[gnome-music/cherry-pick-e05400e9] window: Correct HeaderBar object name

[Marinus Schraal <mschraal src gnome org>]

commit b58d5f91706951325ba1312731317adde0550078
Author: Marinus Schraal <mschraal gnome org>
Date:   Sun Mar 31 09:59:23 2019 +0000

    window: Correct HeaderBar object name
    
    Closes: #265
    
    
    (cherry picked from commit e05400e98140a98be69db67f7c8093d0b14d9445)

 gnomemusic/window.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gnomemusic/window.py b/gnomemusic/window.py
index 5f0cbd42..e90e5d33 100644
--- a/gnomemusic/window.py
+++ b/gnomemusic/window.py
@@ -398,7 +398,7 @@ class Window(Gtk.ApplicationWindow):
 
     @log
     def _on_back_button_pressed(self, gesture, n_press, x, y):
-        self.headerbar._on_back_button_clicked()
+        self._headerbar._on_back_button_clicked()
 
     @log
     def _notify_mode_disconnect(self, data=None):