Apply override for forced-colors media query

DevTools exposes `Emulation.setEmulatedMedia` which allows to emulate
media features. This patch adds support for forced-colors.

Bug: 1216780
Change-Id: If07cc0a35cfc86da386f9fd41b4a7a492f7bf02c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2941047
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Pavel Feldman <pfeldman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#890407}

AUTHORS

@@ -715,6 +715,7 @@ Matthias Reitinger <reimarvin@gmail.com>
 Matthieu Rigolot <matthieu.rigolot@gmail.com>
 Matthieu Vlad Hauglustaine <matt.hauglustaine@gmail.com>
 Max Perepelitsyn <pph34r@gmail.com>
+Max Schmitt <max@schmitt.mx>
 Max Vujovic <mvujovic@adobe.com>
 Mayank Gupta <mayank.g1@samsung.com>
 Mayur Kankanwadi <mayurk.vk@samsung.com>

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

@@ -28,6 +28,20 @@
 
 namespace blink {
 
+namespace {
+static ForcedColors CSSValueIDToForcedColors(CSSValueID id) {
+  switch (id) {
+    case CSSValueID::kActive:
+      return ForcedColors::kActive;
+    case CSSValueID::kNone:
+      return ForcedColors::kNone;
+    default:
+      NOTREACHED();
+      return ForcedColors::kNone;
+  }
+}
+}  // namespace
+
 mojom::blink::PreferredColorScheme CSSValueIDToPreferredColorScheme(
     CSSValueID id) {
   switch (id) {
@@ -241,7 +255,14 @@ bool MediaValues::CalculatePrefersReducedData(LocalFrame* frame) {
           !frame->GetSettings()->GetDataSaverHoldbackWebApi());
 }
 
-ForcedColors MediaValues::CalculateForcedColors() {
+ForcedColors MediaValues::CalculateForcedColors(LocalFrame* frame) {
+  DCHECK(frame);
+  DCHECK(frame->GetSettings());
+  if (const auto* overrides = frame->GetPage()->GetMediaFeatureOverrides()) {
+    MediaQueryExpValue value = overrides->GetOverride("forced-colors");
+    if (value.IsValid())
+      return CSSValueIDToForcedColors(value.id);
+  }
   if (Platform::Current() && Platform::Current()->ThemeEngine())
     return Platform::Current()->ThemeEngine()->GetForcedColors();
   else

third_party/blink/renderer/core/css/media_values.h

@@ -120,7 +120,7 @@ class CORE_EXPORT MediaValues : public GarbageCollected<MediaValues> {
       LocalFrame*);
   static bool CalculatePrefersReducedMotion(LocalFrame*);
   static bool CalculatePrefersReducedData(LocalFrame*);
-  static ForcedColors CalculateForcedColors();
+  static ForcedColors CalculateForcedColors(LocalFrame*);
   static NavigationControls CalculateNavigationControls(LocalFrame*);
   static ScreenSpanning CalculateScreenSpanning(LocalFrame*);
   static DevicePosture CalculateDevicePosture(LocalFrame*);

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

@@ -83,7 +83,7 @@ MediaValuesCached::MediaValuesCachedData::MediaValuesCachedData(
     preferred_contrast = MediaValues::CalculatePreferredContrast(frame);
     prefers_reduced_motion = MediaValues::CalculatePrefersReducedMotion(frame);
     prefers_reduced_data = MediaValues::CalculatePrefersReducedData(frame);
-    forced_colors = MediaValues::CalculateForcedColors();
+    forced_colors = MediaValues::CalculateForcedColors(frame);
     navigation_controls = MediaValues::CalculateNavigationControls(frame);
     screen_spanning = MediaValues::CalculateScreenSpanning(frame);
     device_posture = MediaValues::CalculateDevicePosture(frame);

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

@@ -158,7 +158,7 @@ bool MediaValuesDynamic::PrefersReducedData() const {
 }
 
 ForcedColors MediaValuesDynamic::GetForcedColors() const {
-  return CalculateForcedColors();
+  return CalculateForcedColors(frame_);
 }
 
