You have a piece of pitted pot metal. You will need to sand off all existing chrome, drill out the black pits, fill with Solder-It (
http://www.caswellplating.com/aids/solderit.htm), then plate with Flash Copper, then Nickel, then Chrome, with our Triple Chrome Plating Kit (
http://www.caswellplating.com/kits/triple.htm)