Use worker pool for IO in JsonPrefStore.

chrome/browser/prefs/pref_service.cc

 // Copyright (c) 2012 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 "chrome/browser/prefs/pref_service.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "base/value_conversions.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/extension_pref_store.h"
 #include "chrome/browser/policy/configuration_policy_pref_store.h"
 #include "chrome/browser/prefs/command_line_pref_store.h"
 #include "chrome/browser/prefs/default_pref_store.h"
 #include "chrome/browser/prefs/overlay_user_pref_store.h"
 #include "chrome/browser/prefs/pref_model_associator.h"
 #include "chrome/browser/prefs/pref_notifier_impl.h"
@@ skipping 108 matching lines @@
       ConfigurationPolicyPrefStore::CreateMandatoryPolicyPrefStore();
   ConfigurationPolicyPrefStore* recommended =
       ConfigurationPolicyPrefStore::CreateRecommendedPolicyPrefStore();
 #else
   ConfigurationPolicyPrefStore* managed = NULL;
   ConfigurationPolicyPrefStore* recommended = NULL;
 #endif  // ENABLE_CONFIGURATION_POLICY
 
   CommandLinePrefStore* command_line =
       new CommandLinePrefStore(CommandLine::ForCurrentProcess());
-  JsonPrefStore* user = new JsonPrefStore(
-      pref_filename,
-      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE));
+  scoped_refptr<base::SequencedTaskRunner> io_task_runner =
+      BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
+          BrowserThread::GetBlockingPool()->GetSequenceToken());
+  JsonPrefStore* user = new JsonPrefStore(pref_filename, io_task_runner);
   DefaultPrefStore* default_pref_store = new DefaultPrefStore();
 
   PrefNotifierImpl* pref_notifier = new PrefNotifierImpl();
   PrefModelAssociator* pref_sync_associator = new PrefModelAssociator();
 
   return new PrefService(
       pref_notifier,
       new PrefValueStore(
           managed,
           extension_prefs,
@@ skipping 819 matching lines @@
   return pref_value_store()->PrefValueFromDefaultStore(name_.c_str());
 }
 
 bool PrefService::Preference::IsUserModifiable() const {
   return pref_value_store()->PrefValueUserModifiable(name_.c_str());
 }
 
 bool PrefService::Preference::IsExtensionModifiable() const {
   return pref_value_store()->PrefValueExtensionModifiable(name_.c_str());
 }