Detect and handle the case of our own typo correction extension being installed in parallel

lib/typoBootstrap.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/.
+ * This file is part of the Adblock Plus,
+ * Copyright (C) 2006-2012 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 /**
  * @fileOverview Adds typo correction feature
  */
 
 Cu.import("resource://gre/modules/AddonManager.jsm");
 
 let {Prefs} = require("prefs");
 let urlfixerID = "{0fa2149e-bb2c-4ac2-a8d3-479599819475}";
@@ skipping 16 matching lines @@
       {
         init();
         Prefs.removeListener(onPrefChange);
       }
     }
     
     Prefs.addListener(onPrefChange);
   }
 }
 
-function cleanup()
-{
-  if (addonListener)
-  {
-    AddonManager.removeAddonListener(addonListener);
-    addonListener = null;
-  }
-}
-onShutdown.add(cleanup);

[Wladimir Palant, 2012/11/20 11:13:30]

Seriously, please look around at how this is done everywhere else (search for
onShutdown.add). If we have to remember to keep cleanup handlers in sync with
the code this will become an unmanageable mess. The only way to keep things
manageable is to add a cleanup handler immediately after doing something that
requires reverting. Meaning that after calling AddonManager.addAddonListener()
the next line should be:

    onShutdown.add(function() AddonManager.removeAddonListener(...));

No need for any checks or variable cleanup.

-
 function startTypoCorrection(isInstalledAndEnabled)
 {
   if (isInstalledAndEnabled)
     require("typoFixer").detachWindowObserver();
   else
     require("typoFixer").attachWindowObserver();
   
   if (!addonListener)
   {
     addonListener = {
@@ skipping 13 matching lines @@
           startTypoCorrection(true);
       },
       onUninstalled: function(addon)
       {
         if (addon.id == urlfixerID)
           startTypoCorrection(false);
       }
     }
     
     AddonManager.addAddonListener(addonListener);
+    onShutdown.add(function() AddonManager.removeAddonListener(addonListener));
   }
 }
 
 init();