When I got my bike all the little chrome bits like that line-holder in your
picture were rusty, way worse than yours. I replaced them $$$ ...
Later I learned about some rust killer products, and I dropped my parts
into some oxiliac acid (sold at Ace as "wood bleach") and was amazed.
Mine were so bad the chrome was blistered... it didn't fix that but
all the rust was gone.
Grumpy posted something about how good this was:
http://www.evaporust.com/evaporust.html-Mike