https://build.chromium.org/p/chromium.gpu.fyi/builders/Win7%20Release%20%28New%20Intel%29/builds/23/steps/webgl_conformance_gl_tests/logs/stdio has

[ RUN      ] WebglConformance.conformance_attribs_gl_disabled_vertex_attrib
[1808:3664:0328/171846:INFO:CONSOLE(11)] "Unable to fetch WebGL rendering context for Canvas", source:  (11)
[1808:3664:0328/171846:INFO:CONSOLE(11)] "FAIL Unable to fetch WebGL rendering context for Canvas", source:  (11)
[1808:3664:0328/171846:INFO:CONSOLE(11)] "Uncaught TypeError: Cannot read property 'getParameter' of null", source:  (11)
[1808:3664:0328/171846:INFO:CONSOLE(70)] "Uncaught TypeError: Cannot read property 'getParameter' of null", source: http://127.0.0.1:51744/conformance/attribs/gl-disabled-vertex-attrib.html (70)
[1808:3664:0328/171846:INFO:CONSOLE(11)] "successfullyParsed should be true (of type boolean). Was undefined (of type undefined).", source:  (11)
[1808:3664:0328/171846:INFO:CONSOLE(11)] "FAIL successfullyParsed should be true (of type boolean). Was undefined (of type undefined).", source:  (11)
Traceback (most recent call last):
  File "c:\users\chrome~1.lab\appdata\local\temp\isolated_run4icxnb\third_party\catapult\telemetry\telemetry\internal\story_runner.py", line 84, in _RunStoryAndProcessErrorIfNeeded
    state.RunStory(results)
  File "c:\users\chrome~1.lab\appdata\local\temp\isolated_run4icxnb\content\test\gpu\gpu_tests\gpu_test_base.py", line 122, in RunStory
    RunStoryWithRetries(DesktopGpuSharedPageState, self, results)
  File "c:\users\chrome~1.lab\appdata\local\temp\isolated_run4icxnb\content\test\gpu\gpu_tests\gpu_test_base.py", line 72, in RunStoryWithRetries
    super(cls, shared_page_state).RunStory(results)
  File "c:\users\chrome~1.lab\appdata\local\temp\isolated_run4icxnb\third_party\catapult\telemetry\telemetry\page\shared_page_state.py", line 338, in RunStory
    self._current_page, self._current_tab, results)
  File "c:\users\chrome~1.lab\appdata\local\temp\isolated_run4icxnb\content\test\gpu\gpu_tests\webgl_conformance.py", line 78, in ValidateAndMeasurePage
    raise page_test.Failure(_WebGLTestMessages(tab))
Failure: Unable to fetch WebGL rendering context for Canvas
FAIL Unable to fetch WebGL rendering context for Canvas
Uncaught TypeError: Cannot read property 'getParameter' of null
successfullyParsed should be true (of type boolean). Was undefined (of type undefined).
FAIL successfullyParsed should be true (of type boolean). Was undefined (of type undefined).


[  FAILED  ] WebglConformance.conformance_attribs_gl_disabled_vertex_attrib (354 ms)

This seems to have started at https://build.chromium.org/p/chromium.gpu.fyi/builders/Win7%20Release%20%28New%20Intel%29/builds/23 so I'm suspecting https://chromium.googlesource.com/chromium/src/+/d4100e5324db5db722c4c1de3f1edaed76d6b137