fennec browser load/switch detection + local proxy server

bootstrap.js

var Cc = Components.classes;
var Ci = Components.interfaces;
var Cu = Components.utils;

Cu.import("resource://gre/modules/Services.jsm");

function startup(aData, aReason) {
  var gBaseURL;

  var installSpec = Services.io.newFileURI(aData.installPath).spec;
  if (aData.installPath.isDirectory())
    gBaseURL = installSpec;
  else
    gBaseURL = "jar:" + installSpec + "!/";
 
  var contentURL = gBaseURL + "content.js";

  var messageManager = Cc["@mozilla.org/globalmessagemanager;1"].getService(Ci.nsIChromeFrameMessageManager);
  messageManager.loadFrameScript(contentURL, true);
}

function shutdown(aData, aReason) {}
function install(aData, aReason) {}
function uninstall(aData, aReason) {}

content.js

var Cc = Components.classes;
var Ci = Components.interfaces;
var Cu = Components.utils;
 
addEventListener("load", doCheck, true);
addEventListener("focus", doCheck, true);

function doCheck(event) {
  state = event.originalTarget.body.classList.contains("stereo");
  var req = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance();
  req.open("GET", "http://localhost:3000?stereo=" + state, true);
  req.send();
}

install.rdf

<?xml version="1.0"?>
<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:em="http://www.mozilla.org/2004/em-rdf#">
    <Description about="urn:mozilla:install-manifest">
        <em:id>[email protected]</em:id>
        <em:type>2</em:type>
        <em:name>Simple</em:name>
        <em:version>1.0</em:version>
        <em:bootstrap>true</em:bootstrap>
        <em:creator>Midgley</em:creator>
        <em:targetApplication>
            <Description>
                <em:id>{a23983c0-fd0e-11dc-95ff-0800200c9a66}</em:id>
                <em:minVersion>4.0b4pre</em:minVersion>
                <em:maxVersion>7.*</em:maxVersion>
            </Description>
        </em:targetApplication>
    </Description>
</RDF>