Bug 1762298 - Inherit used color-scheme from embedder <browser> elements. r=nika,dao,Gijs

This allows popups and sidebars to use the chrome preferred
color-scheme.

This moves the responsibility of setting the content-preferred color
scheme to the appropriate browsers to the front-end (via tabs.css).

We still return the PreferredColorSchemeForContent() when there's no
pres context (e.g., for display:none in-process iframes). We could
potentially move a bunch of the pres-context data to the document
instead, but that should be acceptable IMO as for general web content
there's no behavior change in any case.

Differential Revision: https://phabricator.services.mozilla.com/D142578

browser/themes/shared/tabs.css

@@ -17,6 +17,10 @@
   --tabpanel-background-color: #F9F9FB;
 }
 
+#tabbrowser-tabpanels browser {
+  color-scheme: env(-moz-content-preferred-color-scheme);
+}
+
 @media (-moz-content-prefers-color-scheme: dark) {
   :root {
     /* --tabpanel-background-color matches $in-content-page-background in newtab

docshell/base/BrowsingContext.cpp

@@ -703,8 +703,8 @@ void BrowsingContext::SetEmbedderElement(Element* aEmbedder) {
       }
       txn.SetMessageManagerGroup(messageManagerGroup);
 
-      bool useGlobalHistory = !aEmbedder->HasAttr(
-          kNameSpaceID_None, nsGkAtoms::disableglobalhistory);
+      bool useGlobalHistory =
+          !aEmbedder->HasAttr(nsGkAtoms::disableglobalhistory);
       txn.SetUseGlobalHistory(useGlobalHistory);
     }
 
@@ -2781,19 +2781,21 @@ bool BrowsingContext::CanSet(FieldIndex<IDX_TouchEventsOverrideInternal>,
   return XRE_IsParentProcess() && !aSource;
 }
 
+void BrowsingContext::DidSet(FieldIndex<IDX_EmbedderColorScheme>,
+                             dom::PrefersColorSchemeOverride aOldValue) {
+  if (GetEmbedderColorScheme() == aOldValue) {
+    return;
+  }
+  PresContextAffectingFieldChanged();
+}
+
 void BrowsingContext::DidSet(FieldIndex<IDX_PrefersColorSchemeOverride>,
                              dom::PrefersColorSchemeOverride aOldValue) {
   MOZ_ASSERT(IsTop());
   if (PrefersColorSchemeOverride() == aOldValue) {
     return;
   }
-  PreOrderWalk([&](BrowsingContext* aContext) {
-    if (nsIDocShell* shell = aContext->GetDocShell()) {
-      if (nsPresContext* pc = shell->GetPresContext()) {
-        pc->RecomputeBrowsingContextDependentData();
-      }
-    }
-  });
+  PresContextAffectingFieldChanged();
 }
 
 void BrowsingContext::DidSet(FieldIndex<IDX_MediumOverride>,
@@ -2802,13 +2804,7 @@ void BrowsingContext::DidSet(FieldIndex<IDX_MediumOverride>,
   if (GetMediumOverride() == aOldValue) {
     return;
   }
-  PreOrderWalk([&](BrowsingContext* aContext) {
-    if (nsIDocShell* shell = aContext->GetDocShell()) {
-      if (nsPresContext* pc = shell->GetPresContext()) {
-        pc->RecomputeBrowsingContextDependentData();
-      }
-    }
-  });
+  PresContextAffectingFieldChanged();
 }
 
 void BrowsingContext::DidSet(FieldIndex<IDX_DisplayMode>,
@@ -2878,7 +2874,10 @@ void BrowsingContext::DidSet(FieldIndex<IDX_OverrideDPPX>, float aOldValue) {
   if (GetOverrideDPPX() == aOldValue) {
     return;
   }
+  PresContextAffectingFieldChanged();
+}
 
