Example failing build:

https://build.chromium.org/p/chromium.gpu.fyi/builders/Win8%20Debug%20%28NVIDIA%29/builds/14223

[ RUN      ] WebglConformance.conformance_glsl_matrices_glsl_mat4_to_mat3
(INFO) 2016-06-03 06:27:10,845 cache_temperature.EnsurePageCacheTemperature:55  PageCacheTemperature: any
[3108:4076:0603/062711:INFO:CONSOLE(11)] "images are different: at (0,0): ref=(0,0,255,255)  test=(4,4,0,255) tolerance=0", source:  (11)
[3108:4076:0603/062711:INFO:CONSOLE(11)] "FAIL images are different: at (0,0): ref=(0,0,255,255)  test=(4,4,0,255) tolerance=0", source:  (11)
Traceback (most recent call last):
  File "c:\users\chrome~1\appdata\local\temp\runhjhdx1\third_party\catapult\telemetry\telemetry\internal\story_runner.py", line 84, in _RunStoryAndProcessErrorIfNeeded
    state.RunStory(results)
  File "c:\users\chrome~1\appdata\local\temp\runhjhdx1\content\test\gpu\gpu_tests\gpu_test_base.py", line 122, in RunStory
    RunStoryWithRetries(DesktopGpuSharedPageState, self, results)
  File "c:\users\chrome~1\appdata\local\temp\runhjhdx1\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\appdata\local\temp\runhjhdx1\third_party\catapult\telemetry\telemetry\page\shared_page_state.py", line 308, in RunStory
    self._current_page, self._current_tab, results)
  File "c:\users\chrome~1\appdata\local\temp\runhjhdx1\content\test\gpu\gpu_tests\webgl_conformance.py", line 87, in ValidateAndMeasurePage
    raise page_test.Failure(_WebGLTestMessages(tab))
Failure: images are different: at (0,0): ref=(0,0,255,255)  test=(4,4,0,255) tolerance=0
FAIL images are different: at (0,0): ref=(0,0,255,255)  test=(4,4,0,255) tolerance=0

Only seems to happen on D3D9. This is causing problems with the ANGLE CQ. Going to mark as flaky. cc'ing Eric, current GPU sheriff.