mash: Convert ShelfView to wm common types, clean up Shelf access

ash/shelf/shelf_icon_observer.h

Index: ash/shelf/shelf_icon_observer.h
diff --git a/ash/shelf/shelf_icon_observer.h b/ash/shelf/shelf_icon_observer.h
deleted file mode 100644
index 8132a8939e8897bd85667f3cb1ef94a3631a3946..0000000000000000000000000000000000000000
--- a/ash/shelf/shelf_icon_observer.h
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright 2013 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_SHELF_SHELF_ICON_OBSERVER_H_
-#define ASH_SHELF_SHELF_ICON_OBSERVER_H_
-
-#include "ash/ash_export.h"
-
-namespace ash {
-
-class ASH_EXPORT ShelfIconObserver {
- public:
-  // Invoked when any icon on shelf changes position.
-  virtual void OnShelfIconPositionsChanged() = 0;
-
- protected:
-  virtual ~ShelfIconObserver() {}
-};
-
-}  // namespace ash
-
-#endif  // ASH_SHELF_SHELF_ICON_OBSERVER_H_