The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/182f6415d7818beb3daa92fa3f9a966477b370f0

commit 182f6415d7818beb3daa92fa3f9a966477b370f0
Author: Geoff Lang <geofflang@chromium.org>
Date: Tue Nov 07 16:49:09 2017

Mark WebGL attrib-type-match test ask flaky on the new P400 GPUs.

BUG=782254

TBR=zmo@chromium.org
NOTRY=true

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I5c0600e96eef51fc4b3f9e96296cb1513c6aa850
Reviewed-on: https://chromium-review.googlesource.com/757038
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514492}
[modify] https://crrev.com/182f6415d7818beb3daa92fa3f9a966477b370f0/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cd2a25867d1d5bcfb723db453e56361b5dea18ee

commit cd2a25867d1d5bcfb723db453e56361b5dea18ee
Author: Geoff Lang <geofflang@chromium.org>
Date: Wed Nov 08 20:11:33 2017

Mark WebGL2 attrib-type-match as flaky on Windows NVIDIA OpenGL too.

BUG=782254

TBR=zmo@chromium.org
NOTRY=true

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Icaa0946877a0c801e41c7dabb6ff9f574e0d1065
Reviewed-on: https://chromium-review.googlesource.com/759084
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514922}
[modify] https://crrev.com/cd2a25867d1d5bcfb723db453e56361b5dea18ee/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d627550b1f1ed31b8904490a4321b05f3555a927

commit d627550b1f1ed31b8904490a4321b05f3555a927
Author: Jamie Madill <jmadill@chromium.org>
Date: Wed Jun 20 20:24:00 2018

Mark Flaky Windows WebGL test failing.

The test conformance2/rendering/attrib-type-match.html was so flaky
it was failing multiple bot runs. We should mark it failing.

Bug: 782254
Tbr: kbr@chromium.org
Change-Id: I7e634a3ef81d24a692f38140246b5ff5a51d23e6
Reviewed-on: https://chromium-review.googlesource.com/1108477
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568979}
[modify] https://crrev.com/d627550b1f1ed31b8904490a4321b05f3555a927/content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

A couple of recent failing runs:
https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win_angle_rel_ng/1567
https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win_angle_rel_ng/1555

Failure mode is:

[7/138] gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance2_rendering_attrib_type_match failed unexpectedly 13.0560s:
  FLAKY TEST FAILURE, retrying: WebglConformance_conformance2_rendering_attrib_type_match
  FLAKY TEST FAILURE, retrying: WebglConformance_conformance2_rendering_attrib_type_match
...
  Traceback (most recent call last):
    File "c:\b\s\w\ir\third_party\catapult\telemetry\telemetry\testing\serially_executed_browser_test_case.py", line 213, in <lambda>
      return lambda self: based_method(self, *args)
    File "c:\b\s\w\ir\content\test\gpu\gpu_tests\gpu_integration_test.py", line 179, in _RunGpuTest
      self.RunActualGpuTest(url, *args)
    File "c:\b\s\w\ir\content\test\gpu\gpu_tests\webgl_conformance_integration_test.py", line 185, in RunActualGpuTest
      getattr(self, test_name)(test_path, *args[1:])
    File "c:\b\s\w\ir\content\test\gpu\gpu_tests\webgl_conformance_integration_test.py", line 199, in _RunConformanceTest
      self._CheckTestCompletion()
    File "c:\b\s\w\ir\content\test\gpu\gpu_tests\webgl_conformance_integration_test.py", line 195, in _CheckTestCompletion
      self.fail(self._WebGLTestMessages(self.tab))
  AssertionError: should be 255,0,0,255
  at (0, 0) expected: 255,0,0,255 was 0,0,0,255
  FAIL should be 255,0,0,255
  at (0, 0) expected: 255,0,0,255 was 0,0,0,255
  should be 255,0,0,255
  at (0, 0) expected: 255,0,0,255 was 0,0,0,255
  FAIL should be 255,0,0,255
  at (0, 0) expected: 255,0,0,255 was 0,0,0,255
  should be 255,0,0,255
  at (0, 0) expected: 255,0,0,255 was 0,0,0,255
  FAIL should be 255,0,0,255
  at (0, 0) expected: 255,0,0,255 was 0,0,0,255
 

Unfortunately the failure logs don't have the output from the checks which succeeded so it's not clear which checkCanvasRect call in the test failed.

I'm not sure how reproducible this is if the test is run in isolation. Not sure whether this might be state leaking across ANGLE's virtual contexts, or a bug in the OpenGL driver.

From this shard:
https://chromium-swarm.appspot.com/task?id=3e37386542725f10&refresh=10&show_raw=1

The machine is running Windows 10 and NVIDIA's 388.16 driver (seen in the Swarming dimensions on the left hand side).

FYI this is the only config we run the WebGL 2 tests against the GL backend on Windows. I don't know if it's NVIDIA specific from the current failure mode.