If the chrome is pitted from rust blisters, there is no way to restore the part. But if it's just surface rust, an overnight soak in dilute oxalic acid will remove the rust and then you can buff it clean using any one of many methods described above.

Here's a before and after shot of a pair of Bluemel fenders whose stay hardware had a lot of surface rust. One was before treatment with oxaclic acid, the other after.However, if there is no surface finish to protect parts that rust a lot, like this one, it's useful to apply a protective coating to resist further rusting.