This definition appears very rarely
The History of the Native American Boston Breed states that, "The White Terrier and the English Bull Dogs (Who come in many, many colors) were bred together to make the Boston Terrier". Of course the White Terrier was mainly all white and the English Bull Dogs came in various colors. Many of the original Bostons or "Round Heads", as they were first called, where different shades of Brindle. In many of the old pictures I have seen, the first Bostons look very much like Staffordshire Terriers (who also come in many different colors Blue & Chocolate included).