Use mojo Shelf interfaces for both mash and classic ash.

ash/common/shelf/wm_shelf.h

 // Copyright 2016 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_WM_SHELF_H_
 #define ASH_COMMON_SHELF_WM_SHELF_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 21 matching lines @@
 class WmWindow;
 
 // Controller for the shelf state. Exists for the lifetime of each root window
 // controller. Note that the shelf widget may not be created until after login.
 class ASH_EXPORT WmShelf : public ShelfLayoutManagerObserver {
  public:
   // Returns the shelf for the display that |window| is on. Note that the shelf
   // widget may not exist, or the shelf may not be visible.
   static WmShelf* ForWindow(WmWindow* window);
 
+  // Returns if shelf alignment options are enabled, and the user is able to
+  // adjust the alignment (eg. not allowed in guest and supervised user modes).
+  static bool CanChangeShelfAlignment();
+
   virtual void CreateShelfWidget(WmWindow* root);
   void ShutdownShelfWidget();
   void DestroyShelfWidget();
 
   ShelfLayoutManager* shelf_layout_manager() const {
     return shelf_layout_manager_;
   }
 
   ShelfWidget* shelf_widget() { return shelf_widget_.get(); }
 
@@ skipping 119 matching lines @@
   ShelfAutoHideBehavior auto_hide_behavior_ = SHELF_AUTO_HIDE_BEHAVIOR_NEVER;
 
   base::ObserverList<WmShelfObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(WmShelf);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_WM_SHELF_H_