message: In TaskQueueWin fix race in canceling MutlimediaTimer
  Cr-Commit-Position: refs/heads/master@{#30232}
diff: @@ -134,11 +134,15 @@ class MultimediaTimer {
  }
  void Cancel() {
  - ::ResetEvent(event_);
  if (timer_id_) {
  ::timeKillEvent(timer_id_);
  timer_id_ = 0;
  }
  + // Now that timer is killed and not able to set the event, reset the event.
  + // Doing it in opposite order is racy because event may be set between
  + // event was reset and timer is killed leaving MultimediaTimer in surprising
  + // state where both event is set and timer is canceled.
  + ::ResetEvent(event_);
  }
  HANDLE* event_for_wait() { return &event_; }
  