Fix Scaffold having status bar when primary is false (#175156)

When primary is false, `Scaffold` is not at the top of screen, so it
should not have a status bar.
fixes flutter/flutter#175062

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Author: PurplePolyhedron

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

@@ -1955,6 +1955,9 @@ class Scaffold extends StatefulWidget {
   /// If true then the height of the [appBar] will be extended by the height
   /// of the screen's status bar, i.e. the top padding for [MediaQuery].
   ///
+  /// If true, on iOS and macOS, tapping the status bar scrolls the app's
+  /// [PrimaryScrollController] to the top.
+  ///
   /// The default value of this property, like the default value of
   /// [AppBar.primary], is true.
   final bool primary;
@@ -2744,8 +2747,8 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
 
   // iOS FEATURES - status bar tap, back gesture
 
-  // On iOS, tapping the status bar scrolls the app's primary scrollable to the
-  // top. We implement this by looking up the primary scroll controller and
+  // On iOS and macOS, if `primary` is true, tapping the status bar scrolls the app's primary scrollable
+  // to the top. We implement this by looking up the primary scroll controller and
   // scrolling it to the top when tapped.
   void _handleStatusBarTap() {
     final ScrollController? primaryScrollController = PrimaryScrollController.maybeOf(context);
@@ -3155,6 +3158,9 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
     switch (themeData.platform) {
       case TargetPlatform.iOS:
       case TargetPlatform.macOS:
+        if (!widget.primary) {
+          break;
+        }
         _addIfNonNull(
           children,
           GestureDetector(

packages/flutter/test/material/scaffold_test.dart

@@ -614,6 +614,84 @@ void main() {
     }),
   );
 
+  testWidgets(
+    'No status bar when primary is false',
+    (WidgetTester tester) async {
+      await tester.pumpWidget(
+        MaterialApp(
+          theme: ThemeData(platform: debugDefaultTargetPlatformOverride),
+          home: MediaQuery(
+            data: const MediaQueryData(padding: EdgeInsets.only(top: 25.0)), // status bar
+            child: Scaffold(
+              primary: false,
+              body: CustomScrollView(
+                primary: true,
+                slivers: <Widget>[
+                  const SliverAppBar(title: Text('Title')),
+                  SliverList.builder(
+                    itemCount: 20,
+                    itemBuilder: (BuildContext context, int index) {
+                      return SizedBox(height: 100.0, child: Text('$index'));
+                    },
+                  ),
+                ],
+              ),
+            ),
+          ),
+        ),
+      );
+      final ScrollableState scrollable = tester.state(find.byType(Scrollable));
+      scrollable.position.jumpTo(500.0);
+      expect(scrollable.position.pixels, equals(500.0));
+      await tester.tapAt(const Offset(100.0, 10.0));
+      await tester.pumpAndSettle();
+      expect(scrollable.position.pixels, equals(500.0));
+    },
+    variant: const TargetPlatformVariant(<TargetPlatform>{
+      TargetPlatform.iOS,
+      TargetPlatform.macOS,
+    }),
+  );
+
+  // Regression test for https://github.com/flutter/flutter/issues/175062
+  testWidgets(
+    'Top of Scaffold is not blocked when primary is false',
+    (WidgetTester tester) async {
+      bool receivedTap = false;
+      await tester.pumpWidget(
+        MaterialApp(
+          theme: ThemeData(platform: debugDefaultTargetPlatformOverride),
+          home: MediaQuery(
+            data: const MediaQueryData(
+              padding: EdgeInsets.only(top: kToolbarHeight), // status bar
+            ),
+            child: Scaffold(
+              appBar: AppBar(
+                primary: false,
+                title: GestureDetector(
+                  onTap: () {
+                    receivedTap = true;
+                  },
+                  child: const Text('Title'),
+                ),
+              ),
+              primary: false,
+              body: const Text('Scaffold'),
+            ),
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Title'));
+      await tester.pumpAndSettle();
+      expect(receivedTap, true);
+    },
+    variant: const TargetPlatformVariant(<TargetPlatform>{
+      TargetPlatform.iOS,
+      TargetPlatform.macOS,
+    }),
+  );
+
   testWidgets(
     'Tapping the status bar scrolls to top with ease out curve animation',
     (WidgetTester tester) async {