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chromium/chrome/test/data/extensions/platform_apps/web_view/text_selection/guest.html 

<!doctype html>
<html>
<body>
<div style="width:100px; word-wrap: break-word;">AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA</div>
<script>
  document.addEventListener('contextmenu', function(e) {
    console.log('GUEST_CONTEXTMENU');
  });
</script>
</body>
</html>