Looking at this?

http://cautotest/tko/retrieve_logs.cgi?job=/results/81899837-chromeos-test/

in the autoserv.ERROR log I see:

10/21 14:44:50.341 ERROR|                db:0161| 14:44:50 10/21/16: An operational error occured during a database operation: (2006, 'MySQL server has gone away')

Not sure if that's important.

But this looks like the ABORT:

10/21 14:45:40.395 INFO |        server_job:0153| START	----	wolf-tot-paladin/R56-8921.0.0-rc1/bvt-cq/Sound System Validation	timestamp=1477086340	localtime=Oct 21 14:45:40	
10/21 14:45:40.396 INFO |        server_job:0153| 	ABORT	----	wolf-tot-paladin/R56-8921.0.0-rc1/bvt-cq/Sound System Validation	timestamp=1477086340	localtime=Oct 21 14:45:40	
10/21 14:45:40.396 INFO |        server_job:0153| END ABORT	----	wolf-tot-paladin/R56-8921.0.0-rc1/bvt-cq/Sound System Validation	timestamp=1477086340	localtime=Oct 21 14:45:40

OK.  Background data for future debug.  First, the suite
job:
    https://ubercautotest.corp.google.com/afe/#tab_id=view_job&object_id=81899837
... and the test:
    https://ubercautotest.corp.google.com/afe/#tab_id=view_job&object_id=81899883

If you look at how the suite page reports the test, both agree
that the test passed, but the suite's status.log says otherwise.

From the suite's status.log:
	INFO	----	Start bvt-cq	timestamp=1477085050	localtime=Oct 21 14:24:10	
...
	START	----	wolf-tot-paladin/R56-8921.0.0-rc1/bvt-cq/Sound System Validation	timestamp=1477086340	localtime=Oct 21 14:45:40	
		ABORT	----	wolf-tot-paladin/R56-8921.0.0-rc1/bvt-cq/Sound System Validation	timestamp=1477086340	localtime=Oct 21 14:45:40	
	END ABORT	----	wolf-tot-paladin/R56-8921.0.0-rc1/bvt-cq/Sound System Validation	timestamp=1477086340	localtime=Oct 21 14:45:40	

And the complete status.log from the test job:
	INFO	----	----	kernel=3.8.11	localtime=Oct 21 14:37:32	timestamp=1477085852	
	START	----	----	timestamp=1477085869	localtime=Oct 21 14:37:49	
		START	sound_infrastructure	sound_infrastructure	timestamp=1477085869	localtime=Oct 21 14:37:49	
			GOOD	sound_infrastructure	sound_infrastructure	timestamp=1477085872	localtime=Oct 21 14:37:52	completed successfully
		END GOOD	sound_infrastructure	sound_infrastructure	timestamp=1477085872	localtime=Oct 21 14:37:52	
	END GOOD	----	----	timestamp=1477085873	localtime=Oct 21 14:37:53	

The symptoms here look a lot like  bug 632247 :  The suite reports
that the test timed out, yet in reality, the test passed on time.

My leading theory would be that the shard couldn't get the test
results up to the master database on time, but really, I'm only
guessing.

Dropping ownership:  It's not my bailiwick, I don't have expertise,
I'm not deputy or secondary now, and the problem isn't widespread
enough for immediate escalation (which is not to say we can ignore
this).