chromium/ash/webui/scanning/resources/source_select.html

<style include="scanning-shared"></style>
<scan-settings-section>
  <span id="sourceLabel" slot="label" aria-hidden="true">
    [[i18n('sourceDropdownLabel')]]
  </span>
  <div slot="settings">
    <select id="sourceSelect" class="md-select"
        value="{{selectedOption::change}}" disabled="[[disabled]]"
        aria-labelledby="sourceLabel">
      <template is="dom-repeat" items="[[options]]" as="source">
        <option value="[[source.name]]" selected$='[[isDefaultOption(source)]]'>
          [[getSourceTypeAsString(source.type)]]
        </option>
      </template>
      <template is="dom-if" if="[[!options.length]]" restamp>
        <option value="">
          [[i18n('defaultSourceOptionText')]]
        </option>
      </template>
    </select>
  </div>
</scan-settings-section>