In November 2005, Chris Brown’s Scott Storch-produced “Run It!” -- a rewrite of Usher’s “Yeah!” -- topped the Billboard Hot 100, making the 16-year-old singer the first male artist in over a decade to top the chart with a debut single. While there was nowhere to go but down, at least in terms of chart positions, the pop-oriented R&B vocalist was only getting started. By the end of the decade, he was one of the biggest active pop stars, with a clutch of Top Ten singles and platinum albums to his credit, along with constant comparisons to Michael Jackson and several acting roles on the side. His momentum slowed little when, in 2009, he pleaded guilty to assaulting girlfriend Rihanna -- one of the year’s biggest celebrity news stories.