When Mondelez, the marketer of brands from Chips Ahoy to Trident, asked Razorfish to help revamp its e-commerce strategy and more than double online sales within a couple of years, it was only the latest call along those lines to reach a digital agency. Top marketers have tripled the e-commerce requests reaching Razorfish over the past 18 months, according to agency executives, and other shops are reporting growth in the same area.