Right now, prefs from distribution.ini are loaded on final-ui-startup here, which is after distribution extensions are loaded (in response to addons-startup here).

This means that prefs like xpinstall.signatures.dev-root and xpinstall.signatures.required set in distribution.ini are not respected by the very first startup with a distribution with custom extensions.

This ticket tracks loading some parts of the distribution -- potentially only the preferences -- early enough to impact the addons manager.

We've had problems in the past with conflicts between distribution prefs, autoconfig prefs, and global prefs so this is a very fragile situation.

See:

https://bugzilla.mozilla.org/show_bug.cgi?id=947838

Need to make sure those scenarios are tested.