Add OnDisplayMetricsChanged in DisplayObserver.

ash/display/screen_ash.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_DISPLAY_SCREEN_ASH_H_
 #define ASH_DISPLAY_SCREEN_ASH_H_
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 #include "base/observer_list.h"
+#include "ui/gfx/display_observer.h"
 #include "ui/gfx/screen.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace ash {
 namespace  internal {
 class DisplayManager;
 }
@@ skipping 53 matching lines @@
   virtual gfx::Display GetDisplayMatching(
       const gfx::Rect& match_rect) const OVERRIDE;
   virtual gfx::Display GetPrimaryDisplay() const OVERRIDE;
   virtual void AddObserver(gfx::DisplayObserver* observer) OVERRIDE;
   virtual void RemoveObserver(gfx::DisplayObserver* observer) OVERRIDE;
 
  private:
   friend class DisplayManager;
 
   // Notifies observers of display configuration changes.
-  void NotifyBoundsChanged(const gfx::Display& display);
+  void NotifyMetricsChanged(const gfx::Display& display,
+      gfx::DisplayObserver::MetricsType metrics);
   void NotifyDisplayAdded(const gfx::Display& display);
   void NotifyDisplayRemoved(const gfx::Display& display);
 
   // Creates a screen that can be used during shutdown.
   // It simply has a copy of the displays.
   gfx::Screen* CloneForShutdown();
 
   ObserverList<gfx::DisplayObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenAsh);
 };
 
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_SCREEN_ASH_H_