Updated references to the old button classes to the new ones in comments and...

Updated references to the old button classes to the new ones in comments and documentation for classes in the material library. (#62092)

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

@@ -65,7 +65,7 @@ class MaterialBanner extends StatelessWidget {
   /// The set of actions that are displayed at the bottom or trailing side of
   /// the [MaterialBanner].
   ///
-  /// Typically this is a list of [FlatButton] widgets.
+  /// Typically this is a list of [TextButton] widgets.
   ///
   /// These widgets will be wrapped in a [ButtonBar], which introduces 8 pixels
   /// of padding on each side.

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

@@ -600,7 +600,7 @@ class _BottomSheetSuspendedCurve extends ParametricCurve<double> {
 /// ```dart
 /// Widget build(BuildContext context) {
 ///   return Center(
-///     child: RaisedButton(
+///     child: ElevatedButton(
 ///       child: const Text('showModalBottomSheet'),
 ///       onPressed: () {
 ///         showModalBottomSheet<void>(
@@ -615,7 +615,7 @@ class _BottomSheetSuspendedCurve extends ParametricCurve<double> {
 ///                   mainAxisSize: MainAxisSize.min,
 ///                   children: <Widget>[
 ///                     const Text('Modal BottomSheet'),
-///                     RaisedButton(
+///                     ElevatedButton(
 ///                       child: const Text('Close BottomSheet'),
 ///                       onPressed: () => Navigator.pop(context),
 ///                     )

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

@@ -1259,8 +1259,8 @@ class FilterChip extends StatelessWidget
 /// Action chips are displayed after primary content, such as below a card or
 /// persistently at the bottom of a screen.
 ///
-/// The material button widgets, [RaisedButton], [FlatButton], and
-/// [OutlineButton], are an alternative to action chips, which should appear
+/// The material button widgets, [ElevatedButton], [TextButton], and
+/// [OutlinedButton], are an alternative to action chips, which should appear
 /// statically and consistently in a UI.
 ///
 /// Requires one of its ancestors to be a [Material] widget.

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

@@ -208,7 +208,7 @@ class Dialog extends StatelessWidget {
 ///           ),
 ///         ),
 ///         actions: <Widget>[
-///           FlatButton(
+///           TextButton(
 ///             child: Text('Approve'),
 ///             onPressed: () {
 ///               Navigator.of(context).pop();
@@ -311,9 +311,9 @@ class AlertDialog extends StatelessWidget {
   /// The (optional) set of actions that are displayed at the bottom of the
   /// dialog.
   ///
-  /// Typically this is a list of [FlatButton] widgets. It is recommended to
+  /// Typically this is a list of [TextButton] widgets. It is recommended to
   /// set the [textAlign] to [TextAlign.end] for the [Text] within the
-  /// [FlatButton], so that buttons whose labels wrap to an extra line align
+  /// [TextButton], so that buttons whose labels wrap to an extra line align
   /// with the overall [ButtonBar]'s alignment within the dialog.
   ///
   /// These widgets will be wrapped in a [ButtonBar], which introduces 8 pixels
@@ -341,8 +341,8 @@ class AlertDialog extends StatelessWidget {
   ///   title: Text('Title'),
   ///   content: Container(width: 200, height: 200, color: Colors.green),
   ///   actions: <Widget>[
-  ///     RaisedButton(onPressed: () {}, child: Text('Button 1')),
-  ///     RaisedButton(onPressed: () {}, child: Text('Button 2')),
+  ///     ElevatedButton(onPressed: () {}, child: Text('Button 1')),
+  ///     ElevatedButton(onPressed: () {}, child: Text('Button 2')),
   ///   ],
   ///   actionsPadding: EdgeInsets.symmetric(horizontal: 8.0),
   /// )
@@ -613,7 +613,7 @@ class AlertDialog extends StatelessWidget {
 ///
 ///  * [SimpleDialog], for a dialog in which to use this widget.
 ///  * [showDialog], which actually displays the dialog and returns its result.
-///  * [FlatButton], which are commonly used as actions in other kinds of
+///  * [TextButton], which are commonly used as actions in other kinds of
 ///    dialogs, such as [AlertDialog]s.
 ///  * <https://material.io/design/components/dialogs.html#simple-dialog>
 class SimpleDialogOption extends StatelessWidget {

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

@@ -785,7 +785,7 @@ class DropdownButtonHideUnderline extends InheritedWidget {
 ///  * [DropdownMenuItem], the class used to represent the [items].
 ///  * [DropdownButtonHideUnderline], which prevents its descendant dropdown buttons
 ///    from displaying their underlines.
-///  * [RaisedButton], [FlatButton], ordinary buttons that trigger a single action.
+///  * [ElevatedButton], [TextButton], ordinary buttons that trigger a single action.
 ///  * <https://material.io/design/components/menus.html#dropdown-menu>
 class DropdownButton<T> extends StatefulWidget {
   /// Creates a dropdown button.

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

@@ -280,7 +280,7 @@ typedef _CheckContext = bool Function(BuildContext context);
 /// See also:
 ///
 ///  * [GestureDetector], for listening for gestures without ink splashes.
-///  * [RaisedButton] and [FlatButton], two kinds of buttons in material design.
+///  * [ElevatedButton] and [TextButton], two kinds of buttons in material design.
 ///  * [IconButton], which combines [InkResponse] with an [Icon].
 class InkResponse extends StatelessWidget {
   /// Creates an area of a [Material] that responds to touch.
@@ -1198,7 +1198,7 @@ class _InkResponseState extends State<_InkResponseStateWidget>
 /// See also:
 ///
 ///  * [GestureDetector], for listening for gestures without ink splashes.
-///  * [RaisedButton] and [FlatButton], two kinds of buttons in material design.
+///  * [ElevatedButton] and [TextButton], two kinds of buttons in material design.
 ///  * [InkResponse], a variant of [InkWell] that doesn't force a rectangular
 ///    shape on the ink reaction.
 class InkWell extends InkResponse {

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

@@ -231,7 +231,7 @@ class TextTheme with Diagnosticable {
   /// Used for auxiliary text associated with images.
   final TextStyle caption;
 
-  /// Used for text on [RaisedButton] and [FlatButton].
+  /// Used for text on [ElevatedButton], [TextButton] and [OutlinedButton].
   final TextStyle button;
 
   /// The smallest style.

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

@@ -71,6 +71,9 @@ const Color _kDarkThemeSplashColor = Color(0x40CCCCCC);
 ///
 ///   * [FloatingActionButton], only the mini tap target size is increased.
 ///   * [MaterialButton]
+///   * [OutlinedButton]
+///   * [TextButton]
+///   * [ElevatedButton]
 ///   * [OutlineButton]
 ///   * [FlatButton]
 ///   * [RaisedButton]