Provide lazy CommitPendingWrites in addition to eager SavePersistentPrefs.

chrome/browser/prefs/pref_service.cc

 // Copyright (c) 2011 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/command_line.h"
@@ skipping 195 matching lines @@
   UMA_HISTOGRAM_ENUMERATION("PrefService.ReadError", error, 20);
 }
 
 bool PrefService::ReloadPersistentPrefs() {
   return user_pref_store_->ReadPrefs() ==
              PersistentPrefStore::PREF_READ_ERROR_NONE;
 }
 
 bool PrefService::SavePersistentPrefs() {
   DCHECK(CalledOnValidThread());
-
   return user_pref_store_->WritePrefs();
 }
 
 void PrefService::ScheduleSavePersistentPrefs() {
   DCHECK(CalledOnValidThread());
+  user_pref_store_->ScheduleWritePrefs();
+}
 
-  user_pref_store_->ScheduleWritePrefs();
+void PrefService::CommitPendingWrite() {
+  DCHECK(CalledOnValidThread());
+  user_pref_store_->CommitPendingWrite();
 }
 
 void PrefService::RegisterBooleanPref(const char* path,
                                       bool default_value) {
   RegisterPreference(path, Value::CreateBooleanValue(default_value));
 }
 
 void PrefService::RegisterIntegerPref(const char* path, int default_value) {
   RegisterPreference(path, Value::CreateIntegerValue(default_value));
 }
@@ skipping 455 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());
 }