Johnny Depp is a shoo-in for an Oscar nomination in what is arguably the best performance of his career as James “Whitey” Bulger, a small-time Boston hood who grew to become one of the FBI’s most wanted. Scott Cooper’s riveting “Black Mass,” based on the book of the same name by Boston Globe journalists Dick Lehr and Gerard O’Neill, is a brutal and uncompromising piece, right in line with the life of its subject.