chrome.runtime.onMessage.addListener(notify);

function notify(message) {
  console.log("background script received message");
  var title = chrome.i18n.getMessage("notificationTitle");
  var content = chrome.i18n.getMessage("notificationContent", message.url);
  chrome.notifications.create({
    "type": "basic",
    "iconUrl": chrome.extension.getURL("icons/link-48.png"),
    "title": title,
    "message": content
  });
}