chromium/chrome/test/data/android/popup_test.html

<html>
  <head>
    <title>Popup test page</title>
    <script type="text/javascript">
      function spawnWindows() {
        window.open('navigate/one.html');
        window.open('navigate/two.html');
      }
    </script>
  </head>
  <body onload="spawnWindows()">
    Spawning two popup windows...
  </body>
</html>