If you are talking about the piece to the left of the coolant pipe, that is not chrome, but aluminum and part of the engine. (none of the engine is chromed, save for add ons)
What you got there may have been caused by something getting wedged between there and the coolant pipe. Vibration or more than likely heat that had the two parts expanding chipped off the metal.
It could have been ice too if you ride in cold temps, or may just have been a fault in the casting. As long as nothing is leaking out of it I would not worry about it.
I think that is one of the inner channels that accepts the head bolts, to it is possible someone over-torqued the bolt or water got in there and froze???
(Sorry do not have my Vulcan engine handy to look at)