background.html

<!DOCTYPE html>
<html>
  <head>
  </head>
  <body>
    <script>
      function fetchSubtitles(callback, searchString) {
        var xhr = new XMLHttpRequest();
        xhr.onreadystatechange = function(data) {
          if (xhr.readyState == 4) {
            if (xhr.status == 200) {
              callback({"data": xhr.responseText, "search": searchString});
            } else {
              callback(null);
            }
          }
        }
        var url = 'http://www.feliratok.info/index.php?style=old&search='+searchString;
        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) {
        // Only supports the 'fetchTwitterFeed' method, although this could be
        // generalized into a more robust RPC system.
        if (request.action == 'fetchSubtitles'){
	  fetchSubtitles(callback, request.search);
        }
      };

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