The 25-year-old’s support may be the second most valuable out there, after only Barack Obama’s. Chance the Rapper has 7.9 million Twitter followers — more, it’s safe to say, than all 17 candidates for mayor of Chicago combined. Right now, they’re all reading about a woman who until today was one of the race’s more obscure entries: Amara Enyia, the 35-year-old director of the Austin Chamber of Commerce, and a former policy analyst for Mayor Richard M. Daley.