Query Notification setup
The service specification is the name of the service used for query notifications.  The tutorial is focused on SqlDependency, which creates dynamically-named services (GUID appended).  No need to explicitly grant SEND permissions on the service in that case because the creator of the service will have CONTROL permissions on the service anyway.

If you were to use the lower-level SqlNotificationRequest object, then you would need to grant SEND on the service, REFERENCES on the contracts, and RECEIVE on the queues.  That allows a less privileged account to subscribe to query notifications.