Removed PaginatedDataTable ButtonBar special case (#85547)

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

@@ -7,7 +7,6 @@ import 'dart:math' as math;
 import 'package:flutter/gestures.dart' show DragStartBehavior;
 import 'package:flutter/widgets.dart';
 
-import 'button_bar.dart';
 import 'card.dart';
 import 'constants.dart';
 import 'data_table.dart';
@@ -372,17 +371,8 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);
     // HEADER
     final List<Widget> headerWidgets = <Widget>[];
-    double startPadding = 24.0;
     if (_selectedRowCount == 0 && widget.header != null) {
       headerWidgets.add(Expanded(child: widget.header!));
-      if (widget.header is ButtonBar) {
-        // We adjust the padding when a button bar is present, because the
-        // ButtonBar introduces 2 pixels of outside padding, plus 2 pixels
-        // around each button on each side, and the button itself will have 8
-        // pixels internally on each side, yet we want the left edge of the
-        // inside of the button to line up with the 24.0 left inset.
-        startPadding = 12.0;
-      }
     } else if (widget.header != null) {
       headerWidgets.add(Expanded(
         child: Text(localizations.selectedRowCountTitle(_selectedRowCount)),
@@ -501,7 +491,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
                         height: 64.0,
                         color: _selectedRowCount > 0 ? themeData.secondaryHeaderColor : null,
                         child: Padding(
-                          padding: EdgeInsetsDirectional.only(start: startPadding, end: 14.0),
+                          padding: const EdgeInsetsDirectional.only(start: 24, end: 14.0),
                           child: Row(
                             mainAxisAlignment: MainAxisAlignment.end,
                             children: headerWidgets,

packages/flutter/test/material/paginated_data_table_test.dart

@@ -1012,4 +1012,32 @@ void main() {
     expect(icons.elementAt(2).color, arrowHeadColor);
     expect(icons.elementAt(3).color, arrowHeadColor);
   });
+
+  testWidgets('OverflowBar header left alignment', (WidgetTester tester) async {
+    // Test an old special case that tried to align the first child of a ButtonBar
+    // and the left edge of a Text header widget. Still possible with OverflowBar
+    // albeit without any special case in the implementation's build method.
+    Widget buildFrame(Widget header) {
+      return MaterialApp(
+        home: PaginatedDataTable(
+          header: header,
+          rowsPerPage: 2,
+          source: TestDataSource(),
+          columns: const <DataColumn>[
+            DataColumn(label: Text('Name')),
+            DataColumn(label: Text('Calories'), numeric: true),
+            DataColumn(label: Text('Generation')),
+          ],
+        ),
+      );
+    }
+
+    await tester.pumpWidget(buildFrame(const Text('HEADER')));
+    final double headerX = tester.getTopLeft(find.text('HEADER')).dx;
+    final Widget overflowBar = OverflowBar(
+      children: <Widget>[ElevatedButton(onPressed: () {}, child: const Text('BUTTON'))],
+    );
+    await tester.pumpWidget(buildFrame(overflowBar));
+    expect(headerX, tester.getTopLeft(find.byType(ElevatedButton)).dx);
+  });
 }