drawerHeaderをdatabindingで触る

class TimelineActivity : AppCompatActivity() {

    val binding by lazy {
        DataBindingUtil.setContentView<ActivityTimelineBinding>(this, R.layout.activity_timeline)
    }
    val viewModel by lazy { TimelineViewModel() }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding.navView.run {
            DataBindingUtil.bind<NavHeaderTimelineBinding>(getHeaderView(0))
            val headerBinding = DataBindingUtil.getBinding<NavHeaderTimelineBinding>(getHeaderView(0))
            headerBinding.state = viewModel.state
        }
    }