chromium/chrome/test/data/extensions/api_test/bindings/user_gesture_test.html

<!doctype html>
<html>
<style>
  html {
    margin: 0;
    padding: 0;
  }
  body {
    margin: 0;
    padding: 0;
    min-width: 100px;
    min-height: 100px;
  }
</style>
<body>
  Add some text that will cause the page to allow input on the first frame.
</body>
<script src="user_gesture_test.js"></script>
</html>