Enable disk cache in testHostCachePersistence

This fixes the flake.

BUG=740207

Change-Id: I68fd807c8bb9effc1c0e9e15e744146c4b1f15c0
Reviewed-on: https://chromium-review.googlesource.com/574571
Reviewed-by: Misha Efimov <mef@chromium.org>
Commit-Queue: Miriam Gershenson <mgersh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487113}
1 file changed