This bug is a follow-up for https://chromium-review.googlesource.com/#/c/567034/5//COMMIT_MSG@18 - it seems that before this CL the utility process had 2 potential bugs:

Potential bug #1: Field trials do not get synced to the utility process.
Potential  bug #2 : Field trial activations from he utility process are not reported back to the browser process.

Let's use this bug to add regression tests for the issues above (and to verify if the other CL really fixed them).