@Override
  protected synchronized boolean setTimeoutFailure(MasterProcedureEnv env) {
    setState(ProcedureProtos.ProcedureState.RUNNABLE);
    env.getProcedureScheduler().addFront(this);
    return false;
  }
A remote procedure which is used to send verify snapshot request to region server.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/SnapshotVerifyProcedure.java