What song did Brittany sing to Santana in glee?

When Santana confesses her feelings for Brittany she says thanks for singing that song or something. What song did she mean?|||'Songbird' by Fleetwood Mac http://www.youtube.com/watch?v=Ul1oTvjfJ鈥?/a>|||In episode 15 "Sexy", Santana and Brittany sing "Landslide" by Fleetwood Mac. The person above me is referring to episode 19 the "Rumours" episode when Santana sings "Songbird" by Fleetwood Mac to Brittany after she and Artie break up..