pref observer and fixator

app/lib/features/geckoview/features/browser/domain/services/engine_settings_replication.dart

@@ -22,6 +22,7 @@ import 'package:flutter_mozilla_components/flutter_mozilla_components.dart';
 import 'package:riverpod/riverpod.dart';
 import 'package:riverpod_annotation/riverpod_annotation.dart';
 import 'package:weblibre/core/logger.dart';
+import 'package:weblibre/features/geckoview/features/preferences/data/repositories/preference_observer.dart';
 import 'package:weblibre/features/user/domain/repositories/engine_settings.dart';
 import 'package:weblibre/features/user/domain/repositories/general_settings.dart';
 
@@ -134,8 +135,20 @@ class EngineSettingsReplicationService
                 settings.fingerprintingProtectionOverrides,
               );
             }
+            if (previous.value?.enablePdfJs != settings.enablePdfJs) {
+              // ignore: only_use_keep_alive_inside_keep_alive
+              await ref
+                  .read(preferenceFixatorProvider.notifier)
+                  .register('pdfjs.disabled', !settings.enablePdfJs);
+            }
           } else {
             await _service.setDefaultSettings(settings);
+
+            // ignore: only_use_keep_alive_inside_keep_alive
+            await ref
+                .read(preferenceFixatorProvider.notifier)
+                .register('pdfjs.disabled', !settings.enablePdfJs);
+
             initialSettingsSent = true;
           }
         }

app/lib/features/geckoview/features/browser/domain/services/engine_settings_replication.g.dart

@@ -44,7 +44,7 @@ final class EngineSettingsReplicationServiceProvider
 }
 
 String _$engineSettingsReplicationServiceHash() =>
-    r'3c96e6e45537399582fdf6e8b1fafc44c613b89d';
+    r'd28cc58a94f45008a478bf52a9c40d61811b591d';
 
 abstract class _$EngineSettingsReplicationService extends $Notifier<void> {
   void build();

app/lib/features/geckoview/features/browser/presentation/widgets/browser_modules/browser_view.dart

@@ -44,6 +44,7 @@ import 'package:weblibre/features/geckoview/features/browser/domain/providers/li
 import 'package:weblibre/features/geckoview/features/browser/domain/services/browser_data.dart';
 import 'package:weblibre/features/geckoview/features/browser/domain/services/engine_settings_replication.dart';
 import 'package:weblibre/features/geckoview/features/browser/domain/services/proxy_settings_replication.dart';
+import 'package:weblibre/features/geckoview/features/preferences/data/repositories/preference_observer.dart';
 import 'package:weblibre/features/share_intent/domain/entities/shared_content.dart';
 import 'package:weblibre/features/user/data/models/general_settings.dart';
 import 'package:weblibre/features/user/domain/repositories/cache.dart';
@@ -373,6 +374,19 @@ class _BrowserViewState extends ConsumerState<BrowserView>
       },
     );
 
+    ref.listenManual(
+      fireImmediately: true,
+      preferenceFixatorProvider,
+      (previous, next) {},
+      onError: (error, stackTrace) {
+        logger.e(
+          'Error listening to preferenceFixatorProvider',
+          error: error,
+          stackTrace: stackTrace,
+        );
+      },
+    );
+
     ref.listenManual(
       fireImmediately: true,
       proxySettingsReplicationProvider,

app/lib/features/geckoview/features/preferences/data/models/preference_setting.dart

@@ -56,7 +56,7 @@ class PreferenceSetting with FastEquatable {
   final Object value;
 
   @JsonKey(includeFromJson: false, includeToJson: false)
-  final GeckoPrefValue? current;
+  final GeckoPref? current;
 
   bool get isActive => value == current?.value;
 

app/lib/features/geckoview/features/preferences/data/models/preference_setting.g.dart

@@ -80,7 +80,7 @@ abstract class _$PreferenceSettingCWProxy {
 
   PreferenceSetting description(String? description);
 
-  PreferenceSetting current(GeckoPrefValue? current);
+  PreferenceSetting current(GeckoPref? current);
 
   PreferenceSetting requireUserOptIn(bool requireUserOptIn);
 
@@ -97,7 +97,7 @@ abstract class _$PreferenceSettingCWProxy {
     Object value,
     String? title,
     String? description,
-    GeckoPrefValue? current,
+    GeckoPref? current,
     bool requireUserOptIn,
     bool shouldBeDefault,
   });
@@ -121,7 +121,7 @@ class _$PreferenceSettingCWProxyImpl implements _$PreferenceSettingCWProxy {
       call(description: description);
 
   @override
-  PreferenceSetting current(GeckoPrefValue? current) => call(current: current);
+  PreferenceSetting current(GeckoPref? current) => call(current: current);
 
   @override
   PreferenceSetting requireUserOptIn(bool requireUserOptIn) =>
@@ -163,7 +163,7 @@ class _$PreferenceSettingCWProxyImpl implements _$PreferenceSettingCWProxy {
       current: current == const $CopyWithPlaceholder()
           ? _value.current
           // ignore: cast_nullable_to_non_nullable
-          : current as GeckoPrefValue?,
+          : current as GeckoPref?,
       requireUserOptIn:
           requireUserOptIn == const $CopyWithPlaceholder() ||
               requireUserOptIn == null

app/lib/features/geckoview/features/preferences/data/repositories/preference_observer.dart

