app/views/application/_google_analytics.html.erb
<% if (ENV['RAILS_ENV'] == 'production') && (cannot? :escape_analytics, current_user) %>
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', '<%= ENV['google_analytics_id'] %>']);
_gaq.push(['_trackPageview']);
(function() {
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();
</script>
<% end %>