Trigger events for prefers-color-scheme changes.

We triggered style changes as a result of prefers-color-scheme changing,
but we did not trigger 'change' events for matchMedia() as we skipped
the code in Document which did that.

Bug: 962156
Change-Id: Idba3ba9700aa24a2f9370360da22f6102fe82161
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1609821Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659433}

third_party/blink/renderer/core/accessibility/apply_dark_mode_test.cc

@@ -82,7 +82,7 @@ TEST_F(ApplyDarkModeCheckTest, MetaColorSchemeDark) {
       PreferredColorScheme::kDark);
   ColorSchemeSet schemes;
   schemes.Set(ColorScheme::kDark);
-  GetDocument().GetStyleEngine().SetMetaColorScheme(schemes);
+  GetDocument().SetMetaColorScheme(schemes);
   UpdateAllLifecyclePhasesForTest();
 
   // Opting out of forced darkening when dark is among the supported color

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

@@ -1798,7 +1798,6 @@ void StyleEngine::UpdateLayoutTreeRebuildRoot(ContainerNode* ancestor,
 void StyleEngine::UpdateColorScheme() {
   auto* settings = GetDocument().GetSettings();
   DCHECK(settings);
-  PreferredColorScheme old_preferred_scheme = preferred_color_scheme_;
   ColorScheme old_color_scheme = color_scheme_;
 
   preferred_color_scheme_ = settings->GetPreferredColorScheme();
@@ -1824,8 +1823,6 @@ void StyleEngine::UpdateColorScheme() {
       }
     }
   }
-  if (preferred_color_scheme_ != old_preferred_scheme)
-    MediaQueryAffectingValueChanged();
 }
 
 void StyleEngine::ColorSchemeChanged() {

third_party/blink/renderer/core/dom/document.cc

@@ -8010,6 +8010,16 @@ TrustedTypePolicyFactory* Document::GetTrustedTypes() const {
   return ExecutingWindow() ? ExecutingWindow()->trustedTypes() : nullptr;
 }
 
+void Document::SetMetaColorScheme(const ColorSchemeSet& meta_color_scheme) {
+  GetStyleEngine().SetMetaColorScheme(meta_color_scheme);
+  MediaQueryAffectingValueChanged();
+}
+
+void Document::ColorSchemeChanged() {
+  GetStyleEngine().ColorSchemeChanged();
+  MediaQueryAffectingValueChanged();
+}
+
 template class CORE_TEMPLATE_EXPORT Supplement<Document>;
 
 }  // namespace blink

third_party/blink/renderer/core/dom/document.h

@@ -1545,6 +1545,9 @@ class CORE_EXPORT Document : public ContainerNode,
 
   TrustedTypePolicyFactory* GetTrustedTypes() const override;
 
+  void SetMetaColorScheme(const ColorSchemeSet&);
+  void ColorSchemeChanged();
+
  protected:
   void DidUpdateSecurityOrigin() final;
 

third_party/blink/renderer/core/dom/document_test.cc

@@ -41,6 +41,8 @@
 #include "third_party/blink/renderer/bindings/core/v8/isolated_world_csp.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_testing.h"
+#include "third_party/blink/renderer/core/css/media_query_list_listener.h"
+#include "third_party/blink/renderer/core/css/media_query_matcher.h"
 #include "third_party/blink/renderer/core/dom/document_fragment.h"
 #include "third_party/blink/renderer/core/dom/node_with_index.h"
 #include "third_party/blink/renderer/core/dom/range.h"
@@ -343,6 +345,15 @@ class MockWebApplicationCacheHost : public blink::WebApplicationCacheHost {
   bool without_manifest_was_called_ = false;
 };
 
+class PrefersColorSchemeTestListener final : public MediaQueryListListener {
+ public:
+  void NotifyMediaQueryChanged() override { notified_ = true; }
+  bool IsNotified() const { return notified_; }
+
+ private:
+  bool notified_ = false;
+};
+
 }  // anonymous namespace
 
 TEST_F(DocumentTest, CreateRangeAdjustedToTreeScopeWithPositionInShadowTree) {
@@ -1191,6 +1202,24 @@ TEST_F(DocumentTest, ElementFromPointWithPageZoom) {
   EXPECT_EQ(GetDocument().ElementFromPoint(1, 12), GetDocument().body());
 }
 
+TEST_F(DocumentTest, PrefersColorSchemeChanged) {
+  UpdateAllLifecyclePhasesForTest();
+
+  auto* list = GetDocument().GetMediaQueryMatcher().MatchMedia(
+      "(prefers-color-scheme: dark)");
+  auto* listener = MakeGarbageCollected<PrefersColorSchemeTestListener>();
+  list->AddListener(listener);
+
+  EXPECT_FALSE(listener->IsNotified());
+
+  GetDocument().GetSettings()->SetPreferredColorScheme(
+      PreferredColorScheme::kDark);
+
+  GetDocument().ServiceScriptedAnimations(base::TimeTicks());
+
+  EXPECT_TRUE(listener->IsNotified());
+}
+
 /**
  * Tests for viewport-fit propagation.
  */

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

@@ -490,7 +490,7 @@ void HTMLMetaElement::ProcessColorScheme(const AtomicString& content) {
       color_scheme_set.Set(ColorScheme::kDark);
     }
   }
-  GetDocument().GetStyleEngine().SetMetaColorScheme(color_scheme_set);
+  GetDocument().SetMetaColorScheme(color_scheme_set);
 }
 
 void HTMLMetaElement::NameRemoved(const AtomicString& name_value) {

third_party/blink/renderer/core/layout/layout_theme_test.cc

@@ -110,7 +110,7 @@ TEST_F(LayoutThemeTest, RootElementColorChange) {
       PreferredColorScheme::kDark);
   ColorSchemeSet color_schemes;
   color_schemes.Set(ColorScheme::kDark);
-  GetDocument().GetStyleEngine().SetMetaColorScheme(color_schemes);
+  GetDocument().SetMetaColorScheme(color_schemes);
   UpdateAllLifecyclePhasesForTest();
 
   document_element_style = GetDocument().documentElement()->GetComputedStyle();

third_party/blink/renderer/core/page/page.cc

@@ -716,7 +716,7 @@ void Page::SettingsChanged(SettingsDelegate::ChangeType change_type) {
       for (Frame* frame = MainFrame(); frame;
            frame = frame->Tree().TraverseNext()) {
         if (auto* local_frame = DynamicTo<LocalFrame>(frame))
-          local_frame->GetDocument()->GetStyleEngine().ColorSchemeChanged();
+          local_frame->GetDocument()->ColorSchemeChanged();
       }
       break;
     case SettingsDelegate::kSpatialNavigationChange: