Because Sergei Brin (Google founder) is probably a member of the Orthodox Church, and they selebrate Easter April 27. Not 100% sure though.
http://www.google.com/holidaylogos.html seems they stopped a long time ago doing easter for some reason????
I'm sure at least some of their staff is celebrating and having a few days off. The support is pretty slow right now
google did NOT make a holiday doodle for Christmas. The doodle specifically said "Happy Holidays". There was NEVER any mention of Christmas. This has been discussed before, but google will not accept ads from religious groups or churches.