You are right! The topic name is "nttACS" could be improved, and it is used for triggering the restat prompt.
I decided to use observer notifications because that was the easiest way.
Please note, there are no elegant way to prevent other addons to hook-up on this restart trigger while `nttAddonCompatibilityService` is an independent module IMHO.
If you really want this then we should:
* drop the whole restart-on-demand proposal
* move the count-pending-addons stuff back to `nightly`. In this case syncing between component and window object should be done
* convert NTT into __one__ big bootstrap.js
* try to find other resolution

Instead trying hide this trigger from other extensions I vote for correct topic naming.
BTW it's OK to me to convert this interface to a callback interface (like `AddonManager`'s [....listener][1] methods).


[1]: https://developer.mozilla.org/docs/Addons/Add-on_Manager/AddonManager