Moved JsonPrefStore to use SequencedWorkerPool

chrome/browser/prefs/pref_service.cc

Index: chrome/browser/prefs/pref_service.cc
diff --git a/chrome/browser/prefs/pref_service.cc b/chrome/browser/prefs/pref_service.cc
index 10d7078989cfa4f7af59f96d16424134a12e45fb..8ed5ad32a97e3137be9eb5744185b50c76b81776 100644
--- a/chrome/browser/prefs/pref_service.cc
+++ b/chrome/browser/prefs/pref_service.cc
@@ -124,7 +124,8 @@ PrefService* PrefService::CreatePrefService(
     const FilePath& pref_filename,
     policy::PolicyService* policy_service,
     PrefStore* extension_prefs,
-    bool async) {
+    bool async,
+    base::SequencedTaskRunner* sequenced_task_runner) {
   using policy::ConfigurationPolicyPrefStore;
 
 #if defined(OS_LINUX)
@@ -154,9 +155,8 @@ PrefService* PrefService::CreatePrefService(
 
   CommandLinePrefStore* command_line =
       new CommandLinePrefStore(CommandLine::ForCurrentProcess());
-  JsonPrefStore* user = new JsonPrefStore(
-      pref_filename,
-      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE));
+  JsonPrefStore* user = JsonPrefStore::Create(
+      pref_filename, sequenced_task_runner);
   DefaultPrefStore* default_pref_store = new DefaultPrefStore();
 
   PrefNotifierImpl* pref_notifier = new PrefNotifierImpl();