Created attachment 610020 [details] [diff] [review] v1 Stop using enablePrivilege, add an API to SpecialPowers to set a property to a value and use it to set xhr.channel.notificationsCallback.
Comment on attachment 610020 [details] [diff] [review] v1 r=me. I'm impressed there was no eval involved in the impl! ;)
Are you able to use |SpecialPowers.wrap(req).channel.notificationCallbacks = foo| instead?
https://hg.mozilla.org/integration/mozilla-inbound/rev/ba46fc01fb32 I'll file a new bug to try the SpecialPowers.wrap method.