+void BrowsingContext::PresContextAffectingFieldChanged() {
   PreOrderWalk([&](BrowsingContext* aContext) {
     if (nsIDocShell* shell = aContext->GetDocShell()) {
       if (nsPresContext* pc = shell->GetPresContext()) {

docshell/base/BrowsingContext.h

@@ -210,8 +210,12 @@ enum class ExplicitActiveStatus : uint8_t {
   FIELD(AuthorStyleDisabledDefault, bool)                                     \
   FIELD(ServiceWorkersTestingEnabled, bool)                                   \
   FIELD(MediumOverride, nsString)                                             \
-  FIELD(PrefersColorSchemeOverride, mozilla::dom::PrefersColorSchemeOverride) \
-  FIELD(DisplayMode, mozilla::dom::DisplayMode)                               \
+  /* DevTools override for prefers-color-scheme */                            \
+  FIELD(PrefersColorSchemeOverride, dom::PrefersColorSchemeOverride)          \
+  /* prefers-color-scheme override based on the color-scheme style of our     \
+   * <browser> embedder element. */                                           \
+  FIELD(EmbedderColorScheme, dom::PrefersColorSchemeOverride)                 \
+  FIELD(DisplayMode, dom::DisplayMode)                                        \
   /* The number of entries added to the session history because of this       \
    * browsing context. */                                                     \
   FIELD(HistoryEntryCount, uint32_t)                                          \
@@ -1017,6 +1021,11 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
     return IsTop();
   }
 
+  bool CanSet(FieldIndex<IDX_EmbedderColorScheme>,
+              dom::PrefersColorSchemeOverride, ContentParent* aSource) {
+    return CheckOnlyEmbedderCanSet(aSource);
+  }
+
   bool CanSet(FieldIndex<IDX_PrefersColorSchemeOverride>,
               dom::PrefersColorSchemeOverride, ContentParent*) {
     return IsTop();
@@ -1024,9 +1033,14 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
 
   void DidSet(FieldIndex<IDX_InRDMPane>, bool aOldValue);
 
+  void DidSet(FieldIndex<IDX_EmbedderColorScheme>,
+              dom::PrefersColorSchemeOverride aOldValue);
+
   void DidSet(FieldIndex<IDX_PrefersColorSchemeOverride>,
               dom::PrefersColorSchemeOverride aOldValue);
 
+  void PresContextAffectingFieldChanged();
+
   void DidSet(FieldIndex<IDX_MediumOverride>, nsString&& aOldValue);
 
   bool CanSet(FieldIndex<IDX_SuspendMediaWhenInactive>, bool, ContentParent*) {

docshell/base/CanonicalBrowsingContext.cpp

@@ -306,6 +306,7 @@ void CanonicalBrowsingContext::ReplacedBy(
   txn.SetBrowserId(GetBrowserId());
   txn.SetHistoryID(GetHistoryID());
   txn.SetExplicitActive(GetExplicitActive());
+  txn.SetEmbedderColorScheme(GetEmbedderColorScheme());
   txn.SetHasRestoreData(GetHasRestoreData());
   txn.SetShouldDelayMediaFromStart(GetShouldDelayMediaFromStart());
   // As this is a different BrowsingContext, set InitialSandboxFlags to the

dom/base/Document.cpp

@@ -17741,7 +17741,7 @@ ColorScheme Document::PreferredColorScheme(IgnoreRFP aIgnoreRFP) const {
   }
 
   if (nsPresContext* pc = GetPresContext()) {
-    if (auto scheme = pc->GetOverriddenColorScheme()) {
+    if (auto scheme = pc->GetOverriddenOrEmbedderColorScheme()) {
       return *scheme;
     }
   }

dom/base/nsFrameLoader.cpp

@@ -2657,6 +2657,7 @@ bool nsFrameLoader::TryRemoteBrowserInternal() {
       // - about:preferences (in Thunderbird only) so it can load remote
       //     extension options pages for FileLink providers
       // - DevTools webext panels if DevTools is loaded in a content frame
+      // - Chrome mochitests can also do this.
       //
       // Note that the new frame's message manager will not be a child of the
       // chrome window message manager, and, the values of window.top and
@@ -2672,16 +2673,37 @@ bool nsFrameLoader::TryRemoteBrowserInternal() {
         return false;
       }
 
