crbug.com/845501 is an FR to support automatic Key Based Renewal of client certs in the Certificate Enrollment for Chrome OS Extension.

This FR is to support the ability to renew certs automatically while in single app kiosk mode.
If crbug.com/845501 is implemented it will be possible to renew a cert with zero user interaction. 
Single App Kiosk customers would like to be able to do this without having to exit kiosk mode or have a user interact with the device.
The App manifest allows for the primary app to call additional background extensions. In this case the Certificate Enrollment for Chrome OS Extension could be listed as a background extension and loaded when the existing cert is close to expiring.