Google's Web DRM is Worse than I Thought...

It is, but they strip the WEI API from their builds. However, you may want to switch the user agent string to "Vivaldi" because it is "Google Chrome" in the default setting.

Because that's always been my primary browser. But I like to use different profiles for each web service I registered at. Switching profiles on Firefox takes some extra steps, so I used Chromium and now Vivaldi.