gpu: Mark Pixel_OffscreenCanvasWebGLDefault as flaky on Nexus 5X

TBR=kbr@chromium.org
Bug: 1157136

Change-Id: I87d0c0ed495f9d63de622ebeafab8232d90262ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2612838
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Auto-Submit: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840751}
diff --git a/content/test/gpu/gpu_tests/test_expectations/pixel_expectations.txt b/content/test/gpu/gpu_tests/test_expectations/pixel_expectations.txt
index 605699c..4df2d426 100644
--- a/content/test/gpu/gpu_tests/test_expectations/pixel_expectations.txt
+++ b/content/test/gpu/gpu_tests/test_expectations/pixel_expectations.txt
@@ -175,6 +175,7 @@
 crbug.com/883500 [ android-chromium android-nexus-5x ] Pixel_BackgroundImage [ RetryOnFailure ]
 crbug.com/1065514 [ android android-chromium android-nexus-5x ] Pixel_WebGLReadPixelsTabSwitch [ RetryOnFailure ]
 crbug.com/1121476 [ android android-chromium android-nexus-5x ] Pixel_Canvas2DTabSwitch [ RetryOnFailure ]
+crbug.com/1157136 [ android android-chromium android-nexus-5x skia-renderer-disabled ] Pixel_OffscreenCanvasWebGLDefault [ RetryOnFailure ]
 
 # We do not have software H.264 decoding on Android, so it can't survive a
 # context loss which results in hardware decoder loss.