The San Francisco 49ers continued to add depth to the cornerback position by bringing back Perrish Cox on a one-year deal, his agent tweeted Tuesday.Cox is expected to sign this week. He was to be a restricted free agent, but the 49ers didn't tender him.Cox bounced on and off the 49ers' roster last season, but did play in the playoffs. He beat out veteran Eric Wright for playing time in the postseason. However, the 49ers signed Wright two weeks ago, indicating he is a bigger priority moving forward than Cox.