Add a test for tags to configuration_test.
Add a test for tags to configuration_test.

I forgot to do this when first adding the feature.

R=kevmoo@google.com

Review URL: https://codereview.chromium.org//1754503002 .

iglherme/Guttiest,iglherme/Guttiest,kevmoo/test,grouma/test,kevmoo/test,iglherme/Guttiest,grouma/test,kevmoo/test,grouma/test