background.html

<!DOCTYPE html>
<html>
  <head>
  </head>
  <body>
    <script>
      /**
       * Performs an XMLHttpRequest to Wikipedia
       * @param callback Function If the response from fetching url has a
       *     HTTP status of 200, this function is called with a JSON decoded
       *     response.  Otherwise, this function is called with null.
       */
      function doAjaxRequest(url, callback) {
        var xhr = new XMLHttpRequest();
        xhr.onreadystatechange = function(data) {
          if (xhr.readyState == 4) {
            if (xhr.status == 200) {
              var data = xhr.responseText;
              callback(data);
            } else {
              callback(null);
            }
          }
        }
        xhr.open('GET', url, true);
        xhr.send();
      };

      /**
       * Handles data sent via chrome.extension.sendRequest().
       * @param request Object Data sent in the request.
       * @param sender Object Origin of the request.
       * @param callback Function The method to call when the request completes.
       */
      function onRequest(request, sender, callback) {

          if(request.action == 'doAjaxRequest') {
          	doAjaxRequest(request.url, callback);
          }
          if(request.action == 'getSettings') {
			  var username = localStorage["username"];
			  if(username == undefined || username == '') {
				chrome.tabs.create({url:chrome.extension.getURL("options.html")});
			  } else {
              	callback({username: localStorage["username"], password: localStorage["password"] });
			  }
          }
      };

      // Wire up the listener.
      chrome.extension.onRequest.addListener(onRequest);
    </script>
  </body>
</html>