I don't know that frogs do dominance behaviors normally. (Not saying they don't, just that I don't know.) I suspect that it's more likely the female saw something moving and tried to eat it, even if that thing was a whole other frog. That just seems more reasonable considering what I've personally seen of frog behavior patterns. But who knows maybe ADF do have dominance based social behaviors that aren't male v male or disinterested female at mating time.