options/guest mode: only hide the 'Show advanced settings...' link when

chrome/browser/resources/options/browser_options.html

Index: chrome/browser/resources/options/browser_options.html
diff --git a/chrome/browser/resources/options/browser_options.html b/chrome/browser/resources/options/browser_options.html
index eb6b3b65caba017a2fa63d518f313cb19ed1db08..bd4138ee052c238884940628b545aa51786e6e30 100644
--- a/chrome/browser/resources/options/browser_options.html
+++ b/chrome/browser/resources/options/browser_options.html
@@ -997,7 +997,7 @@
   </section>
   </div>  <!-- advanced-settings-container -->
   </div>  <!-- advanced-settings -->
-  <footer>
+  <footer id="advanced-settings-footer">

[Mike Lerman, 2015/01/29 17:56:44]

Why give the footer an id? Can't you jquery-select the footer with just
$('footer')?

[Dan Beam, 2015/01/29 20:07:15]

$() is document.getElementById, not jQuery's sizzle.

I added an ID because doing

  document.querySelector('footer').hidden = true;

breaks if another <footer> is added above it in the page.

  var footers = document.querySelectorAll('footer');
  assert(footers.length == 1);
  footers[0].hidden = true;

is brittle and overkill.

  document.querySelector('#advanced-settings + footer').hidden = true;

breaks if they're not direct siblings and

  document.querySelector('#advanced-settings ~ footer').hidden = true;

is fragile if there's another <footer> added between them.

adding an ID is the only way that doesn't break with a different DOM.

     <a is="action-link" id="advanced-settings-expander"
         i18n-content="showAdvancedSettings"></a>
   </footer>