First, police fatally shot two minority suspects carrying knives. Then transcripts surfaced showing officers using racial slurs in text messages. Finally, a young black woman was shot dead as police tried to pull her from a stolen car. The woman's shooting death Thursday was the tipping point for San Francisco Mayor Ed Lee, who forced Police Chief Greg Suhr to step down after months of mounting pressure. The new chief inherits the daunting task of turning around a troubled department in a city deeply divided by race — and doing it fast. "Reforms, reforms, reforms," acting Police Chief Toney Chaplin...