modules/locale/views_handler_filter_locale_group.inc

<?php

class views_handler_filter_locale_group extends views_handler_filter_in_operator {
  function get_value_options() {
    if (!isset($this->value_options)) {
      $this->value_title = t('Group');
      $groups = module_invoke_all('locale', 'groups');
      // Sort the list.
      asort($groups);
      $this->value_options = $groups;
    }
  }
}