Consider the likelihood ratio test for $H_0: \theta = \theta_0$ versus $H_1: \theta \neq \theta_0$. If the log-likelihood function is $\ell(\theta)$, the statistic $\lambda = -2(\ell(\theta_0) - \ell(\hat{\theta}))$ is used. Under the null hypothesis, what is the asymptotic distribution of $\lambda$ as $n \to \infty$?