Should hardware back button press back action include some metadata?

[brentvatne]

When we press the hardware back button while the drawer is open, we expect it to close the drawer. However, if we fire goBack(null) from the drawer content view while it's open, I'm not sure that we'd expect it to close the drawer - maybe I'm wrong about this. Are there other cases where the drawer back button should be treated slightly differently than goBack(null)?