Add shutdown notification and service refs to SyncServiceObserver.

chrome/browser/extensions/external_pref_loader.cc

Index: chrome/browser/extensions/external_pref_loader.cc
diff --git a/chrome/browser/extensions/external_pref_loader.cc b/chrome/browser/extensions/external_pref_loader.cc
index 1d257b23a7c1e480860e363ffd4311e5bf0e4583..f289f827a1708c6ee90a55b85ed7579774245d79 100644
--- a/chrome/browser/extensions/external_pref_loader.cc
+++ b/chrome/browser/extensions/external_pref_loader.cc
@@ -154,13 +154,9 @@ void ExternalPrefLoader::OnIsSyncingChanged() {
   PostLoadIfPrioritySyncReady();
 }
 
-void ExternalPrefLoader::OnStateChanged() {
-  browser_sync::ProfileSyncService* service =
-      ProfileSyncServiceFactory::GetForProfile(profile_);
-  DCHECK(service);
-  if (!service->CanSyncStart()) {
+void ExternalPrefLoader::OnStateChanged(syncer::SyncService* sync) {
+  if (!sync->CanSyncStart())
     PostLoadAndRemoveObservers();
-  }
 }
 
 bool ExternalPrefLoader::PostLoadIfPrioritySyncReady() {