Hamburger Lane is a quarter-mile, palm-lined stretch of Baldwin Park, California, 30 minutes east of Los Angeles. Halfway down the block, a low-slung building covered in gray siding sits behind a security fence. Knowing what’s inside the little structure helps explain the street’s unusual name. It’s the top-secret corporate test kitchen for In-N-Out Burger, the iconic West Coast chain. Lynsi Snyder, the company’s billionaire president, hovers over a set of double fryers and stove-top griddles…….