Extract shell methods from ApplicationImpl into a base class, and pass this to Initialize() instead.

device/devices_app/devices_apptest.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 <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/run_loop.h"
 #include "device/devices_app/devices_app.h"
 #include "device/devices_app/usb/public/interfaces/device_manager.mojom.h"
-#include "mojo/shell/public/cpp/application_impl.h"
 #include "mojo/shell/public/cpp/application_test_base.h"
 
 namespace device {
 namespace {
 
 class DevicesAppTest : public mojo::test::ApplicationTestBase {
  public:
   DevicesAppTest() {}
   ~DevicesAppTest() override {}
 
   void SetUp() override {
     ApplicationTestBase::SetUp();
-    application_impl()->ConnectToService("mojo:devices", &usb_device_manager_);
+    shell()->ConnectToService("mojo:devices", &usb_device_manager_);
   }
 
   usb::DeviceManager* usb_device_manager() { return usb_device_manager_.get(); }
 
  private:
   usb::DeviceManagerPtr usb_device_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(DevicesAppTest);
 };
 
@@ skipping 10 matching lines @@
   base::RunLoop loop;
   usb::EnumerationOptionsPtr options = usb::EnumerationOptions::New();
   options->filters = mojo::Array<usb::DeviceFilterPtr>(1);
   options->filters[0] = usb::DeviceFilter::New();
   usb_device_manager()->GetDevices(
       std::move(options), base::Bind(&OnGetDevices, loop.QuitClosure()));
   loop.Run();
 }
 
 }  // namespace device