'Returns list of content titles for split_test\'s child.
This overwrites the get_content_titles method included in x_module by default.
WHY THIS OVERWRITE IS NECESSARY: If we fetch *all* of split_test\'s children,
we\'ll end up getting all of the possible conditions users could ever see.
Ex: If split_test shows a video to group A and HTML to group B, the
regular get_content_titles in x_module will get the title of BOTH the video
AND the HTML.
We only want the content titles that should actually be displayed to the user.
split_test\'s .child property contains *only* the child that should actually
be shown to the user, so we call get_content_titles() on only that child.'

def get_content_titles(self):

    return self.child.get_content_titles()
