diff --git a/mozilla/browser/base/content/browser.js b/mozilla/browser/base/content/browser.js
index f0b6fe767dd..57b849b0885 100644
--- a/mozilla/browser/base/content/browser.js
+++ b/mozilla/browser/base/content/browser.js
@@ -5490,6 +5490,24 @@ var OfflineApps = {
            Ci.nsIOfflineCacheUpdateService.ALLOW_NO_WARN);
   },
 
+  // XXX: duplicated in preferences/advanced.js
+  _getOfflineAppUsage: function (host)
+  {
+    var cacheService = Components.classes["@mozilla.org/network/cache-service;1"].
+                       getService(Components.interfaces.nsICacheService);
+    var cacheSession = cacheService.createSession("HTTP-offline",
+                                                  Components.interfaces.nsICache.STORE_OFFLINE,
+                                                  true).
+                       QueryInterface(Components.interfaces.nsIOfflineCacheSession);
+    var usage = cacheSession.getDomainUsage(host);
+
+    var storageManager = Components.classes["@mozilla.org/dom/storagemanager;1"].
+                         getService(Components.interfaces.nsIDOMStorageManager);
+    usage += storageManager.getUsage(host);
+
+    return usage;
+  },
+
   _checkUsage: function(aURI) {
     var pm = Cc["@mozilla.org/permissionmanager;1"].
              getService(Ci.nsIPermissionManager);
@@ -5497,7 +5515,7 @@ var OfflineApps = {
     // if the user has already allowed excessive usage, don't bother checking
     if (pm.testExactPermission(aURI, "offline-app") !=
         Ci.nsIOfflineCacheUpdateService.ALLOW_NO_WARN) {
-      var usage = getOfflineAppUsage(aURI.asciiHost);
+      var usage = this._getOfflineAppUsage(aURI.asciiHost);
       var warnQuota = gPrefService.getIntPref("offline-apps.quota.warn");
       if (usage >= warnQuota * 1024) {
         return true;
diff --git a/mozilla/browser/base/content/utilityOverlay.js b/mozilla/browser/base/content/utilityOverlay.js
index b9f137b8988..07ce25e7f95 100644
--- a/mozilla/browser/base/content/utilityOverlay.js
+++ b/mozilla/browser/base/content/utilityOverlay.js
@@ -656,23 +656,6 @@ function isValidFeed(aData, aPrincipal, aIsFeed)
   return aIsFeed;
 }
 
-function getOfflineAppUsage(host)
-{
-  var cacheService = Components.classes["@mozilla.org/network/cache-service;1"].
-                     getService(Components.interfaces.nsICacheService);
-  var cacheSession = cacheService.createSession("HTTP-offline",
-                                                Components.interfaces.nsICache.STORE_OFFLINE,
-                                                true).
-                     QueryInterface(Components.interfaces.nsIOfflineCacheSession);
-  var usage = cacheSession.getDomainUsage(host);
-
-  var storageManager = Components.classes["@mozilla.org/dom/storagemanager;1"].
-                       getService(Components.interfaces.nsIDOMStorageManager);
-  usage += storageManager.getUsage(host);
-
-  return usage;
-}
-
 // aCalledFromModal is optional
 function openHelpLink(aHelpTopic, aCalledFromModal) {
   var url = Components.classes["@mozilla.org/toolkit/URLFormatterService;1"]
diff --git a/mozilla/browser/components/preferences/advanced.js b/mozilla/browser/components/preferences/advanced.js
index 3aa537aa336..4cf1d5dc1b5 100644
--- a/mozilla/browser/components/preferences/advanced.js
+++ b/mozilla/browser/components/preferences/advanced.js
@@ -207,6 +207,24 @@ var gAdvancedPane = {
                                         "", params);
   },
 
+  // XXX: duplicated in browser.js
+  _getOfflineAppUsage: function (host)
+  {
+    var cacheService = Components.classes["@mozilla.org/network/cache-service;1"].
+                       getService(Components.interfaces.nsICacheService);
+    var cacheSession = cacheService.createSession("HTTP-offline",
+                                                  Components.interfaces.nsICache.STORE_OFFLINE,
+                                                  true).
+                       QueryInterface(Components.interfaces.nsIOfflineCacheSession);
+    var usage = cacheSession.getDomainUsage(host);
+
+    var storageManager = Components.classes["@mozilla.org/dom/storagemanager;1"].
+                         getService(Components.interfaces.nsIDOMStorageManager);
+    usage += storageManager.getUsage(host);
+
+    return usage;
+  },
+
   /**
    * Updates the list of offline applications
    */
@@ -233,7 +251,7 @@ var gAdvancedPane = {
         row.className = "offlineapp";
         row.setAttribute("host", perm.host);
         var converted = DownloadUtils.
-                        convertByteUnits(getOfflineAppUsage(perm.host));
+                        convertByteUnits(this._getOfflineAppUsage(perm.host));
         row.setAttribute("usage",
                          bundle.getFormattedString("offlineAppUsage",
                                                    converted));