Handle UsageTimeLimit with multiple overrides.

On cl https://chromium-review.googlesource.com/c/chromium/src/+/1112051, I changed the override part of UsageTimeLimit policy from a single object to an array. On this cl I change the usage_time_limit_processor to handle this as well. Currently, the only override considered is the latest one.

Bug: 823536
Change-Id: Ia5842edec3fc6127115d7f7b988ec43c437b1713
Reviewed-on: https://chromium-review.googlesource.com/1127399
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Henrique Grandinetti <hgrandinetti@google.com>
Cr-Commit-Position: refs/heads/master@{#574136}
2 files changed