Expand flakiness expectations for Pixel_WebGLSadCanvas

The flakiness is on all platforms.
https://chromium-try-flakes.appspot.com/all_flake_occurrences?key=ahVzfmNocm9taXVtLXRyeS1mbGFrZXNyVQsSBUZsYWtlIkpncHVfdGVzdHMucGl4ZWxfaW50ZWdyYXRpb25fdGVzdC5QaXhlbEludGVncmF0aW9uVGVzdC5QaXhlbF9XZWJHTFNhZENhbnZhcww

Bug: 835867
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: I959dd5e6db6f8ca4f50effeca828a8cd98f6b5fa
Reviewed-on: https://chromium-review.googlesource.com/1062911
Commit-Queue: James Darpinian <jdarpinian@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559410}

content/test/gpu/gpu_tests/pixel_expectations.py

@@ -100,6 +100,5 @@ class PixelExpectations(GpuTestExpectations):
     self.Fail('Pixel_WorkerRAF_OOPD', ['android', 'nvidia'], bug=833902)
 
     # TODO(kbr): temporary suppression for new test.
-    self.Flaky('Pixel_WebGLSadCanvas', ['mac'], bug=575305)
-    self.Flaky('Pixel_WebGLSadCanvas', ['win', 'intel'], bug=575305)
-    self.Fail('Pixel_WebGLSadCanvas', ['android', 'nvidia'], bug=575305)
+    self.Flaky('Pixel_WebGLSadCanvas', ['linux', 'mac', 'win'], bug=575305)
+    self.Fail('Pixel_WebGLSadCanvas', ['android'], bug=575305)