According to the notification letters on that site, those three incidents all involve Google employees' information being leaked by third parties, not Google leaking users' data.

Here's a quote from one of them:

"We recently learned that certain hotel reservations made for Google business travel were among the many reservations affected by a security incident impacting a third-party provider’s electronic reservation system that serves thousands of travel agencies and hotels. This did not affect Google’s systems. However, this incident impacted one of the travel providers used by Googlers, Carlson Wagonlit Travel (CWT)."