Which mobile sportsbooks offer eSports betting?

I was surprised to read that eSports betting is one of the fastest growing betting markets in the world. By the year 2019 it is expected to be in excess of $1 billion U.S. dollars, which is quiet an achievement given how young the market is. It seems kinda bizarre that fully grown adults would bet on games of Quake, Counter Strike or Halo but I guess that's the world we live in now.

I'm a little bit curious about where all this eSports gambling takes place? Are there dedicated eSports bookmakers or does your average NFL sportsbook also accept eSports bets?