@@ -0,0 +1,81 @@
+import 'dart:async';
+
+import 'package:flutter_mozilla_components/flutter_mozilla_components.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:weblibre/features/geckoview/domain/providers.dart';
+
+part 'preference_observer.g.dart';
+
+@Riverpod()
+class PreferenceChangeListener extends _$PreferenceChangeListener {
+  @override
+  Stream<GeckoPref> build() async* {
+    final events = ref.watch(eventServiceProvider);
+
+    await GeckoPrefService().startObserveChanges();
+
+    ref.onDispose(() async {
+      await GeckoPrefService().stopObserveChanges();
+    });
+
+    yield* events.prefUpdateEvent;
+  }
+}
+
+@Riverpod()
+class PreferenceFixator extends _$PreferenceFixator {
+  Future<void> register(String name, Object value) async {
+    await GeckoPrefService().applyPrefs({name: value});
+
+    state = {...state}
+      ..update(
+        name,
+        (_) => value,
+        ifAbsent: () {
+          unawaited(GeckoPrefService().registerPrefForObservation(name));
+          return value;
+        },
+      );
+  }
+
+  Future<void> unregister(String name) async {
+    await GeckoPrefService().unregisterPrefForObservation(name);
+    state = {...state}..remove(name);
+  }
+
+  @override
+  Map<String, Object> build() {
+    ref.listen(preferenceChangeListenerProvider, (previous, next) async {
+      if (next.hasValue) {
+        final setting = stateOrNull?[next.value!.name];
+        if (setting != null && next.value?.value != setting) {
+          await GeckoPrefService().applyPrefs({next.value!.name: setting});
+        }
+      }
+    });
+
+    return {};
+  }
+}
+
+// @Riverpod()
+// class PreferenceObserver extends _$PreferenceObserver {
+//   @override
+//   Stream<GeckoPref> build(String pref) {
+//     final updateStream = ref
+//         .watch(preferenceChangeListenerProvider)
+//         .where((x) => x.name == pref);
+
+//     unawaited(GeckoPrefService().registerPrefForObservation(pref));
+
+//     ref.onDispose(() async {
+//       await GeckoPrefService().unregisterPrefForObservation(pref);
+//     });
+
+//     return GeckoPrefService()
+//         .getPrefs([pref])
+//         .asStream()
+//         .map((value) => value.values.first)
+//         .concatWith([updateStream]);
+//   }
+// }

app/lib/features/geckoview/features/preferences/data/repositories/preference_observer.g.dart

@@ -0,0 +1,109 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'preference_observer.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// ignore_for_file: type=lint, type=warning
+
+@ProviderFor(PreferenceChangeListener)
+const preferenceChangeListenerProvider = PreferenceChangeListenerProvider._();
+
+final class PreferenceChangeListenerProvider
+    extends $StreamNotifierProvider<PreferenceChangeListener, GeckoPref> {
+  const PreferenceChangeListenerProvider._()
+    : super(
+        from: null,
+        argument: null,
+        retry: null,
+        name: r'preferenceChangeListenerProvider',
+        isAutoDispose: true,
+        dependencies: null,
+        $allTransitiveDependencies: null,
+      );
+
+  @override
+  String debugGetCreateSourceHash() => _$preferenceChangeListenerHash();
+
+  @$internal
+  @override
+  PreferenceChangeListener create() => PreferenceChangeListener();
+}
+
+String _$preferenceChangeListenerHash() =>
+    r'668c1bcd0636ec515a5e92ee5ba4ea7a67fa7a6d';
+
+abstract class _$PreferenceChangeListener extends $StreamNotifier<GeckoPref> {
+  Stream<GeckoPref> build();
+  @$mustCallSuper
+  @override
+  void runBuild() {
+    final created = build();
+    final ref = this.ref as $Ref<AsyncValue<GeckoPref>, GeckoPref>;
+    final element =
+        ref.element
+            as $ClassProviderElement<
+              AnyNotifier<AsyncValue<GeckoPref>, GeckoPref>,
+              AsyncValue<GeckoPref>,
+              Object?,
+              Object?
+            >;
+    element.handleValue(ref, created);
+  }
+}
+
+@ProviderFor(PreferenceFixator)
+const preferenceFixatorProvider = PreferenceFixatorProvider._();
+
+final class PreferenceFixatorProvider
+    extends $NotifierProvider<PreferenceFixator, Map<String, Object>> {
+  const PreferenceFixatorProvider._()
+    : super(
+        from: null,
+        argument: null,
+        retry: null,
+        name: r'preferenceFixatorProvider',
+        isAutoDispose: true,
+        dependencies: null,
+        $allTransitiveDependencies: null,
+      );
+
+  @override
+  String debugGetCreateSourceHash() => _$preferenceFixatorHash();
+
+  @$internal
+  @override
+  PreferenceFixator create() => PreferenceFixator();
+
+  /// {@macro riverpod.override_with_value}
+  Override overrideWithValue(Map<String, Object> value) {
+    return $ProviderOverride(
+      origin: this,
+      providerOverride: $SyncValueProvider<Map<String, Object>>(value),
+    );
+  }
+}
+
+String _$preferenceFixatorHash() => r'dfa323859c660d3db74dba7297e2a33b758ed78a';
+
+abstract class _$PreferenceFixator extends $Notifier<Map<String, Object>> {
+  Map<String, Object> build();
+  @$mustCallSuper
+  @override
+  void runBuild() {
+    final created = build();
+    final ref = this.ref as $Ref<Map<String, Object>, Map<String, Object>>;
+    final element =
+        ref.element
+            as $ClassProviderElement<
+              AnyNotifier<Map<String, Object>, Map<String, Object>>,
+              Map<String, Object>,
+              Object?,
+              Object?
+            >;
+    element.handleValue(ref, created);
+  }
+}

