Remove the OnError method from notification delegates.

chrome/browser/notifications/notification_object_proxy.cc

Index: chrome/browser/notifications/notification_object_proxy.cc
diff --git a/chrome/browser/notifications/notification_object_proxy.cc b/chrome/browser/notifications/notification_object_proxy.cc
index c5dab66f001834c57d3ff08ef3ff00ba79afcab5..2b8803f38c63328f7642f3e9e4178c37fab1a553 100644
--- a/chrome/browser/notifications/notification_object_proxy.cc
+++ b/chrome/browser/notifications/notification_object_proxy.cc
@@ -25,10 +25,6 @@ void NotificationObjectProxy::Display() {
   delegate_->NotificationDisplayed();
 }
 
-void NotificationObjectProxy::Error() {
-  delegate_->NotificationError();
-}
-
 void NotificationObjectProxy::Close(bool by_user) {
   delegate_->NotificationClosed(by_user);
 }