Remove window/host accessors from WED; IWYU for WTH

ui/aura/test/ui_controls_factory_aura.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 UI_AURA_TEST_UI_CONTROLS_FACTORY_AURA_H_
 #define UI_AURA_TEST_UI_CONTROLS_FACTORY_AURA_H_
 
 #include "ui/base/test/ui_controls_aura.h"
 
 namespace aura {
-class WindowEventDispatcher;
+class WindowTreeHost;
 
 namespace test {
 
-// TODO(beng): Should be changed to take a WindowTreeHost.
-ui_controls::UIControlsAura* CreateUIControlsAura(
-    WindowEventDispatcher* dispatcher);
+ui_controls::UIControlsAura* CreateUIControlsAura(WindowTreeHost* host);
 
 }  // namespace test
 }  // namespace aura
 
 #endif  // UI_AURA_TEST_UI_CONTROLS_FACTORY_AURA_H_