All migrations in _migrateUIBB are run for new profiles
As far as I can tell, all migrations in _migrateUIBB
method are run for new profiles. Unlike _migrateUITBB
we do not check for this._isNewProfile
to exit early.
It is not a problem right now because all the migrations just clear preferences, but we probably don't want this in the future.
/cc @pierov