Adapted private browsing handling to per-window private browsing in Firefox 20

lib/filterStorage.js

Index: lib/filterStorage.js
===================================================================
--- a/lib/filterStorage.js
+++ b/lib/filterStorage.js
@@ -308,21 +308,26 @@ let FilterStorage = exports.FilterStorag
     subscription.filters.splice(oldPosition, 1);
     subscription.filters.splice(newPosition, 0, filter);
     FilterNotifier.triggerListeners("filter.moved", filter, subscription, oldPosition, newPosition);
   },
 
   /**
    * Increases the hit count for a filter by one
    * @param {Filter} filter
+   * @param {Window} window  Window that the match originated in (required
+   *                         to recognize private browsing mode)
    */
-  increaseHitCount: function(filter)
+  increaseHitCount: function(filter, wnd)
   {
-    if (!Prefs.savestats || PrivateBrowsing.enabled || !(filter instanceof ActiveFilter))
+    if (!Prefs.savestats || PrivateBrowsing.enabledForWindow(wnd) ||
+        PrivateBrowsing.enabled || !(filter instanceof ActiveFilter))
+    {
       return;
+    }
 
     filter.hitCount++;
     filter.lastHit = Date.now();
   },
 
   /**
    * Resets hit count for some filters
    * @param {Array of Filter} filters  filters to be reset, if null all filters will be reset
@@ -707,21 +712,41 @@ function removeSubscriptionFilters(subsc
 
 /**
  * Observer listening to private browsing mode changes.
  * @class
  */
 let PrivateBrowsing = exports.PrivateBrowsing =
 {
   /**
-   * Will be set to true when the private browsing mode is switched on.
+   * Will be set to true when the private browsing mode is switched on globally.
    * @type Boolean
    */
   enabled: false,
 
+  /**
+   * Checks whether private browsing is enabled for a particular window.
+   */
+  enabledForWindow: function(/**Window*/ wnd) /**Boolean*/
+  {
+    try
+    {
+      return wnd.QueryInterface(Ci.nsIInterfaceRequestor)
+                .getInterface(Ci.nsILoadContext)
+                .usePrivateBrowsing;
+    }
+    catch (e)
+    {
+      // Gecko 19 and below will throw NS_NOINTERFACE, this is expected
+      if (e.result != Cr.NS_NOINTERFACE)
+        Cu.reportError(e);
+      return false;
+    }
+  },
+
   init: function()
   {
     if ("@mozilla.org/privatebrowsing;1" in Cc)
     {
       try
       {
         this.enabled = Cc["@mozilla.org/privatebrowsing;1"].getService(Ci.nsIPrivateBrowsingService).privateBrowsingEnabled;
         Services.obs.addObserver(this, "private-browsing", true);