app/lib/features/geckoview/features/preferences/data/repositories/preference_settings.dart

@@ -65,7 +65,7 @@ Future<PreferenceSettingGroup> _preferenceSettingGroup(
 class _PreferenceRepository extends _$PreferenceRepository {
   final _prefManager = GeckoPrefService();
   // Use BehaviorSubject instead of StreamController
-  late BehaviorSubject<Map<String, GeckoPrefValue>> _prefSubject;
+  late BehaviorSubject<Map<String, GeckoPref>> _prefSubject;
 
   Future<void> _updatePrefs() async {
     final prefs = await _prefManager.getAllPrefs();
@@ -83,8 +83,8 @@ class _PreferenceRepository extends _$PreferenceRepository {
   }
 
   @override
-  Raw<Stream<Map<String, GeckoPrefValue>>> build() {
+  Raw<Stream<Map<String, GeckoPref>>> build() {
-    _prefSubject = BehaviorSubject<Map<String, GeckoPrefValue>>();
+    _prefSubject = BehaviorSubject<Map<String, GeckoPref>>();
 
     ref.onDispose(() async {
       await _prefSubject.close();

app/lib/features/geckoview/features/preferences/data/repositories/preference_settings.g.dart

@@ -229,7 +229,7 @@ final class _PreferenceRepositoryProvider
     extends
         $NotifierProvider<
           _PreferenceRepository,
-          Raw<Stream<Map<String, GeckoPrefValue>>>
+          Raw<Stream<Map<String, GeckoPref>>>
         > {
   const _PreferenceRepositoryProvider._()
     : super(
@@ -250,21 +250,22 @@ final class _PreferenceRepositoryProvider
   _PreferenceRepository create() => _PreferenceRepository();
 
   /// {@macro riverpod.override_with_value}
-  Override overrideWithValue(Raw<Stream<Map<String, GeckoPrefValue>>> value) {
+  Override overrideWithValue(Raw<Stream<Map<String, GeckoPref>>> value) {
     return $ProviderOverride(
       origin: this,
-      providerOverride:
+      providerOverride: $SyncValueProvider<Raw<Stream<Map<String, GeckoPref>>>>(
-          $SyncValueProvider<Raw<Stream<Map<String, GeckoPrefValue>>>>(value),
+        value,
+      ),
     );
   }
 }
 
 String _$_preferenceRepositoryHash() =>
-    r'9a98b95677d4070def531ea1e5b900892045a1ef';
+    r'0f6812988a23407f6648e32fb1585984d2433bbc';
 
 abstract class _$PreferenceRepository
-    extends $Notifier<Raw<Stream<Map<String, GeckoPrefValue>>>> {
+    extends $Notifier<Raw<Stream<Map<String, GeckoPref>>>> {
-  Raw<Stream<Map<String, GeckoPrefValue>>> build();
+  Raw<Stream<Map<String, GeckoPref>>> build();
   @$mustCallSuper
   @override
   void runBuild() {
@@ -272,17 +273,17 @@ abstract class _$PreferenceRepository
     final ref =
         this.ref
             as $Ref<
-              Raw<Stream<Map<String, GeckoPrefValue>>>,
+              Raw<Stream<Map<String, GeckoPref>>>,
-              Raw<Stream<Map<String, GeckoPrefValue>>>
+              Raw<Stream<Map<String, GeckoPref>>>
             >;
     final element =
         ref.element
             as $ClassProviderElement<
               AnyNotifier<
-                Raw<Stream<Map<String, GeckoPrefValue>>>,
+                Raw<Stream<Map<String, GeckoPref>>>,
-                Raw<Stream<Map<String, GeckoPrefValue>>>
+                Raw<Stream<Map<String, GeckoPref>>>
               >,
-              Raw<Stream<Map<String, GeckoPrefValue>>>,
+              Raw<Stream<Map<String, GeckoPref>>>,
               Object?,
               Object?
             >;

packages/flutter_mozilla_components/android/src/main/kotlin/eu/weblibre/flutter_mozilla_components/api/GeckoPrefApiImpl.kt

