Reland MD Audio Player.

ui/file_manager/audio_player/elements/track_list.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.
 
 /**
  * @typedef {?{
  *   url: string,
  *   title: string,
  *   artist: string,
  *   artwork: Object,
@@ skipping 148 matching lines @@
         this.set('tracks.' + this.currentTrackIndex + '.active', true);
     },
 
     /**
      * Invoked when the track element is clicked.
      * @param {Event} event Click event.
      */
     trackClicked: function(event) {
       var index = ~~event.currentTarget.getAttribute('index');
       var track = this.tracks[index];
-      if (track)
-        this.selectTrack(track);
+      if (track) {
+        if (event.target.classList.contains('icon')) {
+          // If the play icon on the track is clicked, change the current track
+          // and start playing it regardless of current play state.
+          this.selectTrack(track, true /* force to play */);
+        } else {
+          this.selectTrack(track, false /* force to play */);
+        }
+      }
     },
 
     /**
      * Invoked when the window is resized.
      * @private
      */
     onWindowResize_: function() {
       this.ensureTrackInViewport_(this.currentTrackIndex);
     },
 
@@ skipping 62 matching lines @@
       }
 
       if (!keepCurrentTrack)
         this.currentTrackIndex = this.playOrder[0];
     },
 
     /**
      * Sets the current track.
      * @param {!TrackInfo} track TrackInfo to be set as the current
      *     track.
+     * @param {boolean} forcePlay True if the track should be played regardless

[yawano, 2015/11/18 18:17:29]

small optional nit: forcePlay -> forceToPlay.

[fukino, 2015/11/19 02:14:39]

Done.

+     *     of the current play state (paused/played).
      */
-    selectTrack: function(track) {
+    selectTrack: function(track, forcePlay) {
       var index = -1;
       for (var i = 0; i < this.tracks.length; i++) {
         if (this.tracks[i].url === track.url) {
           index = i;
           break;
         }
       }
       if (index >= 0) {
         // TODO(yoshiki): Clean up the flow and the code around here.
-        if (this.currentTrackIndex == index)
+        if (this.currentTrackIndex === index) {
           this.replayCurrentTrack();
-        else
+        } else {
           this.currentTrackIndex = index;
+          if (forcePlay)
+            this.fire('play');
+        }
       }
     },
 
     /**
      * Request to replay the current music.
      */
     replayCurrentTrack: function() {
       this.fire('replay');
     },
 
@@ skipping 38 matching lines @@
 
       var newTrackIndex = this.playOrder[newPlayOrder];
       console.assert(
           (0 <= newTrackIndex && newTrackIndex < this.tracks.length),
           'Insufficient TrackList.playOrder. New Play Order: ' + newPlayOrder);
 
       return newTrackIndex;
     },
   });
 })();  // Anonymous closure