blink: Fix gpu rasterization yuv decoding tests

Fix enable/disable YUV decoding flags and rebaseline necessary tests.
JPEG YUV decoding was enabled by default in M87, so these tests should be cleaned
up in the near future. Primarily, this change is a fix-up for crrev.com/c/2415373.

Bug: 919627
Change-Id: I04d8c9822a8343fc4ba9730560cac72b7b178fab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2417067
Commit-Queue: Sasha McIntosh <sashamcintosh@chromium.org>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Reviewed-by: Andres Calderon Jaramillo <andrescj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#831101}

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -685,11 +685,11 @@
     },
     {
       name: "DecodeJpeg420ImagesToYUV",
-      status: "test",
+      status: "stable",
     },
     {
       name: "DecodeLossyWebPImagesToYUV",
-      status: "test",
+      status: "stable",
     },
     {
       name: "DelayAsyncScriptExecutionUntilFinishedParsing",

third_party/blink/web_tests/VirtualTestSuites

@@ -98,16 +98,14 @@
   {
     "prefix": "gpu-rasterization",
     "bases": ["images"],
-    "args": ["--enable-gpu-rasterization",
-             "--enable-features=DecodeLossyWebPImagesToYUV",
-             "--enable-features=DecodeJpeg420ImagesToYUV"]
+    "args": ["--enable-gpu-rasterization"]
   },
   {
     "prefix": "gpu-rasterization-disable-yuv",
     "bases": ["images/yuv-decode-eligible"],
     "args": ["--enable-gpu-rasterization",
-             "--disable-features=DecodeLossyWebPImagesToYUV",
-             "--disable-features=DecodeJpeg420ImagesToYUV"]
+             "--disable-blink-features=DecodeLossyWebPImagesToYUV",
+             "--disable-blink-features=DecodeJpeg420ImagesToYUV"]
   },
   {
     "prefix": "exotic-color-space",

third_party/blink/web_tests/virtual/gpu-rasterization-disable-yuv/README.md

-# Test suite to run images/yuv-decode-eligible with GPU rasterization
-# and with the DecodeLossyWebPImagesToYUV feature disabled. This is because
-# YUV decoding will eventually become the default for many image decoding
-# cases and receives test coverage through virtual/gpu-rasterization. However
-# there are some cases where images might not go through YUV decoding, so this
-# test suite maintains coverage of those.
+Test suite to run images/yuv-decode-eligible with --enable-gpu-rasterization
+--disable-blink-features=DecodeLossyWebPImagesToYUV and
+--disable-blink-features=DecodeJpeg420ImagesToYUV. 
+
+YUV decoding is the default for many image decoding cases and receives test
+coverage through virtual/gpu-rasterization. This suite maintains coverage for
+images that do not use YUV decoding.

third_party/blink/web_tests/virtual/gpu-rasterization/README.md

-# Test suite to run images/ with GPU rasterization and with the flag 
-# --enable-features=DecodeLossyWebPImagesToYUV until it is enabled by
-# default.
-# 
-# This allows YUV decoding and rasterization for images that would support it:
-# currently just lossy WebP images without alpha that have been fully loaded at
-# decode time. Because incremental YUV decoding hasn't been implemented
-# (crbug.com/943519), the tests that go down this path also use JavaScript to
-# ensure all image data has been received before we attempt decoding.
+Test suite to run images/ with --enable-gpu-rasterization.
+
+This suite tests YUV decoding and rasterization for images that have been fully
+loaded at decode time and formats that support it, e.g.
+* lossy WebP images without alpha that  and
+* JPEG YUV images with a 4:2:0 subsampling.
+
+Because incremental YUV decoding hasn't been implemented (crbug.com/943519), the
+WebP tests use JavaScript to ensure all image data has been received before we
+attempt decoding.