The feature used to be disabled by default but enabled in experiments.
When we disabled experiments we removed the explicit disablement of the
feature. Now the feaure has been flipped enabled by default on Linux and
Mac/Windows are being enabled by default in upstream versions.
Explicitly disabling it again, assuming we still want to. @jumde

Chromium change:

https://chromium.googlesource.com/chromium/src/+/65932d46ee07af807713aaca6f8f081412d26db8

commit 65932d46ee07af807713aaca6f8f081412d26db8
Author: Henrik Grunell <grunell@chromium.org>
Date:   Wed Jun 12 09:05:03 2019 +0000

    Enable AudioServiceAudioStreams and AudioServiceOutOfProcess by default on Linux.

    Bug: 672469,832666

Upstream changes:

https://chromium.googlesource.com/chromium/src/+/f1623e97a8c7174f684e32267cc85872199a7a22

commit f1623e97a8c7174f684e32267cc85872199a7a22
Author: Henrik Grunell <grunell@chromium.org>
Date:   Mon Aug 12 20:58:24 2019 +0000

    Enable audio process with kill at hang by default on Mac.

    Enables features AudioServiceOutOfProcess and
    AudioServiceOutOfProcessKillAtHang by default on Mac.

    Also
    * Fixes audio process study names for Win and Linux in field trial
      config.
    * Sets default audio service teardown to 15 minutes on all
      platforms since it has been launched on all platforms (corrects
      a miss in some of the previous launches).

    This change is similar to the previous launch for Linux:
    https://chromium-review.googlesource.com/c/chromium/src/+/1648499

    Bug: 974450

https://chromium.googlesource.com/chromium/src/+/8a41113b970a3b6c892d97a0f54a76da674a216a

commit 8a41113b970a3b6c892d97a0f54a76da674a216a
Author: Henrik Grunell <grunell@chromium.org>
Date:   Mon Aug 19 09:25:19 2019 +0000

    Enable audio process with kill at hang by default on Windows.

    Bug: 974448