-      if (!(specIgnoringRef.EqualsLiteral("about:addons") ||
-            specIgnoringRef.EqualsLiteral(
-                "chrome://mozapps/content/extensions/aboutaddons.html") ||
+      const bool allowed = [&] {
+        const nsLiteralCString kAllowedURIs[] = {
+            "about:addons"_ns,
+            "chrome://mozapps/content/extensions/aboutaddons.html"_ns,
 #ifdef MOZ_THUNDERBIRD
-            specIgnoringRef.EqualsLiteral("about:3pane") ||
-            specIgnoringRef.EqualsLiteral("about:message") ||
-            specIgnoringRef.EqualsLiteral("about:preferences") ||
+            "about:3pane"_ns,
+            "about:message"_ns,
+            "about:preferences"_ns,
 #endif
-            specIgnoringRef.EqualsLiteral(
-                "chrome://browser/content/webext-panels.xhtml"))) {
+            "chrome://browser/content/webext-panels.xhtml"_ns,
+        };
+
+        for (const auto& allowedURI : kAllowedURIs) {
+          if (specIgnoringRef.Equals(allowedURI)) {
+            return true;
+          }
+        }
+
+        if (xpc::IsInAutomation() &&
+            StringBeginsWith(specIgnoringRef,
+                             "chrome://mochitests/content/chrome/"_ns)) {
+          return true;
+        }
+        return false;
+      }();
+
+      if (!allowed) {
+        NS_WARNING(
+            nsPrintfCString("Forbidden remote frame from content docshell %s",
+                            specIgnoringRef.get())
+                .get());
         return false;
       }
     }

image/test/mochitest/test_mq_dynamic_svg.html

@@ -20,16 +20,29 @@ function snapshotsEqual() {
   return compareSnapshots(s1, s2, true)[0];
 }
 
+function waitForColorSchemeToBe(scheme) {
+  return new Promise(resolve => {
+    let mq = matchMedia(`(prefers-color-scheme: ${scheme})`);
+    if (mq.matches) {
+      resolve();
+    } else {
+      mq.addEventListener("change", resolve, { once: true });
+    }
+  });
+}
+
 async function run() {
   let loadedFrame1 = new Promise(resolve => f1.onload = resolve);
   let loadedFrame2 = new Promise(resolve => f2.onload = resolve);
   await SpecialPowers.pushPrefEnv({ set: [["layout.css.prefers-color-scheme.content-override", 1]] });
+  await waitForColorSchemeToBe("light");
   f1.src = "mq_dynamic_svg_test.html";
   f2.src = "mq_dynamic_svg_ref.html";
   await loadedFrame1;
   await loadedFrame2;
   ok(!snapshotsEqual(), "In light mode snapshot comparison should be false");
   await SpecialPowers.pushPrefEnv({ set: [["layout.css.prefers-color-scheme.content-override", 0]] });
+  await waitForColorSchemeToBe("dark");
   ok(snapshotsEqual(), "In dark mode snapshot comparison should be true");
   SimpleTest.finish();
 }

layout/base/nsPresContext.cpp

@@ -285,7 +285,7 @@ nsPresContext::nsPresContext(dom::Document* aDocument, nsPresContextType aType)
 #ifdef DEBUG
       mInitialized(false),
 #endif
-      mColorSchemeOverride(dom::PrefersColorSchemeOverride::None) {
+      mOverriddenOrEmbedderColorScheme(dom::PrefersColorSchemeOverride::None) {
 #ifdef DEBUG
   PodZero(&mLayoutPhaseCount);
 #endif
@@ -869,12 +869,12 @@ void nsPresContext::AttachPresShell(mozilla::PresShell* aPresShell) {
   UpdateCharSet(doc->GetDocumentCharacterSet());
 }
 
-Maybe<ColorScheme> nsPresContext::GetOverriddenColorScheme() const {
+Maybe<ColorScheme> nsPresContext::GetOverriddenOrEmbedderColorScheme() const {
   if (IsPrintingOrPrintPreview()) {
     return Some(ColorScheme::Light);
   }
 
-  switch (mColorSchemeOverride) {
+  switch (mOverriddenOrEmbedderColorScheme) {
     case dom::PrefersColorSchemeOverride::Dark:
       return Some(ColorScheme::Dark);
     case dom::PrefersColorSchemeOverride::Light:
@@ -905,9 +905,23 @@ void nsPresContext::RecomputeBrowsingContextDependentData() {
   SetTextZoom(browsingContext->TextZoom());
   SetOverrideDPPX(browsingContext->OverrideDPPX());
 
