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* Add function GetEndOfCurrent interval to obtain the last end of the
interval which contains the current time.
* Add function MaterializeIntervalsToLocalTimezone, which materializes
the given intervals to the current local timezone.
* Add function TimeIsInsideCrosSettingsIntervals, which checks if the
current time is inside the intervals set in cros settings. It then
returns the localized string of the end of the interval that contains
the current time.

BUG=chromium:852860
TEST=added unittests

Change-Id: Ife32e31c8a929827fd14ab9f108c49eacb9c32c3
Reviewed-on: https://chromium-review.googlesource.com/1132676Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582403}