Use OnceCallback on Mojo interfaces in //ash

chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_item_controller.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 CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_APP_DEFERRED_LAUNCHER_ITEM_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_APP_DEFERRED_LAUNCHER_ITEM_CONTROLLER_H_
 
 #include <string>
 
 #include "ash/public/cpp/shelf_item_delegate.h"
@@ skipping 16 matching lines @@
   ~ArcAppDeferredLauncherItemController() override;
 
   base::TimeDelta GetActiveTime() const;
 
   int event_flags() const { return event_flags_; }
 
   // ash::ShelfItemDelegate:
   void ItemSelected(std::unique_ptr<ui::Event> event,
                     int64_t display_id,
                     ash::ShelfLaunchSource source,
-                    const ItemSelectedCallback& callback) override;
+                    ItemSelectedCallback callback) override;
   void ExecuteCommand(uint32_t command_id, int32_t event_flags) override;
   void Close() override;
 
  private:
   // The flags of the event that caused the ARC app to be activated. These will
   // be propagated to the launch event once the app is actually launched.
   const int event_flags_;
 
   base::WeakPtr<ArcAppDeferredLauncherController> host_;
   const base::Time start_time_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcAppDeferredLauncherItemController);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_APP_DEFERRED_LAUNCHER_ITEM_CONTROLLER_H_