Having sync set up with builds of Firefox from different channels can cause trouble if we're changing a pref's default value, because sync currently syncs all prefs regardless of whether they have a default value (bug 744626). To mitigate this for the current prefs whose defaults are changing in the current trains, we should stop syncing these prefs:
I think it makes sense to stop syncing autoFill regardless of Sync's behavior, since it isn't user-exposed in any way. We can re-add the other two when Sync's behavior is changed.
Created attachment 616826 [details] [diff] [review]