As far as I understand, the authentication state (such as the oauth2 bearer token) would be stored in a same cr-buildbucket-client element object which originally may be reused for different change pages.

Then, I believe when buildbucket.js was simplified at the end of 2017 (https://chromium-review.googlesource.com/c/infra/gerrit-plugins/buildbucket/+/814619) it was changed so that cr-buildbucket-view and cr-buildbucket-client are always created fresh when a new change is viewed.

So, I think it no longer makes sense to have a property called _sharedAuthState which is supposed to maybe persist across different changes.

Same for tricium plugin.