Google will be able to block third-party apps from using the Google Calendar Provider API Obviously, giving third-party companies the ability to view your Calendar events can pose a security risk.

The new toggle essentially lets you control whether Google Calendar shares your event data with other apps on your device (the ones tapping into the Calendar Provider API).

Google just made the lives of third-party calendar developers much easier. Rather than having to constantly poll Google Calendar servers for updates, the Calendar API now supports push notifications.