Remove MediaQueryPrefersColorScheme runtime flag.

This feature has been enabled since M-76.

Bug: 889087
Change-Id: I54fbf2851fe7da7c442f6abb05010405f7f27fca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1992321Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729917}

third_party/blink/renderer/core/css/media_query_exp.cc

@@ -80,11 +80,9 @@ static inline bool FeatureWithValidIdent(const String& media_feature,
            ident == CSSValueID::kRec2020;
   }
 
-  if (RuntimeEnabledFeatures::MediaQueryPrefersColorSchemeEnabled()) {
-    if (media_feature == media_feature_names::kPrefersColorSchemeMediaFeature) {
-      return ident == CSSValueID::kNoPreference || ident == CSSValueID::kDark ||
-             ident == CSSValueID::kLight;
-    }
+  if (media_feature == media_feature_names::kPrefersColorSchemeMediaFeature) {
+    return ident == CSSValueID::kNoPreference || ident == CSSValueID::kDark ||
+           ident == CSSValueID::kLight;
   }
 
   if (media_feature == media_feature_names::kPrefersReducedMotionMediaFeature)

third_party/blink/renderer/core/css/style_engine_test.cc

@@ -1494,8 +1494,6 @@ TEST_F(StyleEngineTest, MediaQueriesChangeDefaultFontSize) {
 }
 
 TEST_F(StyleEngineTest, MediaQueriesChangeColorScheme) {
-  ScopedMediaQueryPrefersColorSchemeForTest feature_scope(true);
-
   GetDocument().body()->SetInnerHTMLFromString(R"HTML(
     <style>
       body { color: red }
@@ -1521,8 +1519,6 @@ TEST_F(StyleEngineTest, MediaQueriesChangeColorScheme) {
 }
 
 TEST_F(StyleEngineTest, MediaQueriesChangeColorSchemeForcedDarkMode) {
-  ScopedMediaQueryPrefersColorSchemeForTest feature_scope(true);
-
   GetDocument().GetSettings()->SetForceDarkModeEnabled(true);
   ColorSchemeHelper color_scheme_helper;
   color_scheme_helper.SetPreferredColorScheme(GetDocument(),
@@ -1668,8 +1664,6 @@ TEST_F(StyleEngineTest, MediaQueriesChangeForcedColorsAndPreferredColorScheme) {
 }
 
 TEST_F(StyleEngineTest, MediaQueriesColorSchemeOverride) {
-  ScopedMediaQueryPrefersColorSchemeForTest feature_scope(true);
-
   EXPECT_EQ(PreferredColorScheme::kLight,
             Platform::Current()->ThemeEngine()->PreferredColorScheme());
 

third_party/blink/renderer/core/html/html_meta_element_test.cc

@@ -30,13 +30,11 @@ namespace blink {
 class HTMLMetaElementTest : public PageTestBase,
                             private ScopedDisplayCutoutAPIForTest,
                             private ScopedMetaColorSchemeForTest,
-                            private ScopedMediaQueryPrefersColorSchemeForTest,
                             private ScopedCSSColorSchemeForTest {
  public:
   HTMLMetaElementTest()
       : ScopedDisplayCutoutAPIForTest(true),
         ScopedMetaColorSchemeForTest(true),
-        ScopedMediaQueryPrefersColorSchemeForTest(true),
         ScopedCSSColorSchemeForTest(true) {}
   void SetUp() override {
     PageTestBase::SetUp();

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1007,10 +1007,6 @@
     {
       name: "MediaQueryNavigationControls",
     },
-    {
-      name: "MediaQueryPrefersColorScheme",
-      status: "stable",
-    },
     {
       name: "MediaQueryShape",
       status: "experimental",