Convert //ash from scoped_ptr to std::unique_ptr

ash/system/tray_update.h

 // Copyright (c) 2012 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_SYSTEM_TRAY_UPDATE_H_
 #define ASH_SYSTEM_TRAY_UPDATE_H_
 
+#include <memory>
+
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_image_item.h"
 #include "ash/system/user/update_observer.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 
 namespace views {
 class View;
 }
 
 namespace ash {
 
 namespace tray {
 class UpdateNagger;
 }
 
 class TrayUpdate : public TrayImageItem,
                    public UpdateObserver {
  public:
   explicit TrayUpdate(SystemTray* system_tray);
   ~TrayUpdate() override;
 
  private:
   // Overridden from TrayImageItem.
   bool GetInitialVisibility() override;
   views::View* CreateDefaultView(user::LoginStatus status) override;
   views::View* CreateDetailedView(user::LoginStatus status) override;
   void DestroyDetailedView() override;
 
   // Overridden from UpdateObserver.
   void OnUpdateRecommended(const UpdateInfo& info) override;
 
   // Used to nag the user in case the tray has been hidden too long with an
   // unseen update notification.
-  scoped_ptr<tray::UpdateNagger> nagger_;
+  std::unique_ptr<tray::UpdateNagger> nagger_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayUpdate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_UPDATE_H_