@@ -9,15 +9,17 @@ package eu.weblibre.flutter_mozilla_components.api
 import eu.weblibre.flutter_mozilla_components.GlobalComponents
 import eu.weblibre.flutter_mozilla_components.feature.PrefManagerFeature
 import eu.weblibre.flutter_mozilla_components.feature.ResultConsumer
+import eu.weblibre.flutter_mozilla_components.pigeons.GeckoPref
 import eu.weblibre.flutter_mozilla_components.pigeons.GeckoPrefApi
-import eu.weblibre.flutter_mozilla_components.pigeons.GeckoPrefValue
 import mozilla.components.ExperimentalAndroidComponentsApi
 import mozilla.components.concept.engine.preferences.Branch
+import mozilla.components.concept.engine.preferences.BrowserPrefObserverDelegate
+import mozilla.components.concept.engine.preferences.BrowserPreference
 import mozilla.components.support.ktx.android.org.json.toList
 import org.json.JSONObject
 import org.json.JSONArray
 
-class GeckoPrefApiImpl : GeckoPrefApi {
+class GeckoPrefApiImpl : GeckoPrefApi, BrowserPrefObserverDelegate {
     private val components by lazy {
         requireNotNull(GlobalComponents.components) { "Components not initialized" }
     }
@@ -46,28 +48,32 @@ class GeckoPrefApiImpl : GeckoPrefApi {
     }
 
     override fun getPrefList(callback: (Result<List<String>>) -> Unit) {
-        PrefManagerFeature.scheduleRequest("getPrefList", Unit, object : ResultConsumer<JSONObject> {
+        PrefManagerFeature.scheduleRequest(
-            override fun success(result: JSONObject) {
+            "getPrefList",
-                callback(Result.success(result.getJSONArray("result").toList()))
+            Unit,
-            }
+            object : ResultConsumer<JSONObject> {
+                override fun success(result: JSONObject) {
+                    callback(Result.success(result.getJSONArray("result").toList()))
+                }
 
-            override fun error(errorCode: String, errorMessage: String?, errorDetails: Any?) {
+                override fun error(errorCode: String, errorMessage: String?, errorDetails: Any?) {
-                callback(Result.failure(Exception("$errorCode $errorMessage $errorDetails")))
+                    callback(Result.failure(Exception("$errorCode $errorMessage $errorDetails")))
-            }
+                }
-        })
+            })
     }
 
     @OptIn(ExperimentalAndroidComponentsApi::class)
     override fun getPrefs(
         preferenceFilter: List<String>,
-        callback: (Result<Map<String, GeckoPrefValue>>) -> Unit
+        callback: (Result<Map<String, GeckoPref>>) -> Unit
     ) {
         components.core.engine.getBrowserPrefs(
             preferenceFilter, onSuccess = {
                 callback(
                     Result.success(
                         it.associate {
-                            it.pref to GeckoPrefValue(
+                            it.pref to GeckoPref(
+                                name = it.pref,
                                 value = it.value,
                                 defaultValue = it.defaultValue,
                                 userValue = it.userValue,
@@ -85,7 +91,7 @@ class GeckoPrefApiImpl : GeckoPrefApi {
     @OptIn(ExperimentalAndroidComponentsApi::class)
     override fun applyPrefs(
         prefs: Map<String, Any>,
-        callback: (Result<Map<String, GeckoPrefValue>>) -> Unit
+        callback: (Result<Map<String, GeckoPref>>) -> Unit
     ) {
         var fault: Boolean = false;
 
@@ -148,7 +154,7 @@ class GeckoPrefApiImpl : GeckoPrefApi {
         for (pref in preferenceNames) {
             components.core.engine.clearBrowserUserPref(
                 pref = pref,
-                onSuccess = {},
+                onSuccess = { },
                 onError = {
                     callback(Result.failure(Exception("${it.message} ${it.cause}")))
                     fault = true
@@ -159,5 +165,49 @@ class GeckoPrefApiImpl : GeckoPrefApi {
                 return;
             }
         }
+
+        callback(Result.success(Unit))
+    }
+
+    override fun startObserveChanges() {
+        components.core.engine.registerPrefObserverDelegate(this);
+    }
+
+    override fun stopObserveChanges() {
+        components.core.engine.unregisterPrefObserverDelegate();
+    }
+
+    override fun registerPrefForObservation(name: String, callback: (Result<Unit>) -> Unit) {
+        components.core.engine.registerPrefForObservation(
+            name,
+            onSuccess = {
+                callback(Result.success(Unit))
+            },
+            onError = {
+                callback(Result.failure(Exception("${it.message} ${it.cause}")))
+            })
+    }
+
+    override fun unregisterPrefForObservation(name: String, callback: (Result<Unit>) -> Unit) {
+        components.core.engine.unregisterPrefForObservation(
+            name,
+            onSuccess = {
+                callback(Result.success(Unit))
+            },
+            onError = {
+                callback(Result.failure(Exception("${it.message} ${it.cause}")))
+            })
+    }
+
+    override fun onPreferenceChange(observedPreference: BrowserPreference<*>) {
+        components.flutterEvents.onPreferenceChange(
+            System.currentTimeMillis(), GeckoPref(
+                name = observedPreference.pref,
+                value = observedPreference.value,
+                defaultValue = observedPreference.defaultValue,
+                userValue = observedPreference.userValue,
+                hasUserChangedValue = observedPreference.hasUserChangedValue,
+            )
+        ) { _ -> }
     }
 }

packages/flutter_mozilla_components/android/src/main/kotlin/eu/weblibre/flutter_mozilla_components/pigeons/Gecko.g.kt

