Retry all WebGL 2.0 conformance tests on Pixel 2 / passthrough / Android P.

Flakiness - sometimes infrequent, sometimes frequent - is seen across
a large number of WebGL conformance tests on this configuration.
Flakiness is seen in other suites (e.g. validating) as well, which
will be addressed in other bugs.

Limit the suppression to Android P in case a later OS / driver upgrade
fixes this issue.

Bug: 1132297
Change-Id: Ib8aa70a29c3aa79e84cb3977d65f25a3510cc7d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2432320
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Commit-Queue: James Darpinian <jdarpinian@chromium.org>
Auto-Submit: Kenneth Russell <kbr@chromium.org>
Reviewed-by: James Darpinian <jdarpinian@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810881}

content/test/gpu/gpu_tests/test_expectations/webgl2_conformance_expectations.txt

-# tags: [ android
+# tags: [ android android-pie
 #         chromeos
 #         linux
 #         mac highsierra mojave sierra catalina
@@ -881,6 +881,13 @@ crbug.com/951628 [ android no-passthrough ] conformance/rendering/blending.html
 crbug.com/1000354 [ android no-passthrough ] conformance2/extensions/ext-texture-norm16.html [ Skip ]
 
 # Qualcomm (Pixel 2) failures
+
+# TODO(kbr): flakiness is seen on this configuration with the
+# passthrough command decoder across many different WebGL conformance
+# tests. Limit this blanket suppression to Android P in case this is
+# caused by driver bugs.
+crbug.com/1132297 [ android-pie qualcomm-adreno-(tm)-540 passthrough ] * [ RetryOnFailure ]
+
 crbug.com/906737 [ android qualcomm ] conformance/extensions/webgl-compressed-texture-astc.html [ Failure ]
 crbug.com/906742 [ android qualcomm no-passthrough ] conformance2/glsl3/compare-structs-containing-arrays.html [ Failure ]
 crbug.com/1008535 [ android qualcomm-adreno-(tm)-540 passthrough ] conformance2/textures/misc/tex-image-with-bad-args-from-dom-elements.html [ Skip ]