Ask HN: Chrome browser phones home, how to disable this?

When I startup Google-chrome it "phones home" - makes a TLS connection to Google and exchnages some data. Does anyone know what this data is?

It happens with the open source version as well... so this must be documented, and there must be a way to turn it off?

Edit: 1. You can confirm this using a network traffic analyzer. 2. Start page is set to about:blank