content-policy.js

const { Cc, Ci } = require("chrome");
const xpcom = require("xpcom");

const { Class } = require("api-utils/heritage");

exports.preventCrossRequest = Class({
  extends: xpcom.Unknown,
  interfaces: ["nsIContentPolicy"],
  shouldLoad: function (contType, contLoc, reqOrig, ctx, typeGuess, extra) {
    
    return Ci.nsIContentPolicy.REJECT;

  },

  shouldProcess: function (contType, contLoc, reqOrig, ctx, mimeType, extra) {
    return Ci.nsIContentPolicy.ACCEPT;
  }
});

let factory = xpcom.Factory({
  Component:   exports.preventCrossRequest,
  description: "Implements content policy to prevent cross requests",
  contract:    "@lduros.net/PreventCrossRequest-policy"
});

var catman = Cc["@mozilla.org/categorymanager;1"].getService(Ci.nsICategoryManager);
catman.addCategoryEntry("content-policy", "prevent-cross-request.preventCrossRequest", factory.contract, false, true);