Though a grant is not actually delivered into the possession of the grantee, it is yet to be deemed constructively delivered in the following cases: 1. When, by the agreement of the parties, the instrument is understood to be delivered at the time of execution and the circumstances are such that the grantee is entitled to immediate delivery; or 2. When it is delivered to a stranger for the benefit of a grantee and the grantee's assent is shown or may be presumed.