Use OnceCallback on Mojo interfaces in //ash

chrome/browser/ui/ash/launcher/arc_app_window_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_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_
 
 #include <string>
 #include <unordered_set>
 
 #include "base/macros.h"
 #include "chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h"
 
 // Shelf item delegate for ARC app windows.
 class ArcAppWindowLauncherItemController
     : public AppWindowLauncherItemController {
  public:
   explicit ArcAppWindowLauncherItemController(const std::string& arc_app_id);
 
   ~ArcAppWindowLauncherItemController() override;
 
   // AppWindowLauncherItemController overrides:
   void ItemSelected(std::unique_ptr<ui::Event> event,
                     int64_t display_id,
                     ash::ShelfLaunchSource source,
-                    const ItemSelectedCallback& callback) override;
+                    ItemSelectedCallback callback) override;
   ash::MenuItemList GetAppMenuItems(int event_flags) override;
   void ExecuteCommand(uint32_t command_id, int32_t event_flags) override;
 
   void AddTaskId(int task_id);
   void RemoveTaskId(int task_id);
   bool HasAnyTasks() const;
 
  private:
   std::unordered_set<int> task_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcAppWindowLauncherItemController);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_