Revert "Add optional param to useRootNavigator when showSearch (#84581)" (#84827)

This reverts commit a65328b4.

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

@@ -35,12 +35,6 @@ import 'theme.dart';
 /// call. Call [SearchDelegate.close] before re-using the same delegate instance
 /// for another [showSearch] call.
 ///
-/// The `useRootNavigator` argument is used to determine whether to push the
-/// search page to the [Navigator] furthest from or nearest to the given
-/// `context`. By default, `useRootNavigator` is `true` and the search page
-/// route created by this method is pushed to the furthest navigator to the
-/// given `context`. It can not be `null`.
-///
 /// The transition to the search page triggered by this method looks best if the
 /// screen triggering the transition contains an [AppBar] at the top and the
 /// transition is called from an [IconButton] that's part of [AppBar.actions].
@@ -60,14 +54,12 @@ Future<T?> showSearch<T>({
   required BuildContext context,
   required SearchDelegate<T> delegate,
   String? query = '',
-  bool useRootNavigator = true,
 }) {
   assert(delegate != null);
   assert(context != null);
-  assert(useRootNavigator != null);
   delegate.query = query ?? delegate.query;
   delegate._currentBody = _SearchBody.suggestions;
-  return Navigator.of(context, rootNavigator: useRootNavigator).push(_SearchPageRoute<T>(
+  return Navigator.of(context).push(_SearchPageRoute<T>(
     delegate: delegate,
   ));
 }

packages/flutter/test/material/search_test.dart

@@ -841,66 +841,6 @@ void main() {
     expect(find.text('Suggestions'), findsNothing);
     expect(selectedResults, <String>['Result']);
   });
-
-  testWidgets('showSearch with useRootNavigator', (WidgetTester tester) async {
-    final MyNavigatorObserver rootObserver = MyNavigatorObserver();
-    final MyNavigatorObserver localObserver = MyNavigatorObserver();
-
-    final _TestEmptySearchDelegate delegate = _TestEmptySearchDelegate(
-      result: 'Result',
-      suggestions: 'Suggestions',
-    );
-
-    await tester.pumpWidget(MaterialApp(
-      navigatorObservers: <NavigatorObserver>[rootObserver],
-      home: Navigator(
-        observers: <NavigatorObserver>[localObserver],
-        onGenerateRoute: (RouteSettings settings) {
-          if (settings.name == 'nested') {
-            return MaterialPageRoute<dynamic>(
-              builder: (BuildContext context) => Column(
-                mainAxisAlignment: MainAxisAlignment.center,
-                children: <Widget>[
-                  TextButton(
-                      onPressed: () async {
-                        await showSearch(context: context, delegate: delegate);
-                      },
-                      child: const Text('showSearchRootNavigator')),
-                  TextButton(
-                      onPressed: () async {
-                        await showSearch(context: context, delegate: delegate, useRootNavigator: false);
-                      },
-                      child: const Text('showSearchLocalNavigator')),
-                ],
-              ),
-              settings: settings,
-            );
-          }
-          throw UnimplementedError();
-        },
-        initialRoute: 'nested',
-      ),
-    ));
-
-    expect(rootObserver.pushCount, 0);
-    expect(localObserver.pushCount, 0);
-
-    // showSearch normal and back
-    await tester.tap(find.text('showSearchLocalNavigator'));
-    await tester.pumpAndSettle();
-    await tester.tap(find.byTooltip('Close'));
-    await tester.pumpAndSettle();
-    expect(rootObserver.pushCount, 0);
-    expect(localObserver.pushCount, 1);
-
-    // showSearch with rootNavigator
-    await tester.tap(find.text('showSearchRootNavigator'));
-    await tester.pumpAndSettle();
-    await tester.tap(find.byTooltip('Close'));
-    await tester.pumpAndSettle();
-    expect(rootObserver.pushCount, 1);
-    expect(localObserver.pushCount, 1);
-  });
 }
 
 class TestHomePage extends StatelessWidget {
@@ -1086,16 +1026,3 @@ class _TestEmptySearchDelegate extends SearchDelegate<String> {
     );
   }
 }
-
-class MyNavigatorObserver extends NavigatorObserver {
-  int pushCount = 0;
-
-  @override
-  void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) {
-    // don't count the root route
-    if (<String>['nested', '/'].contains(route.settings.name)) {
-      return;
-    }
-    pushCount++;
-  }
-}