Move Screen, its impls, DisplayObserver and DisplayChangeNotifier to ui/display

ash/system/web_notification/ash_popup_alignment_delegate.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_SYSTEM_WEB_NOTIFICATION_ASH_POPUP_ALIGNMENT_DELEGATE_H_
 #define ASH_SYSTEM_WEB_NOTIFICATION_ASH_POPUP_ALIGNMENT_DELEGATE_H_
 
 #include <stdint.h>
 
 #include "ash/ash_export.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
 #include "ash/shelf/shelf_types.h"
 #include "ash/shell_observer.h"
 #include "base/macros.h"
 #include "ui/display/display_observer.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/message_center/views/popup_alignment_delegate.h"
 
 namespace aura {
 class Window;
 }
 
-namespace gfx {
+namespace display {
 class Screen;
 }
 
-namespace display {
-using Screen = gfx::Screen;
-}
-
 namespace ash {
 
 class AshPopupAlignmentDelegateTest;
 class ShelfLayoutManager;
 class WebNotificationTrayTest;
 
 // The PopupAlignmentDelegate subclass for Ash. It needs to handle alignment of
 // the shelf and its autohide state.
 class ASH_EXPORT AshPopupAlignmentDelegate
     : public message_center::PopupAlignmentDelegate,
@@ skipping 49 matching lines @@
   gfx::Rect work_area_;
   ShelfLayoutManager* shelf_;
   int system_tray_height_;
 
   DISALLOW_COPY_AND_ASSIGN(AshPopupAlignmentDelegate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_WEB_NOTIFICATION_ASH_POPUP_ALIGNMENT_DELEGATE_H_