main.js

var pageMod = require("page-mod");

pageMod.add(new pageMod.PageMod({
  include: "*",
  contentScriptWhen: 'start',
  contentScript: 'new ' + function WorkerScope() {
    console.log("exec");

    var htmlMutation = function(e) {
      var node = document.querySelector('object, embed');
      console.log("node = ", node);
      if (node) {
        node.parentNode.removeChild(node);
      }
    };
    
    var documentMutation = document.addEventListener('DOMNodeInserted', function() {
      if (htmlMutation) {
        document.addEventListener('DOMSubtreeModified', htmlMutation, false);
        htmlMutation = null;
      }
      document.removeEventListener(documentMutation);
    }, false);
  }
}));