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

ui/message_center/views/desktop_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 UI_MESSAGE_CENTER_VIEWS_DESKTOP_POPUP_ALIGNMENT_DELEGATE_H_
 #define UI_MESSAGE_CENTER_VIEWS_DESKTOP_POPUP_ALIGNMENT_DELEGATE_H_
 
 #include <stdint.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 gfx {
+namespace display {
 class Screen;
 }
 
-namespace display {
-using Screen = gfx::Screen;
-}
-
 namespace message_center {
 namespace test {
 class MessagePopupCollectionTest;
 }
 
 // The PopupAlignmentDelegate for non-ash Windows/Linux desktop.
 class MESSAGE_CENTER_EXPORT DesktopPopupAlignmentDelegate
     : public PopupAlignmentDelegate,
       public display::DisplayObserver {
  public:
@@ skipping 30 matching lines @@
   int64_t display_id_;
   display::Screen* screen_;
   gfx::Rect work_area_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopPopupAlignmentDelegate);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_DESKTOP_POPUP_ALIGNMENT_DELEGATE_H_