Cal. Corporations Code § 2318

Any corporation existing on the first day of January, 1873, formed under the laws of this state, and still existing, which has not already elected to continue its existence under the prior law, may, at any time, elect to continue its existence under the provisions of this code applicable thereto by the unanimous vote of all its directors, or such election may be made at any annual meeting of the shareholders, or at any meeting called by the directors especially for considering the subject, if voted by shareholders representing a majority of the voting power, or may be made by the directors upon the written consent of that number of the shareholders. A certificate of the action of the directors, signed by them and their secretary, when the election is made by their unanimous vote, or upon the written consent of the shareholders, or a certificate of the proceedings of the meeting of the shareholders, when the election is made at any such meeting, signed by the chairperson and secretary of the meeting and a majority of the directors, shall be filed in the office of the Secretary of State, and thereafter the corporation continues its existence under the provisions of this code which are applicable thereto, and possesses all the rights, and powers, and is subject to all the obligations, restrictions, and limitations prescribed thereby.