chromium/content/shell/resources/shell_devtools_discovery_page.html

<html>
<head>
<title>Content shell remote debugging</title>
<style>
</style>

<script>
function onLoad() {
  var tabs_list_request = new XMLHttpRequest();
  tabs_list_request.open("GET", "/json/list?t=" + new Date().getTime(), true);
  tabs_list_request.onreadystatechange = onReady;
  tabs_list_request.send();
}

function onReady() {
  if(this.readyState == 4 && this.status == 200) {
    if(this.response != null)
      var responseJSON = JSON.parse(this.response);
      for (var i = 0; i < responseJSON.length; ++i)
        appendItem(responseJSON[i]);
  }
}

function appendItem(item_object) {
  var frontend_ref;
  if (item_object.devtoolsFrontendUrl) {
    frontend_ref = document.createElement("a");
    frontend_ref.href = item_object.devtoolsFrontendUrl;
    frontend_ref.title = item_object.title;
  } else {
    frontend_ref = document.createElement("div");
    frontend_ref.title = "The tab already has active debugging session";
  }

  var text = document.createElement("div");
  if (item_object.title)
    text.innerText = item_object.title;
  else
    text.innerText = "(untitled tab)";
  text.style.cssText = "background-image:url(" + item_object.faviconUrl + ")";
  frontend_ref.appendChild(text);

  var item = document.createElement("p");
  item.appendChild(frontend_ref);

  document.getElementById("items").appendChild(item);
}
</script>
</head>
<body onload='onLoad()'>
  <div id='caption'>Inspectable WebContents</div>
  <div id='items'></div>
</body>
</html>