Use OnceCallback on Mojo interfaces in //ash

chrome/browser/ui/ash/launcher/app_window_launcher_item_controller.h

 // Copyright 2014 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_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ASH_LAUNCHER_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_
 
 #include <list>
 #include <string>
 
@@ skipping 27 matching lines @@
   void RemoveWindow(ui::BaseWindow* window);
 
   void SetActiveWindow(aura::Window* window);
   ui::BaseWindow* GetAppWindow(aura::Window* window);
 
   // ash::ShelfItemDelegate overrides:
   AppWindowLauncherItemController* AsAppWindowLauncherItemController() override;
   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;
 
   // aura::WindowObserver overrides:
   void OnWindowPropertyChanged(aura::Window* window,
                                const void* key,
                                intptr_t old) override;
 
   // Get the number of running applications/incarnations of this.
   size_t window_count() const { return windows_.size(); }
@@ skipping 29 matching lines @@
   // Pointer to the most recently active app window
   ui::BaseWindow* last_active_window_ = nullptr;
 
   // Scoped list of observed windows (for removal on destruction)
   ScopedObserver<aura::Window, aura::WindowObserver> observed_windows_;
 
   DISALLOW_COPY_AND_ASSIGN(AppWindowLauncherItemController);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_LAUNCHER_APP_WINDOW_LAUNCHER_ITEM_CONTROLLER_H_