--- a/browser/base/content/sanitize.js
+++ b/browser/base/content/sanitize.js
@@ -199,34 +199,23 @@ Sanitizer.prototype = {
       {
         return true;
       }
     },
 
     offlineApps: {
       clear: function ()
       {
-        const Cc = Components.classes;
-        const Ci = Components.interfaces;
-        var cacheService = Cc["@mozilla.org/network/cache-service;1"].
-                           getService(Ci.nsICacheService);
-        try {
-          // Offline app data is "timeless", and doesn't respect
-          // the setting of timespan, it always clears everything
-          cacheService.evictEntries(Ci.nsICache.STORE_OFFLINE);
-        } catch(er) {}
-
-        var storageManagerService = Cc["@mozilla.org/dom/storagemanager;1"].
-                                    getService(Ci.nsIDOMStorageManager);
-        storageManagerService.clearOfflineApps();
+        Components.utils.import("resource:///modules/offlineAppCache.jsm");
+        OfflineAppCacheHelper.clear();
       },
 
       get canClear()
       {
-          return true;
+        return true;
       }
     },
 
     history: {
       clear: function ()
       {
         var globalHistory = Components.classes["@mozilla.org/browser/global-history;2"]
                                       .getService(Components.interfaces.nsIBrowserHistory);

--- a/browser/components/preferences/advanced.js
+++ b/browser/components/preferences/advanced.js
@@ -63,17 +63,18 @@ var gAdvancedPane = {
 
 #ifdef MOZ_UPDATER
     this.updateReadPrefs();
 #endif
     this.updateOfflineApps();
 #ifdef MOZ_CRASHREPORTER
     this.initSubmitCrashes();
 #endif
-    this.updateActualCacheSize();
+    this.updateActualCacheSize("disk");
+    this.updateActualCacheSize("offline");
   },
 
   /**
    * Stores the identity of the current tab in preferences so that the selected
    * tab can be persisted between openings of the preferences window.
    */
   tabSelectionChanged: function ()
   {
@@ -197,40 +198,45 @@ var gAdvancedPane = {
    * Displays a dialog in which proxy settings may be changed.
    */
   showConnections: function ()
   {
     document.documentElement.openSubDialog("chrome://browser/content/preferences/connection.xul",
                                            "", null);
   },
  
-  // Retrieves the amount of space currently used by disk cache
-  updateActualCacheSize: function ()
+  // Retrieves the amount of space currently used by disk or offline cache
+  updateActualCacheSize: function (device)
   {
     var visitor = {
       visitDevice: function (deviceID, deviceInfo)
       {
-        if (deviceID == "disk") {
-          var actualSizeLabel = document.getElementById("actualCacheSize");
+        if (deviceID == device) {
+          var actualSizeLabel = document.getElementById(device == "disk" ?
+                                                        "actualDiskCacheSize" :
+                                                        "actualAppCacheSize");
           var sizeStrings = DownloadUtils.convertByteUnits(deviceInfo.totalSize);
           var prefStrBundle = document.getElementById("bundlePreferences");
-          var sizeStr = prefStrBundle.getFormattedString("actualCacheSize",
-                                                          sizeStrings);
+          var sizeStr = prefStrBundle.getFormattedString(device == "disk" ?
+                                                         "actualDiskCacheSize" :
+                                                         "actualAppCacheSize",
+                                                         sizeStrings);
           actualSizeLabel.value = sizeStr;
         }
         // Do not enumerate entries
         return false;
       },
 
       visitEntry: function (deviceID, entryInfo)
       {
         // Do not enumerate entries.
         return false;
       }
     };
+
     var cacheService =
       Components.classes["@mozilla.org/network/cache-service;1"]
                 .getService(Components.interfaces.nsICacheService);
     cacheService.visitEntries(visitor);
   },
 
   updateCacheSizeUI: function (smartSizeEnabled)
   {
@@ -269,21 +275,33 @@ var gAdvancedPane = {
   },
 
   /**
    * Clears the cache.
    */
   clearCache: function ()
   {
     var cacheService = Components.classes["@mozilla.org/network/cache-service;1"]
-                         	       .getService(Components.interfaces.nsICacheService);
+                                 .getService(Components.interfaces.nsICacheService);
     try {
       cacheService.evictEntries(Components.interfaces.nsICache.STORE_ANYWHERE);
     } catch(ex) {}
-    this.updateActualCacheSize();
+    this.updateActualCacheSize("disk");
+  },
+
+  /**
+   * Clears the application cache.
+   */
+  clearOfflineAppCache: function ()
+  {
+    Components.utils.import("resource:///modules/offlineAppCache.jsm");
+    OfflineAppCacheHelper.clear();
+
+    this.updateActualCacheSize("offline");
+    this.updateOfflineApps();
   },
 
   readOfflineNotify: function()
   {
     var pref = document.getElementById("browser.offline-apps.notify");
     var button = document.getElementById("offlineNotifyExceptions");
     button.disabled = !pref.value;
     return pref.value;
@@ -427,16 +445,17 @@ var gAdvancedPane = {
                        .getService(Components.interfaces.nsIPermissionManager);
     pm.remove(host, "offline-app",
               Components.interfaces.nsIPermissionManager.ALLOW_ACTION);
     pm.remove(host, "offline-app",
               Components.interfaces.nsIOfflineCacheUpdateService.ALLOW_NO_WARN);
 
     list.removeChild(item);
     gAdvancedPane.offlineAppSelected();
+    this.updateActualCacheSize("offline");
   },
 
