[Gallery app] Make the background page use BackgroundBase class

ui/file_manager/gallery/js/gallery.js

 // 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.
 
 /**
  * Overrided metadata worker's path.
  * @type {string}
  */
 ContentProvider.WORKER_SCRIPT = '/js/metadata_worker.js';
 
@@ skipping 885 matching lines @@
 Gallery.prototype.debugMe = function() {
   this.mosaicMode_.debugMe();
 };
 
 /**
  * Singleton gallery.
  * @type {Gallery}
  */
 var gallery = null;
 
+var loadTimeDataPromise = new Promise(function(fulfill, reject) {
+  chrome.fileManagerPrivate.getStrings(function(strings) {
+    window.loadTimeData.data = strings;
+    i18nTemplate.process(document, loadTimeData);
+    fulfill();
+  });
+});
+
 /**
  * Initialize the window.
  * @param {!BackgroundComponents} backgroundComponents Background components.

[fukino, 2015/02/16 04:16:38]

nit: This comment looks incorrect.

[yoshiki, 2015/02/16 07:35:55]

Done.

  */
-window.initialize = function(backgroundComponents) {
-  window.loadTimeData.data = backgroundComponents.stringData;
-  gallery = new Gallery(backgroundComponents.volumeManager);
-};
+var volumeManagerPromise = new Promise(function(fulfill, reject) {
+  var volumeManager = new VolumeManagerWrapper(
+      VolumeManagerWrapper.DriveEnabledStatus.DRIVE_ENABLED);
+  volumeManager.ensureInitialized(fulfill.bind(null, volumeManager));
+});
+
+var initializePromise =
+    Promise.all([loadTimeDataPromise, volumeManagerPromise]).
+    then(function(args) {
+      var volumeManager = args[1];
+      var gallery = new Gallery(volumeManager);
+      return gallery;
+    });
 
 /**
  * Loads entries.
  * @param {!Array.<Entry>} selectedEntries Array of selected entries.

[fukino, 2015/02/16 04:16:38]

ditto

[yoshiki, 2015/02/16 07:35:55]

Done.

  */
-window.loadEntries = function(selectedEntries) {
-  gallery.load(selectedEntries);
-};
+initializePromise.then(function(gallery) {
+  util.URLsToEntries(window.appState.urls, function(entries) {
+    gallery.load(entries);
+  });
+});
 
 /**
  * Enteres the debug mode.
  */
 window.debugMe = function() {
-  gallery.debugMe();
+  initializePromise.then(function(gallery) {
+    gallery.debugMe();
+  });
 };