Despite setting SO_REUSEADDR and SO_REUSEPORT, UDPSocketTest.SharedMulticastAddress (being added in https://chromium-review.googlesource.com/c/chromium/src/+/1298298) times out in the chromeos-amd64-generic-rel tryjob. This implies that the multicast messages are not being shared with all the listening sockets despite efforts to configure them to do so.

Disabling the test for OS_CHROMEOS for now.  Not a huge priority since until https://chromium-review.googlesource.com/c/chromium/src/+/1298298, for a long time, multicast sockets didn't share messages well for anything except Windows.