What is the limitation period for a plaintiff to amend the cause of action?

This is the second appeal in this case. In the first (Thompson v. California Brewing Co., 150 Cal.App.2d 469, 310 P.2d 436) this court reversed a judgment sustaining demurrers without leave to amend, as to the first two causes of action. It held (150 Cal.App.2d at page 477, 310 P.2d at page 440) that those causes of action, one upon an express contract and one upon an implied in fact contract, were on their face barred by the two year limitation period prescribed by section 339, subdivision 1, of the Code of Civil Procedure. This was because the complaint, when supplemented pursuant to Code of Civil Procedure, 426, subdivision 3, showed on its face that the defendants' use of plaintiff's idea began more than two years before the action was filed. It also held (150 Cal.App.2d at page 478, 310 P.2d at page 441) that plaintiff should be given an opportunity to amend by pleading 'facts which, if they exist, negative the seeming bar of the statute as to the first and second counts.'