The 49ers traded a pass rusher for a receiver this morning, sending preseason finale star Cam Johnson to the Colts for a conditional draft pick. That made room on the 53-man roster for wide receiver Chris Harper, whom the 49ers signed from the Seahawks practice squad.San Francisco 49ers linebacker Cam Johnson, left, lands on the ball in the end zone for a touchdown after blocking a punt by San Diego Chargers punter Mike Scifres during the second half of an NFL preseason football game, Thursday, Aug. 29, 2013, in San Diego.