$\sqrt n(2\bar X-\theta)\overset{d}{\longrightarrow} N(0,\theta^2/3)$, so the square is $\theta^2\chi^2_1/3$

Let $X_1,\dots,X_n$ be a random sample from $U(0,\theta)$. Then the asymptotic distribution of $3n(2\bar X-\theta)^2$ is: