Issue 2950 - Don`t rely on Services.mm, it isn`t available before Gecko 39

lib/main.js

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
 let {Services} = Cu.import("resource://gre/modules/Services.jsm", {});
 
 let {Prefs} = require("prefs");
 let {WindowObserver} = require("windowObserver");
@@ skipping 30 matching lines @@
   let data = event.target.responseText.replace(/%%CLASS%%/g, elementMarkerClass);
   let styleService = Cc["@mozilla.org/content/style-sheet-service;1"].getService(Ci.nsIStyleSheetService);
   let styleURI = Services.io.newURI("data:text/css," + encodeURIComponent(data), null, null);
   styleService.loadAndRegisterSheet(styleURI, Ci.nsIStyleSheetService.USER_SHEET);
   onShutdown.add(() => styleService.unregisterSheet(styleURI, Ci.nsIStyleSheetService.USER_SHEET));
 }, false);
 request.send(null);
 
 // Load our developer tools actor
 let frameScript = "chrome://elemhidehelper/content/frameScript.js?" + elementMarkerClass;
-Services.mm.loadFrameScript(frameScript, true);
+let messageManager = Cc["@mozilla.org/globalmessagemanager;1"]
+  .getService(Ci.nsIFrameScriptLoader);
+messageManager.loadFrameScript(frameScript, true);
 onShutdown.add(() => {
-  Services.mm.removeDelayedFrameScript(frameScript);
-  Services.mm.broadcastAsyncMessage("ElemHideHelper:Shutdown");
+  messageManager.removeDelayedFrameScript(frameScript);
+  messageManager.QueryInterface(Ci.nsIMessageBroadcaster).broadcastAsyncMessage("ElemHideHelper:Shutdown");
 });
 
 // Load overlay asynchonously and start attaching to windows once done
 request = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance(Ci.nsIJSXMLHttpRequest);
 request.open("GET", "chrome://elemhidehelper/content/overlay.xul");
 request.addEventListener("load", function(event)
 {
   if (onShutdown.done)
     return;
 
@@ skipping 28 matching lines @@
       if (element)
         element.parentNode.removeChild(element);
 
       for (let child = window.document.firstChild; child; child = child.nextSibling)
         if (child.nodeType == child.PROCESSING_INSTRUCTION_NODE && child.data.indexOf("elemhidehelper-node") >= 0)
           child.parentNode.removeChild(child);
     }
   });
 }, false);
 request.send(null);