Use theme function instead of hard-coded markup in grouped Views display plugin

Currently, the output of the views display plugin into popups or tooltips has hard-coded html:

        $descriptions = array();
        foreach ($record as $k => $v) {
          foreach ($handlers as $hid => $handler) {
            $rendered_record[$handler->field_alias] = $handler->advanced_render($v);
          }
          $item = '';
          if ($data_source['name_field']) {
            $name_field = $fields[$data_source['name_field']]['field_alias'];
            $item .= "<h2 class='point-title'>". $rendered_record[$name_field] ."</h2>";
          } 
          if ($data_source['description_field']) {
            $description_field = $fields[$data_source['description_field']]['field_alias'];
            $item .= "<div class='point-content'>". $rendered_record[$description_field] ."</div>";
          }
          $descriptions[] = $item;
        }

This needs to go into a theme function.