Use mojo Shelf interfaces for both mash and classic ash.

ash/common/shelf/shelf_widget.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_COMMON_SHELF_SHELF_WIDGET_H_
 #define ASH_COMMON_SHELF_SHELF_WIDGET_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 21 matching lines @@
 class ASH_EXPORT ShelfWidget : public views::Widget,
                                public views::WidgetObserver,
                                public ShelfBackgroundAnimatorObserver,
                                public ShelfLayoutManagerObserver {
  public:
   ShelfWidget(WmWindow* shelf_container, WmShelf* wm_shelf);
   ~ShelfWidget() override;
 
   void CreateStatusAreaWidget(WmWindow* status_container);
 
-  // Returns if shelf alignment option is enabled, and the user is able to
-  // adjust the alignment (guest and supervised mode users cannot for example).
-  static bool ShelfAlignmentAllowed();
-
   void OnShelfAlignmentChanged();
 
   // DEPRECATED: Prefer WmShelf::GetAlignment().
   ShelfAlignment GetAlignment() const;
 
   // Sets the shelf's background type.
   void SetPaintsBackground(ShelfBackgroundType background_type,
                            BackgroundAnimatorChangeType change_type);
   ShelfBackgroundType GetBackgroundType() const;
 
@@ skipping 85 matching lines @@
   ShelfView* shelf_view_;
   ShelfBackgroundAnimator background_animator_;
   bool activating_as_fallback_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfWidget);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_SHELF_WIDGET_H_