Add hintStyle in SearchDelegate (flutter#30388)

SearchDelegate hintStyle parameter

Author: guojiex

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

@@ -466,6 +466,7 @@ class _SearchPageState<T> extends State<_SearchPage<T>> {
             decoration: InputDecoration(
               border: InputBorder.none,
               hintText: searchFieldLabel,
+              hintStyle: theme.inputDecorationTheme.hintStyle,
             ),
           ),
           actions: widget.delegate.buildActions(context),

packages/flutter/test/material/search_test.dart

@@ -91,6 +91,20 @@ void main() {
     expect(find.text('Suggestions'), findsOneWidget);
   });
 
+  testWidgets('Hint text color overridden', (WidgetTester tester) async {
+    final _TestSearchDelegate delegate = _TestSearchDelegate();
+
+    await tester.pumpWidget(TestHomePage(
+      delegate: delegate,
+    ));
+    await tester.tap(find.byTooltip('Search'));
+    await tester.pumpAndSettle();
+
+    final TextField textField = tester.widget<TextField>(find.byType(TextField));
+    final Color hintColor = textField.decoration.hintStyle.color;
+    expect(hintColor, delegate.hintTextColor);
+  });
+
   testWidgets('Requests suggestions', (WidgetTester tester) async {
     final _TestSearchDelegate delegate = _TestSearchDelegate();
 
@@ -644,6 +658,15 @@ class _TestSearchDelegate extends SearchDelegate<String> {
   final String suggestions;
   final String result;
   final List<Widget> actions;
+  final Color hintTextColor = Colors.green;
+
+  @override
+  ThemeData appBarTheme(BuildContext context) {
+    final ThemeData theme = Theme.of(context);
+    return theme.copyWith(
+      inputDecorationTheme: InputDecorationTheme(hintStyle: TextStyle(color: hintTextColor)),
+    );
+  }
 
   @override
   Widget buildLeading(BuildContext context) {
@@ -680,4 +703,4 @@ class _TestSearchDelegate extends SearchDelegate<String> {
   List<Widget> buildActions(BuildContext context) {
     return actions;
   }
-}
+}