NEW YORK (AdAge.com) -- Laura McCorvie has a big marketing job at the world's second-biggest food company. But her chief concern isn't TV ad spending, or even what's happening on Facebook. She spends her time with customers -- only most of us call them retailers. Shopper marketing may be the fastest-growing segment of the marketing industry, particularly in consumer package goods.

The reason is, in an era of increasing media fragmentation, supermarkets have become the only true mass medium. Walmart, for instance, can guarantee more eyeballs than the finales of "Lost" and "American Idol" every week. And as consumers have gotten increasingly price sensitive, retailers have started marketing their own lower-priced private labels. The result is a bevy of marketing-savvy clients, all demanding special promotions, flavors or other partnerships.

"My focus is helping the customer grow because if the customer doesn't grow, Kraft can't grow," Ms. McCorvie said, adding that she tries to take a "very external view" of understanding their business, meaning "how to bring the best of Kraft to meet those needs and priorities [using] our portfolio, the actual product and packaging, the types of inventory or merchandising, the type of promotions and programs. All of that needs to be centered on the customers' needs and interests."

She is about to have a lot more on her plate. Kraft, of course, completed its acquisition of Cadbury in February. While the acquisition allows Kraft to build share in the chocolate market, one of the reasons behind the deal was to take over Cadbury's supply chain, which has greater access to convenience stores, kiosks and newsstands. Kraft CEO Irene Rosenfeld has set a company goal of being the biggest force in global snacking.

For Ms. McCorvie, that means adapting Kraft's approach for these new outlets. The marketer's core competency has been in traditional grocery stores. She took on a similar challenge in her last job, as senior VP-customer and consumer strategy of PepsiCo, where she also helped the company evolve to offer the right products to the right consumers in the right stores.

"When you go into a Costco, you don't expect the same thing you'd expect at 7-Eleven, even if you're the same person but going in for different reasons," Ms. McCorvie said. "One size doesn't fit all."

Moving forward, Ms. McCorvie said that Kraft will continue to lean on mobile applications such as Kraft's iFood Assistant. "We want to go further," she said, adding that Kraft should be able to help consumers not only find things in the store, but also build shopping lists and get recipe ideas even if they're on special diets.

For women just getting started in their careers, Ms. McCorvie suggests keeping all doors open. "If you just go along and are open to new things, it's amazing the new experiences you'll have," she said. "Throughout my career, if anyone told me what I'd be doing, I'd have told them no way."