[pitivi] previewers: Use methods to access bin pads

[Thibault Saunier <tsaunier src gnome org>]

commit 325377da699227184b840a5d019ee4dd21cedda8
Author: Thibault Saunier <tsaunier igalia com>
Date:   Sun May 5 18:47:35 2019 -0400

    previewers: Use methods to access bin pads
    
    Instead of accessing instance structure fields
    Working around https://gitlab.gnome.org/GNOME/pygobject/issues/325
    but this is more correct anyway

 pitivi/timeline/previewers.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/pitivi/timeline/previewers.py b/pitivi/timeline/previewers.py
index 3dac15b1..1d5f92f9 100644
--- a/pitivi/timeline/previewers.py
+++ b/pitivi/timeline/previewers.py
@@ -85,8 +85,10 @@ class PreviewerBin(Gst.Bin, Loggable):
 
         self.internal_bin = Gst.parse_bin_from_description(bin_desc, True)
         self.add(self.internal_bin)
-        self.add_pad(Gst.GhostPad.new(None, self.internal_bin.sinkpads[0]))
-        self.add_pad(Gst.GhostPad.new(None, self.internal_bin.srcpads[0]))
+        sinkpad, = [pad for pad in self.internal_bin.iterate_sink_pads()]
+        self.add_pad(Gst.GhostPad.new(None, sinkpad))
+        srcpad, = [pad for pad in self.internal_bin.iterate_src_pads()]
+        self.add_pad(Gst.GhostPad.new(None, srcpad))
 
     def finalize(self, proxy=None):
         """Finalizes the previewer, saving data to the disk if needed."""