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This change uses ICU time library to handle time calculations. This is
done because it handles rollovers, DST calculations and other tricky
edge cases. Each time calculation now also uses the time zone of the
device instead of relying on base::Time::LocalExplode and
base::Time::FromLocalExploded.

BUG=924762
TEST=Unit tests.

Change-Id: I6fd8a17cd9f96994516cbaea06158d17abb467fd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1684642
Commit-Queue: Abhishek Bhardwaj <abhishekbh@chromium.org>
Reviewed-by: Greg Thompson <grt@chromium.org>
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#678942}