Google Analytics doesn't track the referral, why?

Here the solution how simple to track the referral in 

<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');

ga('create', 'UA-XXXXXX-X', 'auto');
ga('set', 'referrer', document.referrer);
ga('send', 'pageview');

</script>

(Image-1) Google Analytics track the referral!