[macOS] Toggling AX preferences does not update form control appearance

https://bugs.webkit.org/show_bug.cgi?id=264170
rdar://117914468

Reviewed by Wenson Hsieh.

cfprefsd is blocked in the GPU process. Consequently, any changes to
preferences are not automatically reflected to the process. For this reason,
there is existing logic for the UI process to notify the child processes of
preference changes.

Note that AppKit caches the value of some accessibility settings. The WebContent
process already works around this by invalidating the cache whenever an
accessibility setting is modified. However, the GPU process does not currently
use the same logic. Consequently, the AppKit's cache of accessibility settings
remains frozen in the GPU process.

To fix, ensure the cache is invalidated, by moving logic from `WebProcessCocoa`
into `AuxiliaryProcessCocoa`. This approach ensures that all child processes
invalidate the relevant cache.

* Source/WebCore/PAL/pal/spi/mac/HIServicesSPI.h:
* Source/WebKit/Shared/AuxiliaryProcess.h:
(WebKit::AuxiliaryProcess::accessibilitySettingsDidChange):
* Source/WebKit/Shared/Cocoa/AuxiliaryProcessCocoa.mm:
(WebKit::invertColorsPreferenceKey):
(WebKit::AuxiliaryProcess::handleAXPreferenceChange):

Additionally invalidate the cache when the "Differentiate without color"
setting is toggled.

(WebKit::handleAXPreferenceChange): Deleted.
* Source/WebKit/WebProcess/WebProcess.h:
* Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm:
(WebKit::WebProcess::handlePreferenceChange):
(WebKit::WebProcess::accessibilitySettingsDidChange):
(WebKit::invertColorsPreferenceKey): Deleted.

Canonical link: https://commits.webkit.org/270221@main

Source/WebCore/PAL/pal/spi/mac/HIServicesSPI.h

@@ -152,6 +152,8 @@ extern CFStringRef kAXInterfaceReduceMotionStatusDidChangeNotification;
 
 extern CFStringRef kAXInterfaceIncreaseContrastKey;
 
+extern CFStringRef kAXInterfaceDifferentiateWithoutColorKey;
+
 WTF_EXTERN_C_END
 
 #endif // USE(APPLE_INTERNAL_SDK)

Source/WebKit/Shared/AuxiliaryProcess.h

@@ -149,6 +149,8 @@ class AuxiliaryProcess : public IPC::Connection::Client, public IPC::MessageSend
     virtual void preferenceDidUpdate(const String& domain, const String& key, const std::optional<String>& encodedValue);
     virtual void handlePreferenceChange(const String& domain, const String& key, id value);
     virtual void dispatchSimulatedNotificationsForPreferenceChange(const String& key) { }
+
+    virtual void accessibilitySettingsDidChange() { }
 #endif
     void applyProcessCreationParameters(const AuxiliaryProcessCreationParameters&);
 
@@ -169,6 +171,10 @@ class AuxiliaryProcess : public IPC::Connection::Client, public IPC::MessageSend
     bool allowsFirstPartyForCookies(const WebCore::RegistrableDomain&, HashSet<WebCore::RegistrableDomain>&);
 
 private:
+#if ENABLE(CFPREFS_DIRECT_MODE)
+    void handleAXPreferenceChange(const String& domain, const String& key, id value);
+#endif
+
     virtual bool shouldOverrideQuarantine() { return true; }
 
     // IPC::MessageSender

Source/WebKit/Shared/Cocoa/AuxiliaryProcessCocoa.mm

@@ -46,6 +46,7 @@
 #endif
 
 #if PLATFORM(MAC)
+#import "AppKitSPI.h"
 #import <pal/spi/mac/HIServicesSPI.h>
 #endif
 
@@ -208,7 +209,15 @@ static void initializeTimerCoalescingPolicy()
 }
 #endif
 
-static void handleAXPreferenceChange(const String& domain, const String& key, id value)
+#if USE(APPKIT)
+static const WTF::String& invertColorsPreferenceKey()
+{
+    static NeverDestroyed<WTF::String> key(MAKE_STATIC_STRING_IMPL("whiteOnBlack"));
+    return key;
+}
+#endif
+
+void AuxiliaryProcess::handleAXPreferenceChange(const String& domain, const String& key, id value)
 {
 #if HAVE(UPDATE_WEB_ACCESSIBILITY_SETTINGS)
     if (!libAccessibilityLibrary())
@@ -228,6 +237,14 @@ static void handleAXPreferenceChange(const String& domain, const String& key, id
             _AXSSetDarkenSystemColors([(NSNumber *)value boolValue]);
 #endif
     }
+
+#if USE(APPKIT)
+    auto cfKey = key.createCFString();
+    if (CFEqual(cfKey.get(), kAXInterfaceReduceMotionKey) || CFEqual(cfKey.get(), kAXInterfaceIncreaseContrastKey) || CFEqual(cfKey.get(), kAXInterfaceDifferentiateWithoutColorKey) || key == invertColorsPreferenceKey()) {
+        [NSWorkspace _invalidateAccessibilityDisplayValues];
+        accessibilitySettingsDidChange();
+    }
+#endif
 }
 
 void AuxiliaryProcess::handlePreferenceChange(const String& domain, const String& key, id value)

Source/WebKit/WebProcess/WebProcess.h

@@ -649,6 +649,8 @@ class WebProcess : public AuxiliaryProcess
 #if ENABLE(CFPREFS_DIRECT_MODE)
     void handlePreferenceChange(const String& domain, const String& key, id value) final;
     void dispatchSimulatedNotificationsForPreferenceChange(const String& key) final;
+
+    void accessibilitySettingsDidChange() final;
 #endif
 
     void setNetworkProcessConnectionID(IPC::Connection::UniqueID);

Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm

@@ -1294,12 +1294,6 @@ static float currentBacklightLevel()
     static NeverDestroyed<WTF::String> userHighlightColorPreferenceKey(MAKE_STATIC_STRING_IMPL("AppleHighlightColor"));
     return userHighlightColorPreferenceKey;
 }
-
-static const WTF::String& invertColorsPreferenceKey()
-{
-    static NeverDestroyed<WTF::String> key(MAKE_STATIC_STRING_IMPL("whiteOnBlack"));
-    return key;
-}
 #endif
 
 static const WTF::String& captionProfilePreferenceKey()
@@ -1344,22 +1338,19 @@ static float currentBacklightLevel()
         WTF::languageDidChange();
     }
 
-#if USE(APPKIT)
-    auto cfKey = key.createCFString();
-    if (CFEqual(cfKey.get(), kAXInterfaceReduceMotionKey) || CFEqual(cfKey.get(), kAXInterfaceIncreaseContrastKey) || key == invertColorsPreferenceKey()) {
-        [NSWorkspace _invalidateAccessibilityDisplayValues];
-        for (auto& page : m_pageMap.values())
-            page->accessibilitySettingsDidChange();
-    }
-#endif
-
     AuxiliaryProcess::handlePreferenceChange(domain, key, value);
 }
 
 void WebProcess::notifyPreferencesChanged(const String& domain, const String& key, const std::optional<String>& encodedValue)
 {
     preferenceDidUpdate(domain, key, encodedValue);
 }
+
+void WebProcess::accessibilitySettingsDidChange()
+{
+    for (auto& page : m_pageMap.values())
+        page->accessibilitySettingsDidChange();
+}
 #endif
 
 void WebProcess::grantAccessToAssetServices(Vector<WebKit::SandboxExtension::Handle>&& assetServicesHandles)