--- a/dom/settings/SettingsManager.js
+++ b/dom/settings/SettingsManager.js
@@ -19,30 +19,34 @@ Cu.import("resource://gre/modules/XPCOMU
 Cu.import("resource://gre/modules/Services.jsm");
 
 XPCOMUtils.defineLazyServiceGetter(this, "cpmm",
                                    "@mozilla.org/childprocessmessagemanager;1",
                                    "nsIMessageSender");
 
 const nsIClassInfo            = Ci.nsIClassInfo;
 const SETTINGSLOCK_CONTRACTID = "@mozilla.org/settingsLock;1";
-const SETTINGSLOCK_CID        = Components.ID("{ef95ddd0-6308-11e1-b86c-0800200c9a66}");
+const SETTINGSLOCK_CID        = Components.ID("{60c9357c-3ae0-4222-8f55-da01428470d5}");
 const nsIDOMSettingsLock      = Ci.nsIDOMSettingsLock;
 
 function SettingsLock(aSettingsManager)
 {
   this._open = true;
   this._isBusy = false;
   this._requests = new Queue();
   this._settingsManager = aSettingsManager;
   this._transaction = null;
 }
 
 SettingsLock.prototype = {
 
+  get closed() {
+    return !this._open;
+  },
+
   process: function process() {
     let lock = this;
     lock._open = false;
     let store = lock._transaction.objectStore(SETTINGSSTORE_NAME);
 
     while (!lock._requests.isEmpty()) {
       let info = lock._requests.dequeue();
       if (DEBUG) debug("info: " + info.intent);

--- a/dom/settings/SettingsManager.manifest
+++ b/dom/settings/SettingsManager.manifest
@@ -1,6 +1,6 @@
 component {c40b1c70-00fb-11e2-a21f-0800200c9a66} SettingsManager.js
 contract @mozilla.org/settingsManager;1 {c40b1c70-00fb-11e2-a21f-0800200c9a66}
 category JavaScript-navigator-property mozSettings @mozilla.org/settingsManager;1
 
-component {ef95ddd0-6308-11e1-b86c-0800200c9a66} SettingsManager.js
-contract @mozilla.org/settingsLock;1 {ef95ddd0-6308-11e1-b86c-0800200c9a66}
+component {60c9357c-3ae0-4222-8f55-da01428470d5} SettingsManager.js
+contract @mozilla.org/settingsLock;1 {60c9357c-3ae0-4222-8f55-da01428470d5}

--- a/dom/settings/tests/test_settings_basics.html
+++ b/dom/settings/tests/test_settings_basics.html
@@ -693,16 +693,43 @@ var steps = [
     req = lock.get("screen.brightness");
     req.onsuccess = function () {
       check(req.result["screen.brightness"], 0.7, "get done");
       next();
     }
     req.onerror = onFailure;
   },
   function() {
+    ok(true, "Test closed attribute on a valid lock");
+    var lock = mozSettings.createLock();
+    is(lock.closed, false, "closed attribute is false on creation");
+    req = lock.get("screen.brightness");
+    req.onsuccess = function () {
+      is(lock.closed, false, "closed attribute is false on success callback");
+      next();
+    }
+    req.onerror = onFailure;
+  },
+  function () {
+    ok(true, "Test closed attribute on invalid lock");
+    var lockx = mozSettings.createLock();
+    var cb = function() {
+      var reqx = null;
+      try {
+        reqx = lockx.set(wifiNetworks0);
+        ok(false, "should have thrown");
+      } catch (ex) {
+        is(lockx.closed, true, "closed attribute is true");
+        ok(true, "Caught Exception");
+        next();
+      }
+    }
+    SimpleTest.executeSoon(cb);
+  },
+  function() {
     ok(true, "Clear DB");
     var lock = mozSettings.createLock();
     req = lock.clear();
     req.onsuccess = function () {
       ok(true, "Deleted the database");
       next();
     };
     req.onerror = onFailure;