Divide volume_manager.js into files for each classes and extract interfaces from them.

ui/file_manager/file_manager/background/js/launcher_search.js

 // Copyright 2015 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.
 
 /**
  * Provides drive search results to chrome launcher.
  * @constructor
  * @struct
  */
 function LauncherSearch() {
@@ skipping 99 matching lines @@
  */
 LauncherSearch.prototype.onQueryStarted_ = function(queryId, query, limit) {
   this.queryId_ = queryId;
 
   // Request an instance of volume manager to ensure that all volumes are
   // initialized. When user searches while background page of Files.app is not
   // running, it happens that this method is executed before all volumes are
   // initialized. In this method, chrome.fileManagerPrivate.searchDriveMetadata
   // resolves url internally, and it fails if filesystem of the url is not
   // initialized.
-  VolumeManager.getInstance().then(function() {
+  volumeManagerFactory.getInstance().then(function() {
     chrome.fileManagerPrivate.searchDriveMetadata(
         {
           query: query,
           types: 'ALL',
           maxResults: limit
         }, function(results) {
           // If query is already changed, discard the results.
           if (queryId !== this.queryId_ || results.length === 0)
             return;
 
@@ skipping 44 matching lines @@
 };
 
 /**
  * Handles onOpenResult event.
  * @param {string} itemId
  */
 LauncherSearch.prototype.onOpenResult_ = function(itemId) {
   // Request an instance of volume manager to ensure that all volumes are
   // initialized. webkitResolveLocalFileSystemURL in util.urlToEntry fails if
   // filesystem of the url is not initialized.
-  VolumeManager.getInstance().then(function() {
+  volumeManagerFactory.getInstance().then(function() {
     util.urlToEntry(itemId).then(function(entry) {
       if (entry.isDirectory) {
         // If it's directory, open the directory with file manager.
         launchFileManager(
             { currentDirectoryURL: entry.toURL() },
             undefined, /* App ID */
             LaunchType.FOCUS_SAME_OR_CREATE);
       } else {
         // If the file is not directory, try to execute default task.
         chrome.fileManagerPrivate.getFileTasks([entry], function(tasks) {
@@ skipping 47 matching lines @@
  * @param {string} selectionURL A url to be selected.
  * @private
  */
 LauncherSearch.prototype.openFileManagerWithSelectionURL_ = function(
     selectionURL) {
   launchFileManager(
       {selectionURL: selectionURL},
       undefined, /* App ID */
       LaunchType.FOCUS_SAME_OR_CREATE);
 };