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

device/devices_app/usb/device_manager_impl_unittest.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 <set>
 #include <string>
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 40 matching lines @@
 
  protected:
   MockUsbService& mock_usb_service() {
     return device_client_->mock_usb_service();
   }
 
   DeviceManagerPtr ConnectToDeviceManager() {
     PermissionProviderPtr permission_provider;
     permission_provider_.Bind(mojo::GetProxy(&permission_provider));
     DeviceManagerPtr device_manager;
-    new DeviceManagerImpl(mojo::GetProxy(&device_manager),
-                          permission_provider.Pass(),
-                          base::ThreadTaskRunnerHandle::Get());
+    DeviceManagerImpl::Create(permission_provider.Pass(),
+                              mojo::GetProxy(&device_manager));
     return device_manager.Pass();
   }
 
  private:
   FakePermissionProvider permission_provider_;
   scoped_ptr<TestDeviceClient> device_client_;
   scoped_ptr<base::MessageLoop> message_loop_;
 };
 
 void ExpectDevicesAndThen(const std::set<std::string>& expected_guids,
@@ skipping 152 matching lines @@
     base::RunLoop loop;
     device_manager->GetDeviceChanges(base::Bind(&ExpectDeviceChangesAndThen,
                                                 added_guids, removed_guids,
                                                 loop.QuitClosure()));
     loop.Run();
   }
 }
 
 }  // namespace usb
 }  // namespace device