Fix AppBar centerTitle position with actions. (#106256)

packages/flutter/lib/src/widgets/navigation_toolbar.dart

@@ -153,7 +153,7 @@ class _ToolbarLayout extends MultiChildLayoutDelegate {
       if (centerMiddle) {
         middleStart = (size.width - middleSize.width) / 2.0;
         if (middleStart + middleSize.width > size.width - trailingWidth) {
-          middleStart = size.width - trailingWidth - middleSize.width;
+          middleStart = size.width - trailingWidth - middleSize.width - middleSpacing;
         } else if (middleStart < middleStartMargin) {
           middleStart = middleStartMargin;
         }

packages/flutter/test/material/app_bar_test.dart

@@ -401,7 +401,7 @@ void main() {
       const SizedBox(width: 48.0),
     ];
     await tester.pumpWidget(buildApp());
-    expect(tester.getTopLeft(title).dx, 800 - 620 - 48 - 48);
+    expect(tester.getTopLeft(title).dx, 800 - 620 - 48 - 48 - 16);
     expect(tester.getSize(title).width, equals(620.0));
   });
 
@@ -456,7 +456,7 @@ void main() {
       const SizedBox(width: 48.0),
     ];
     await tester.pumpWidget(buildApp());
-    expect(tester.getTopRight(title).dx, 620 + 48 + 48);
+    expect(tester.getTopRight(title).dx, 620 + 48 + 48 + 16);
     expect(tester.getSize(title).width, equals(620.0));
   });
 
@@ -3575,4 +3575,34 @@ void main() {
     expect(preferredHeight, 64);
     expect(preferredSize.height, 64);
   });
+
+  testWidgets('AppBar title with actions should have the same position regardless of centerTitle', (WidgetTester tester) async {
+    final Key titleKey = UniqueKey();
+    bool centerTitle = false;
+
+    Widget buildApp() {
+      return MaterialApp(
+        home: Scaffold(
+          appBar: AppBar(
+            centerTitle: centerTitle,
+            title: Container(
+              key: titleKey,
+              constraints: BoxConstraints.loose(const Size(1000.0, 1000.0)),
+            ),
+            actions: const <Widget>[
+              SizedBox(width: 48.0),
+            ],
+          ),
+        ),
+      );
+    }
+
+    await tester.pumpWidget(buildApp());
+    final Finder title = find.byKey(titleKey);
+    expect(tester.getTopLeft(title).dx, 16.0);
+
+    centerTitle = true;
+    await tester.pumpWidget(buildApp());
+    expect(tester.getTopLeft(title).dx, 16.0);
+  });
 }