Update uses of ButtonTheme.bar: pass along the current Theme's colorScheme (#22827)

* Update uses of ButtonTheme.bar

* updated gallery themes

* Remove unnecessary const

Fixes #22789

examples/flutter_gallery/lib/demo/material/cards_demo.dart

@@ -129,6 +129,7 @@ class TravelDestinationItem extends StatelessWidget {
               ),
               // share, explore buttons
               ButtonTheme.bar(
+                colorScheme: theme.colorScheme,
                 child: ButtonBar(
                   alignment: MainAxisAlignment.start,
                   children: <Widget>[

examples/flutter_gallery/lib/gallery/themes.dart

@@ -24,15 +24,17 @@ TextTheme _buildTextTheme(TextTheme base) {
 
 ThemeData _buildDarkTheme() {
   const Color primaryColor = Color(0xFF0175c2);
+  const Color secondaryColor = Color(0xFF13B9FD);
   final ThemeData base = ThemeData.dark();
   final ColorScheme colorScheme = const ColorScheme.dark().copyWith(
     primary: primaryColor,
+    secondary: secondaryColor,
   );
   return base.copyWith(
     primaryColor: primaryColor,
     buttonColor: primaryColor,
     indicatorColor: Colors.white,
-    accentColor: const Color(0xFF13B9FD),
+    accentColor: secondaryColor,
     canvasColor: const Color(0xFF202124),
     scaffoldBackgroundColor: const Color(0xFF202124),
     backgroundColor: const Color(0xFF202124),
@@ -49,8 +51,10 @@ ThemeData _buildDarkTheme() {
 
 ThemeData _buildLightTheme() {
   const Color primaryColor = Color(0xFF0175c2);
+  const Color secondaryColor = Color(0xFF13B9FD);
   final ColorScheme colorScheme = const ColorScheme.light().copyWith(
     primary: primaryColor,
+    secondary: secondaryColor,
   );
   final ThemeData base = ThemeData.light();
   return base.copyWith(
@@ -60,7 +64,7 @@ ThemeData _buildLightTheme() {
     indicatorColor: Colors.white,
     splashColor: Colors.white24,
     splashFactory: InkRipple.splashFactory,
-    accentColor: const Color(0xFF13B9FD),
+    accentColor: secondaryColor,
     canvasColor: Colors.white,
     scaffoldBackgroundColor: Colors.white,
     backgroundColor: Colors.white,

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

@@ -952,6 +952,7 @@ class _DatePickerDialogState extends State<_DatePickerDialog> {
       ),
     );
     final Widget actions = ButtonTheme.bar(
+      colorScheme: theme.buttonTheme.colorScheme,
       child: ButtonBar(
         children: <Widget>[
           FlatButton(

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

@@ -274,6 +274,7 @@ class AlertDialog extends StatelessWidget {
 
     if (actions != null) {
       children.add(ButtonTheme.bar(
+        colorScheme: Theme.of(context).colorScheme,
         child: ButtonBar(
           children: actions,
         ),
@@ -625,4 +626,4 @@ Future<T> showDialog<T>({
     transitionDuration: const Duration(milliseconds: 150),
     transitionBuilder: _buildMaterialDialogTransitions,
   );
-}
+}
\ No newline at end of file

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

@@ -400,6 +400,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
                   opacity: 0.54
                 ),
                 child: ButtonTheme.bar(
+                  colorScheme: themeData.colorScheme,
                   child: Ink(
                     height: 64.0,
                     color: _selectedRowCount > 0 ? themeData.secondaryHeaderColor : null,

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

@@ -1605,6 +1605,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
           ),
           child: SafeArea(
             child: ButtonTheme.bar(
+              colorScheme: themeData.colorScheme,
               child: SafeArea(
                 top: false,
                 child: ButtonBar(

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

@@ -212,6 +212,7 @@ class SnackBar extends StatelessWidget {
     ];
     if (action != null) {
       children.add(ButtonTheme.bar(
+        colorScheme: theme.colorScheme,
         padding: const EdgeInsets.symmetric(horizontal: _kSnackBarPadding),
         textTheme: ButtonTextTheme.accent,
         child: action,

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

@@ -1541,6 +1541,7 @@ class _TimePickerDialogState extends State<_TimePickerDialog> {
     );
 
     final Widget actions = ButtonTheme.bar(
+      colorScheme: theme.colorScheme,
       child: ButtonBar(
         children: <Widget>[
           FlatButton(