She didn't use Melodyne and I don't hear chorus either, only multitracking. You can hear the tiny flaws and wavers in her voice that imply the vocal was untreated apart from some compression and yeah, a bit too much reverb.ms_sunlight said:.
On the Autotune issue: pitch correction may well have been used, probably Melodyne. If it's used carefully and she's got basically good singing pitch you won't get obvious "artifacts", and it's very difficult to tell with such an overprocessed vocal.
It's a sad sign about the music business that people presume everyone uses pitch correction these days. Some singers can actually sing you know.