AudioPlayer: Update layout to show the volume slider without using popup.

ui/file_manager/audio_player/js/background.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.
 
 /**
  * Icon of the audio player.
  * TODO(yoshiki): Consider providing an exact size icon, instead of relying
  * on downsampling by ash.
  *
  * @type {string}
  * @const
  */
 var AUDIO_PLAYER_ICON = 'icons/audio-player-64.png';
 
 var AUDIO_PLAYER_APP_URL = 'audio_player.html';
 
 /**
  * Configuration of the audio player panel.
  * @type {Object}
  */
 var audioPlayerCreateOptions = {
   id: 'audio-player',
   type: 'panel',
   minHeight: 4 + 48 + 96,  // 4px: border-top, 48px: track, 96px: controller
-  minWidth: 280,
+  minWidth: 320,
   height: 4 + 48 + 96,  // collapsed
-  width: 280,
+  width: 320,
   frame: {
     color: '#fafafa'
   }
 };
 
 /**
  * @constructor
  * @extends {BackgroundBase}
  */
 function AudioPlayerBackground() {
@@ skipping 86 matching lines @@
     audioPlayer.setIcon(AUDIO_PLAYER_ICON);
     audioPlayer.rawAppWindow.focus();
     return AUDIO_PLAYER_APP_URL;
   }).catch(function(error) {
     console.error('Launch failed' + error.stack || error);
     return Promise.reject(error);
   });
 }
 
 background.setLaunchHandler(open);