Update for Flutter 3.10 beta (#1746)

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [ ] All existing and new tests are passing.

---------

Co-authored-by: David Iglesias <ditman@gmail.com>
Co-authored-by: Mark Thompson <2554588+MarkTechson@users.noreply.github.com>
Co-authored-by: John Ryan <ryjohn@google.com>

material_3_demo/lib/constants.dart

@@ -13,6 +13,13 @@ const double largeWidthBreakpoint = 1500;
 
 const double transitionLength = 500;
 
+// Whether the user has chosen a theme color via a direct [ColorSeed] selection,
+// or an image [ColorImageProvider].
+enum ColorSelectionMethod {
+  colorSeed,
+  image,
+}
+
 enum ColorSeed {
   baseColor('M3 Baseline', Color(0xff6750a4)),
   indigo('Indigo', Colors.indigo),
@@ -29,6 +36,25 @@ enum ColorSeed {
   final Color color;
 }
 
+enum ColorImageProvider {
+  leaves('Leaves',
+      'https://flutter.github.io/assets-for-api-docs/assets/material/content_based_color_scheme_1.png'),
+  peonies('Peonies',
+      'https://flutter.github.io/assets-for-api-docs/assets/material/content_based_color_scheme_2.png'),
+  bubbles('Bubbles',
+      'https://flutter.github.io/assets-for-api-docs/assets/material/content_based_color_scheme_3.png'),
+  seaweed('Seaweed',
+      'https://flutter.github.io/assets-for-api-docs/assets/material/content_based_color_scheme_4.png'),
+  seagrapes('Sea Grapes',
+      'https://flutter.github.io/assets-for-api-docs/assets/material/content_based_color_scheme_5.png'),
+  petals('Petals',
+      'https://flutter.github.io/assets-for-api-docs/assets/material/content_based_color_scheme_6.png');
+
+  const ColorImageProvider(this.label, this.url);
+  final String label;
+  final String url;
+}
+
 enum ScreenSelected {
   component(0),
   color(1),