Remove most occurences of PrefRegistrySyncable::UNSYNCABLE_PREF

chrome/browser/web_resource/promo_resource_service.cc

Index: chrome/browser/web_resource/promo_resource_service.cc
diff --git a/chrome/browser/web_resource/promo_resource_service.cc b/chrome/browser/web_resource/promo_resource_service.cc
index 140dff07407d912ff98c9c8ca0bd68816d2931b3..3fdeda2b4a8fdd4777440fd52ad4e5ebcfcadf3e 100644
--- a/chrome/browser/web_resource/promo_resource_service.cc
+++ b/chrome/browser/web_resource/promo_resource_service.cc
@@ -71,10 +71,7 @@ void PromoResourceService::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   // TODO(dbeam): This is registered only for migration; remove in M28
   // when all prefs have been cleared.  http://crbug.com/168887
-  registry->RegisterStringPref(
-      prefs::kNtpPromoResourceCacheUpdate,
-      "0",
-      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterStringPref(prefs::kNtpPromoResourceCacheUpdate, "0");
   NotificationPromo::RegisterProfilePrefs(registry);
 }