Each agency when it provides by contract for the operation or maintenance of records containing personal information to accomplish an agency function, shall cause, consistent with its authority, the requirements of this chapter to be applied to those records. For purposes of Article 10 (commencing with Section 1798.55), any contractor and any employee of the contractor, if the contract is agreed to on or after July 1, 1978, shall be considered to be an employee of an agency. Local government functions mandated by the state are not deemed agency functions within the meaning of this section.