'Update URL if the tab changed.'

def on_tab_changed(self, tab):

    self._hover_url = None
    if tab.url().isValid():
        self._normal_url = urlutils.safe_display_string(tab.url())
    else:
        self._normal_url = ''
    self.on_load_status_changed(tab.load_status().name)
    self._update_url()
