Comment 92 for bug 294712

...and sorry again, I had thought nsContentBlocker dealt with the additions and removals of the content policy. Apparently it uses nsIPermissionManager to deal with that. So the permission manager controls the per-site policies while the pref controls the overall image blocking. nsContentBlocker just implements nsIContentPolicy and provides the methods to check for the policies.

I'll update the patch later today, hopefully.