Robots are coming to a Walmart Inc. near you, and not just as a gimmick. The world’s largest retailer is rolling out 360 autonomous floor-scrubbing robots in some of its stores in the U.S. by the end of the January, it said in a joint statement with Brain Corp., which makes the machines. The autonomous janitors can clean floors on their own even when customers are around, according to the San Diego-based startup.