chromium/ash/webui/common/resources/network/network_choose_mobile.html

<style include="cr-shared-style network-shared md-select iron-flex">
  /* Leave some space between button and select. */
  select {
    margin-inline-start: 8px;
  }
</style>
<div class="property-box first two-line">
  <div class="flex layout vertical">
    <div>[[i18n('networkChooseMobile')]]</div>
    <div class="cr-secondary-text">
      [[getSecondaryText_(managedProperties, deviceState)]]
    </div>
  </div>
  <cr-button on-click="onScanTap_"
      disabled="[[!getEnableScanButton_(managedProperties,
          deviceState, disabled)]]">
    [[i18n('networkCellularScan')]]
  </cr-button>
  <select class="md-select" on-change="onChange_"
      value="[[selectedMobileNetworkId_]]"
      disabled="[[!getEnableSelectNetwork_(managedProperties,
          deviceState, disabled)]]"
      aria-label="[[i18n('networkChooseMobile')]]">
    <template is="dom-repeat" items="[[mobileNetworkList_]]">
      <option value="[[item.networkId]]"
          disabled="[[getMobileNetworkIsDisabled_(item)]]">
        [[getName_(item)]]
      </option>
    </template>
  </select>
</div>