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

lib/typoFixer.js

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 let {Prefs} = require("prefs");
 let {WindowObserver} = require("windowObserver");
 let {getSchemeCorrection, isKnownScheme, getDomainCorrection, getDomainReferral, onWhitelistEntryAdded} = require("typoRules");
 let {processTypedDomain, processDomainCorrection, processFalsePositive} = require("typoCollector");
 let appIntegration = require("typoAppIntegration");
 let netError = require("typoNetError");
 
-// Attach our handlers to all browser windows
-new WindowObserver(
+let typoWindowObserver = null;
+
+exports.attachWindowObserver = attachWindowObserver;
+function attachWindowObserver()
 {
-  applyToWindow: function(window)
+  if (typoWindowObserver)
+    return;
+  
+  // Attach our handlers to all browser windows
+  typoWindowObserver = new WindowObserver(
   {
-    if (!appIntegration.isKnownWindow(window))
-      return;
-    
-    netError.applyToWindow(window);
-    appIntegration.applyToWindow(window, correctURL);
-  },
+    applyToWindow: function(window)
+    {
+      if (!appIntegration.isKnownWindow(window))
+        return;
+      
+      netError.applyToWindow(window);
+      appIntegration.applyToWindow(window, correctURL);
+    },
 
-  removeFromWindow: function(window)
-  {
-    if (!appIntegration.isKnownWindow(window))
-      return;
-    
-    netError.removeFromWindow(window);
-    appIntegration.removeFromWindow(window);
-  }
-});
+    removeFromWindow: function(window)
+    {
+      if (!appIntegration.isKnownWindow(window))
+        return;
+      
+      netError.removeFromWindow(window);
+      appIntegration.removeFromWindow(window);
+    }
+  });
+}
+attachWindowObserver();
+
+exports.detachWindowObserver = detachWindowObserver;
+function detachWindowObserver()
+{
+  if (!typoWindowObserver)
+    return;
+  
+  // Detach our handlers from all browser windows
+  typoWindowObserver.shutdown();
+  typoWindowObserver = null;
+}
 
 function parseURL(url)
 {
   if (/^\s*((?:\w+:)?\/*(?:[^\/#]*@)?)([^\/:#]*)/.test(url))
     return [RegExp.$1, RegExp.$2.toLowerCase(), RegExp.rightContext];
   else
     return [url, null, null];
 }
 
 function isIPAddress(domain)
@@ skipping 143 matching lines @@
     stringBundle = Services.strings.createBundle("chrome://" + require("info").addonName + "/locale/typo.properties?" + Math.random());
   let result = [
     stringBundle.GetStringFromName("urlfixer.isItCorrect"),
     stringBundle.GetStringFromName("urlfixer.yes"),
     stringBundle.GetStringFromName("urlfixer.no")
   ];
 
   getInfobarTexts = function() result;
   return getInfobarTexts();
 }