Provide lazy CommitPendingWrites in addition to eager SavePersistentPrefs.

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 373a86f55381230ba1761978065a277cb6b56416..d9588b56a1b83f14d71fc1f33ddd08f0b6844789 100644
--- a/chrome/browser/prefs/pref_service.cc
+++ b/chrome/browser/prefs/pref_service.cc
@@ -213,16 +213,19 @@ bool PrefService::ReloadPersistentPrefs() {
 
 bool PrefService::SavePersistentPrefs() {
   DCHECK(CalledOnValidThread());
-
   return user_pref_store_->WritePrefs();
 }
 
 void PrefService::ScheduleSavePersistentPrefs() {
   DCHECK(CalledOnValidThread());
-
   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));