With upstream upgrading Polymer 1.x to Polymer 2.x (gerrit 3.1) (or maybe Polymer 3 in gerrit 3.2) we will need to prepare for that upgrade.
Polymer 2.x is a very significant update.
We need to split this https://github.com/wikimedia/puppet/blob/401a720657b00c9ad7c3651ee4b45756572131ea/modules/gerrit/templates/gerrit.config.erb#L86 up so that it uses style="" instead of classes. This is due to how shadow dom works under Polymer 2.x.
Installing this https://github.com/dburm/pg-test-result-plugin/blob/master/test_result-0.1.html should mean we doin't have to do the above.
For the theme, i am working with upstream so we can keep our theme, but the way we do the theme will change.