Revert "Revert "Fix up reference times for period changes.""

This reverts commit d6598315a36eaad3e4e45f51e0f1cc986e539896.

Reason for revert: Including divide-by-zero fix

Test: build no longer breaks
Change-Id: I186f020d9a6edd6793f52bcb234b2cc68b42e69a
2 files changed