modifier_up_event_;
 
   DISALLOW_COPY_AND_ASSIGN(StickyKeysHandler);
 };
 
 }  // namespace ash
 
 #endif  // ASH_STICKY_KEYS_STICKY_KEYS_CONTROLLER_H_