Host chromeos4-row5-rack11-host9. It has audio_loopback_dongle and doesn't have chameleon label.

The test log should show its rms value.
We should check whether any sine tone is recorded.
If rms_value is too small, maybe we can set the gain higher.

We can replace 10.wav with a new sine tone file
sox -b 16 -r 48000 -c 2 -n out.raw synth 5 sine 300 sine 300
sox -b 16 -r 48000 -c 2 -e signed -v 0.8 out.raw out_2.raw

https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/762694
This should fix most audio_CrasLoopback and audio_AlsaLoopback failures.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/c1fa31ac12706c22d0dfd3940247ab11cb5ff562

commit c1fa31ac12706c22d0dfd3940247ab11cb5ff562
Author: Wu-Cheng Li <wuchengli@google.com>
Date: Tue Nov 14 16:04:18 2017

audio_test_data: move AudioTestDataGenerateOnDemand files out.

- SIMPLE_FREQUENCY_LOUD_WAVE_FILE, LEFT_CHANNEL_TEST_FILE, and
  RIGHT_CHANNEL_TEST_FILE are all only used once. There is no
  need to put them in audio_test_data.
- AudioTestDataGenerateOnDemand are generated dynamically.
  Putting them in audio_test_data does not save storage.
- Other AudioTestData in audio_test_data are static files and
  do not need to call generate_file. AudioTestDataGenerateOnDemand
  files are inconsistent if we put them in audio_test_data.
  For example, generate_file of LEFT_CHANNEL_TEST_FILE and
  RIGHT_CHANNEL_TEST_FILE is not called, which is a bug.

BUG= chromium:783534 
TEST=Run audio_AudioWebRTCLoopback and
     audio_LeftRightInternalSpeaker on eve.

Change-Id: I44085d754619a86a92f70c7aa17b48c4b0bcb59c
Reviewed-on: https://chromium-review.googlesource.com/763787
Commit-Ready: Wu-Cheng Li <wuchengli@chromium.org>
Tested-by: Wu-Cheng Li <wuchengli@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>
Reviewed-by: Wu-Cheng Li <wuchengli@chromium.org>

[modify] https://crrev.com/c1fa31ac12706c22d0dfd3940247ab11cb5ff562/client/cros/audio/audio_test_data.py
[modify] https://crrev.com/c1fa31ac12706c22d0dfd3940247ab11cb5ff562/server/site_tests/audio_AudioWebRTCLoopback/audio_AudioWebRTCLoopback.py
[modify] https://crrev.com/c1fa31ac12706c22d0dfd3940247ab11cb5ff562/server/site_tests/audio_LeftRightInternalSpeaker/audio_LeftRightInternalSpeaker.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/d12628359c71e44ad79f774a517fc238d21d9734

commit d12628359c71e44ad79f774a517fc238d21d9734
Author: Wu-Cheng Li <wuchengli@google.com>
Date: Thu Nov 16 04:21:05 2017

audio_test_data: refactor AudioTestDataGenerateOnDemand

AudioTestDataGenerateOnDemand inherited audio_test_data. audio_test_data
takes the audio file from a constructor parameter. But
AudioTestDataGenerator generates the audio file from generate_file
method. It is inconsistent and makes adding a volume_scale parameter
difficult. Change AudioTestDataGenerateOnDemand to a simple function
that returns AudioTestData.

BUG= chromium:783534 
TEST=Run audio_AudioWebRTCLoopback and audio_LeftRightInternalSpeaker
     on eve.

Change-Id: Iaf46946d7fff03161645cb4b8448a6d51bdc6adc
Reviewed-on: https://chromium-review.googlesource.com/771492
Commit-Ready: Wu-Cheng Li <wuchengli@chromium.org>
Tested-by: Wu-Cheng Li <wuchengli@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>

[modify] https://crrev.com/d12628359c71e44ad79f774a517fc238d21d9734/client/cros/audio/audio_test_data.py
[modify] https://crrev.com/d12628359c71e44ad79f774a517fc238d21d9734/server/site_tests/audio_AudioWebRTCLoopback/audio_AudioWebRTCLoopback.py
[modify] https://crrev.com/d12628359c71e44ad79f774a517fc238d21d9734/server/site_tests/audio_LeftRightInternalSpeaker/audio_LeftRightInternalSpeaker.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/f8b787abcd28d3de21e60ea9819bf6f469216990

commit f8b787abcd28d3de21e60ea9819bf6f469216990
Author: Wu-Cheng Li <wuchengli@google.com>
Date: Thu Nov 16 18:46:56 2017

audio_CrasLoopback/audio_AlsaLoopback: use sine wave for input.

The original test input file is a multitone file. It may be
similar to noise and be reduced to very small rms. Use a sine
wave so the test result is stable. Also reducing noise is
unnecessary after we switch to sine wave.

BUG= chromium:783534 
TEST=Run audio_CrasLoopback and audio_AlsaLoopback on eve and
     nyan big.

Change-Id: I63d0d42ba31bfe19a84d3658b435ebb443912856
Reviewed-on: https://chromium-review.googlesource.com/762694
Commit-Ready: Wu-Cheng Li <wuchengli@chromium.org>
Tested-by: Wu-Cheng Li <wuchengli@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>

[modify] https://crrev.com/f8b787abcd28d3de21e60ea9819bf6f469216990/client/site_tests/audio_CrasLoopback/audio_CrasLoopback.py
[modify] https://crrev.com/f8b787abcd28d3de21e60ea9819bf6f469216990/client/cros/audio/audio_test_data.py
[modify] https://crrev.com/f8b787abcd28d3de21e60ea9819bf6f469216990/client/site_tests/audio_AlsaLoopback/audio_AlsaLoopback.py
[delete] https://crrev.com/aa013fadbffb3d551661519fb693e5524bdd54ca/client/site_tests/audio_CrasLoopback/10SEC.wav
[delete] https://crrev.com/aa013fadbffb3d551661519fb693e5524bdd54ca/client/site_tests/audio_AlsaLoopback/10SEC.wav

CL in #7 was picked up by 10136.0.0.

All green for three versions. I added audio_CrasLoopback to the email of test failure alert list.