   // UPDATE TAB
 
   /*
    * Preferences:
    *
    * app.update.enabled

--- a/browser/components/preferences/advanced.xul
+++ b/browser/components/preferences/advanced.xul
@@ -229,22 +229,22 @@
             <hbox align="center">
               <description flex="1" control="connectionSettings">&connectionDesc.label;</description>
               <button id="connectionSettings" icon="network" label="&connectionSettings.label;"
                       accesskey="&connectionSettings.accesskey;"
                       oncommand="gAdvancedPane.showConnections();"/>
             </hbox>
           </groupbox>
 
-          <!-- Cache/Offline apps -->
-          <groupbox id="offlineGroup">
-            <caption label="&offlineStorage.label;"/>
- 
+          <!-- Cache -->
+          <groupbox id="cacheGroup">
+            <caption label="&httpCache.label;"/>
+
             <hbox align="center">
-              <label id="actualCacheSize" flex="1"/>
+              <label id="actualDiskCacheSize" flex="1"/>
               <button id="clearCacheButton" icon="clear"
                       label="&clearCacheNow.label;" accesskey="&clearCacheNow.accesskey;"
                       oncommand="gAdvancedPane.clearCache();"/>
             </hbox>
             <checkbox preference="browser.cache.disk.smart_size.enabled"
                       id="allowSmartSize" flex="1"
                       onsyncfrompreference="return gAdvancedPane.readSmartSizeEnabled();"
                       label="&overrideSmartCacheSize.label;" 
@@ -255,29 +255,41 @@
                      value="&limitCacheSizeBefore.label;"/>
               <textbox id="cacheSize" type="number" size="4" max="1024"
                        preference="browser.cache.disk.capacity"
                        onsyncfrompreference="return gAdvancedPane.readCacheSize();"
                        onsynctopreference="return gAdvancedPane.writeCacheSize();"
                        aria-labelledby="useCacheBefore cacheSize useCacheAfter"/>
               <label id="useCacheAfter" flex="1">&limitCacheSizeAfter.label;</label>
             </hbox>
+          </groupbox>
+
+          <!-- Offline apps -->
+          <groupbox id="offlineGroup">
+            <caption label="&offlineStorage2.label;"/>
+
+            <hbox align="center">
+              <label id="actualAppCacheSize" flex="1"/>
+              <button id="clearOfflineAppCacheButton" icon="clear"
+                      label="&clearOfflineAppCacheNow.label;" accesskey="&clearOfflineAppCacheNow.accesskey;"
+                      oncommand="gAdvancedPane.clearOfflineAppCache();"/>
+            </hbox>
             <hbox align="center">
               <checkbox id="offlineNotify" flex="1"
                         label="&offlineNotify.label;" accesskey="&offlineNotify.accesskey;"
                         preference="browser.offline-apps.notify"
                         onsyncfrompreference="return gAdvancedPane.readOfflineNotify();"/>
               <button id="offlineNotifyExceptions"
                       label="&offlineNotifyExceptions.label;"
                       accesskey="&offlineNotifyExceptions.accesskey;"
                       oncommand="gAdvancedPane.showOfflineExceptions();"/>
             </hbox>
             <hbox>
               <vbox flex="1">
-                <label id="offlineAppsListLabel">&offlineAppsList.label;</label>
+                <label id="offlineAppsListLabel">&offlineAppsList2.label;</label>
                 <listbox id="offlineAppsList"
                          style="height: &offlineAppsList.height;;"
                          flex="1"
                          aria-labelledby="offlineAppsListLabel"
                          onselect="gAdvancedPane.offlineAppSelected(event);">
                 </listbox>
               </vbox>
               <vbox pack="end">

--- a/browser/locales/en-US/chrome/browser/preferences/advanced.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/advanced.dtd
@@ -35,29 +35,33 @@
 <!ENTITY networkTab.label                "Network">
 
 <!ENTITY connection.label                "Connection">
 
 <!ENTITY connectionDesc.label            "Configure how &brandShortName; connects to the Internet">
 <!ENTITY connectionSettings.label        "Settings…">
 <!ENTITY connectionSettings.accesskey    "e">
 
-<!ENTITY offlineStorage.label            "Offline Storage">
+<!ENTITY httpCache.label                 "Cached Web Content">
+
+<!ENTITY offlineStorage2.label           "Offline Web Content and User Data">
 
 <!-- LOCALIZATION NOTE:
   The entities limitCacheSizeBefore.label and limitCacheSizeAfter.label appear on a single
   line in preferences as follows:
 
