Or he could try automotive chrome polish and a rag....

All of these methods only serve to reduce the appearance of the corrosion. It won't be gone. The only way is to remove pitting is an extensive process.....the part must be stripped and all corrosion must be removed. This is usually done chemically. Any pits must be filled usually with a braze or copper and smoothed. Then the the part would be fully polished and get a copper plating. This is also polished and inspected before going to the chrome plating tank. The full process is more detailed, and includes a trip or two through acid baths, but that's the gist of it. Some pieces (depending on their intended use) will get an oven bake treatment to reduce or eliminate hydrogen, which may cause embrittlement in some case.

Plastic is a different process (vacuum metalizing) altogether.

In any event, it is not usually a cheap process, and can get quite expensive depending on how bad the pitting is, how challenging and complex the shape and size of the part, etc.

The process is similar for most other metal plating materials, like..nickel, brass, etc. The solutions for the type of bath differ.
In almost all cases, the chemicals used go from nasty to downright deadly (cyanide for gold plating).


Whichever method (from previous suggestions) is used, finish with a good wax and buff to keep it looking good, and maintain it !


Cheers,

Joe