Issue 2879 - Restructure existing process script, split it up into multiple modules

lib/child/bootstrap.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/.
  */
 
 "use strict";

[Wladimir Palant, 2016/11/17 08:42:58]

This is very close to lib/child/bootstrap.js we use in Adblock Plus. The
differences are:

* "use strict"
* messageManager is declared explicitly (we cannot just use `this` within a
function because with "use strict" it won't be defined).
* Function shutdown protects against reentry, won't do anything if we have
onShutdown.done.
* Not expecting the script URL as parameter for shutdown message - I don't
remember what issue this was working around in Adblock Plus but it was working
fine without in EHH.
* Shutdown message is called ElemHideHelper:Shutdown rather than
AdblockPlus:Shutdown.

[saroyanm, 2016/11/22 14:58:31]

Acknowledged.

 
 (function(messageManager)
 {
   const Cc = Components.classes;
   const Ci = Components.interfaces;
   const Cr = Components.results;
   const Cu = Components.utils;
 
-  let {Loader, main, unload} = Cu.import("resource://gre/modules/commonjs/toolkit/loader.js", {});

[saroyanm, 2016/11/24 17:46:10]

Nit: Exceeding 80 chars.

[Wladimir Palant, 2016/12/01 09:40:49]

Done.

+  let {Loader, main, unload} = Cu.import(
+    "resource://gre/modules/commonjs/toolkit/loader.js", {}
+  );
   let {Services} = Cu.import("resource://gre/modules/Services.jsm", {});
 
   Cu.importGlobalProperties(["atob", "btoa", "File", "URL", "URLSearchParams",
       "TextDecoder", "TextEncoder"]);
 
   let shutdownHandlers = [];
   let onShutdown =
   {
     done: false,
     add: function(handler)
@@ skipping 17 matching lines @@
 
     let loader = Loader({
       paths: {
         "": info.addonRoot + "lib/"
       },
       globals: {
         Components, Cc, Ci, Cu, Cr, atob, btoa, File, URL, URLSearchParams,
         TextDecoder, TextEncoder, onShutdown
       },
       modules: {
         info, messageManager

[saroyanm, 2016/11/22 14:58:31]

In AdblockPlus we are defining the modules:
modules: {"info": info, "messageManager": this}

Should this be defined like:
modules: {"info": info, "messageManager": messageManager} ?

[Wladimir Palant, 2016/11/24 14:16:29]

Why? This short notation is available starting with Firefox 34 and we are
starting to use it. The code in Adblock Plus is simply older.

[saroyanm, 2016/11/24 17:46:10]

Oh, I was referring actually to your initial comment regarding the differences
in bootstrap file. 
Acknowledged.

       },
       id: info.addonID
     });
     onShutdown.add(() => unload(loader, "disable"))
 
     main(loader, "child/main");
   }
 
   function shutdown(message)

[saroyanm, 2016/11/22 14:58:31]

message parameter is not being used, probably can be omitted.

[Wladimir Palant, 2016/11/24 14:16:29]

It sure can be but it is still being passed in so I'd rather not omit it.

   {
     if (onShutdown.done)
       return;
 
     onShutdown.done = true;
     for (let i = shutdownHandlers.length - 1; i >= 0; i --)
     {
       try
       {
         shutdownHandlers[i]();
       }
       catch (e)
       {
         Cu.reportError(e);
       }
     }
     shutdownHandlers = null;
   }
 
   messageManager.addMessageListener("ElemHideHelper:Shutdown", shutdown);
   onShutdown.add(() =>
   {
     messageManager.removeMessageListener("ElemHideHelper:Shutdown", shutdown);
   });
 
   init();
 })(this);