If the owners (as defined in the law under which it is proposed to proceed) of 15 per cent of the area of the proposed assessment district do not so demand the making of the investigation provided by this division, the legislative body shall be at full liberty to proceed under the statute under which it has declared its intention to carry through the contemplated proceedings without any further restrictions whatsoever by reason of the terms or provisions of this division except that the majority protest provisions of this division shall apply.