I have discussed with Yu-Hsuan about the test.

We already has a test that stress output streams and it is quite stable.
https://stainless.corp.google.com/search?view=matrix&row=model&col=build&first_date=2018-11-08&last_date=2018-11-21&test=%5Eaudio_CrasOutputStress%24&exclude_cts=false&exclude_not_run=false&exclude_non_release=true&exclude_au=true&exclude_acts=true&exclude_retried=true&exclude_non_production=false

Some modification needs to be done:

1. Add the check of delay. We can dump audio thread log and check its output. 
  We have added "highest_hw_level" field to the log so we can check that high delay had ever happened.

2. Currently the test stress in a way that it repeatedly adding stream and removing stream such that the number of stream varies between 2 and 3. We can make it more randomly so the number of stream varies between 0,1,2,3 (maybe more).

3. Add different test case so we can have three control files targeting:
 a. output only
 b. input only
 c. output and input at the same time.

4. Add the test to fail alert list.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/759f572f8ffac905587eabea71e2c7fdf6f36bbb

commit 759f572f8ffac905587eabea71e2c7fdf6f36bbb
Author: Yu-Hsuan Hsu <yuhsuan@google.com>
Date: Thu Nov 22 06:49:19 2018

[autotest] audio_CrasOutputStress: Change number of streams varies

There are some updates in this change.
1. Change number of streams varies [2, 3] to [0, 1, 2, 3]
2. Only get buffer level from normal run state.
   (The original version may get it from no stream state.)
3. Add audio_diagnostics log.

BUG=chromium:907220
TEST=Run audio_CrasOutputStress test on peppy and eve.

Change-Id: I61c447db48390f678733383a3468d5dae2af81d5
Reviewed-on: https://chromium-review.googlesource.com/1345176
Commit-Ready: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Tested-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>

[modify] https://crrev.com/759f572f8ffac905587eabea71e2c7fdf6f36bbb/client/site_tests/audio_CrasOutputStress/audio_CrasOutputStress.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/a0281e27347381fd4533d000e629a545153ffa8b

commit a0281e27347381fd4533d000e629a545153ffa8b
Author: Yu-Hsuan Hsu <yuhsuan@google.com>
Date: Sat Dec 01 09:08:39 2018

[autotest] audio_CrasOutputStress: Add input streams in stress test

We have several new test cases of the test.
1. output only
2. input only
3. output and input at the same time

BUG=chromium:907220
TEST=Run audio_CrasOutputStress test on peppy and eve.

Change-Id: I2e04a466b129bb04646ab8436da3dc728f1ca837
Reviewed-on: https://chromium-review.googlesource.com/1351310
Commit-Ready: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Tested-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>

[add] https://crrev.com/a0281e27347381fd4533d000e629a545153ffa8b/client/site_tests/audio_CrasOutputStress/control.output_only
[modify] https://crrev.com/a0281e27347381fd4533d000e629a545153ffa8b/client/site_tests/audio_CrasOutputStress/audio_CrasOutputStress.py
[modify] https://crrev.com/a0281e27347381fd4533d000e629a545153ffa8b/client/site_tests/audio_CrasOutputStress/control
[add] https://crrev.com/a0281e27347381fd4533d000e629a545153ffa8b/client/site_tests/audio_CrasOutputStress/control.input_only

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/2cb1598098e924863e786a71500b08fd8400c4e8

commit 2cb1598098e924863e786a71500b08fd8400c4e8
Author: Yu-Hsuan Hsu <yuhsuan@google.com>
Date: Sat Dec 15 06:40:26 2018

autotest-test-audio: Rename audio_CrasOutputStress to audio_CrasStress

Rename audio_CrasOutputStress test to audio_CrasStress test.

BUG=chromium:907220
TEST=None
CQ-DEPEND=CL:1375489

Change-Id: Icc2c12757b6c87f8c0fe3da4f2852569f12a27f6
Reviewed-on: https://chromium-review.googlesource.com/1375469
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Hsinyu Chao <hychao@chromium.org>

[modify] https://crrev.com/2cb1598098e924863e786a71500b08fd8400c4e8/chromeos-base/autotest-tests-audio/autotest-tests-audio-9999.ebuild

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/b29364f6caedcfefa012405e65b163d77c7dfc1c

commit b29364f6caedcfefa012405e65b163d77c7dfc1c
Author: Yu-Hsuan Hsu <yuhsuan@google.com>
Date: Sat Dec 15 06:40:26 2018

[autotest] audio_CrasStress: Rename from audio_CrasOutputStress

Rename audio_CrasOutputStress test to audio_CrasStress test.

BUG=chromium:907220
TEST=Run audio_CrasStress test on peppy and eve.
CQ-DEPEND=CL:1375469

Change-Id: I23ab571c551dc92af6ab35a2fb449dbe6e458ceb
Reviewed-on: https://chromium-review.googlesource.com/1375489
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Hsinyu Chao <hychao@chromium.org>

[rename] https://crrev.com/b29364f6caedcfefa012405e65b163d77c7dfc1c/client/site_tests/audio_CrasStress/control
[rename] https://crrev.com/b29364f6caedcfefa012405e65b163d77c7dfc1c/client/site_tests/audio_CrasStress/control.input_only
[rename] https://crrev.com/b29364f6caedcfefa012405e65b163d77c7dfc1c/client/site_tests/audio_CrasStress/control.output_only
[rename] https://crrev.com/b29364f6caedcfefa012405e65b163d77c7dfc1c/client/site_tests/audio_CrasStress/audio_CrasStress.py

This issue has an owner, a component and a priority, but is still listed as untriaged or unconfirmed. By definition, this bug is triaged. Changing status to "assigned". Please reach out to me if you disagree with how I've done this.