-  auto oldOverride = mColorSchemeOverride;
-  mColorSchemeOverride = browsingContext->Top()->PrefersColorSchemeOverride();
-  if (oldOverride != mColorSchemeOverride) {
+  auto oldScheme = mDocument->PreferredColorScheme();
+  auto* top = browsingContext->Top();
+  mOverriddenOrEmbedderColorScheme = [&] {
+    auto overriden = top->PrefersColorSchemeOverride();
+    if (overriden != PrefersColorSchemeOverride::None) {
+      return overriden;
+    }
+    for (auto* cur = browsingContext; cur; cur = cur->GetParent()) {
+      auto embedder = cur->GetEmbedderColorScheme();
+      if (embedder != PrefersColorSchemeOverride::None) {
+        return embedder;
+      }
+    }
+    return PrefersColorSchemeOverride::None;
+  }();
+
+  if (mDocument->PreferredColorScheme() != oldScheme) {
     // We need to restyle because not only media queries have changed, system
     // colors may as well via the prefers-color-scheme meta tag / effective
     // color-scheme property value.
@@ -918,7 +932,6 @@ void nsPresContext::RecomputeBrowsingContextDependentData() {
 
   if (doc == mDocument) {
     // Medium doesn't apply to resource documents, etc.
-    auto* top = browsingContext->Top();
     RefPtr<nsAtom> mediumToEmulate;
     if (MOZ_UNLIKELY(!top->GetMediumOverride().IsEmpty())) {
       nsAutoString lower;

layout/base/nsPresContext.h

@@ -580,11 +580,11 @@ class nsPresContext : public nsISupports, public mozilla::SupportsWeakPtr {
 
   float GetOverrideDPPX() const { return mMediaEmulationData.mDPPX; }
 
-  // Gets the forced color-scheme if any via either DevTools emulation or
-  // printing.
+  // Gets the forced color-scheme if any via either our embedder, or DevTools
+  // emulation, or printing.
   //
   // NOTE(emilio): This might be called from an stylo thread.
-  Maybe<mozilla::ColorScheme> GetOverriddenColorScheme() const;
+  Maybe<mozilla::ColorScheme> GetOverriddenOrEmbedderColorScheme() const;
 
   /**
    * Recomputes the data dependent on the browsing context, like zoom and text
@@ -1377,7 +1377,7 @@ class nsPresContext : public nsISupports, public mozilla::SupportsWeakPtr {
   // FIXME(emilio): These would be better packed on top of the bitfields, but
   // that breaks bindgen in win32.
   FontVisibility mFontVisibility = FontVisibility::Unknown;
-  mozilla::dom::PrefersColorSchemeOverride mColorSchemeOverride;
+  mozilla::dom::PrefersColorSchemeOverride mOverriddenOrEmbedderColorScheme;
 
  protected:
   virtual ~nsPresContext();

layout/base/tests/chrome/chrome.ini

@@ -94,6 +94,7 @@ support-files =
   bug1041200_frame.html
   bug1041200_window.html
 [test_chrome_content_integration.xhtml]
+[test_color_scheme_browser.xhtml]
 [test_default_background.xhtml]
 [test_dialog_with_positioning.html]
 tags = openwindow

