Tentative fix for the CF crashes in https://crbug.com/754422.

Bug: chromium:754422
Change-Id: I0dcb6b8860cb0bf20b3566ffba08e6772398ee65
Reviewed-on: https://chromium-review.googlesource.com/632176Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47591}