[gnome-music] Fix sensitivity prev & next buttons

[Seif Lotfy <seiflotfy src gnome org>]

commit e9b3f8575ce3c98b4263db605d797444971ecc1f
Author: Shivani Poddar <shivani poddar92 gmail com>
Date:   Tue May 7 02:36:43 2013 +0530

    Fix sensitivity prev & next buttons
    
    Signed-off-by: Seif Lotfy <seif lotfy com>

 src/player.js |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)
---
diff --git a/src/player.js b/src/player.js
index 41e7f43..6e0a9b8 100644
--- a/src/player.js
+++ b/src/player.js
@@ -112,12 +112,19 @@ const Player = new Lang.Class({
         this._setDuration(media.get_duration());
         this.songTotalTimeLabel.set_label(this.secondsToString (media.get_duration()));
         this.progressScale.sensitive = true;
-        this.prevBtn.set_sensitive(true);
         this.playBtn.set_sensitive(true);
-        this.nextBtn.set_sensitive(true);
-
         // FIXME: site contains the album's name. It's obviously a hack to remove
+        let tmp = this.currentTrack.copy();
+        if(this.playlist.iter_next(tmp))
+            this.nextBtn.set_sensitive(true);
+        else
+            this.nextBtn.set_sensitive(false);
 
+        tmp = this.currentTrack.copy();
+        if(this.playlist.iter_previous(tmp))
+            this.prevBtn.set_sensitive(true);
+        else
+            this.prevBtn.set_sensitive(false);
         pixbuf = this.cache.lookup (ART_SIZE, media.get_artist (), media.get_string(Grl.METADATA_KEY_ALBUM));
         this.coverImg.set_from_pixbuf (pixbuf);