Fix race condition in test
Fix race condition in test

The |done| function comes from |it| not |describe|. Previously, we were just
ending the test right away.

R=rafaelw@chromium.org

Review URL: https://codereview.chromium.org/754463003

chinmaygarde/mojo,afandria/mojo,collinjackson/mojo,afandria/mojo,chinmaygarde/mojo,collinjackson/mojo,jianglu/mojo,chinmaygarde/mojo,collinjackson/mojo,chinmaygarde/mojo,chinmaygarde/mojo,collinjackson/mojo,jianglu/mojo,afandria/mojo,chinmaygarde/mojo,collinjackson/mojo,afandria/mojo,afandria/mojo,afandria/mojo,collinjackson/mojo,jianglu/mojo,afandria/mojo,jianglu/mojo,chinmaygarde/mojo,jianglu/mojo,afandria/mojo,jianglu/mojo,chinmaygarde/mojo,jianglu/mojo,collinjackson/mojo,collinjackson/mojo,jianglu/mojo,collinjackson/mojo,chinmaygarde/mojo