Any county, city and county, city, school district, or other public corporation within the state which was a self-insured employer under the “Workmen’s Compensation, Insurance and Safety Act,” enacted by Chapter 176 of the Statutes of 1913, may provide such medical, and hospital treatment, including nursing, medicines, medical and surgical supplies, crutches, and apparatus, including artificial members, which is reasonably required to cure or relieve from the effects of an injury to a former employee who was covered under such act, without regard to the 90-day limitation of subdivision (a) of Section 15 of such act for medical treatment. The provisions of this section shall not be operative in any such county, city and county, city, school district, or other public corporation unless adopted by a resolution of the governing body of such public entity.