function openURL(url) {
  chrome.tabs.create({ "url": url })
}

function addLinks() {
  var links = document.getElementsByTagName("a");
  for (var i = 0; i < links.length; i++) {
    var url = links[i].getAttribute("url");
    if (url)
      links[i].addEventListener("click", function () {
        openURL(this.getAttribute("url"));
      });
  }
}

window.addEventListener("load", function () {
  addLinks();