@@ -2196,7 +2196,8 @@ data class AddonCollection (
 }
 
 /** Generated class from Pigeon that represents data sent in messages. */
-data class GeckoPrefValue (
+data class GeckoPref (
+  val name: String,
   val value: Any? = null,
   val defaultValue: Any? = null,
   val userValue: Any? = null,
@@ -2204,16 +2205,18 @@ data class GeckoPrefValue (
 )
  {
   companion object {
-    fun fromList(pigeonVar_list: List<Any?>): GeckoPrefValue {
+    fun fromList(pigeonVar_list: List<Any?>): GeckoPref {
-      val value = pigeonVar_list[0]
+      val name = pigeonVar_list[0] as String
-      val defaultValue = pigeonVar_list[1]
+      val value = pigeonVar_list[1]
-      val userValue = pigeonVar_list[2]
+      val defaultValue = pigeonVar_list[2]
-      val hasUserChangedValue = pigeonVar_list[3] as Boolean
+      val userValue = pigeonVar_list[3]
-      return GeckoPrefValue(value, defaultValue, userValue, hasUserChangedValue)
+      val hasUserChangedValue = pigeonVar_list[4] as Boolean
+      return GeckoPref(name, value, defaultValue, userValue, hasUserChangedValue)
     }
   }
   fun toList(): List<Any?> {
     return listOf(
+      name,
       value,
       defaultValue,
       userValue,
@@ -2221,7 +2224,7 @@ data class GeckoPrefValue (
     )
   }
   override fun equals(other: Any?): Boolean {
-    if (other !is GeckoPrefValue) {
+    if (other !is GeckoPref) {
       return false
     }
     if (this === other) {
@@ -2546,7 +2549,7 @@ private open class GeckoPigeonCodec : StandardMessageCodec() {
       }
       191.toByte() -> {
         return (readValue(buffer) as? List<Any?>)?.let {
-          GeckoPrefValue.fromList(it)
+          GeckoPref.fromList(it)
         }
       }
       else -> super.readValueOfType(type, buffer)
@@ -2802,7 +2805,7 @@ private open class GeckoPigeonCodec : StandardMessageCodec() {
         stream.write(190)
         writeValue(stream, value.toList())
       }
-      is GeckoPrefValue -> {
+      is GeckoPref -> {
         stream.write(191)
         writeValue(stream, value.toList())
       }
@@ -3761,9 +3764,13 @@ interface GeckoIconsApi {
 /** Generated interface from Pigeon that represents a handler of messages from Flutter. */
 interface GeckoPrefApi {
   fun getPrefList(callback: (Result<List<String>>) -> Unit)
-  fun getPrefs(preferenceFilter: List<String>, callback: (Result<Map<String, GeckoPrefValue>>) -> Unit)
+  fun getPrefs(preferenceFilter: List<String>, callback: (Result<Map<String, GeckoPref>>) -> Unit)
-  fun applyPrefs(prefs: Map<String, Any>, callback: (Result<Map<String, GeckoPrefValue>>) -> Unit)
+  fun applyPrefs(prefs: Map<String, Any>, callback: (Result<Map<String, GeckoPref>>) -> Unit)
   fun resetPrefs(preferenceNames: List<String>, callback: (Result<Unit>) -> Unit)
+  fun startObserveChanges()
+  fun stopObserveChanges()
+  fun registerPrefForObservation(name: String, callback: (Result<Unit>) -> Unit)
+  fun unregisterPrefForObservation(name: String, callback: (Result<Unit>) -> Unit)
 
