Chrome Version (from the about:version page): 70.0.3518.0 (from ./chrrome/VERSION)
Is this the most recent version: yes
OS + version: Ubuntu 16.04.5 LTS
CPU architecture (32-bit / 64-bit): 64
Window manager: Gnome
URLs (if relevant): NA
Behavior in Linux Firefox: NA
Behavior in Windows Chrome (if you have access to it): NA

What steps will reproduce the problem?
(1) Build Layout tests
gn gen out/Release
ninja -C out/Release blink_tests
(2) Run Layout test
python third_party/blink/tools/run_web_tests.py -t Release

What is the expected result?
All tests pass

What happens instead?
Test external/wpt/webaudio/the-audio-api/the-audiocontext-interface/audiocontextoptions.html fails with following error:
....
FAIL X balanced baseLatency is not greater than or equal to 0.011609977324263039. Got 0.01. assert_true: expected true got false
....

As I understand this test (external/wpt/webaudio/the-audio-api/the-audiocontext-interface/audiocontextoptions.html)
fails starting from https://chromium-review.googlesource.com/c/chromium/src/+/1067100 commit.

Before this commit fake audio device with low latency was used for latency measurement.
After this commit real audio device is used for latency measurement (media/audio/alsa or media/audio/pulse in linux case).

In terms of Chrome latency is equal frame_buffer_size / sample_rate
sample_rate is the same for all audio context types (i.e. for "balanced", "interactive" or "playback")
frame_buffer_size is differ for all types. It is calculated in content/renderer/media/renderer_webaudiodevice_impl.cc, GetOutputBufferSize.
for interactive it is equal some hardcoded value: 512 for pulse_audio or 2048 for alsa for example. For fake audio device it was 128 and this test finished successfully
for balanced it is equal sample_rate / 100 for Linux case. Starting from above-mentioned commit balanced latency becomes more then interactive one.
As result the test fails.

The strange thing is that according Google build bot result this test always passes (I checked actual results here: https://ci.chromium.org/p/chromium/g/chromium.linux/console).