The former police officer seen kneeling for about nine minutes on George Floyd’s neck before he died in spring is due to go on trial, and Minneapolis is on edge, protesting, barricading and boarding up. Several hundred people supporting the conviction of former Officer Derek Chauvin on murder charges gathered across the Mississippi River on Saturday in front of the governor’s mansion in St. Paul, chanting, “Prosecute the police!” More protests were planned Sunday and Monday outside the courthouse where the case will be heard in downtown Minneapolis, now lined with protective concrete...