All city or town plats or any addition or additions thereto, heretofore made and recorded in the county auditor's office of any county in Washington state, showing lots, blocks, streets, alleys or public grounds, shall be conclusive evidence of the location and size of the lots, blocks and public grounds and the location and width of each and every street or alley marked, laid down or appearing on such plat, and that all the right, title, interest or estate which the person or persons making or recording such plat, or causing the same to be made, or recorded, had at the time of making or recording such plat in or to such streets, alleys or public grounds was thereby dedicated to public use, whether the same was made, executed or acknowledged in accordance with the provisions of the laws of this state in force at the time of making the same or not.