Remove ShelfItemDelegate::IsDraggable; check for app list button.

ash/common/shelf/app_list_shelf_item_delegate.h

 // 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_COMMON_SHELF_APP_LIST_SHELF_ITEM_DELEGATE_H_
 #define ASH_COMMON_SHELF_APP_LIST_SHELF_ITEM_DELEGATE_H_
 
 #include "ash/common/shelf/shelf_item_delegate.h"
 #include "base/macros.h"
 
 namespace ash {
 class ShelfModel;
 
 // ShelfItemDelegate for TYPE_APP_LIST.
 class AppListShelfItemDelegate : public ShelfItemDelegate {
  public:
   // Initializes the app list item in the shelf data model and creates an
   // AppListShelfItemDelegate which will be owned by |shelf_model|.
   static void CreateAppListItemAndDelegate(ShelfModel* shelf_model);
 
   AppListShelfItemDelegate();
   ~AppListShelfItemDelegate() override;
 
   // ShelfItemDelegate:
   ShelfItemDelegate::PerformedAction ItemSelected(
       const ui::Event& event) override;
   base::string16 GetTitle() override;
   ShelfMenuModel* CreateApplicationMenu(int event_flags) override;
-  bool IsDraggable() override;
   bool CanPin() const override;
   void Close() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AppListShelfItemDelegate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_APP_LIST_SHELF_ITEM_DELEGATE_H_