Revert "Revert "Make the metrics library respect the policy settings instead of the consent file.""

This reverts commit aa91d046ac27a9bdc96e6cd9438741d98f1cef66

Change-Id: I1c84fb86d6eb56a5a8e88136c98104394be697b2
Reviewed-on: http://gerrit.chromium.org/gerrit/4614


Reviewed-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Ken Mixter <kmixter@chromium.org>
Tested-by: Ken Mixter <kmixter@chromium.org>