Probably handle it similarly to how Chrome handles an extension asking for new permissions. It disables the add-on and gives the user a small non-intrusive notification on the options menu. Opening the notification notified the user about the change in permissions and asks them if they want to re-enable the add-on or remove it from Chrome.
Good solution, perhaps two simple options at browser install: Default / Custom. That way you don't have to uninstall all the stuff at the end.
deleted by creator
Probably handle it similarly to how Chrome handles an extension asking for new permissions. It disables the add-on and gives the user a small non-intrusive notification on the options menu. Opening the notification notified the user about the change in permissions and asks them if they want to re-enable the add-on or remove it from Chrome.