chrome/browser/resources/settings/controls/settings_dropdown_menu.html

<link rel="import" href="chrome://resources/html/md_select_css.html">
<link rel="import" href="chrome://resources/html/polymer.html">
<link rel="import" href="pref_control_behavior.html">
<link rel="import" href="../i18n_setup.html">
<link rel="import" href="../prefs/pref_util.html">
<link rel="import" href="../settings_shared_css.html">
<link rel="import" href="../settings_vars_css.html">

<dom-module id="settings-dropdown-menu">
  <template>
    <style include="settings-shared md-select">
      /* Hide "Custom" value when unselectable. */
      option:disabled {
        display: none;
      }
    </style>
    <div class="md-select-wrapper">
      <select class="md-select" id="dropdownMenu" on-change="onChange_"
          disabled="[[shouldDisableMenu_(disabled, menuOptions)]]">
        <template is="dom-repeat" items="[[menuOptions]]">
          <option value="[[item.value]]">[[item.name]]</option>
        </template>
        <option value="[[notFoundValue_]]"
            disabled="[[!showNotFoundValue_(menuOptions, pref.value)]]">
          $i18n{custom}
        </option>
      </select>
      <span class="md-select-underline"></span>
    </div>
  </template>
  <script src="settings_dropdown_menu.js"></script>
</dom-module>