Use OnceCallback on Mojo interfaces in //ash

chrome/browser/ui/ash/launcher/arc_playstore_shortcut_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_PLAYSTORE_SHORTCUT_LAUNCHER_ITEM_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_PLAYSTORE_SHORTCUT_LAUNCHER_ITEM_CONTROLLER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "chrome/browser/ui/ash/launcher/app_shortcut_launcher_item_controller.h"
 
 class ArcAppLauncher;
 
 class ArcPlaystoreShortcutLauncherItemController
     : public AppShortcutLauncherItemController {
  public:
   ArcPlaystoreShortcutLauncherItemController();
   ~ArcPlaystoreShortcutLauncherItemController() override;
 
   // AppShortcutLauncherItemController overrides:
   void ItemSelected(std::unique_ptr<ui::Event> event,
                     int64_t display_id,
                     ash::ShelfLaunchSource source,
-                    const ItemSelectedCallback& callback) override;
+                    ItemSelectedCallback callback) override;
 
  private:
   std::unique_ptr<ArcAppLauncher> playstore_launcher_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcPlaystoreShortcutLauncherItemController);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_PLAYSTORE_SHORTCUT_LAUNCHER_ITEM_CONTROLLER_H_