Who pays the cost of revising road signage when a stadium is renamed?

I live in Orange County, CA. They have re-sold the naming rights: the "Arrowhead Pond" (home of the NHL Ducks) has been renamed the "Honda Center". The signage on the stadium itself has been changed -- but the directional road signs have not. I guess the freeway signs are the domain of CalTrans, and the signs on the surface streets are the domain of the city of Anaheim. But who pays the true costs of replacing these road signs. Do the taxpayers pay the cost, or does the facility have to pay the municipal entity? Anyone with civil service experience want to chime in?