I didnt read down through the whole thing, but according to this Harry M. Stevens provided the Ebetts Field dogs.
http://www.baseball-fever.com/archive/index.php/t-46196.html
Yeah, it says the Dodger Dog inventor (Arthur) went back to his Coney Island upbringing and the Nathan’s hot dogs at Ebbitt Field. True or not, who knows? Even following up on Stevens’s bio and devlopment of the concession busines doesn’t get into what brand of dawgs he sold.