 NavigationControls MediaValuesDynamic::GetNavigationControls() const {

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

@@ -1840,6 +1840,48 @@ TEST_F(StyleEngineTest, MediaQueriesChangeForcedColorsAndPreferredColorScheme) {
                 GetCSSPropertyColor()));
 }
 
+TEST_F(StyleEngineTest, MediaQueriesForcedColorsOverride) {
+  GetDocument().body()->setInnerHTML(R"HTML(
+    <style>
+      body {
+        forced-color-adjust: none;
+      }
+      @media (forced-colors: none) {
+        body { color: red }
+      }
+      @media (forced-colors: active) {
+        body { color: green }
+      }
+    </style>
+    <body></body>
+  )HTML");
+
+  UpdateAllLifecyclePhases();
+  EXPECT_EQ(MakeRGB(255, 0, 0),
+            GetDocument().body()->GetComputedStyle()->VisitedDependentColor(
+                GetCSSPropertyColor()));
+
+  ColorSchemeHelper color_scheme_helper(GetDocument());
+  GetDocument().GetPage()->SetMediaFeatureOverride("forced-colors", "active");
+
+  UpdateAllLifecyclePhases();
+  EXPECT_EQ(MakeRGB(0, 128, 0),
+            GetDocument().body()->GetComputedStyle()->VisitedDependentColor(
+                GetCSSPropertyColor()));
+
+  GetDocument().GetPage()->SetMediaFeatureOverride("forced-colors", "none");
+  UpdateAllLifecyclePhases();
+  EXPECT_EQ(MakeRGB(255, 0, 0),
+            GetDocument().body()->GetComputedStyle()->VisitedDependentColor(
+                GetCSSPropertyColor()));
+
+  GetDocument().GetPage()->ClearMediaFeatureOverrides();
+  UpdateAllLifecyclePhases();
+  EXPECT_EQ(MakeRGB(255, 0, 0),
+            GetDocument().body()->GetComputedStyle()->VisitedDependentColor(
+                GetCSSPropertyColor()));
+}
+
 TEST_F(StyleEngineTest, MediaQueriesColorSchemeOverride) {
   ColorSchemeHelper color_scheme_helper(GetDocument());
   color_scheme_helper.SetPreferredColorScheme(

third_party/blink/web_tests/inspector-protocol/emulation/set-css-media-feature-override-expected.txt

@@ -25,6 +25,14 @@ matchMedia("(color-gamut: rec2020)").matches: true
 matchMedia("(color-gamut: rec2020)").matches applied: 7px x 7px
 matchMedia("(color-gamut: __invalid__)").matches: false
 matchMedia("(color-gamut: __invalid__)").matches applied: 3px x 2px
+matchMedia("(forced-colors: __invalid__)").matches: false
+matchMedia("(forced-colors: __invalid__)").matches applied: 3px x 2px
+matchMedia("(forced-colors: active)").matches: true
+matchMedia("(forced-colors: active)").matches applied: 3px x 2px
+matchMedia("(forced-colors: none)").matches: true
+matchMedia("(forced-colors: none)").matches applied: 3px x 2px
+matchMedia("(forced-colors: __invalid__)").matches: false
+matchMedia("(forced-colors: __invalid__)").matches applied: 3px x 2px
 matchMedia("(prefers-color-scheme: dark) and (prefers-reduced-motion: reduce)").matches: true
 matchMedia("(prefers-color-scheme: dark) and (prefers-reduced-motion: reduce)").matches applied: 999px x 999px
 matchMedia("(prefers-color-scheme: __invalid__)").matches: false

third_party/blink/web_tests/inspector-protocol/emulation/set-css-media-feature-override.js

@@ -56,6 +56,13 @@
   await setEmulatedMediaFeature('color-gamut', 'rec2020');
   await setEmulatedMediaFeature('color-gamut', '__invalid__');
 
+  // Test `forced-colors`.
+  // https://drafts.csswg.org/mediaqueries-5/#forced-colors
+  await setEmulatedMediaFeature('forced-colors', '__invalid__');
+  await setEmulatedMediaFeature('forced-colors', 'active');
+  await setEmulatedMediaFeature('forced-colors', 'none');
+  await setEmulatedMediaFeature('forced-colors', '__invalid__');
+
   // Test combinations.
   await setEmulatedMediaFeatures({
     features: [