   companion object {
     /** The codec used by GeckoPrefApi. */
@@ -3798,7 +3805,7 @@ interface GeckoPrefApi {
           channel.setMessageHandler { message, reply ->
             val args = message as List<Any?>
             val preferenceFilterArg = args[0] as List<String>
-            api.getPrefs(preferenceFilterArg) { result: Result<Map<String, GeckoPrefValue>> ->
+            api.getPrefs(preferenceFilterArg) { result: Result<Map<String, GeckoPref>> ->
               val error = result.exceptionOrNull()
               if (error != null) {
                 reply.reply(GeckoPigeonUtils.wrapError(error))
@@ -3818,7 +3825,7 @@ interface GeckoPrefApi {
           channel.setMessageHandler { message, reply ->
             val args = message as List<Any?>
             val prefsArg = args[0] as Map<String, Any>
-            api.applyPrefs(prefsArg) { result: Result<Map<String, GeckoPrefValue>> ->
+            api.applyPrefs(prefsArg) { result: Result<Map<String, GeckoPref>> ->
               val error = result.exceptionOrNull()
               if (error != null) {
                 reply.reply(GeckoPigeonUtils.wrapError(error))
@@ -3851,6 +3858,76 @@ interface GeckoPrefApi {
           channel.setMessageHandler(null)
         }
       }
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.startObserveChanges$separatedMessageChannelSuffix", codec)
+        if (api != null) {
+          channel.setMessageHandler { _, reply ->
+            val wrapped: List<Any?> = try {
+              api.startObserveChanges()
+              listOf(null)
+            } catch (exception: Throwable) {
+              GeckoPigeonUtils.wrapError(exception)
+            }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.stopObserveChanges$separatedMessageChannelSuffix", codec)
+        if (api != null) {
+          channel.setMessageHandler { _, reply ->
+            val wrapped: List<Any?> = try {
+              api.stopObserveChanges()
+              listOf(null)
+            } catch (exception: Throwable) {
+              GeckoPigeonUtils.wrapError(exception)
+            }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.registerPrefForObservation$separatedMessageChannelSuffix", codec)
+        if (api != null) {
+          channel.setMessageHandler { message, reply ->
+            val args = message as List<Any?>
+            val nameArg = args[0] as String
+            api.registerPrefForObservation(nameArg) { result: Result<Unit> ->
+              val error = result.exceptionOrNull()
+              if (error != null) {
+                reply.reply(GeckoPigeonUtils.wrapError(error))
+              } else {
+                reply.reply(GeckoPigeonUtils.wrapResult(null))
+              }
+            }
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.unregisterPrefForObservation$separatedMessageChannelSuffix", codec)
+        if (api != null) {
+          channel.setMessageHandler { message, reply ->
+            val args = message as List<Any?>
+            val nameArg = args[0] as String
+            api.unregisterPrefForObservation(nameArg) { result: Result<Unit> ->
+              val error = result.exceptionOrNull()
+              if (error != null) {
+                reply.reply(GeckoPigeonUtils.wrapError(error))
+              } else {
+                reply.reply(GeckoPigeonUtils.wrapResult(null))
+              }
+            }
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
     }
   }
 }
@@ -4422,6 +4499,23 @@ class GeckoStateEvents(private val binaryMessenger: BinaryMessenger, private val
       } 
     }
   }
+  fun onPreferenceChange(timestampArg: Long, valueArg: GeckoPref, callback: (Result<Unit>) -> Unit)
+{
+    val separatedMessageChannelSuffix = if (messageChannelSuffix.isNotEmpty()) ".$messageChannelSuffix" else ""
+    val channelName = "dev.flutter.pigeon.flutter_mozilla_components.GeckoStateEvents.onPreferenceChange$separatedMessageChannelSuffix"
+    val channel = BasicMessageChannel<Any?>(binaryMessenger, channelName, codec)
+    channel.send(listOf(timestampArg, valueArg)) {
+      if (it is List<*>) {
+        if (it.size > 1) {
+          callback(Result.failure(FlutterError(it[0] as String, it[1] as String, it[2] as String?)))
+        } else {
+          callback(Result.success(Unit))
+        }
+      } else {
+        callback(Result.failure(GeckoPigeonUtils.createConnectionError(channelName)))
+      } 
+    }
+  }
 }
 /** Generated class from Pigeon that represents Flutter messages that can be called from Kotlin. */
 class GeckoLogging(private val binaryMessenger: BinaryMessenger, private val messageChannelSuffix: String = "") {

packages/flutter_mozilla_components/lib/flutter_mozilla_components.dart

@@ -42,7 +42,7 @@ export 'src/pigeons/gecko.g.dart'
         DohSettingsMode,
         EmailHitResult,
         GeckoEngineSettings,
-        GeckoPrefValue,
+        GeckoPref,
         GeckoSuggestion,
         GeckoSuggestionType,
         GeoHitResult,

packages/flutter_mozilla_components/lib/src/domain/services/gecko_event.dart

@@ -39,6 +39,7 @@ class GeckoEventService extends GeckoStateEvents {
   final _findResultsSubject = PublishSubject<FindResultsEvent>();
   final _longPressSubject = PublishSubject<LongPressEvent>();
   final _scrollEventSubject = PublishSubject<ScrollEvent>();
+  final _prefUpdateSubject = PublishSubject<GeckoPref>();
 
   final _tabAddedSubject = PublishSubject<String>();
 
@@ -59,6 +60,7 @@ class GeckoEventService extends GeckoStateEvents {
   Stream<FindResultsEvent> get findResultsEvent => _findResultsSubject.stream;
   Stream<LongPressEvent> get longPressEvent => _longPressSubject.stream;
   Stream<ScrollEvent> get scrollEvent => _scrollEventSubject.stream;
+  Stream<GeckoPref> get prefUpdateEvent => _prefUpdateSubject.stream;
 
   Stream<String> get tabAddedStream => _tabAddedSubject.stream;
 
@@ -177,6 +179,11 @@ class GeckoEventService extends GeckoStateEvents {
     ));
   }
 
+  @override
+  void onPreferenceChange(int timestamp, GeckoPref value) {
+    _prefUpdateSubject.addWhenMoreRecent(timestamp, value.name, value);
+  }
+
   GeckoEventService.setUp({
     BinaryMessenger? binaryMessenger,
     String messageChannelSuffix = '',
@@ -189,6 +196,8 @@ class GeckoEventService extends GeckoStateEvents {
   }
 
   void dispose() {
+    unawaited(_viewStateSubject.close());
+    unawaited(_engineStateSubject.close());
     unawaited(_tabListSubject.close());
     unawaited(_selectedTabSubject.close());
     unawaited(_tabContentSubject.close());
@@ -196,10 +205,12 @@ class GeckoEventService extends GeckoStateEvents {
     unawaited(_readerableSubject.close());
     unawaited(_securityInfoSubject.close());
     unawaited(_iconChangeSubject.close());
+    unawaited(_iconUpdateSubject.close());
     unawaited(_thumbnailSubject.close());
     unawaited(_findResultsSubject.close());
     unawaited(_longPressSubject.close());
     unawaited(_scrollEventSubject.close());
     unawaited(_tabAddedSubject.close());
+    unawaited(_prefUpdateSubject.close());
   }
 }

packages/flutter_mozilla_components/lib/src/domain/services/gecko_pref.dart

@@ -13,19 +13,35 @@ class GeckoPrefService {
     return _apiInstance.getPrefList();
   }
 
