From and after the time when the Planning Commission shall have adopted a major street plan, the City Council may establish an official map of the whole or any part of the City theretofore existing and established by law as public streets. Such official map may also show the location of the lines of streets on plats of subdivisions which shall have been approved by the Planning Commission. The City Council may make, from time to time, other additions to or modifications of the official map by placing thereto the lines of proposed new streets or street extensions, widenings, narrowings or vacations which have been accurately surveyed and definitely located; provided, that before taking such action, the City Council shall hold a public hearing thereon, that such proposed addition to or modification of the official map shall be submitted to the Planning Commission for its approval. In the event of Planning Commission disapproval, such addition or modification shall require the favorable vote of not less than a majority of the entire membership of the City Council. The placing of any street or street lines upon the official map shall not in and of itself constitute or be deemed to constitute the opening or establishment of any street or the taking or acceptance of any land for street purposes. Upon adopting the ordinance creating the official map, the City Council shall direct that such ordinance be recorded in the office of the county recorder. (Prior code § 21-3)