Remove scrollbar deprecations isAlwaysShown and hoverThickness (flutter#127351)

The deprecated `[RawScrollbar/Scrollbar/CupertinoScrollbar/ScrollbarThemeData].isAlwaysShown` has expired and is removed in thi PR.
Also, `Scrollbar.hoverThickness` is also removed after having expired.

The replacement for `isAlwaysShown` is `thumbVisibility`. This deprecation was introduced in flutter#96957. The name change came from new behaviors like a track that is conditionally visible. Since the original API only referred to the thumb, the name was changed to reflect this intention. This change is supported by dart fix. � 

The replacement for `hoverThickness` is `ScrollbarThemeData.thickness`, which is a MaterialStateProperty that allows for the thickness to respond to multiple states including hover. This deprecation was introduced in flutter#97173. This change is not supported by dart fix. �  

Part of flutter#127042

Author: Piinks

packages/flutter/lib/src/cupertino/scrollbar.dart

@@ -53,8 +53,7 @@ const double _kScrollbarCrossAxisMargin = 3.0;
 /// {@tool dartpad}
 /// When [thumbVisibility] is true, the scrollbar thumb will remain visible without the
 /// fade animation. This requires that a [ScrollController] is provided to controller,
-/// or that the [PrimaryScrollController] is available. [isAlwaysShown] is
-/// deprecated in favor of `thumbVisibility`.
+/// or that the [PrimaryScrollController] is available.
 ///
 /// ** See code in examples/api/lib/cupertino/scrollbar/cupertino_scrollbar.1.dart **
 /// {@end-tool}
@@ -82,20 +81,10 @@ class CupertinoScrollbar extends RawScrollbar {
     this.radiusWhileDragging = defaultRadiusWhileDragging,
     ScrollNotificationPredicate? notificationPredicate,
     super.scrollbarOrientation,
-    @Deprecated(
-      'Use thumbVisibility instead. '
-      'This feature was deprecated after v2.9.0-1.0.pre.',
-    )
-    bool? isAlwaysShown,
   }) : assert(thickness < double.infinity),
        assert(thicknessWhileDragging < double.infinity),
-       assert(
-         isAlwaysShown == null || thumbVisibility == null,
-         'Scrollbar thumb appearance should only be controlled with thumbVisibility, '
-         'isAlwaysShown is deprecated.'
-       ),
        super(
-         thumbVisibility: isAlwaysShown ?? thumbVisibility ?? false,
+         thumbVisibility: thumbVisibility ?? false,
          fadeDuration: _kScrollbarFadeDuration,
          timeToFade: _kScrollbarTimeToFade,
          pressDuration: const Duration(milliseconds: 100),

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

@@ -95,26 +95,12 @@ class Scrollbar extends StatelessWidget {
     this.notificationPredicate,
     this.interactive,
     this.scrollbarOrientation,
-    @Deprecated(
-      'Use thumbVisibility instead. '
-      'This feature was deprecated after v2.9.0-1.0.pre.',
-    )
-    this.isAlwaysShown,
     @Deprecated(
       'Use ScrollbarThemeData.trackVisibility to resolve based on the current state instead. '
       'This feature was deprecated after v3.4.0-19.0.pre.',
     )
     this.showTrackOnHover,
-    @Deprecated(
-      'Use ScrollbarThemeData.thickness to resolve based on the current state instead. '
-      'This feature was deprecated after v2.9.0-1.0.pre.',
-    )
-    this.hoverThickness,
-  }) : assert(
-         thumbVisibility == null || isAlwaysShown == null,
-         'Scrollbar thumb appearance should only be controlled with thumbVisibility, '
-         'isAlwaysShown is deprecated.'
-       );
+  });
 
   /// {@macro flutter.widgets.Scrollbar.child}
   final Widget child;
@@ -131,20 +117,8 @@ class Scrollbar extends StatelessWidget {
   /// If the thumb visibility is related to the scrollbar's material state,
   /// use the global [ScrollbarThemeData.thumbVisibility] or override the
   /// sub-tree's theme data.
-  ///
-  /// Replaces deprecated [isAlwaysShown].
   final bool? thumbVisibility;
 
-  /// {@macro flutter.widgets.Scrollbar.isAlwaysShown}
-  ///
-  /// To show the scrollbar thumb based on a [MaterialState], use
-  /// [ScrollbarThemeData.thumbVisibility].
-  @Deprecated(
-    'Use thumbVisibility instead. '
-    'This feature was deprecated after v2.9.0-1.0.pre.',
-  )
-  final bool? isAlwaysShown;
-
   /// {@macro flutter.widgets.Scrollbar.trackVisibility}
   ///
   /// If this property is null, then [ScrollbarThemeData.trackVisibility] of
@@ -172,21 +146,6 @@ class Scrollbar extends StatelessWidget {
   )
   final bool? showTrackOnHover;
 
