playbin3: Re-enable buffering message handling

Buffering messages are only sent for the active group (in case there
is more than one).

If the inactive group posts buffering messages we keep the last one
around and will post it once it becomes the playing one.

gst/playback/gstplaybin3.c

@@ -2431,6 +2431,7 @@ gst_play_bin3_handle_message (GstBin * bin, GstMessage * msg)
     GstSourceGroup *group = NULL, *other_group = NULL;
     gboolean changed = FALSE;
     guint group_id;
+    GstMessage *buffering_msg;
 
     if (!gst_message_parse_group_id (msg, &group_id)) {
       GST_ERROR_OBJECT (bin,
@@ -2465,30 +2466,30 @@ gst_play_bin3_handle_message (GstBin * bin, GstMessage * msg)
     if (group->playing == FALSE)
       changed = TRUE;
     group->playing = TRUE;
+    buffering_msg = group->pending_buffering_msg;
+    group->pending_buffering_msg = NULL;
     GST_SOURCE_GROUP_UNLOCK (group);
+
     GST_SOURCE_GROUP_LOCK (other_group);
     other_group->playing = FALSE;
     GST_SOURCE_GROUP_UNLOCK (other_group);
+
     debug_groups (playbin);
     GST_PLAY_BIN3_UNLOCK (playbin);
     if (changed)
       gst_play_bin3_check_group_status (playbin);
     else
       GST_DEBUG_OBJECT (bin, "Groups didn't changed");
-  }
-#if 0
-  else if (GST_MESSAGE_TYPE (msg) == GST_MESSAGE_BUFFERING) {
-    GstSourceGroup *group = playbin->curr_group;
-    gboolean pending;
-
-    /* drop buffering messages from child queues while we are switching
-     * groups (because the application set a new uri in about-to-finish)
-     * if the playsink queue still has buffers to play */
+    /* If there was a pending buffering message to send, do it now */
+    if (buffering_msg)
+      GST_BIN_CLASS (parent_class)->handle_message (bin, buffering_msg);
+  } else if (GST_MESSAGE_TYPE (msg) == GST_MESSAGE_BUFFERING) {
+    GstSourceGroup *group;
 
+    /* Only post buffering messages for group which is currently playing */
+    group = find_source_group_owner (playbin, msg->src);
     GST_SOURCE_GROUP_LOCK (group);
-    pending = group->stream_changed_pending;
-
-    if (pending) {
+    if (!group->playing) {
       GST_DEBUG_OBJECT (playbin, "Storing buffering message from pending group "
           "%p %" GST_PTR_FORMAT, group, msg);
       gst_message_replace (&group->pending_buffering_msg, msg);
@@ -2496,9 +2497,7 @@ gst_play_bin3_handle_message (GstBin * bin, GstMessage * msg)
       msg = NULL;
     }
     GST_SOURCE_GROUP_UNLOCK (group);
-  }
-#endif
-  if (GST_MESSAGE_TYPE (msg) == GST_MESSAGE_STREAM_COLLECTION) {
+  } else if (GST_MESSAGE_TYPE (msg) == GST_MESSAGE_STREAM_COLLECTION) {
     GstStreamCollection *collection = NULL;
 
     gst_message_parse_stream_collection (msg, &collection);