Fix ListTile's default iconColor token used & update examples (#120444)

Author: TahaTesser

dev/tools/gen_defaults/lib/list_tile_template.dart

@@ -42,7 +42,7 @@ class _${blockName}DefaultsM3 extends ListTileThemeData {
   Color? get selectedColor => ${componentColor('md.comp.list.list-item.selected.trailing-icon')};
 
   @override
-  Color? get iconColor => ${componentColor('md.comp.list.list-item.unselected.trailing-icon')};
+  Color? get iconColor => ${componentColor('md.comp.list.list-item.trailing-icon')};
 }
 ''';
 }

examples/api/lib/material/list_tile/list_tile.0.dart

@@ -17,7 +17,8 @@ class ListTileApp extends StatelessWidget {
       theme: ThemeData(
         listTileTheme: const ListTileThemeData(
           textColor: Colors.white,
-        )
+        ),
+        useMaterial3: true,
       ),
       home: const LisTileExample(),
     );

examples/api/lib/material/list_tile/list_tile.1.dart

@@ -13,8 +13,9 @@ class ListTileApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return const MaterialApp(
-      home: LisTileExample(),
+    return MaterialApp(
+      theme: ThemeData(useMaterial3: true),
+      home: const LisTileExample(),
     );
   }
 }

examples/api/lib/material/list_tile/list_tile.2.dart

@@ -14,7 +14,7 @@ class ListTileApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      theme: ThemeData(colorSchemeSeed: const Color(0xff6750a4), useMaterial3: true),
+      theme: ThemeData(useMaterial3: true),
       home: const ListTileExample(),
     );
   }

examples/api/lib/material/list_tile/list_tile.3.dart

@@ -14,7 +14,7 @@ class ListTileApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      theme: ThemeData(colorSchemeSeed: const Color(0xff6750a4), useMaterial3: true),
+      theme: ThemeData(useMaterial3: true),
       home: const ListTileExample(),
     );
   }

examples/api/lib/material/list_tile/list_tile.selected.0.dart

@@ -13,8 +13,9 @@ class ListTileApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return const MaterialApp(
-      home: LisTileExample(),
+    return MaterialApp(
+      theme: ThemeData(useMaterial3: true),
+      home: const LisTileExample(),
     );
   }
 }

packages/flutter/lib/src/material/list_tile.dart

@@ -474,7 +474,7 @@ class ListTile extends StatelessWidget {
   /// Defines the default color for [leading] and [trailing] icons.
   ///
   /// If this property is null and [selected] is false then [ListTileThemeData.iconColor]
-  /// is used. If that is also null and [ThemeData.useMaterial3] is true, [ColorScheme.onSurface]
+  /// is used. If that is also null and [ThemeData.useMaterial3] is true, [ColorScheme.onSurfaceVariant]
   /// is used, otherwise if [ThemeData.brightness] is [Brightness.light], [Colors.black54] is used,
   /// and if [ThemeData.brightness] is [Brightness.dark], the value is null.
   ///
@@ -1593,7 +1593,7 @@ class _LisTileDefaultsM3 extends ListTileThemeData {
   Color? get selectedColor => _colors.primary;
 
   @override
-  Color? get iconColor => _colors.onSurface;
+  Color? get iconColor => _colors.onSurfaceVariant;
 }
 
 // END GENERATED TOKEN PROPERTIES - LisTile

packages/flutter/test/material/list_tile_test.dart

@@ -1882,10 +1882,10 @@ void main() {
     expect(iconColor(trailingKey), colorScheme.primary);
 
     await tester.pumpWidget(buildFrame(selected: false));
-    expect(iconColor(leadingKey), colorScheme.onSurface);
-    expect(iconColor(titleKey), colorScheme.onSurface);
-    expect(iconColor(subtitleKey), colorScheme.onSurface);
-    expect(iconColor(trailingKey), colorScheme.onSurface);
+    expect(iconColor(leadingKey), colorScheme.onSurfaceVariant);
+    expect(iconColor(titleKey), colorScheme.onSurfaceVariant);
+    expect(iconColor(subtitleKey), colorScheme.onSurfaceVariant);
+    expect(iconColor(trailingKey), colorScheme.onSurfaceVariant);
   });
 
   testWidgets('ListTile font size', (WidgetTester tester) async {