Disable DOMParserIncludeShadowRoots for testing

This adds a fieldtrial testing config that disables the
DOMParserIncludeShadowRoots flag for tests, and flips the polarity
of the virtual suite to continue testing the enabled case. This
flag will be test-disabled via Finch.

Bug: 329330085
Change-Id: I07ce9781073dc2db6299b7f5ba7303e1632779ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5376737
Commit-Queue: Mason Freed <masonf@chromium.org>
Reviewed-by: Di Zhang <dizhangg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1276252}

testing/variations/fieldtrial_testing_config.json

@@ -5244,6 +5244,27 @@
             ]
         }
     ],
+    "DOMParserIncludeShadowRoots": [
+        {
+            "platforms": [
+                "android",
+                "chromeos",
+                "chromeos_lacros",
+                "fuchsia",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Disabled",
+                    "disable_features": [
+                        "DOMParserIncludeShadowRoots"
+                    ]
+                }
+            ]
+        }
+    ],
     "DXGIWaitableSwapChain": [
         {
             "platforms": [

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1460,6 +1460,7 @@
     // When enabled, this allows users of DOMParser to do:
     // (new DOMParser()).parseFromString(...,{includeShadowRoots:true}).
     // This is being deprecated and removed: crbug.com/329330085.
+    // The fieldtrial_testing_config currently disables this feature for tests.
     {
       name: "DOMParserIncludeShadowRoots",
       status: "stable",

third_party/blink/web_tests/VirtualTestSuites

@@ -1476,14 +1476,14 @@
     "expires": "May 1, 2024"
   },
   {
-    "prefix": "domparser-includeshadowroots-disabled",
-    "platforms": ["Linux"],
+    "prefix": "domparser-includeshadowroots-enabled",
+    "platforms": ["Linux","Mac"],
     "owners": ["masonf@chromium.org"],
     "bases": [
       "shadow-dom/declarative-domparser-usecounter.html",
       "external/wpt/shadow-dom/declarative/declarative-shadow-dom-opt-in.html"
     ],
-    "args": ["--disable-blink-features=DOMParserIncludeShadowRoots"],
+    "args": ["--enable-blink-features=DOMParserIncludeShadowRoots"],
     "expires": "Oct 15, 2024"
   },
   {

third_party/blink/web_tests/virtual/domparser-includeshadowroots-disabled/README.md

@@ -1,5 +0,0 @@
-# Overview
-
-This suite tests the case where includeShadowRoots is disabled on parseFromString via
-`--disable-blink-features=DOMParserIncludeShadowRoots`.
-

third_party/blink/web_tests/virtual/domparser-includeshadowroots-disabled/external/wpt/shadow-dom/declarative/declarative-shadow-dom-opt-in-expected.txt

@@ -1,3 +0,0 @@
-This is a testharness.js-based test.
-Harness: the test ran to completion.
-

third_party/blink/web_tests/virtual/domparser-includeshadowroots-enabled/README.md

@@ -0,0 +1,5 @@
+# Overview
+
+This suite tests the case where includeShadowRoots is enabled on parseFromString via
+`--enable-blink-features=DOMParserIncludeShadowRoots`.
+

third_party/blink/web_tests/virtual/domparser-includeshadowroots-enabled/shadow-dom/declarative-domparser-usecounter-expected.txt

@@ -0,0 +1,4 @@
+CONSOLE WARNING: The includeShadowRoots parameter to parseFromString has been deprecated, and will be removed very soon. Please use parseHTMLUnsafe() or setHTMLUnsafe() instead.
+This is a testharness.js-based test.
+Harness: the test ran to completion.
+