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

components/filesystem/files_test_base.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 "components/filesystem/files_test_base.h"
 
 #include <utility>
 
 #include "components/filesystem/public/interfaces/directory.mojom.h"
 #include "components/filesystem/public/interfaces/types.mojom.h"
-#include "mojo/shell/public/cpp/application_impl.h"
+#include "mojo/shell/public/cpp/shell.h"
 #include "mojo/util/capture_util.h"
 
 namespace filesystem {
 
 FilesTestBase::FilesTestBase() : binding_(this) {
 }
 
 FilesTestBase::~FilesTestBase() {
 }
 
 void FilesTestBase::SetUp() {
   ApplicationTestBase::SetUp();
-  application_impl()->ConnectToService("mojo:filesystem", &files_);
+  shell()->ConnectToService("mojo:filesystem", &files_);
 }
 
 void FilesTestBase::OnFileSystemShutdown() {
 }
 
 void FilesTestBase::GetTemporaryRoot(DirectoryPtr* directory) {
   FileError error = FileError::FAILED;
   files()->OpenFileSystem("temp", GetProxy(directory),
                           binding_.CreateInterfacePtrAndBind(),
                           mojo::Capture(&error));
   ASSERT_TRUE(files().WaitForIncomingResponse());
   ASSERT_EQ(FileError::OK, error);
 }
 
 }  // namespace filesystem