code: def find_bookmark_file ():
      
      if sys.platform != 'darwin':
          return u""
      try:
          dirname = get_profile_dir()
          if os.path.isdir(dirname):
              fname = os.path.join(dirname, u"Bookmarks.plist")
              if os.path.isfile(fname):
                  return fname
      except Exception:
          pass
      return u""
docs: Return the bookmark file of the Default profile.
      Returns absolute filename if found, or empty string if no bookmark file
      could be found.