[totem] backend: Fix warning if there's no chapter support

[Bastien Nocera <hadess src gnome org>]

commit bff8d4c61ccf5982b2c82750291e6eecb79a82b8
Author: Bastien Nocera <hadess hadess net>
Date:   Sat Jul 14 23:24:53 2012 +0100

    backend: Fix warning if there's no chapter support

 src/backend/bacon-video-widget.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/backend/bacon-video-widget.c b/src/backend/bacon-video-widget.c
index 6d96491..b2696ce 100644
--- a/src/backend/bacon-video-widget.c
+++ b/src/backend/bacon-video-widget.c
@@ -2890,6 +2890,10 @@ bacon_video_widget_has_previous_track (BaconVideoWidget *bvw)
     return TRUE;
 
   fmt = gst_format_get_by_nick ("chapter");
+  /* If chapter isn't registered, then there's no chapters support */
+  if (fmt == GST_FORMAT_UNDEFINED)
+    return FALSE;
+
   if (gst_element_query_position (bvw->priv->play, fmt, &val))
     return (val > 0);