I would try bleach first, soak it overnight in a tub of bleach. I've also heard that coca cola will remove chrome plating but I haven't tried it yet. I've used Mr Muscle oven cleaner in the past too and that worked well enough. Let me know how you get on.
Do you mean chrome paint that's on resin, or a factory applied chrome finish..?? Chrome paint I normally use Isopropyl Alcohol. Factory chrome, I use bleach overnight, then scrub with water and an old toothbrush.