Use schema revision 16163887.
Add the 'checkin' action, which is accompanied by the 'checkin'
property. The action is logged at the following seconds
(Fibonacci numbers) after the page loads: 1, 2, 3, 5, 8, 13, 21,
34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765.
The `checkin` property contains the values listed above.
Bug: T147314
Change-Id: Ib9ec7bd0e60aa34a04e32222b025347f6ee31794
