Activity: remove deprecated _shared_activity member

Use the get_shared_activity method instead

Signed-off-by: Simon Schampijer <simon@laptop.org>
Reviewed-by: Gonzalo Odiard <gonzalo@laptop.org>
Acked-by: Daniel Drake <dsd@laptop.org>

src/sugar3/activity/activity.py

@@ -768,7 +768,7 @@ class Activity(Window, Gtk.Container):
 
         The shared activity is of type sugar3.presence.activity.Activity
         """
-        return self._shared_activity
+        return self.shared_activity
 
     def get_shared(self):
         """Returns TRUE if the activity is shared on the mesh."""
@@ -962,9 +962,6 @@ class Activity(Window, Gtk.Container):
     def get_document_path(self, async_cb, async_err_cb):
         async_err_cb(NotImplementedError())
 
-    # DEPRECATED
-    _shared_activity = property(lambda self: self.shared_activity, None)
-
 
 class _ClientHandler(dbus.service.Object, DBusProperties):
     def __init__(self, bundle_id, got_channel_cb):