ash: Rename LauncherIconObserver to ShelfIconObserver.

ash/launcher/launcher_icon_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 ASH_LAUNCHER_LAUNCHER_ICON_OBSERVER_H_
-#define ASH_LAUNCHER_LAUNCHER_ICON_OBSERVER_H_
-
-#include "ash/ash_export.h"
-#include "base/basictypes.h"
-
-namespace ash {
-
-class ASH_EXPORT LauncherIconObserver {
- public:
-  // Invoked when any icon on launcher changes position.
-  virtual void OnLauncherIconPositionsChanged() = 0;
-
- protected:
-  virtual ~LauncherIconObserver() {}
-};
-
-}  // namespace ash
-
-#endif  // ASH_LAUNCHER_LAUNCHER_ICON_OBSERVER_H_