Play automatically when reloading the audio player with new songs.

chrome/browser/resources/file_manager/foreground/js/media/audio_player.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';
 
 /**
  * TODO(mtomasz): Rewrite the entire audio player.
  *
  * @param {HTMLElement} container Container element.
@@ skipping 22 matching lines @@
   // two sets of TrackInfo instances. We could fiddle with a single set instead
   // but it would make keeping the list scroll position very tricky.
   this.trackList_ = createChild('track-list');
   this.trackStack_ = createChild('track-stack');
 
   createChild('title-button collapse').addEventListener(
       'click', this.onExpandCollapse_.bind(this));
 
   this.audioControls_ = new FullWindowAudioControls(
       createChild(), this.advance_.bind(this), this.onError_.bind(this));
-
   this.audioControls_.attachMedia(createChild('', 'audio'));
 
   chrome.fileBrowserPrivate.getStrings(function(strings) {
     container.ownerDocument.title = strings['AUDIO_PLAYER_TITLE'];
     this.errorString_ = strings['AUDIO_ERROR'];
     this.offlineString_ = strings['AUDIO_OFFLINE'];
     AudioPlayer.TrackInfo.DEFAULT_ARTIST =
         strings['AUDIO_PLAYER_DEFAULT_ARTIST'];
   }.bind(this));
 
@@ skipping 13 matching lines @@
 AudioPlayer.load = function() {
   document.ondragstart = function(e) { e.preventDefault() };
 
   // TODO(mtomasz): Consider providing an exact size icon, instead of relying
   // on downsampling by ash.
   chrome.app.window.current().setIcon(
       'foreground/images/media/2x/audio_player.png');
 
   AudioPlayer.instance =
       new AudioPlayer(document.querySelector('.audio-player'));
-  reload();
+  AudioPlayer.instance.load(window.appState);

[hirono, 2014/01/17 05:12:12]

Can we keep the line as reload() since the reload function is updated?

[mtomasz, 2014/01/17 05:14:30]

What do you mean? Can you clarify, please?

[hirono, 2014/01/17 05:18:48]

This CL replaces "reload()" with "AudioPlayer.instance.load(...)", but the
implementation of realod function is also changed as well. So we don't need to
change the line.

[mtomasz, 2014/01/17 05:27:42]

That's right, but I think it is spaghetti to call reload() from load(). That's
why I changed it. WDYT?

[hirono, 2014/01/17 05:32:27]

I got it. Then lgtm!

 };
 
 util.addPageLoadHandler(AudioPlayer.load);
 
 /**
  * Unload the player.
  */
 function unload() {
   if (AudioPlayer.instance)
     AudioPlayer.instance.onUnload();
 }
 
 /**
  * Reload the player.
  */
 function reload() {
-  if (window.appState) {
-    util.saveAppState();
-    AudioPlayer.instance.load(window.appState);
-    return;
-  }
+  AudioPlayer.instance.load(window.appState);
 }
 
 /**
  * Load a new playlist.
  * @param {Playlist} playlist Playlist object passed via mediaPlayerPrivate.
  */
 AudioPlayer.prototype.load = function(playlist) {
   this.playlistGeneration_++;
   this.audioControls_.pause();
   this.currentTrack_ = -1;
 
-  // Save the app state, in case of restart.
-  window.appState = playlist;
+  // Save the app state, in case of restart. Make a copy of the object, so the
+  // playlist member is not changed after entries are resolved.
+  window.appState = JSON.parse(JSON.stringify(playlist));
   util.saveAppState();
 
   util.URLsToEntries(playlist.items, function(entries) {
     this.entries_ = entries;
     this.invalidTracks_ = {};
     this.cancelAutoAdvance_();
 
     if (this.entries_.length <= 1)
       this.container_.classList.add('single-track');
     else
@@ skipping 87 matching lines @@
  * @private
  */
 AudioPlayer.prototype.select_ = function(newTrack, opt_restoreState) {
   if (this.currentTrack_ == newTrack) return;
 
   this.changeSelectionInList_(this.currentTrack_, newTrack);
   this.changeSelectionInStack_(this.currentTrack_, newTrack);
 
   this.currentTrack_ = newTrack;
 
-  if (window.appState) {
-    window.appState.position = this.currentTrack_;
-    window.appState.time = 0;
-    util.saveAppState();
-  } else {
-    util.platform.setPreference(AudioPlayer.TRACK_KEY, this.currentTrack_);
-  }
+  window.appState.position = this.currentTrack_;
+  window.appState.time = 0;
+  util.saveAppState();
 
   this.scrollToCurrent_(false);
 
   var currentTrack = this.currentTrack_;
   var entry = this.entries_[currentTrack];
   this.fetchMetadata_(entry, function(metadata) {
     if (this.currentTrack_ != currentTrack)
       return;
     this.audioControls_.load(entry, opt_restoreState);
 
@@ skipping 383 matching lines @@
  * Restore the state after page/app reload.
  */
 FullWindowAudioControls.prototype.restorePlayState = function() {
   if (this.restoreWhenLoaded_) {
     this.restoreWhenLoaded_ = false;  // This should only work once.
     if (this.decodeState())
       return;
   }
   this.play();
 };