It started with pizzas and Walmart groceries delivered in a self-driving car from Ford. Now robot-driven food is catching on with even more new companies and apps. GM's Cruise is working with food delivery service DoorDash to bring your meal from a restaurant to your front door. The two companies announced Thursday that "select customers" in the San Francisco area would soon get to experience autonomous food delivery from one merchant with one self-driving vehicle. More vehicles and restaurants are expected to join in the next six months.