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..0dcf2980ace3b903d49069eae1a60b8f97b1e99b 100644
--- a/chrome/browser/prefs/pref_service.cc
+++ b/chrome/browser/prefs/pref_service.cc
@@ -28,6 +28,7 @@
 #include "chrome/common/json_pref_store.h"
 #include "content/browser/browser_thread.h"
 #include "content/common/notification_service.h"
+#include "content/common/notification_source.h"
 #include "grit/chromium_strings.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
@@ -139,6 +140,7 @@ PrefService::PrefService(PrefStore* managed_platform_prefs,
                          DefaultPrefStore* default_store)
     : user_pref_store_(user_prefs),
       default_store_(default_store) {
+  user_pref_store_->SetNotificationSource(Source<PrefService>(this));
   pref_notifier_.reset(new PrefNotifierImpl(this));
   pref_value_store_.reset(
       new PrefValueStore(managed_platform_prefs,
@@ -213,16 +215,19 @@ 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));