-  /// The thickness of the scrollbar when a hover state is active and
-  /// [showTrackOnHover] is true.
-  ///
-  /// If this property is null, then [ScrollbarThemeData.thickness] of
-  /// [ThemeData.scrollbarTheme] is used to resolve a thickness. If that is also
-  /// null, the default value is 12.0 pixels.
-  ///
-  /// This is deprecated, use [ScrollbarThemeData.thickness] to resolve based on
-  /// the current state instead.
-  @Deprecated(
-    'Use ScrollbarThemeData.thickness to resolve based on the current state instead. '
-    'This feature was deprecated after v2.9.0-1.0.pre.',
-  )
-  final double? hoverThickness;
-
   /// The thickness of the scrollbar in the cross axis of the scrollable.
   ///
   /// If null, the default value is platform dependent. On [TargetPlatform.android],
@@ -216,7 +175,7 @@ class Scrollbar extends StatelessWidget {
   Widget build(BuildContext context) {
     if (Theme.of(context).platform == TargetPlatform.iOS) {
       return CupertinoScrollbar(
-        thumbVisibility: isAlwaysShown ?? thumbVisibility ?? false,
+        thumbVisibility: thumbVisibility ?? false,
         thickness: thickness ?? CupertinoScrollbar.defaultThickness,
         thicknessWhileDragging: thickness ?? CupertinoScrollbar.defaultThicknessWhileDragging,
         radius: radius ?? CupertinoScrollbar.defaultRadius,
@@ -229,10 +188,9 @@ class Scrollbar extends StatelessWidget {
     }
     return _MaterialScrollbar(
       controller: controller,
-      thumbVisibility: isAlwaysShown ?? thumbVisibility,
+      thumbVisibility: thumbVisibility,
       trackVisibility: trackVisibility,
       showTrackOnHover: showTrackOnHover,
-      hoverThickness: hoverThickness,
       thickness: thickness,
       radius: radius,
       notificationPredicate: notificationPredicate,
@@ -250,7 +208,6 @@ class _MaterialScrollbar extends RawScrollbar {
     super.thumbVisibility,
     super.trackVisibility,
     this.showTrackOnHover,
-    this.hoverThickness,
     super.thickness,
     super.radius,
     ScrollNotificationPredicate? notificationPredicate,
@@ -264,7 +221,6 @@ class _MaterialScrollbar extends RawScrollbar {
        );
 
   final bool? showTrackOnHover;
-  final double? hoverThickness;
 
   @override
   _MaterialScrollbarState createState() => _MaterialScrollbarState();
@@ -280,7 +236,7 @@ class _MaterialScrollbarState extends RawScrollbarState<_MaterialScrollbar> {
   late bool _useAndroidScrollbar;
 
   @override
-  bool get showScrollbar => widget.thumbVisibility ?? _scrollbarTheme.thumbVisibility?.resolve(_states) ?? _scrollbarTheme.isAlwaysShown ?? false;
+  bool get showScrollbar => widget.thumbVisibility ?? _scrollbarTheme.thumbVisibility?.resolve(_states) ?? false;
 
   @override
   bool get enableGestures => widget.interactive ?? _scrollbarTheme.interactive ?? !_useAndroidScrollbar;
@@ -370,8 +326,7 @@ class _MaterialScrollbarState extends RawScrollbarState<_MaterialScrollbar> {
   MaterialStateProperty<double> get _thickness {
     return MaterialStateProperty.resolveWith((Set<MaterialState> states) {
       if (states.contains(MaterialState.hovered) && _trackVisibility.resolve(states)) {
-        return widget.hoverThickness
-          ?? _scrollbarTheme.thickness?.resolve(states)
+        return _scrollbarTheme.thickness?.resolve(states)
           ?? _kScrollbarThicknessWithTrack;
       }
       // The default scrollbar thickness is smaller on mobile.

