Try disabling surface layers for videos in WebGL tests.

See whether passing --disable-features=UseSurfaceLayerForVideo
improves the reliability of these tests.

Tbr: kainino@chromium.org
Tbr: dalecurtis@chromium.org
Bug: 830901
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: Id56d57c331ae416b5492a25609d869ebdba26ec3
Reviewed-on: https://chromium-review.googlesource.com/1155940
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579481}

content/test/gpu/gpu_tests/webgl_conformance_integration_test.py

@@ -254,7 +254,10 @@ class WebGLConformanceIntegrationTest(gpu_integration_test.GpuIntegrationTest):
       '--disable-gpu-watchdog',
       # TODO(http://crbug.com/832952): Remove this when WebXR spec is more
       # stable and setCompatibleXRDevice is part of the conformance test.
-      '--disable-blink-features=WebXR'
+      '--disable-blink-features=WebXR',
+      # TODO(crbug.com/830901): see whether disabling this feature
+      # makes the WebGL video upload tests reliable again.
+      '--disable-features=UseSurfaceLayerForVideo',
     ]
     # Note that the overriding of the default --js-flags probably
     # won't interact well with RestartBrowserIfNecessaryWithArgs, but