Do you use Encrypted Media Extensions?
If so, you may be interested in EME Logger: a Chrome extension from Google that logs EME events and calls to the DevTools console along with debugging information.
You can install EME Logger extension from the Chrome Web Store..
The code for EME Logger is available at github.com/google/eme_logger. Patches, bug reports and feature requests welcome.
More information about EME is available from the HTML5 Rocks article EME WTF?