All day hospitals and rehabilitation centers maintained by the State Department of Developmental Services shall be subject to the provisions of this code pertaining to the admission, transfer, and discharge of patients at the state hospitals, except that all admissions to such facilities shall be subject to the approval of the chief officer thereof. Charges for services rendered to patients at such facilities shall be determined pursuant to Section 4431. The liability for such charges shall be governed by the provisions of Article 4 (commencing with Section 6715) of Chapter 3 of Part 2 of Division 6 of this code and Chapter 4 (commencing with Section 7500) of Division 7 of this code.