Stack trace (from https://chromium-swarm.appspot.com/task?id=424e7471a91e7110&refresh=10&show_raw=1):

[29/98] telemetry.internal.backends.chrome_inspector.devtools_client_backend_unittest.DevToolsClientBackendTest.testTracing failed unexpectedly 40.2671s:
  Traceback (most recent call last):
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/testing/browser_test_case.py", line 39, in WrappedMethod
      method(self)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend_unittest.py", line 95, in testTracing
      devtools_client.StopChromeTracing()
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py", line 464, in StopChromeTracing
      backend = self.FirstTabBackend()
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py", line 489, in FirstTabBackend
      return next(self._IterInspectorBackends(['page']), None)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py", line 485, in _IterInspectorBackends
      yield context_map.GetInspectorBackend(context['id'])
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend.py", line 598, in GetInspectorBackend
      self._app_backend.app, self._devtools_client, context)
    File "/b/s/w/ir/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 52, in traced_function
      return func(*args, **kwargs)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py", line 72, in __init__
      self._log = inspector_log.InspectorLog(self._websocket)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_log.py", line 19, in __init__
      self._Enable()
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_log.py", line 29, in _Enable
      self._inspector_websocket.SyncRequest({'method': 'Log.enable'}, timeout)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket.py", line 132, in SyncRequest
      res = self._Receive(timeout)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket.py", line 190, in _Receive
      self._HandleNotification(result)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_websocket.py", line 203, in _HandleNotification
      self._domain_handlers[domain_name](result)
    File "/b/s/w/ir/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 52, in traced_function
      return func(*args, **kwargs)
    File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py", line 484, in _HandleInspectorDomainNotification
      raise exception
  DevtoolsTargetCrashException: Devtools target crashed
  ********************************************************************************
  (/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py:539 _AddDebuggingInformation) Received a socket error in the browser connection and the tab no longer exists. The tab probably crashed.
  ********************************************************************************
  (/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py:540 _AddDebuggingInformation) Debugger url: ws://127.0.0.1:41454/devtools/page/1C0E35591A5D60C451DA390EEE72E53E
  Found Minidump: False
  Stack Trace:
  ********************************************************************************
  	Cannot get stack trace on CrOS
  ********************************************************************************
  Standard output:
  ********************************************************************************
  	Cannot get standard output on CrOS
  ********************************************************************************
  System log:
  (Not implemented)

Disabling the test here: https://chromium-review.googlesource.com/c/catapult/+/1404270

The following revision refers to this bug:
  https://chromium.googlesource.com/catapult/+/daced929e547fb83ac8555a154074c546f10294a

commit daced929e547fb83ac8555a154074c546f10294a
Author: Roman Sorokin <rsorokin@chromium.org>
Date: Thu Jan 10 13:20:08 2019

[Sheriff] Disable DevToolsClientBackendTest.testTracing

There is a lot of flakiness (see bug)

Set NOTRY due to crbug.com/920573.

BUG= chromium:920454 
TEST=none
TBR=perezju@chromium.org
NOTRY=true

Change-Id: Ie31cd5bd301b264576897adb4cd3f19fe6e59ce1
Reviewed-on: https://chromium-review.googlesource.com/c/1404270
Commit-Queue: Roman Sorokin <rsorokin@chromium.org>
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>

[modify] https://crrev.com/daced929e547fb83ac8555a154074c546f10294a/telemetry/telemetry/internal/backends/chrome_inspector/devtools_client_backend_unittest.py

 Issue 919911  has been merged into this issue.

 Issue 919831  has been merged into this issue.

 Issue 919796  has been merged into this issue.

telemetry.core.tracing_controller_unittest.StartupTracingTest.testCloseBrowserBeforeTracingIsStopped is flaky.

Findit has detected 16 new flake occurrences of this test. List
of all flake occurrences can be found at:
https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyjQELEgVGbGFrZSKBAWNocm9taXVtQHRlbGVtZXRyeV91bml0dGVzdHNAdGVsZW1ldHJ5LmNvcmUudHJhY2luZ19jb250cm9sbGVyX3VuaXR0ZXN0LlN0YXJ0dXBUcmFjaW5nVGVzdC50ZXN0Q2xvc2VCcm93c2VyQmVmb3JlVHJhY2luZ0lzU3RvcHBlZAw.

Since these tests are still flaky, this issue has been moved back onto the Sheriff Bug Queue if it hasn't already.

This flaky test was previously tracked in  bug 919831 .

