Chrome Version: (copy from chrome://version) Version 65.0.3325.209
OS: (e.g. Win10, MacOS 10.12, etc...) ChromeOS 10323.67.5 (Official Build) stable-channel eve

What steps will reproduce the problem?
(1) Play audio in one tab (eg. https://www.youtube.com/watch?v=1Xyro90ZzW8)
(2) Open a second tab which has muted video autoplay, possibly ads (eg. https://www.allmusic.com/song/green-river-mt0011386323)

What is the expected result?
Audio on tab 1 continues while muted video on tab 2 starts to run. If the user turns on audio for the video in tab 2, best case scenario is tab 1 automatically pauses. If this is infeasible, both play until I manually mute / pause either tab's media player. 

What happens instead?
When the muted video on tab 2 starts to play, tab 1's video automatically pauses.
Sometimes the audio on tab 1 dips for < 1s, (similar to when receiving a notification on Android). Not sure the cause, it happens even when I'm on tab 3 with no media playing. (eg. bugs.chromium.org)


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