What is the test for establishing title by agreed boundary?

"The agreed-boundary doctrine constitutes a firmly established exception to the general rule that accords determinative legal effect to the description of land contained in a deed." (Bryant v. Blevins (1994) 9 Cal.4th 47, 54.) "Although the agreed-boundary doctrine is well established in California, our case law has recognized that the doctrine properly may be invoked only under carefully specified circumstances. . . . 'The requirements of proof necessary to establish a title by agreed boundary are well settled by the decisions in this state. [Citations.] The doctrine requires that there be [(1)] an uncertainty as to the true boundary line, [(2)] an agreement between the coterminous owners fixing the line, and [(3)] acceptance and acquiescence in the line so fixed for a period equal to the statute of limitations or under such circumstances that substantial loss would be caused by a change of its position.' " (Id. at p. 55.)