GitLab

- Improve the documentation of TimeDelta::InXYZ methods to clarify that they return a truncated value (aka rounded towards zero).
- Add a new InDaysFloored method to convert a TimeDelta into a floored number of days.
- Fix the implementation of InMillisecondsRoundedUp for negative time deltas.

Bug: 831545
Change-Id: I4afd256308f6f28ff459925772059fdfc5824995
Reviewed-on: https://chromium-review.googlesource.com/1049906Reviewed-by: Yuri Wiitala <miu@chromium.org>
Commit-Queue: Quentin Fiard <qfiard@google.com>
Cr-Commit-Position: refs/heads/master@{#561334}