Lay's, the nation's largest salty snack maker, on Friday will announce plans to roll out next week Lay's Wavy Potato Chips Dipped in Milk Chocolate. For Lay's, it's all about growing beyond the constraints of the salty snack. There are, after all, growing consumer demands for flavor mash-ups. And others want to snack healthier. Even then, snack foods are a $31 billion market — and growing, reports IBISWorld, the market research specialist.