Otherwise user code can produce an exception and we will crash.

R=jakob@chromium.org

Bug: chromium:736302
Change-Id: I078150909b0348a63e8c375b508e34fc4751b4ab
Reviewed-on: https://chromium-review.googlesource.com/565628
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46566}