layout/base/tests/chrome/test_color_scheme_browser.xhtml

@@ -0,0 +1,77 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+      windowtype="Toolkit:PictureInPicture"
+      chromemargin="0,0,0,0">
+  <head>
+    <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+    <script src="chrome://mochikit/content/chrome-harness.js"></script>
+    <style>
+      #light { color-scheme: light }
+      #dark { color-scheme: dark }
+    </style>
+  </head>
+  <body>
+    <div id="dynamic-test">
+      <xul:browser type="content" remote="true" src="about:blank" class="remote" />
+      <xul:browser type="content" src="about:blank" class="nonremote" />
+    </div>
+    <div id="light">
+      <xul:browser type="content" remote="true" src="about:blank" class="remote" />
+      <xul:browser type="content" src="about:blank" class="nonremote" />
+    </div>
+    <div id="dark">
+      <xul:browser type="content" remote="true" src="about:blank" class="remote" />
+      <xul:browser type="content" src="about:blank" class="nonremote" />
+    </div>
+    <script><![CDATA[
+      async function getBrowserColorScheme(browser) {
+        return SpecialPowers.spawn(browser, [], () => {
+          return content.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+        });
+      }
+      async function tick() {
+        return new Promise(resolve => {
+          requestAnimationFrame(() => requestAnimationFrame(resolve));
+        });
+      }
+      async function testElement(id, expected) {
+        let element = document.getElementById(id);
+        for (let browser of element.querySelectorAll("browser")) {
+          let scheme = await getBrowserColorScheme(browser);
+          is(scheme, expected, `${id}: ${browser.className} should be ${expected}`);
+        }
+      }
+      add_task(async function test_browser_color_scheme() {
+        for (let id of ["dynamic-test", "light", "dark"]) {
+          let expected = id == "dynamic-test"
+                ? (matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light")
+                : id;
+          await testElement(id, expected);
+        }
+      });
+
+      add_task(async function test_browser_color_scheme_dynamic_style() {
+        let dynamicTest = document.getElementById("dynamic-test");
+        for (let value of ["light", "dark"]) {
+          await tick();
+          dynamicTest.style.colorScheme = value;
+          await testElement("dynamic-test", value);
+        }
+        dynamicTest.style.colorScheme = "";
+        await tick();
+      });
+
+      add_task(async function test_browser_color_scheme_dynamic_system() {
+        for (let dark of [true, false]) {
+          await SpecialPowers.pushPrefEnv({ set: [["ui.systemUsesDarkTheme", dark ? 1 : 0]] });
+          await tick();
+          await testElement("dynamic-test", dark ? "dark" : "light");
+          await SpecialPowers.popPrefEnv();
+        }
+      });
+    ]]></script>
+  </body>
+</html>
+

layout/generic/nsContainerFrame.cpp

@@ -779,7 +779,7 @@ void nsContainerFrame::SyncWindowProperties(nsPresContext* aPresContext,
     windowWidget->SetWindowShadowStyle(shadow);
 
     // For macOS, apply color scheme overrides to the top level window widget.
-    if (auto scheme = aPresContext->GetOverriddenColorScheme()) {
+    if (auto scheme = aPresContext->GetOverriddenOrEmbedderColorScheme()) {
       windowWidget->SetColorScheme(scheme);
     }
   }

layout/generic/nsSubDocumentFrame.cpp

@@ -203,6 +203,8 @@ void nsSubDocumentFrame::ShowViewer() {
       frameloader->UpdatePositionAndSize(this);
     }
 
+    MaybeUpdateEmbedderColorScheme();
+
     if (!weakThis.IsAlive()) {
       return;
     }
@@ -807,9 +809,49 @@ nsresult nsSubDocumentFrame::AttributeChanged(int32_t aNameSpaceID,
   return NS_OK;
 }
 
+void nsSubDocumentFrame::MaybeUpdateEmbedderColorScheme() {
+  if (!mContent->IsXULElement()) {
+    // We only do this for XUL <browser>s.
+    return;
+  }
+
+  nsFrameLoader* fl = mFrameLoader.get();
+  if (!fl) {
+    return;
+  }
+
+  BrowsingContext* bc = fl->GetExtantBrowsingContext();
+  if (!bc) {
+    return;
+  }
+
+  auto usedColorScheme = LookAndFeel::ColorSchemeForFrame(this);
+  bool needUpdate = [&] {
+    switch (bc->GetEmbedderColorScheme()) {
+      case PrefersColorSchemeOverride::Light:
+        return usedColorScheme != ColorScheme::Light;
+      case PrefersColorSchemeOverride::Dark:
+        return usedColorScheme != ColorScheme::Dark;
+      case PrefersColorSchemeOverride::None:
+      case PrefersColorSchemeOverride::EndGuard_:
+        return true;
+    }
+  }();
+  if (!needUpdate) {
+    return;
+  }
+
+  auto value = usedColorScheme == ColorScheme::Dark
+                   ? PrefersColorSchemeOverride::Dark
+                   : PrefersColorSchemeOverride::Light;
+  Unused << bc->SetEmbedderColorScheme(value);
+}
+
 void nsSubDocumentFrame::DidSetComputedStyle(ComputedStyle* aOldComputedStyle) {
   nsAtomicContainerFrame::DidSetComputedStyle(aOldComputedStyle);
 
+  MaybeUpdateEmbedderColorScheme();
+
   // If this presshell has invisible ancestors, we don't need to propagate the
   // visibility style change to the subdocument since the subdocument should
   // have already set the IsUnderHiddenEmbedderElement flag in

layout/generic/nsSubDocumentFrame.h

@@ -133,6 +133,7 @@ class nsSubDocumentFrame final : public nsAtomicContainerFrame,
   void ResetFrameLoader(RetainPaintData);
   void ClearRetainedPaintData();
 
