For a customer project, I recently needed to take a closer look at best strategies of deploying Chromium settings to thrillions of client machines in a corporate network.
Unfortunately, the information on how to deploy site-wide Chromium browser policies are a little scattered over the internet and the intertwining of Chromium preferences and Chromium policies required deeper introspection.
Here, I'd like to provide the result of that research, namely a list of references that has been studied before setting up Chromium policies for the customer's proof-of-concept.
The difference between preferences and policies are explained here: https://www.chromium.org/administrators/configuring-other-preferences
The site-admin (or distro package maintainer) can pre-configure the user's Chromium experience via a master preferences file (/etc/chromium/master_preferences). This master preferences file is the template for the user's preferences file and gets copied over into the Chromium user profile folder on first browser start.
Note: By studying the recent Chromium code it was found out that /etc/chromium/master_preferences is the legacy filename of the initial preferences file. The new filename is /etc/chromium/initial_preferences. We will continue with master_preferences here as most Linux distributions still provide the initial preferences via this file. Whereas the new filename is already supported by Chromium in openSUSE/SLES, it is not yet support by Chromium in Debian/Ubuntu. (See Debian bug #992178).