One possible way of knowing if a listener was registered is to use a "trampoline" much like we do in chrome bootstrap for the event.  Basically replace the default "addListener" method for the event with your own handler that decorates the default addListener and also triggers some natively-persisted boolean that "the app does care".  If the boolean isn't set, we can just discard the message and not restart the app.  Same could apply for all events, and perhaps we want to write a more generalized solution to this type of problem.