+  void MaybeUpdateEmbedderColorScheme();
   void PropagateIsUnderHiddenEmbedderElementToSubView(
       bool aIsUnderHiddenEmbedderElement);
 

layout/style/test/test_non_content_accessible_env_vars.html

@@ -9,6 +9,7 @@ const NON_CONTENT_ACCESSIBLE_ENV_VARS = [
   "-moz-gtk-csd-minimize-button-position",
   "-moz-gtk-csd-maximize-button-position",
   "-moz-gtk-csd-close-button-position",
+  "-moz-content-preferred-color-scheme",
 ];
 
 const div = document.querySelector("div");

servo/components/style/custom_properties.rs

@@ -64,6 +64,20 @@ fn get_safearea_inset_right(device: &Device) -> VariableValue {
     VariableValue::pixels(device.safe_area_insets().right)
 }
 
+fn get_content_preferred_color_scheme(device: &Device) -> VariableValue {
+    use crate::gecko::media_features::PrefersColorScheme;
+    let prefers_color_scheme = unsafe {
+        crate::gecko_bindings::bindings::Gecko_MediaFeatures_PrefersColorScheme(
+            device.document(),
+            /* use_content = */ true,
+        )
+    };
+    VariableValue::ident(match prefers_color_scheme {
+        PrefersColorScheme::Light => "light",
+        PrefersColorScheme::Dark => "dark",
+    })
+}
+
 static ENVIRONMENT_VARIABLES: [EnvironmentVariable; 4] = [
     make_variable!(atom!("safe-area-inset-top"), get_safearea_inset_top),
     make_variable!(atom!("safe-area-inset-bottom"), get_safearea_inset_bottom),
@@ -90,7 +104,7 @@ macro_rules! lnf_int_variable {
     }};
 }
 
-static CHROME_ENVIRONMENT_VARIABLES: [EnvironmentVariable; 5] = [
+static CHROME_ENVIRONMENT_VARIABLES: [EnvironmentVariable; 6] = [
     lnf_int_variable!(
         atom!("-moz-gtk-csd-titlebar-radius"),
         TitlebarRadius,
@@ -112,6 +126,7 @@ static CHROME_ENVIRONMENT_VARIABLES: [EnvironmentVariable; 5] = [
         GTKCSDMaximizeButtonPosition,
         integer
     ),
+    make_variable!(atom!("-moz-content-preferred-color-scheme"), get_content_preferred_color_scheme),
 ];
 
 impl CssEnvironment {
@@ -319,6 +334,11 @@ impl VariableValue {
         })
     }
 
+    /// Create VariableValue from an int.
+    fn ident(ident: &'static str) -> Self {
+        Self::from_token(Token::Ident(ident.into()))
+    }
+
     /// Create VariableValue from a float amount of CSS pixels.
     fn pixels(number: f32) -> Self {
         // FIXME (https://github.com/servo/rust-cssparser/issues/266):

toolkit/components/thumbnails/BackgroundPageThumbs.jsm

@@ -380,6 +380,7 @@ const BackgroundPageThumbs = {
     // thumbnails are blank and transparent -- but setting the style does.
     browser.style.width = bwidth + "px";
     browser.style.height = (bwidth * sheight.value) / swidth.value + "px";
+    browser.style.colorScheme = "env(-moz-content-preferred-color-scheme)";
 
     this._parentWin.document.documentElement.appendChild(browser);
 

xpcom/ds/StaticAtoms.py

@@ -2246,6 +2246,7 @@ STATIC_ATOMS = [
     Atom("_moz_gtk_csd_reversed_placement", "-moz-gtk-csd-reversed-placement"),
     Atom("_moz_gtk_csd_menu_radius", "-moz-gtk-csd-menu-radius"),
     Atom("_moz_content_prefers_color_scheme", "-moz-content-prefers-color-scheme"),
+    Atom("_moz_content_preferred_color_scheme", "-moz-content-preferred-color-scheme"),
     Atom("_moz_proton_places_tooltip", "-moz-proton-places-tooltip"),
     Atom("_moz_system_dark_theme", "-moz-system-dark-theme"),
     # application commands