Simplify volume manager in Files app.

chrome/browser/resources/file_manager/common/js/util.js

 // Copyright (c) 2012 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.
 
 'use strict';
 
 /**
  * Namespace for utility functions.
  */
 var util = {};
@@ skipping 1061 matching lines @@
 };
 
 /**
  * Compares two entries.
  * @param {Entry|Object} entry1 The entry to be compared. Can be a fake.
  * @param {Entry|Object} entry2 The entry to be compared. Can be a fake.
  * @return {boolean} True if the both entry represents a same file or
  *     directory. Returns true if both entries are null.
  */
 util.isSameEntry = function(entry1, entry2) {
-  // Currently, we can assume there is only one root.
-  // When we support multi-file system, we need to look at filesystem, too.
-  return (entry1 && entry2 && entry1.toURL() === entry2.toURL()) ||
-      (!entry1 && !entry2);
+  if (!entry1 && !entry2)
+    return true;
+  if (!entry1 || !entry2)
+    return false;
+  return entry1.toURL() === entry2.toURL();
 };
 
 /**
+ * Compares two file systems.
+ * @param {DOMFileSystem} fileSystem1 The file system to be compared.
+ * @param {DOMFileSystem} fileSystem2 The file system to be compared.
+ * @return {boolean} True if the both file systems are equal. Also, returns true
+ *     if both file systems are null.
+ */
+util.isSameFileSystem = function(fileSystem1, fileSystem2) {
+  if (!fileSystem1 && !fileSystem2)
+    return true;
+  if (!fileSystem1 || !fileSystem2)
+    return false;
+  return util.isSameEntry(fileSystem1.root, fileSystem2.root);
+};
+
+/**
  * Checks if the child entry is a descendant of another entry. If the entries
  * point to the same file or directory, then returns false.
  *
  * @param {DirectoryEntry|Object} ancestorEntry The ancestor directory entry.
  *     Can be a fake.
  * @param {Entry|Object} childEntry The child entry. Can be a fake.
  * @return {boolean} True if the child entry is contained in the ancestor path.
  */
 util.isDescendantEntry = function(ancestorEntry, childEntry) {
   if (!ancestorEntry.isDirectory)
@@ skipping 181 matching lines @@
  * @enum {string}
  * @const
  */
 util.VolumeType = Object.freeze({
   DRIVE: 'drive',
   DOWNLOADS: 'downloads',
   REMOVABLE: 'removable',
   ARCHIVE: 'archive',
   CLOUD_DEVICE: 'cloud_device'
 });