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

mandoline/ui/desktop_ui/browser_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 "base/macros.h"
 #include "mandoline/ui/desktop_ui/public/interfaces/launch_handler.mojom.h"
-#include "mojo/shell/public/cpp/application_impl.h"
 #include "mojo/shell/public/cpp/application_test_base.h"
 
 namespace mandoline {
 
 class BrowserTest : public mojo::test::ApplicationTestBase {
  public:
   BrowserTest() : ApplicationTestBase() {}
   ~BrowserTest() override {}
 
   // mojo::test::ApplicationTestBase:
   void SetUp() override {
     mojo::test::ApplicationTestBase::SetUp();
-    application_impl()->ConnectToService("mojo:desktop_ui", &launch_handler_);
+    shell()->ConnectToService("mojo:desktop_ui", &launch_handler_);
     ASSERT_TRUE(launch_handler_.is_bound());
   }
 
  protected:
   LaunchHandlerPtr launch_handler_;
 
  private:
   MOJO_DISALLOW_COPY_AND_ASSIGN(BrowserTest);
 };
 
 // A simple sanity check for connecting to the LaunchHandler.
 TEST_F(BrowserTest, LaunchHandlerBasic) {
   ASSERT_TRUE(launch_handler_.is_bound());
   launch_handler_->LaunchURL(mojo::String::From("data:text/html,foo"));
   EXPECT_TRUE(launch_handler_.is_bound());
 }
 
 }  // namespace mandoline