All code for this is part of the quitter project on github:
https://github.com/mozilla-extensions/quitter

This is within the mozilla-extensions organization so that we can sign the .xpi.

To update code, please submit a PR to the github repo.  Once that is merged in, a JIRA ticket (ex [ADDONSOPS-194](https://mozilla-hub.atlassian.net/browse/ADDONSOPS-194)) is needed to resign the .xpi.