Provide the DeviceManager service to the renderer directly, no app.

device/devices_app/public/cpp/devices_app_factory.cc

 // Copyright 2015 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.
 
 #include "device/devices_app/public/cpp/devices_app_factory.h"
 
 #include "device/devices_app/devices_app.h"
 
 namespace device {
 
 // static
-scoped_ptr<mojo::ApplicationDelegate> DevicesAppFactory::CreateApp(
-    scoped_refptr<base::SequencedTaskRunner> service_task_runner) {
-  return scoped_ptr<mojo::ApplicationDelegate>(
-      new DevicesApp(service_task_runner));
+scoped_ptr<mojo::ApplicationDelegate> DevicesAppFactory::CreateApp() {
+  return scoped_ptr<mojo::ApplicationDelegate>(new DevicesApp());
 }
 
 }  // namespace device