chrome/browser/resources/help/help_page.html

<div id="help-page" class="page" hidden>
  <div class="close-button"></div>
  <h1 i18n-content="aboutTitle"></h1>
  <include src="help_content.html">
  <div class="action-area">
    <div class="button-strip">
      <button id="about-done" class="default-button" i18n-content="done">
      </button>
    </div>
  </div>
</div>