   &limitCacheSizeBefore.label [textbox for cache size in MB] &limitCacheSizeAfter.label;
 -->
 <!ENTITY limitCacheSizeBefore.label      "Limit cache to">
 <!ENTITY limitCacheSizeBefore.accesskey  "L">
 <!ENTITY limitCacheSizeAfter.label       "MB of space">
 <!ENTITY clearCacheNow.label             "Clear Now">
 <!ENTITY clearCacheNow.accesskey         "C">
+<!ENTITY clearOfflineAppCacheNow.label   "Clear Now">
+<!ENTITY clearOfflineAppCacheNow.accesskey "N">
 <!ENTITY overrideSmartCacheSize.label    "Override automatic cache management">
 <!ENTITY overrideSmartCacheSize.accesskey "O">
 
 <!ENTITY updateTab.label                 "Update">
 
 <!ENTITY updateApp.label                 "&brandShortName; updates:">
 <!ENTITY updateAuto.label                "Automatically install updates (recommended: improved security)">
 <!ENTITY updateAuto.accesskey            "A">
@@ -79,17 +83,17 @@
 <!ENTITY enableSearchUpdate.label        "Search Engines">
 <!ENTITY enableSearchUpdate.accesskey    "E">
 
 <!ENTITY offlineNotify.label             "Tell me when a website asks to store data for offline use">
 <!ENTITY offlineNotify.accesskey         "T">
 <!ENTITY offlineNotifyExceptions.label   "Exceptions…">
 <!ENTITY offlineNotifyExceptions.accesskey "x">
 
-<!ENTITY offlineAppsList.label           "The following websites have stored data for offline use:">
+<!ENTITY offlineAppsList2.label          "The following websites are allowed to store data for offline use:">
 <!ENTITY offlineAppsList.height          "7em">
 <!ENTITY offlineAppsListRemove.label     "Remove…">
 <!ENTITY offlineAppsListRemove.accesskey "R">
 <!ENTITY offlineAppRemove.confirm        "Remove offline data">
 
 <!ENTITY encryptionTab.label             "Encryption">
 
 <!ENTITY protocols.label                 "Protocols">

--- a/browser/locales/en-US/chrome/browser/preferences/preferences.properties
+++ b/browser/locales/en-US/chrome/browser/preferences/preferences.properties
@@ -100,17 +100,24 @@ offlineAppRemoveConfirm=Remove offline d
 #   %1$S = size (in bytes or megabytes, ...)
 #   %2$S = unit of measure (bytes, KB, MB, ...)
 offlineAppUsage=%1$S %2$S
 
 offlinepermissionstext=The following websites are not allowed to store data for offline use:
 offlinepermissionstitle=Offline Data
 
 ####Preferences::Advanced::Network
-#LOCALIZATION NOTE: The next string is for the disk usage of the http cache.
-#   e.g., "Your cache is currently using 200 MB"
+#LOCALIZATION NOTE: The next string is for the disk usage of the web content cache.
+#   e.g., "Your web content cache is currently using 200 MB"
 #   %1$S = size
 #   %2$S = unit (MB, KB, etc.)
-actualCacheSize=Your cache is currently using %1$S %2$S of disk space
+actualDiskCacheSize=Your web content cache is currently using %1$S %2$S of disk space
+
+####Preferences::Advanced::Network
+#LOCALIZATION NOTE: The next string is for the disk usage of the application cache.
+#   e.g., "Your application cache is currently using 200 MB"
+#   %1$S = size
+#   %2$S = unit (MB, KB, etc.)
+actualAppCacheSize=Your application cache is currently using %1$S %2$S of disk space
 
 syncUnlink.title=Do you want to unlink your device?
 syncUnlink.label=This device will no longer be associated with your Sync account. All of your personal data, both on this device and in your Sync account, will remain intact.
 syncUnlinkConfirm.label=Unlink

--- a/browser/modules/Makefile.in
+++ b/browser/modules/Makefile.in
@@ -46,16 +46,17 @@ include $(topsrcdir)/config/config.mk
 
 ifdef ENABLE_TESTS
 DIRS += test
 endif
 
 EXTRA_JS_MODULES = \
 	openLocationLastURL.jsm \
 	NetworkPrioritizer.jsm \
+	offlineAppCache.jsm \
 	$(NULL)
 
 ifeq ($(MOZ_WIDGET_TOOLKIT),windows) 
 EXTRA_JS_MODULES += \
 	WindowsPreviewPerTab.jsm \
 	WindowsJumpLists.jsm \
 	$(NULL)
 endif

new file mode 100644
--- /dev/null
+++ b/browser/modules/offlineAppCache.jsm
@@ -0,0 +1,54 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2011
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Honza Bambas <honzab.moz@firemni.cz>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+ 
+let EXPORTED_SYMBOLS = ["OfflineAppCacheHelper"];
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+let OfflineAppCacheHelper = {
+  clear: function() {
+    var cacheService = Cc["@mozilla.org/network/cache-service;1"].
+                       getService(Ci.nsICacheService);
+    try {
+      cacheService.evictEntries(Ci.nsICache.STORE_OFFLINE);
+    } catch(er) {}
+
+    var storageManagerService = Cc["@mozilla.org/dom/storagemanager;1"].
+                                getService(Ci.nsIDOMStorageManager);
+    storageManagerService.clearOfflineApps();
+  }
+};