diff -r 000000000000 -r 6474c204b198 dom/filesystem/FileSystemBase.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/filesystem/FileSystemBase.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,78 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/FileSystemBase.h"
+
+#include "DeviceStorageFileSystem.h"
+#include "nsCharSeparatedTokenizer.h"
+
+namespace mozilla {
+namespace dom {
+
+// static
+already_AddRefed<FileSystemBase>
+FileSystemBase::FromString(const nsAString& aString)
+{
+  if (StringBeginsWith(aString, NS_LITERAL_STRING("devicestorage-"))) {
+    // The string representation of devicestorage file system is of the format:
+    // devicestorage-StorageType-StorageName
+
+    nsCharSeparatedTokenizer tokenizer(aString, char16_t('-'));
+    tokenizer.nextToken();
+
+    nsString storageType;
+    if (tokenizer.hasMoreTokens()) {
+      storageType = tokenizer.nextToken();
+    }
+
+    nsString storageName;
+    if (tokenizer.hasMoreTokens()) {
+      storageName = tokenizer.nextToken();
+    }
+
+    nsRefPtr<DeviceStorageFileSystem> f =
+      new DeviceStorageFileSystem(storageType, storageName);
+    return f.forget();
+  }
+  return nullptr;
+}
+
+FileSystemBase::FileSystemBase()
+  : mShutdown(false)
+  , mIsTesting(false)
+{
+}
+
+FileSystemBase::~FileSystemBase()
+{
+}
+
+void
+FileSystemBase::Shutdown()
+{
+  mShutdown = true;
+}
+
+nsPIDOMWindow*
+FileSystemBase::GetWindow() const
+{
+  return nullptr;
+}
+
+bool
+FileSystemBase::IsSafeFile(nsIFile* aFile) const
+{
+  return false;
+}
+
+bool
+FileSystemBase::IsSafeDirectory(Directory* aDir) const
+{
+  return false;
+}
+
+} // namespace dom
+} // namespace mozilla