Provide lazy CommitPendingWrites in addition to eager SavePersistentPrefs.

content/common/notification_type.h

Index: content/common/notification_type.h
diff --git a/content/common/notification_type.h b/content/common/notification_type.h
index c91c3f5c783050f2d22bf8aabf15404a0b79b78d..d565abf05dc36b3cd9e07dc7545e676ec2785c5a 100644
--- a/content/common/notification_type.h
+++ b/content/common/notification_type.h
@@ -775,6 +775,12 @@ class NotificationType {
     // asynchronous initalization of a PrefService.
     PREF_INITIALIZATION_COMPLETED,
 
+#if defined(OS_CHROMEOS)
+    // Sent after successful write of persistent preferences or if there is
+    // nothing to write on CommitPendingWrite call. Source is PrefService.
+    PREF_COMMITTED,
+#endif
+
     // Sent when a default request context has been created, so calling
     // Profile::GetDefaultRequestContext() will not return NULL.  This is sent
     // on the thread where Profile::GetRequestContext() is first called, which