credit card autofill in Safari (OS X)

Safari on the new OS X will autofill credit cards: http://www.macstories.net/roundups/os-x-mavericks-tips-tricks-and-details/#safari

Does anyone know if this is using Request Autocomplete or not? http://www.chromium.org/developers/using-requestautocomplete

I poked around but couldn't find any evidence that it's using the same API. It seems like it should!