Remove last dependencies on ui/base from ui/gfx

ui/gfx/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_GFX_DISPLAY_OBSERVER_H_
 #define UI_GFX_DISPLAY_OBSERVER_H_
 
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 class Display;
 
 // Observers for display configuration changes.
 // TODO(oshima): consolidate |WorkAreaWatcherObserver| and
 // |DisplaySettingsProvier|. crbug.com/122863.
-class UI_EXPORT DisplayObserver {
+class GFX_EXPORT DisplayObserver {
  public:
   // Called when the |display|'s bound has changed.
   virtual void OnDisplayBoundsChanged(const Display& display) = 0;
 
   // Called when |new_display| has been added.
   virtual void OnDisplayAdded(const Display& new_display) = 0;
 
   // Called when |old_display| has been removed.
   virtual void OnDisplayRemoved(const Display& old_display) = 0;
 
  protected:
   virtual ~DisplayObserver();
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_DISPLAY_OBSERVER_H_