The provisions of Sections 27000.7, 27000.8, and 27000.9 shall become effective only in those counties in which, prior to the first date of the period for filing declarations of candidacy for the office of county treasurer, county tax collector, or county treasurer-tax collector, the board of supervisors by majority vote at a regular meeting with all members present, enact an ordinance adopting the provisions of those sections. That ordinance may be repealed by the board of supervisors at any time.