Chrome Version: 66.0.3359.203
Chrome OS Version: 10452.99.0
Chrome OS Platform: Cave
Network info: Wifi

Please specify Cr-* of the system to which this bug/feature applies (add
the label below).

Steps To Reproduce:
(1)Start playing 2 to 3 videos and 1 local audio for stress test
(2)observe audio
(3)

Expected Result:
-- No audio issue

Actual Result:
-- Observed Crackling noise.
 
How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
-- only once observed after running more than 5hrs.

feedback report: 85507028373

We'll try to repo issue on M68 or M69.