diff --git a/dom/devicestorage/DeviceStorage.h b/dom/devicestorage/DeviceStorage.h
index 11b7817bbe7..3f2b0d99010 100644
--- a/dom/devicestorage/DeviceStorage.h
+++ b/dom/devicestorage/DeviceStorage.h
@@ -224,6 +224,8 @@ public:
   already_AddRefed<DOMRequest> UsedSpace(ErrorResult& aRv);
   already_AddRefed<DOMRequest> Available(ErrorResult& aRv);
 
+  bool Default();
+
   // Uses XPCOM GetStorageName
 
   static void CreateDeviceStorageFor(nsPIDOMWindow* aWin,
diff --git a/dom/devicestorage/nsDeviceStorage.cpp b/dom/devicestorage/nsDeviceStorage.cpp
index 89c877618d4..5fa3e357630 100644
--- a/dom/devicestorage/nsDeviceStorage.cpp
+++ b/dom/devicestorage/nsDeviceStorage.cpp
@@ -3043,11 +3043,18 @@ nsDOMDeviceStorage::GetRootDirectoryForFile(const nsAString& aName, nsIFile** aR
   return ds->mRootDirectory->Clone(aRootDirectory);
 }
 
-NS_IMETHODIMP
-nsDOMDeviceStorage::GetDefault(bool* aDefault) {
+bool
+nsDOMDeviceStorage::Default()
+{
   nsString defaultStorageName;
   GetWritableStorageName(mStorageType, defaultStorageName);
-  *aDefault = mStorageName.Equals(defaultStorageName);
+  return mStorageName.Equals(defaultStorageName);
+}
+
+NS_IMETHODIMP
+nsDOMDeviceStorage::GetDefault(bool* aDefault)
+{
+  *aDefault = Default();
   return NS_OK;
 }
 
diff --git a/dom/webidl/DeviceStorage.webidl b/dom/webidl/DeviceStorage.webidl
index 72c4385cc1a..faa25374858 100644
--- a/dom/webidl/DeviceStorage.webidl
+++ b/dom/webidl/DeviceStorage.webidl
@@ -44,4 +44,8 @@ interface DeviceStorage : EventTarget {
   // Note that the storageName is just a name (like sdcard), and doesn't
   // include any path information.
   readonly attribute DOMString storageName;
+
+  // Determines if this storage area is the one which will be used by default
+  // for storing new files.
+  readonly attribute boolean default;
 };