-  Future<Map<String, GeckoPrefValue>> getAllPrefs() async {
+  Future<Map<String, GeckoPref>> getAllPrefs() async {
     return _apiInstance.getPrefs(await getPrefList());
   }
 
-  Future<Map<String, GeckoPrefValue>> getPrefs(List<String> prefs) {
+  Future<Map<String, GeckoPref>> getPrefs(List<String> prefs) {
     return _apiInstance.getPrefs(prefs);
   }
 
-  Future<Map<String, GeckoPrefValue>> applyPrefs(Map<String, Object> prefs) {
+  Future<Map<String, GeckoPref>> applyPrefs(Map<String, Object> prefs) {
     return _apiInstance.applyPrefs(prefs);
   }
 
   Future<void> resetPrefs(List<String> prefs) {
     return _apiInstance.resetPrefs(prefs);
   }
+
+  Future<void> startObserveChanges() {
+    return _apiInstance.startObserveChanges();
+  }
+
+  Future<void> stopObserveChanges() {
+    return _apiInstance.stopObserveChanges();
+  }
+
+  Future<void> registerPrefForObservation(String name) {
+    return _apiInstance.registerPrefForObservation(name);
+  }
+
+  Future<void> unregisterPrefForObservation(String name) {
+    return _apiInstance.unregisterPrefForObservation(name);
+  }
 }

packages/flutter_mozilla_components/lib/src/pigeons/gecko.g.dart

@@ -2788,14 +2788,17 @@ class AddonCollection {
 ;
 }
 
-class GeckoPrefValue {
+class GeckoPref {
-  GeckoPrefValue({
+  GeckoPref({
+    required this.name,
     this.value,
     this.defaultValue,
     this.userValue,
     required this.hasUserChangedValue,
   });
 
+  String name;
+
   Object? value;
 
   Object? defaultValue;
@@ -2806,6 +2809,7 @@ class GeckoPrefValue {
 
   List<Object?> _toList() {
     return <Object?>[
+      name,
       value,
       defaultValue,
       userValue,
@@ -2816,20 +2820,21 @@ class GeckoPrefValue {
   Object encode() {
     return _toList();  }
 
-  static GeckoPrefValue decode(Object result) {
+  static GeckoPref decode(Object result) {
     result as List<Object?>;
-    return GeckoPrefValue(
+    return GeckoPref(
-      value: result[0],
+      name: result[0]! as String,
-      defaultValue: result[1],
+      value: result[1],
-      userValue: result[2],
+      defaultValue: result[2],
-      hasUserChangedValue: result[3]! as bool,
+      userValue: result[3],
+      hasUserChangedValue: result[4]! as bool,
     );
   }
 
   @override
   // ignore: avoid_equals_and_hash_code_on_mutable_classes
   bool operator ==(Object other) {
-    if (other is! GeckoPrefValue || other.runtimeType != runtimeType) {
+    if (other is! GeckoPref || other.runtimeType != runtimeType) {
       return false;
     }
     if (identical(this, other)) {
@@ -3038,7 +3043,7 @@ class _PigeonCodec extends StandardMessageCodec {
     }    else if (value is AddonCollection) {
       buffer.putUint8(190);
       writeValue(buffer, value.encode());
-    }    else if (value is GeckoPrefValue) {
+    }    else if (value is GeckoPref) {
       buffer.putUint8(191);
       writeValue(buffer, value.encode());
     } else {
@@ -3193,7 +3198,7 @@ class _PigeonCodec extends StandardMessageCodec {
       case 190: 
         return AddonCollection.decode(readValue(buffer)!);
       case 191: 
-        return GeckoPrefValue.decode(readValue(buffer)!);
+        return GeckoPref.decode(readValue(buffer)!);
       default:
         return super.readValueOfType(type, buffer);
     }
@@ -4357,7 +4362,7 @@ class GeckoPrefApi {
     }
   }
 
-  Future<Map<String, GeckoPrefValue>> getPrefs(List<String> preferenceFilter) async {
+  Future<Map<String, GeckoPref>> getPrefs(List<String> preferenceFilter) async {
     final String pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.getPrefs$pigeonVar_messageChannelSuffix';
     final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
       pigeonVar_channelName,
@@ -4381,11 +4386,11 @@ class GeckoPrefApi {
         message: 'Host platform returned null value for non-null return value.',
       );
     } else {
-      return (pigeonVar_replyList[0] as Map<Object?, Object?>?)!.cast<String, GeckoPrefValue>();
+      return (pigeonVar_replyList[0] as Map<Object?, Object?>?)!.cast<String, GeckoPref>();
     }
   }
 
