[rhythmbox] xfade: add some missing locking

[Jonathan Matthew <jmatthew src gnome org>]

commit b625b0991f3a2b5de014f626fd822bfae6b9cafe
Author: Jonathan Matthew <jonathan d14n org>
Date:   Fri Nov 9 08:54:16 2012 +1000

    xfade: add some missing locking

 backends/gstreamer/rb-player-gst-xfade.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/backends/gstreamer/rb-player-gst-xfade.c b/backends/gstreamer/rb-player-gst-xfade.c
index ac821f2..7c9dbca 100644
--- a/backends/gstreamer/rb-player-gst-xfade.c
+++ b/backends/gstreamer/rb-player-gst-xfade.c
@@ -1180,6 +1180,8 @@ perform_seek (RBXFadeStream *stream)
 	GstEvent *event;
 
 	rb_debug ("sending seek event..");
+	g_mutex_lock (&stream->lock);
+
 	event = gst_event_new_seek (1.0, GST_FORMAT_TIME,
 				    GST_SEEK_FLAG_FLUSH,
 				    GST_SEEK_TYPE_SET, stream->seek_target,
@@ -1200,6 +1202,8 @@ perform_seek (RBXFadeStream *stream)
 	default:
 		break;
 	}
+
+	g_mutex_unlock (&stream->lock);
 }
 
 static gboolean