The San Francisco 49ers are getting a veteran cornerback. But they might not be done adding at the position before the draft.An NFL source confirmed the team will sign Minnesota free agent Chris Cook. He is expected to sign a team-friendly one-year deal. The team still has interest in Seattle cornerback Walter Thurmond, who is vising the 49ers on Friday, and have interest in retaining Tarell Brown.Cook will battle for a roster spot. He has experience and at 6-foot-2, he is big for a cornerback.