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

components/filesystem/public/cpp/prefs/pref_service_factory.h

 // Copyright 2016 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.
 
 #ifndef COMPONENTS_FILESYSTEM_PUBLIC_CPP_PREFS_PREF_SERVICE_FACTORY_H_
 #define COMPONENTS_FILESYSTEM_PUBLIC_CPP_PREFS_PREF_SERVICE_FACTORY_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "components/prefs/pref_service.h"
 
 namespace mojo {
-class ApplicationImpl;
+class Shell;
 }
 
 class PrefRegistry;
 
 namespace filesystem {
 
 // This factory method creates a PrefService for the local process based on the
 // preference registry passed in. This PrefService will synchronize with a JSON
 // file in the mojo:filesystem.
-scoped_ptr<PrefService> CreatePrefService(mojo::ApplicationImpl* application,
+scoped_ptr<PrefService> CreatePrefService(mojo::Shell* shell,
                                           PrefRegistry* registry);
 
 }  // namespace filesystem
 
 #endif  // COMPONENTS_FILESYSTEM_PUBLIC_CPP_PREFS_PREF_SERVICE_FACTORY_H_