Remove the OnError method from notification delegates.

content/child/notifications/notification_manager.cc

Index: content/child/notifications/notification_manager.cc
diff --git a/content/child/notifications/notification_manager.cc b/content/child/notifications/notification_manager.cc
index 9271f877e4940cf4aeac20a43a2b3db0792a476a..4ffc890718f619cea3df70ecfb9f88353f116cef 100644
--- a/content/child/notifications/notification_manager.cc
+++ b/content/child/notifications/notification_manager.cc
@@ -131,7 +131,6 @@ bool NotificationManager::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(NotificationManager, message)
     IPC_MESSAGE_HANDLER(PlatformNotificationMsg_DidShow, OnShow);
-    IPC_MESSAGE_HANDLER(PlatformNotificationMsg_DidError, OnError);
     IPC_MESSAGE_HANDLER(PlatformNotificationMsg_DidClose, OnClose);
     IPC_MESSAGE_HANDLER(PlatformNotificationMsg_DidClick, OnClick);
     IPC_MESSAGE_UNHANDLED(handled = false)
@@ -148,14 +147,6 @@ void NotificationManager::OnShow(int id) {
   iter->second->dispatchShowEvent();
 }
 
-void NotificationManager::OnError(int id) {
-  const auto& iter = active_notifications_.find(id);
-  if (iter == active_notifications_.end())
-    return;
-
-  iter->second->dispatchErrorEvent();
-}
-
 void NotificationManager::OnClose(int id) {
   const auto& iter = active_notifications_.find(id);
   if (iter == active_notifications_.end())