Chron readers got a surprise this morning when, for the first time, the paper ran an ad at the bottom of its “Bay Area” or B-section, where most of the local news is located. The move is hardly surprising since Hearst Corp. said in September that the Chron has lost $330 million since it bought the paper in 2000. Newspapers owned by MediaNews Group, such as the Oakland Tribune and San Mateo County Times, have been running ads on the front page for a couple of years now. And on Feb. 3, the Press Club reported that John Armstrong, publisher of the Contra Costa Times, said his paper and the Mercury News are also considering ads on the fronts of sections and page one. He said they could start sometime in the next three months. The Coco Times and Merc were acquired by MediaNews in August.