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

@@ -45,26 +45,15 @@ class ScrollbarThemeData with Diagnosticable {
     this.mainAxisMargin,
     this.minThumbLength,
     this.interactive,
-    @Deprecated(
-      'Use thumbVisibility instead. '
-      'This feature was deprecated after v2.9.0-1.0.pre.',
-    )
-    this.isAlwaysShown,
     @Deprecated(
       'Use ScrollbarThemeData.trackVisibility to resolve based on the current state instead. '
       'This feature was deprecated after v3.4.0-19.0.pre.',
     )
     this.showTrackOnHover,
-  }) : assert(
-         isAlwaysShown == null || thumbVisibility == null,
-         'Scrollbar thumb appearance should only be controlled with thumbVisibility, '
-         'isAlwaysShown is deprecated.'
-       );
+  });
 
   /// Overrides the default value of [Scrollbar.thumbVisibility] in all
   /// descendant [Scrollbar] widgets.
-  ///
-  /// Replaces deprecated [isAlwaysShown].
   final MaterialStateProperty<bool?>? thumbVisibility;
 
   /// Overrides the default value of [Scrollbar.thickness] in all
@@ -86,16 +75,6 @@ class ScrollbarThemeData with Diagnosticable {
   )
   final bool? showTrackOnHover;
 
-  /// Overrides the default value of [Scrollbar.isAlwaysShown] in all
-  /// descendant [Scrollbar] widgets.
-  ///
-  /// Deprecated in favor of [thumbVisibility].
-  @Deprecated(
-    'Use thumbVisibility instead. '
-    'This feature was deprecated after v2.9.0-1.0.pre.',
-  )
-  final bool? isAlwaysShown;
-
   /// Overrides the default value of [Scrollbar.interactive] in all
   /// descendant [Scrollbar] widgets.
   final bool? interactive;
@@ -169,12 +148,6 @@ class ScrollbarThemeData with Diagnosticable {
     double? crossAxisMargin,
     double? mainAxisMargin,
     double? minThumbLength,
-    @Deprecated(
-      'Use thumbVisibility instead. '
-      'This feature was deprecated after v2.9.0-1.0.pre.',
-    )
-    bool? isAlwaysShown,
-
     @Deprecated(
       'Use ScrollbarThemeData.trackVisibility to resolve based on the current state instead. '
       'This feature was deprecated after v3.4.0-19.0.pre.',
@@ -186,7 +159,6 @@ class ScrollbarThemeData with Diagnosticable {
       thickness: thickness ?? this.thickness,
       trackVisibility: trackVisibility ?? this.trackVisibility,
       showTrackOnHover: showTrackOnHover ?? this.showTrackOnHover,
-      isAlwaysShown: isAlwaysShown ?? this.isAlwaysShown,
       interactive: interactive ?? this.interactive,
       radius: radius ?? this.radius,
       thumbColor: thumbColor ?? this.thumbColor,
@@ -212,7 +184,6 @@ class ScrollbarThemeData with Diagnosticable {
       thickness: MaterialStateProperty.lerp<double?>(a?.thickness, b?.thickness, t, lerpDouble),
       trackVisibility: MaterialStateProperty.lerp<bool?>(a?.trackVisibility, b?.trackVisibility, t, _lerpBool),
       showTrackOnHover: _lerpBool(a?.showTrackOnHover, b?.showTrackOnHover, t),
-      isAlwaysShown: _lerpBool(a?.isAlwaysShown, b?.isAlwaysShown, t),
       interactive: _lerpBool(a?.interactive, b?.interactive, t),
       radius: Radius.lerp(a?.radius, b?.radius, t),
       thumbColor: MaterialStateProperty.lerp<Color?>(a?.thumbColor, b?.thumbColor, t, Color.lerp),
@@ -230,7 +201,6 @@ class ScrollbarThemeData with Diagnosticable {
     thickness,
     trackVisibility,
     showTrackOnHover,
-    isAlwaysShown,
     interactive,
     radius,
     thumbColor,
@@ -254,7 +224,6 @@ class ScrollbarThemeData with Diagnosticable {
       && other.thickness == thickness
       && other.trackVisibility == trackVisibility
       && other.showTrackOnHover == showTrackOnHover
-      && other.isAlwaysShown == isAlwaysShown
       && other.interactive == interactive
       && other.radius == radius
       && other.thumbColor == thumbColor
@@ -272,7 +241,6 @@ class ScrollbarThemeData with Diagnosticable {
     properties.add(DiagnosticsProperty<MaterialStateProperty<double?>>('thickness', thickness, defaultValue: null));
     properties.add(DiagnosticsProperty<MaterialStateProperty<bool?>>('trackVisibility', trackVisibility, defaultValue: null));
     properties.add(DiagnosticsProperty<bool>('showTrackOnHover', showTrackOnHover, defaultValue: null));
-    properties.add(DiagnosticsProperty<bool>('isAlwaysShown', isAlwaysShown, defaultValue: null));
     properties.add(DiagnosticsProperty<bool>('interactive', interactive, defaultValue: null));
     properties.add(DiagnosticsProperty<Radius>('radius', radius, defaultValue: null));
     properties.add(DiagnosticsProperty<MaterialStateProperty<Color?>>('thumbColor', thumbColor, defaultValue: null));