Also, not saying this is "debug only" just saying that was the config I tested on.  I ran into this trying to figure out why oop raster wasn't turning on for Android or Linux.

@enne: is that with --enable-oop-rasterization? Does it also repro without?

According to https://chromium-review.googlesource.com/c/chromium/src/+/982098/5/content/renderer/render_thread_impl.cc#2510 we don't support GrContext if oop raster is on, and that's because we don't support GLES2Interface (that predates this patch). Maybe before this patch we were claiming GrContext support in that case, but would fail when trying to use it?
Should we change GetGpuRasterizationCapabilities to also return support if no GrContext, but RasterInterface is there?

Whoops.  Sorry to cry wolf.  You're quite right, piman.  If oop rasterization is on, then gpu rasterization fails to be supported.  Without that flag, then it appears to turn on properly.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/72cf4278866ef427a2cd3c49b7df3844f12faff7

commit 72cf4278866ef427a2cd3c49b7df3844f12faff7
Author: Adrienne Walker <enne@chromium.org>
Date: Mon Apr 02 23:04:35 2018

Fix oop raster disabling itself

After https://chromium-review.googlesource.com/c/chromium/src/+/982098,
enabling oop rasterization by the command line disables gpu rasterization
which in turn disables oop rasterization and uses software rasterization
instead.

This also fixes uses of GrContext that are no longer supported in
GpuImageDecodeCache.

Bug:  826987 ,  793508 
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;master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Ifdf1f18eb34e9e63eeb6e39cb66a6ab77e10afcd
Reviewed-on: https://chromium-review.googlesource.com/986744
Reviewed-by: Antoine Labour <piman@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547548}
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/cc/paint/oop_pixeltest.cc
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/cc/tiles/gpu_image_decode_cache.cc
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/cc/tiles/gpu_image_decode_cache.h
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/cc/tiles/gpu_image_decode_cache_unittest.cc
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/cc/trees/layer_tree_host_impl.cc
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/cc/trees/layer_tree_host_impl.h
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/components/viz/test/test_web_graphics_context_3d.cc
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/components/viz/test/test_web_graphics_context_3d.h
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/content/renderer/webgraphicscontext3d_provider_impl.cc
[modify] https://crrev.com/72cf4278866ef427a2cd3c49b7df3844f12faff7/gpu/command_buffer/service/gles2_cmd_decoder.cc