How to add  to the header
Try this, it works for me, I just tested. I don't think you need #type and http-equiv needs to match in the html head call. 

/**
 * Implements template_preprocess_html().
 *
 */
function mytheme_preprocess_html(&amp;$vars) {

    $element = array(
        '#tag' =&gt; 'meta',
        '#attributes' =&gt; array(
          'http-equiv' =&gt; 'X-UA-Compatible',
          'content' =&gt; 'IE=edge,chrome=1'
        ),
      );
      drupal_add_html_head($element, 'http_equiv');

}


Beyond that, if it does not work, then you have some other issue. Be sure to clear all caches.