2920. (a) A mortgage is a contract by which specific property,
including an estate for years in real property, is hypothecated for
the performance of an act, without the necessity of a change of
possession.
(b) For purposes of Sections 2924 to 2924h, inclusive, “mortgage”
also means any security device or instrument, other than a deed of
trust, that confers a power of sale affecting real property or an
estate for years therein, to be exercised after breach of the
obligation so secured, including a real property sales contract, as
defined in Section 2985, which contains such a provision.