Move DisplayManager and DisplayChangeObserverX11 from aura to ash.

ui/aura/display_observer.h

-// Copyright (c) 2012 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_DISPLAY_OBSERVER_H_
-#define UI_AURA_DISPLAY_OBSERVER_H_
-
-#include "ui/aura/aura_export.h"
-
-namespace gfx {
-class Display;
-}
-
-namespace aura {
-
-// Observers for display configuration changes.
-class AURA_EXPORT DisplayObserver {
- public:
-  // Called when the |display|'s bound has changed.
-  virtual void OnDisplayBoundsChanged(const gfx::Display& display) = 0;
-
-  // Called when |new_display| has been added.
-  virtual void OnDisplayAdded(const gfx::Display& new_display) = 0;
-
-  // Called when |old_display| has been removed.
-  virtual void OnDisplayRemoved(const gfx::Display& old_display) = 0;
-
- protected:
-  virtual ~DisplayObserver();
-};
-
-}  // namespace aura
-
-#endif  // UI_AURA_DISPLAY_OBSERVER_H_