GitLab

Added a setting to enable/disable prefetch in downloads settings.
This settings will not be visible if prefetching feature is not enabled.
UX: https://gallery.googleplex.com/projects/MCHbtQVoQ2HCZa-WKS_VfBWp/files/MCHtA7U1iMGr6yF79JTTnBdio_aEa3M5pNg

Bug: 850588
Change-Id: Icb1f4a504c88878ada36c9e642819669e9ee7409
Reviewed-on: https://chromium-review.googlesource.com/1139590
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
Reviewed-by: Xing Liu <xingliu@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580070}