GitLab

The mode is deterministically kPrefetchOnly. It's not necessary to
propagate it.

Bug: 755921
Change-Id: Ib297fba318436d78d72be3c1f2507bb86a372ba5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2592273Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837589}