Chrome user data browser metrics

I have a private instance setup and it has been working fine until a few days ago. The server location drop down list became empty so it looked like the server was not picking up the agent. The issue turned out to be that the agent ran out of disk space.

It seems that chrome is saving a lot of data in [user]/AppData/local/Google/Chrome/UserData/BrowserMetrics. This never gets cleaned and so disk space filled up.

I am wondering if anyone knows how to disable chrome from storing these files or if WPT is using them. I could write a script to clean the files everyday but I want to understand where they came from and how they are being used.