[Files.app] Initial implementation of new audio player

chrome/browser/resources/file_manager/background/js/background.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';
 
 /**
  * Number of runtime errors catched in the background page.
  * @type {number}
  */
@@ skipping 665 matching lines @@
         // For mounted devices just focus any Files.app window. The mounted
         // volume will appear on the navigation list.
         var type = action == 'auto-open' ? LaunchType.FOCUS_ANY_OR_CREATE :
             LaunchType.FOCUS_SAME_OR_CREATE;
         launchFileManager(appState, /* App ID */ undefined, type, nextStep);
       });
       break;
   }
 };
 
-/**
- * Audio player window create options.
- * @type {Object}
- * @const
- */
-var AUDIO_PLAYER_CREATE_OPTIONS = Object.freeze({
-  type: 'panel',
-  hidden: true,
-  minHeight: 35 + 58,
-  minWidth: 280,
-  height: 35 + 58,
-  width: 280
+// The instance of audio player. Until it's ready, this is null.
+var audioPlayer = null;
+
+// Queue to serializes the initialization, launching and reloading of the audio
+// player, so races won't happen.
+var audioPlayerInitializationQueue = new AsyncUtil.Queue();
+
+audioPlayerInitializationQueue.run(function(callback) {
+  chrome.commandLinePrivate.hasSwitch(
+      'file-manager-enable-new-audio-player',
+      function(newAudioPlayerEnabled) {
+        var audioPlayerHTML =
+            newAudioPlayerEnabled ? 'audio_player.html' : 'mediaplayer.html';
+
+        /**
+         * Audio player window create options.
+         * @type {Object}
+         */
+        var audioPlayerCreateOptions = Object.freeze({
+          type: 'panel',
+          hidden: true,
+          minHeight: newAudioPlayerEnabled ? 116 : (35 + 58),
+          minWidth: newAudioPlayerEnabled ? 292 : 280,
+          height: newAudioPlayerEnabled ? 356 : (35 + 58),
+          width: newAudioPlayerEnabled ? 292 : 280,
+        });
+
+        audioPlayer = new SingletonAppWindowWrapper(audioPlayerHTML,
+                                                    audioPlayerCreateOptions);
+        callback();
+      });
 });
 
-var audioPlayer = new SingletonAppWindowWrapper('mediaplayer.html',
-                                                AUDIO_PLAYER_CREATE_OPTIONS);
-
 /**
  * Launch the audio player.
  * @param {Object} playlist Playlist.
  */
 function launchAudioPlayer(playlist) {
-  audioPlayer.launch(playlist);
+  audioPlayerInitializationQueue.run(function(callback) {
+    audioPlayer.launch(playlist);
+    callback();
+  });
 }
 
 var videoPlayer = new SingletonAppWindowWrapper('video_player.html',
                                                 {hidden: true});
 
 /**
  * Launch the video player.
  * @param {string} url Video url.
  */
 function launchVideoPlayer(url) {
@@ skipping 36 matching lines @@
             var appState = JSON.parse(items[key]);
             launchFileManager(appState, id);
           } catch (e) {
             console.error('Corrupt launch data for ' + id);
           }
         }
       }
     }
   });
 
-  // Reopen sub-applications.
-  audioPlayer.reopen();
+  // Reopen audio player.
+  audioPlayerInitializationQueue.run(function(callback) {
+    audioPlayer.reopen();
+    callback();
+  });
+
+  // Reopen video player.
   videoPlayer.reopen();
 };
 
 /**
  * Handles clicks on a custom item on the launcher context menu.
  * @param {OnClickData} info Event details.
  * @private
  */
 Background.prototype.onContextMenuClicked_ = function(info) {
   if (info.menuItemId == 'new-window') {
@@ skipping 37 matching lines @@
     contexts: ['launcher'],
     title: str('NEW_WINDOW_BUTTON_LABEL')
   });
 };
 
 /**
  * Singleton instance of Background.
  * @type {Background}
  */
 window.background = new Background();