The millennial heir to Sweden's tradition of frothy, incessantly catchy pop, Max Martin wasn't an international star like ABBA, Roxette, or Ace of Base. But as a songwriter and producer, he spearheaded the late-'90s teen pop revival by crafting a ubiquitous string of worldwide hits for Britney Spears, *NSYNC, and the Backstreet Boys, among many others. He then modified his sound during the 2000s, embracing the use of slick guitars and pop/rock melodies while penning such chart-topping singles as Bon Jovi's "It's My Life" and Kelly Clarkson's "Since U Been Gone." Number one hit...