I quite often the last couple of days get fails in gpu_tests.webgl_conformance_integration_test.WebGLConformanceIntegrationTest.WebglConformance_conformance_textures_misc_texture_corner_case_videos on bots running optional tests. 

Example: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win_optional_gpu_tests_rel/5732

  Traceback (most recent call last):
    _RunGpuTest at content\test\gpu\gpu_tests\gpu_integration_test.py:138
      self.RunActualGpuTest(url, *args)
    RunActualGpuTest at content\test\gpu\gpu_tests\webgl_conformance_integration_test.py:186
      getattr(self, test_name)(test_path, *args[1:])
    _RunConformanceTest at content\test\gpu\gpu_tests\webgl_conformance_integration_test.py:200
      self._CheckTestCompletion()
    _CheckTestCompletion at content\test\gpu\gpu_tests\webgl_conformance_integration_test.py:196
      self.fail(self._WebGLTestMessages(self.tab))
    fail at .swarming_module\bin\Lib\unittest\case.py:410
      raise self.failureException(msg)
  AssertionError: shouldBe 0,255,0
  at (4, 4) expected: 0,255,0 was 0,0,0
  
  testing: Video whose natural size is larger than coded size due to uncommon pixel shape (Sample Aspect Ratio)
  video type: video/mp4; codecs="avc1.42E01E, mp4a.40.2"
  tolerance: 18
  Testing texImage2D with flipY=true bindingTarget=TEXTURE_2D
  Checking lower left corner
  FAIL shouldBe 0,255,0
  at (4, 4) expected: 0,255,0 was 0,0,0
  Checking upper left corner
  shouldBe 255,0,0
  at (4, 24) expected: 255,0,0 was 0,0,0
  FAIL shouldBe 255,0,0
  at (4, 24) expected: 255,0,0 was 0,0,0
  Testing texImage2D with flipY=false bindingTarget=TEXTURE_2D
  Checking lower left corner
  Checking upper left corner
  Testing texSubImage2D with flipY=true bindingTarget=TEXTURE_2D
  Checking lower left corner
  shouldBe 0,255,0
  at (4, 4) expected: 0,255,0 was 0,0,0
  FAIL shouldBe 0,255,0
  at (4, 4) expected: 0,255,0 was 0,0,0
  Checking upper left corner
  shouldBe 255,0,0
  at (4, 24) expected: 255,0,0 was 0,0,0
  FAIL shouldBe 255,0,0
  at (4, 24) expected: 255,0,0 was 0,0,0
  Testing texSubImage2D with flipY=false bindingTarget=TEXTURE_2D
  Checking lower left corner
  shouldBe 255,0,0
  at (4, 4) expected: 255,0,0 was 0,0,0
  FAIL shouldBe 255,0,0
  at (4, 4) expected: 255,0,0 was 0,0,0
  Checking upper left corner
  shouldBe 0,255,0
  at (4, 24) expected: 0,255,0 was 0,0,0
  FAIL shouldBe 0,255,0
  at (4, 24) expected: 0,255,0 was 0,0,0
  Testing with 2D canvas
  Checking lower left corner
  shouldBe 0,255,0
  at (4, 24) expected: 0,255,0 was 0,0,0
  FAIL shouldBe 0,255,0
  at (4, 24) expected: 0,255,0 was 0,0,0
  Checking upper left corner
  shouldBe 255,0,0
  at (4, 4) expected: 255,0,0 was 0,0,0
  FAIL shouldBe 255,0,0
  at (4, 4) expected: 255,0,0 was 0,0,0
  
  Locals:
    msg : u'shouldBe 0,255,0
at (4, 4) expected: 0,255,0 was 0,0,0

testing: Video whose natural size is larger than coded size due to uncommon pixel shape (Sample Aspect Ratio)
video type: video/mp4; codecs="avc1.42E01E, mp4a.40.2"
tolerance: 18
Testing texImage2D with flipY=true bindingTarget=TEXTURE_2D
Checking lower left corner
FAIL shouldBe 0,255,0
at (4, 4) expected: 0,255,0 was 0,0,0
Checking upper left corner
shouldBe 255,0,0
at (4, 24) expected: 255,0,0 was 0,0,0
FAIL shouldBe 255,0,0
at (4, ... nat (4, 4) expected: 255,0,0 was 0,0,0
Checking upper left corner
shouldBe 0,255,0
at (4, 24) expected: 0,255,0 was 0,0,0
FAIL shouldBe 0,255,0
at (4, 24) expected: 0,255,0 was 0,0,0
Testing with 2D canvas
Checking lower left corner
shouldBe 0,255,0
at (4, 24) expected: 0,255,0 was 0,0,0
FAIL shouldBe 0,255,0
at (4, 24) expected: 0,255,0 was 0,0,0
Checking upper left corner
shouldBe 255,0,0
at (4, 4) expected: 255,0,0 was 0,0,0
FAIL shouldBe 255,0,0
at (4, 4) expected: 255,0,0 was 0,0,0
' (truncated)