-  Future<Map<String, GeckoPrefValue>> applyPrefs(Map<String, Object> prefs) async {
+  Future<Map<String, GeckoPref>> applyPrefs(Map<String, Object> prefs) async {
     final String pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.applyPrefs$pigeonVar_messageChannelSuffix';
     final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
       pigeonVar_channelName,
@@ -4409,7 +4414,7 @@ class GeckoPrefApi {
         message: 'Host platform returned null value for non-null return value.',
       );
     } else {
-      return (pigeonVar_replyList[0] as Map<Object?, Object?>?)!.cast<String, GeckoPrefValue>();
+      return (pigeonVar_replyList[0] as Map<Object?, Object?>?)!.cast<String, GeckoPref>();
     }
   }
 
@@ -4435,6 +4440,98 @@ class GeckoPrefApi {
       return;
     }
   }
+
+  Future<void> startObserveChanges() async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.startObserveChanges$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(null);
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else {
+      return;
+    }
+  }
+
+  Future<void> stopObserveChanges() async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.stopObserveChanges$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(null);
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else {
+      return;
+    }
+  }
+
+  Future<void> registerPrefForObservation(String name) async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.registerPrefForObservation$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(<Object?>[name]);
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else {
+      return;
+    }
+  }
+
+  Future<void> unregisterPrefForObservation(String name) async {
+    final String pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoPrefApi.unregisterPrefForObservation$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(<Object?>[name]);
+    final List<Object?>? pigeonVar_replyList =
+        await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else {
+      return;
+    }
+  }
 }
 
 class GeckoMlApi {
@@ -4809,6 +4906,8 @@ abstract class GeckoStateEvents {
 
   void onScrollChange(int timestamp, String tabId, int scrollY);
 
+  void onPreferenceChange(int timestamp, GeckoPref value);
+
   static void setUp(GeckoStateEvents? api, {BinaryMessenger? binaryMessenger, String messageChannelSuffix = '',}) {
     messageChannelSuffix = messageChannelSuffix.isNotEmpty ? '.$messageChannelSuffix' : '';
     {
@@ -5252,6 +5351,34 @@ abstract class GeckoStateEvents {
         });
       }
     }
+    {
+      final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+          'dev.flutter.pigeon.flutter_mozilla_components.GeckoStateEvents.onPreferenceChange$messageChannelSuffix', pigeonChannelCodec,
+          binaryMessenger: binaryMessenger);
+      if (api == null) {
+        pigeonVar_channel.setMessageHandler(null);
+      } else {
+        pigeonVar_channel.setMessageHandler((Object? message) async {
+          assert(message != null,
+          'Argument for dev.flutter.pigeon.flutter_mozilla_components.GeckoStateEvents.onPreferenceChange was null.');
+          final List<Object?> args = (message as List<Object?>?)!;
+          final int? arg_timestamp = (args[0] as int?);
+          assert(arg_timestamp != null,
+              'Argument for dev.flutter.pigeon.flutter_mozilla_components.GeckoStateEvents.onPreferenceChange was null, expected non-null int.');
+          final GeckoPref? arg_value = (args[1] as GeckoPref?);
+          assert(arg_value != null,
+              'Argument for dev.flutter.pigeon.flutter_mozilla_components.GeckoStateEvents.onPreferenceChange was null, expected non-null GeckoPref.');
+          try {
+            api.onPreferenceChange(arg_timestamp!, arg_value!);
+            return wrapResponse(empty: true);
+          } on PlatformException catch (e) {
+            return wrapResponse(error: e);
+          }          catch (e) {
+            return wrapResponse(error: PlatformException(code: 'error', message: e.toString()));
+          }
+        });
+      }
+    }
   }
 }
 

packages/flutter_mozilla_components/pigeons/gecko.dart

@@ -1075,13 +1075,15 @@ abstract class GeckoIconsApi {
   IconResult loadIcon(IconRequest request);
 }
 
-class GeckoPrefValue {
+class GeckoPref {
+  final String name;
   final Object? value;
   final Object? defaultValue;
   final Object? userValue;
   final bool hasUserChangedValue;
 
-  GeckoPrefValue(
+  GeckoPref(
+    this.name,
     this.value,
     this.defaultValue,
     this.userValue,
@@ -1094,11 +1096,18 @@ abstract class GeckoPrefApi {
   @async
   List<String> getPrefList();
   @async
-  Map<String, GeckoPrefValue> getPrefs(List<String> preferenceFilter);
+  Map<String, GeckoPref> getPrefs(List<String> preferenceFilter);
   @async
-  Map<String, GeckoPrefValue> applyPrefs(Map<String, Object> prefs);
+  Map<String, GeckoPref> applyPrefs(Map<String, Object> prefs);
   @async
   void resetPrefs(List<String> preferenceNames);
+
+  void startObserveChanges();
+  void stopObserveChanges();
+  @async
+  void registerPrefForObservation(String name);
+  @async
+  void unregisterPrefForObservation(String name);
 }
 
 @HostApi()
@@ -1198,6 +1207,7 @@ abstract class GeckoStateEvents {
   void onLongPress(int timestamp, String id, HitResult hitResult);
 
   void onScrollChange(int timestamp, String tabId, int scrollY);
+  void onPreferenceChange(int timestamp, GeckoPref value);
 }
 
 @FlutterApi()