b/5497100 Fix substring requests in DayView. Do not merge

We had a case where we could request a substring of -1 length. This
puts a protection around it and fixes the bug that caused the bad
request.

Cherry pick of https://android-git.corp.google.com/g/#/c/144336/

Change-Id: Ia8c2aa48653ac0dbb29d8a157bf7505682d7cec4