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

ash/common/shelf/shelf_window_watcher_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_SHELF_WINDOW_WATCHER_ITEM_DELEGATE_H_
 #define ASH_COMMON_SHELF_SHELF_WINDOW_WATCHER_ITEM_DELEGATE_H_
 
 #include "ash/common/shelf/shelf_item_delegate.h"
 #include "ash/common/shelf/shelf_item_types.h"
 #include "base/macros.h"
 
 namespace ash {
 
 class WmWindow;
 
 // ShelfItemDelegate for the items created by ShelfWindowWatcher.
 class ShelfWindowWatcherItemDelegate : public ShelfItemDelegate {
  public:
   ShelfWindowWatcherItemDelegate(ShelfID id, WmWindow* window);
   ~ShelfWindowWatcherItemDelegate() override;
 
  private:
   // ShelfItemDelegate overrides:
   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;
 
   ShelfID id_;
   // The window associated with this item. Not owned.
   WmWindow* window_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfWindowWatcherItemDelegate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_SHELF_WINDOW_WATCHER_ITEM_DELEGATE_H_