experimental gecko unmount setting

apps/weblibre/lib/features/user/data/models/general_settings.dart

@@ -205,6 +205,15 @@ class GeneralSettings with FastEquatable {
   /// overriding [globalDesktopMode] for that visit. See `hostMatchesRule`.
   final List<String> desktopModeSites;
 
+  /// Developer setting: when true, the GeckoView is unmounted whenever a
+  /// full-cover route (settings, tab tray, search, …) is on top, freeing the
+  /// engine's resources while it is occluded. On Android 12 and lower (API
+  /// <= 31) this behavior is always applied to work around a native
+  /// visibility bug; on Android 13+ the engine normally stays mounted to
+  /// avoid reload/flicker, and this flag opts into the off-route unmounting
+  /// there too. Defaults to false.
+  final bool unmountGeckoViewOffRoute;
+
   GeneralSettings({
     required this.themeMode,
     required this.uiScaleFactor,
@@ -269,6 +278,7 @@ class GeneralSettings with FastEquatable {
     required this.pureBlack,
     required this.globalDesktopMode,
     required this.desktopModeSites,
+    required this.unmountGeckoViewOffRoute,
   });
 
   GeneralSettings.withDefaults({
@@ -335,6 +345,7 @@ class GeneralSettings with FastEquatable {
     bool? pureBlack,
     bool? globalDesktopMode,
     List<String>? desktopModeSites,
+    bool? unmountGeckoViewOffRoute,
   }) : themeMode = themeMode ?? ThemeMode.dark,
        uiScaleFactor = uiScaleFactor ?? defaultUiScaleFactor,
        disableAnimations = disableAnimations ?? false,
@@ -410,7 +421,8 @@ class GeneralSettings with FastEquatable {
        acceptSuggestionOnSubmit = acceptSuggestionOnSubmit ?? false,
        pureBlack = pureBlack ?? false,
        globalDesktopMode = globalDesktopMode ?? false,
-       desktopModeSites = desktopModeSites ?? const [];
+       desktopModeSites = desktopModeSites ?? const [],
+       unmountGeckoViewOffRoute = unmountGeckoViewOffRoute ?? false;
 
   factory GeneralSettings.fromJson(Map<String, dynamic> json) {
     // Migrate legacy `newTabPosition` setting to direction settings.
@@ -551,5 +563,6 @@ class GeneralSettings with FastEquatable {
     pureBlack,
     globalDesktopMode,
     desktopModeSites,
+    unmountGeckoViewOffRoute,
   ];
 }

apps/weblibre/lib/features/user/data/models/general_settings.g.dart

@@ -153,6 +153,8 @@ abstract class _$GeneralSettingsCWProxy {
 
   GeneralSettings desktopModeSites(List<String> desktopModeSites);
 
+  GeneralSettings unmountGeckoViewOffRoute(bool unmountGeckoViewOffRoute);
+
   /// Creates a new instance with the provided field values.
   /// Passing `null` to a nullable field nullifies it, while `null` for a non-nullable field is ignored. To update a single field use `GeneralSettings(...).copyWith.fieldName(value)`.
   ///
@@ -224,6 +226,7 @@ abstract class _$GeneralSettingsCWProxy {
     bool pureBlack,
     bool globalDesktopMode,
     List<String> desktopModeSites,
+    bool unmountGeckoViewOffRoute,
   });
 }
 
@@ -503,6 +506,10 @@ class _$GeneralSettingsCWProxyImpl implements _$GeneralSettingsCWProxy {
   GeneralSettings desktopModeSites(List<String> desktopModeSites) =>
       call(desktopModeSites: desktopModeSites);
 
+  @override
+  GeneralSettings unmountGeckoViewOffRoute(bool unmountGeckoViewOffRoute) =>
+      call(unmountGeckoViewOffRoute: unmountGeckoViewOffRoute);
+
   @override
   /// Creates a new instance with the provided field values.
   /// Passing `null` to a nullable field nullifies it, while `null` for a non-nullable field is ignored. To update a single field use `GeneralSettings(...).copyWith.fieldName(value)`.
@@ -577,6 +584,7 @@ class _$GeneralSettingsCWProxyImpl implements _$GeneralSettingsCWProxy {
     Object? pureBlack = const $CopyWithPlaceholder(),
     Object? globalDesktopMode = const $CopyWithPlaceholder(),
     Object? desktopModeSites = const $CopyWithPlaceholder(),
+    Object? unmountGeckoViewOffRoute = const $CopyWithPlaceholder(),
   }) {
     return GeneralSettings(
       themeMode: themeMode == const $CopyWithPlaceholder() || themeMode == null
@@ -950,6 +958,12 @@ class _$GeneralSettingsCWProxyImpl implements _$GeneralSettingsCWProxy {
           ? _value.desktopModeSites
           // ignore: cast_nullable_to_non_nullable
           : desktopModeSites as List<String>,
+      unmountGeckoViewOffRoute:
+          unmountGeckoViewOffRoute == const $CopyWithPlaceholder() ||
+              unmountGeckoViewOffRoute == null
+          ? _value.unmountGeckoViewOffRoute
+          // ignore: cast_nullable_to_non_nullable
+          : unmountGeckoViewOffRoute as bool,
     );
   }
 }
@@ -1089,6 +1103,7 @@ GeneralSettings _$GeneralSettingsFromJson(
   desktopModeSites: (json['desktopModeSites'] as List<dynamic>?)
       ?.map((e) => e as String)
       .toList(),
+  unmountGeckoViewOffRoute: json['unmountGeckoViewOffRoute'] as bool?,
 );
 
 Map<String, dynamic> _$GeneralSettingsToJson(
@@ -1171,6 +1186,7 @@ Map<String, dynamic> _$GeneralSettingsToJson(
   'pureBlack': instance.pureBlack,
   'globalDesktopMode': instance.globalDesktopMode,
   'desktopModeSites': instance.desktopModeSites,
+  'unmountGeckoViewOffRoute': instance.unmountGeckoViewOffRoute,
 };
 
 const _$ThemeModeEnumMap = {