If the result above is wrong, please file a bug using this link:
https://bugs.chromium.org/p/chromium/issues/entry?status=Unconfirmed&labels=Pri-1,Test-Findit-Wrong&components=Tools%3ETest%3EFindit%3EFlakiness&summary=%5BFindit%5D%20Flake%20Detection%20-%20Wrong%20result%3A%20telemetry.core.tracing_controller_unittest.StartupTracingTest.testCloseBrowserBeforeTracingIsStopped&comment=Link%20to%20flake%20details%3A%20https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyjQELEgVGbGFrZSKBAWNocm9taXVtQHRlbGVtZXRyeV91bml0dGVzdHNAdGVsZW1ldHJ5LmNvcmUudHJhY2luZ19jb250cm9sbGVyX3VuaXR0ZXN0LlN0YXJ0dXBUcmFjaW5nVGVzdC50ZXN0Q2xvc2VCcm93c2VyQmVmb3JlVHJhY2luZ0lzU3RvcHBlZAw

Automatically posted by the findit-for-me app (https://goo.gl/Ot9f7N).

Achuith - looks like Chrome is crashing when trying to run tracing. Strange that this only seems to be happening on ChromeOs on the "with patch" test?

The following revision refers to this bug:
  https://chromium.googlesource.com/catapult/+/775ce3b01f6bdc38937284a9cccc9dadd1e3fa10

commit 775ce3b01f6bdc38937284a9cccc9dadd1e3fa10
Author: Roman Sorokin <rsorokin@chromium.org>
Date: Thu Jan 10 14:15:20 2019

[Sheriff] Disable some telemetry tests on ChromeOS due to flakiness

Set NOTRY due to crbug.com/920573.

BUG= chromium:920454 
TEST=none
NOTRY=true

Change-Id: I0d56a1663afe6e8b72d12943446192e3e7d3901c
Reviewed-on: https://chromium-review.googlesource.com/c/1404272
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Roman Sorokin <rsorokin@chromium.org>

[modify] https://crrev.com/775ce3b01f6bdc38937284a9cccc9dadd1e3fa10/telemetry/telemetry/core/tracing_controller_unittest.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/87c124c7b5920c046ad1f417f60b87f1e1f5ce08

commit 87c124c7b5920c046ad1f417f60b87f1e1f5ce08
Author: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Date: Thu Jan 10 17:09:56 2019

Roll src/third_party/catapult 79517a0b0327..daced929e547 (1 commits)

https://chromium.googlesource.com/catapult.git/+log/79517a0b0327..daced929e547


git log 79517a0b0327..daced929e547 --date=short --no-merges --format='%ad %ae %s'
2019-01-10 rsorokin@chromium.org [Sheriff] Disable DevToolsClientBackendTest.testTracing


Created with:
  gclient setdep -r src/third_party/catapult@daced929e547

The AutoRoll server is located here: https://autoroll.skia.org/r/catapult-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel

BUG= chromium:920454 
TBR=sullivan@chromium.org

Change-Id: Ia45c0c2b9c5e86de9d3095464456426e69ecc803
Reviewed-on: https://chromium-review.googlesource.com/c/1404807
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#621616}
[modify] https://crrev.com/87c124c7b5920c046ad1f417f60b87f1e1f5ce08/DEPS

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e663cad2d794c7018611f6c43516f0dfb35aaeb6

commit e663cad2d794c7018611f6c43516f0dfb35aaeb6
Author: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Date: Thu Jan 10 18:45:25 2019

Roll src/third_party/catapult daced929e547..775ce3b01f6b (1 commits)

https://chromium.googlesource.com/catapult.git/+log/daced929e547..775ce3b01f6b


git log daced929e547..775ce3b01f6b --date=short --no-merges --format='%ad %ae %s'
2019-01-10 rsorokin@chromium.org [Sheriff] Disable some telemetry tests on ChromeOS due to flakiness


Created with:
  gclient setdep -r src/third_party/catapult@775ce3b01f6b

The AutoRoll server is located here: https://autoroll.skia.org/r/catapult-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel

BUG= chromium:920454 
TBR=sullivan@chromium.org

Change-Id: I4e66f8fea6abb01eed9a3d0ff493824dcf854914
Reviewed-on: https://chromium-review.googlesource.com/c/1405528
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#621668}
[modify] https://crrev.com/e663cad2d794c7018611f6c43516f0dfb35aaeb6/DEPS

Believe this is a dupe of 920471.