Pref service: add support for tracked prefs.

services/preferences/persistent_pref_store_factory.cc

 // Copyright 2017 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 "services/preferences/persistent_pref_store_factory.h"
 
 #include <memory>
 #include <utility>
 
 #include "components/prefs/json_pref_store.h"
 #include "components/prefs/pref_filter.h"
 #include "services/preferences/persistent_pref_store_impl.h"
+#include "services/preferences/tracked/tracked_persistent_pref_store_factory.h"
 
 namespace prefs {
 namespace {
 
 std::unique_ptr<PersistentPrefStoreImpl> CreateSimplePersistentPrefStore(
     mojom::SimplePersistentPrefStoreConfigurationPtr config,
     base::SequencedWorkerPool* worker_pool,
     base::Closure on_initialized) {
   return base::MakeUnique<PersistentPrefStoreImpl>(
       new JsonPrefStore(config->pref_filename,
                         JsonPrefStore::GetTaskRunnerForFile(
                             config->pref_filename.DirName(), worker_pool),
                         nullptr),
-      nullptr, std::move(on_initialized));
+      std::move(on_initialized));
 }
 
 }  // namespace
 
 std::unique_ptr<PersistentPrefStoreImpl> CreatePersistentPrefStore(
     mojom::PersistentPrefStoreConfigurationPtr configuration,
     base::SequencedWorkerPool* worker_pool,
     base::Closure on_initialized) {
   if (configuration->is_simple_configuration()) {
     return CreateSimplePersistentPrefStore(
         std::move(configuration->get_simple_configuration()), worker_pool,
         std::move(on_initialized));
   }
+  if (configuration->is_tracked_configuration()) {
+    return base::MakeUnique<PersistentPrefStoreImpl>(
+        CreateTrackedPersistentPrefStore(
+            std::move(configuration->get_tracked_configuration()), worker_pool),
+        std::move(on_initialized));
+  }
   NOTREACHED();
   return nullptr;
 }
 
 }  // namespace prefs