mash: Add a simple, temporary preferences store.

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

Index: components/filesystem/public/cpp/prefs/pref_service_factory.cc
diff --git a/components/filesystem/public/cpp/prefs/pref_service_factory.cc b/components/filesystem/public/cpp/prefs/pref_service_factory.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b2209e75b9a80990c355823f3c2a517a3fe013e6
--- /dev/null
+++ b/components/filesystem/public/cpp/prefs/pref_service_factory.cc
@@ -0,0 +1,46 @@
+// 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.
+
+#include "components/filesystem/public/cpp/prefs/pref_service_factory.h"
+
+#include "base/bind.h"
+#include "base/prefs/pref_notifier_impl.h"
+#include "base/prefs/pref_registry.h"
+#include "base/prefs/pref_service.h"
+#include "base/prefs/pref_value_store.h"
+#include "base/prefs/value_map_pref_store.h"
+#include "base/prefs/writeable_pref_store.h"
+#include "components/filesystem/public/cpp/prefs/filesystem_json_pref_store.h"
+#include "mojo/shell/public/cpp/application_impl.h"
+
+namespace filesystem {
+
+namespace {
+
+// Do-nothing default implementation.
+void DoNothingHandleReadError(PersistentPrefStore::PrefReadError error) {}
+
+}  // namespace
+
+scoped_ptr<PrefService> CreatePrefService(mojo::ApplicationImpl* application,
+                                          PrefRegistry* pref_registry) {
+  filesystem::FileSystemPtr filesystem;
+  application->ConnectToService("mojo:filesystem", &filesystem);
+
+  scoped_refptr<FilesystemJsonPrefStore> user_prefs =
+      new FilesystemJsonPrefStore("preferences.json", std::move(filesystem),
+                                  nullptr /* TODO(erg): pref filter */);
+
+  PrefNotifierImpl* pref_notifier = new PrefNotifierImpl();
+  scoped_ptr<PrefService> pref_service(new PrefService(
+      pref_notifier,
+      new PrefValueStore(nullptr, nullptr, nullptr, nullptr, user_prefs.get(),
+                         nullptr, pref_registry->defaults().get(),
+                         pref_notifier),
+      user_prefs.get(), pref_registry, base::Bind(&DoNothingHandleReadError),
+      true /* async */));
+  return pref_service;
+}
+
+}  // namespace filesystem