Add an unittest for background/volume_manager.js

chrome/test/data/file_manager/unit_tests/mocks/mock_file_system.js

Index: chrome/test/data/file_manager/unit_tests/mocks/mock_file_system.js
diff --git a/chrome/test/data/file_manager/unit_tests/mocks/mock_file_system.js b/chrome/test/data/file_manager/unit_tests/mocks/mock_file_system.js
deleted file mode 100644
index 58c4e23db0c1c2f64089cdb10571510dd81959ff..0000000000000000000000000000000000000000
--- a/chrome/test/data/file_manager/unit_tests/mocks/mock_file_system.js
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-/**
- * Mock class for DOMFileSystem.
- * @param {string} volumeId Volume ID for the file system.
- * @constructor
- */
-function MockFileSystem(volumeId) {
-  this.name = '';
-  this.root = new MockFileEntry(volumeId, '/');
-}