Niccol, who is leaving Chipotle Mexican Grill, will become CEO and chairman the moment he joins Starbucks on September 9. By contrast, Laxman Narasimhan spent more than five months as the CEO-in-training under company patriarch Howard Schultz and he never took on the board chairman position. Only after an intense period of shadowing Schultz did he gain the ability to set the company's strategy.