https://ci.chromium.org/p/chromium/builders/luci.chromium.try/mac_chromium_rel_ng/212927
https://chromium-swarm.appspot.com/task?id=41e590615ef54610&refresh=10&show_raw=1

WebglConformance_conformance_textures_misc_texture_size_cube_maps failed:
[358/469] gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance_textures_misc_texture_size_cube_maps failed unexpectedly 2.3035s:
  
  Traceback (most recent call last):
    _RunGpuTest at content/test/gpu/gpu_tests/gpu_integration_test.py:155
      self.RunActualGpuTest(url, *args)
    RunActualGpuTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:199
      getattr(self, test_name)(test_path, *args[1:])
    _RunConformanceTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:288
      self._CheckTestCompletion()
    _CheckTestCompletion at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:284
      self.fail(self._WebGLTestMessages(self.tab))
    fail at .swarming_module/lib/python2.7/unittest/case.py:410
      raise self.failureException(msg)
  AssertionError: 0, 64, 128, 64 should be yellow
  at (76, 75) expected: 255,255,0,255 was 255,255,6,255
  FAIL 0, 64, 128, 64 should be yellow
  at (76, 75) expected: 255,255,0,255 was 255,255,6,255


https://ci.chromium.org/p/chromium/builders/luci.chromium.try/mac_chromium_rel_ng/212925
https://chromium-swarm.appspot.com/task?id=41e58d208838a910&refresh=10&show_raw=1

WebglConformance_conformance_textures_misc_texture_size failed:
[357/469] gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance_textures_misc_texture_size failed unexpectedly 2.4565s:
  
  Traceback (most recent call last):
    _RunGpuTest at content/test/gpu/gpu_tests/gpu_integration_test.py:155
      self.RunActualGpuTest(url, *args)
    RunActualGpuTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:199
      getattr(self, test_name)(test_path, *args[1:])
    _RunConformanceTest at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:288
      self._CheckTestCompletion()
    _CheckTestCompletion at content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:284
      self.fail(self._WebGLTestMessages(self.tab))
    fail at .swarming_module/lib/python2.7/unittest/case.py:410
      raise self.failureException(msg)
  AssertionError: 2D texture of size 2048x2048 with mips should draw with blue
  at (1, 0) expected: 0,255,0,255 was 0,255,0,251


The rendered values are off by a little bit per color channel.

Mysterious; seen across multiple bots; haven't seen this failure mode before. Possible cause of some flaky pixel test failures in Issue 917040 too?

Will mark these tests flaky and increase their tolerance.