isMoving_(pointerEvent) {
    return (
      this.dragging_ ||
      Math.abs(pointerEvent.clientX - this.down_.clientX) >
        this.moveTolerance_ ||
      Math.abs(pointerEvent.clientY - this.down_.clientY) > this.moveTolerance_
    );
  }
@param {PointerEvent} pointerEvent Pointer
event.
@return {boolean} Is moving.
@private