zone_settimeout_hook.js

var originalDelegate = window.setTimeout;
window.setTimeout = function(callback, delay) {
  var zone = Zone.current;
  var task = {
    zone: zone,
    type: 'macroTask',
    source: 'setTimeout',
    data: {
      delay: delay
    },
    callback: callback,
    schedule: () => {
      task.zone.onScheduleTask(..., zone, task);
      task.zone.macroTaskCount ++;
      if (task.zone.macroTaskCount === 1) {
        task.zone.onHasTask(...,zone, {macroTask: true});
      }
      originalDelegate.call(window, function() {
        task.zone.onInvokeTask(..., zone, task, this);
        var result = task.callback.call(this, delay);
        task.zone.macroTaskCount --;
        if (task.zone.macroTaskCount === 0) {
          task.zone.onHasTask(...,zone, {macroTask: false});
        }
        return result;
      }, task.data.delay);
      return task;
    }
  };  

  // onSchedule hooks
  task = task.schedule();
}