Pass null to the callback when zero events are available.
Pass null to the callback when zero events are available.

Also initialize startTime and endTime to blank strings instead of
undefined.

ChaosEngine/google-calendar-crx,bonaime/google-calendar-crx,Steindi01/google-calendar-crx,bonaime/google-calendar-crx,CooperLuan/google-calendar-crx,Steindi01/google-calendar-crx,YOTOV-LIMITED/google-calendar-crx,manastungare/google-calendar-crx,thanhpd/google-calendar-crx,manastungare/google-calendar-crx,YOTOV-LIMITED/google-calendar-crx,thanhpd/google-calendar-crx,CooperLuan/google-calendar-crx,ChaosEngine/google-calendar-crx