chrome/browser/resources/chromeos/login/oobe_screen_update.html

<div class="step right hidden animated" id="update">
  <div class="step-contents">
    <div id="update-cancel-hint" hidden>
      <p i18n-content="cancelUpdateHint"></p>
    </div>
    <div id="update-screen-curtain">
      <div id="checking-updates-label" i18n-content="checkingForUpdatesMsg">
      </div>
      <div id="update-checking-progress" aria-live="polite">
        <div class="throbber"></div>
        <div i18n-content="checkingForUpdates"></div>
      </div>
    </div>
    <div id="update-screen-main" hidden>
      <p id="update-upper-label"></p>
      <p id="update-bottom-label" i18n-content="installingUpdateDesc"></p>
      <progress id="update-progress-bar" max="100" value="0"></progress>
      <p id="estimated-time-left" class="progress-message" hidden></p>
      <p id="progress-message" class="progress-message" hidden></p>
    </div>
  </div>
  <div id="update-extra-controls" class="step-extra-controls">
    <div id="update-accessibility">
      <a id="update-accessibility-link" href="#"
         i18n-content="accessibilityLink"></a>
    </div>
  </div>
</div>