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

ui/file_manager/audio_player/js/background.js

Index: ui/file_manager/audio_player/js/background.js
diff --git a/ui/file_manager/audio_player/js/background.js b/ui/file_manager/audio_player/js/background.js
index 587c08166d3fddb088154266177824ea780cff13..4a11a1ab3e9c99557b57b6bcbdc565ee375e9d59 100644
--- a/ui/file_manager/audio_player/js/background.js
+++ b/ui/file_manager/audio_player/js/background.js
@@ -22,9 +22,9 @@ 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'
   }