GitLab

Move system profile persistence to MetricsService.

Bug: 
Change-Id: I5c31dc53de267dd9699a83af926f8a575bab18a0
Reviewed-on: https://chromium-review.googlesource.com/592689
Commit-Queue: Steven Holte <holte@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491573}