Fix a race condition in preference metric reporting.

base/prefs/pref_service_factory.cc

 // Copyright 2013 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 "base/prefs/pref_service_factory.h"
 
 #include "base/bind.h"
 #include "base/prefs/default_pref_store.h"
 #include "base/prefs/json_pref_store.h"
+#include "base/prefs/pref_filter.h"
 #include "base/prefs/pref_notifier_impl.h"
 #include "base/prefs/pref_service.h"
 
 #include "base/prefs/pref_value_store.h"
 
 namespace base {
 
 namespace {
 
 // Do-nothing default implementation.
@@ skipping 10 matching lines @@
       user_prefs_(NULL),
       recommended_prefs_(NULL),
       read_error_callback_(base::Bind(&DoNothingHandleReadError)),
       async_(false) {}
 
 PrefServiceFactory::~PrefServiceFactory() {}
 
 void PrefServiceFactory::SetUserPrefsFile(
     const base::FilePath& prefs_file,
     base::SequencedTaskRunner* task_runner) {
-  user_prefs_ = new JsonPrefStore(prefs_file, task_runner);
+  user_prefs_ = new JsonPrefStore(
+      prefs_file, task_runner, scoped_ptr<PrefFilter>());
 }
 
 scoped_ptr<PrefService> PrefServiceFactory::Create(
     PrefRegistry* pref_registry) {
   PrefNotifierImpl* pref_notifier = new PrefNotifierImpl();
   scoped_ptr<PrefService> pref_service(
       new PrefService(pref_notifier,
                       new PrefValueStore(managed_prefs_.get(),
                                          supervised_user_prefs_.get(),
                                          extension_prefs_.get(),
                                          command_line_prefs_.get(),
                                          user_prefs_.get(),
                                          recommended_prefs_.get(),
                                          pref_registry->defaults().get(),
                                          pref_notifier),
                       user_prefs_.get(),
                       pref_registry,
                       read_error_callback_,
                       async_));
   return pref_service.Pass();
 }
 
 }  // namespace base