That is interesting, I am seeing the code executing the GA tracker send method.
Can you please open your browser developer tools, and in the development console execute the following google analytics commands:
ga('create', 'UA-72781383-3', 'auto');
ga('send', 'pageview', {
'page': '?ajax_search=test',
'title': 'Ajax Search'
});..then immediately afterwards check the realtime window, it should display a pageview tracked like this: https://i.imgur.com/uQuTQut.png
