It seems this was broken late last week and recovered over the weekend. It's broken again now and difficult to get CLs to pass through.

Random sampling of the failed builds shows consistently that gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance2_attribs_gl_bindAttribLocation_aliasing_inactive is failing with:

====

gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance2_attribs_gl_bindAttribLocation_aliasing_inactive failed unexpectedly 1.6487s:
  
  Traceback (most recent call last):
    _RunGpuTest at content/test/gpu/gpu_tests/gpu_integration_test.py:132
      self.RunActualGpuTest(url, *args)
    RunActualGpuTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:188
      getattr(self, test_name)(test_path, *args[1:])
    _RunConformanceTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:202
      self._CheckTestCompletion()
    _CheckTestCompletion at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:198
      self.fail(self._WebGLTestMessages(self.tab))
    fail at .swarming_module/lib/python2.7/unittest/case.py:410
      raise self.failureException(msg)
  AssertionError: Link should fail when both attributes are aliased to location 0
  FAIL Link should fail when both attributes are aliased to location 0
  Link should fail when both attributes are aliased to location 1
  FAIL Link should fail when both attributes are aliased to location 1
  Link should fail when both attributes are aliased to location 2
  FAIL Link should fail when both attributes are aliased to location 2
  Link should fail when both attributes are aliased to location 3
  FAIL Link should fail when both attributes are aliased to location 3
  Link should fail when both attributes are aliased to location 4
  FAIL Link should fail when both attributes are aliased to location 4
  Link should fail when both attributes are aliased to location 5
  FAIL Link should fail when both attributes are aliased to location 5
  Link should fail when both attributes are aliased to location 6
  FAIL Link should fail when both attributes are aliased to location 6

  ...etc...


The first failure occurred after this skia roll: https://chromium-review.googlesource.com/c/chromium/src/+/1024271