At a technology conference in mid-2014, the Google co-founder Sergey Brin presented the company's first prototype for a self-driving car. Watching in the audience was Travis Kalanick, chief executive of Uber, the ride-hailing start-up.
Mr. Brin's presentation in Rancho Palos Verdes, Calif. — including a video of a compact two-seater autonomously doing laps around a parking lot — jolted Mr. Kalanick, according to two people who spoke with him. Google, the search giant — long considered an Uber ally — seemed to be turning on him. And even as Uber was a growing force to be reckoned with, it was lacking in self-driving car technology, an important field of study that might affect the future of transportation.