Refactor splash example to not use material_ui - #191380

Converts examples/splash to widgets-only so it no longer cross-imports the Material layer.

splash pulled in package:material_ui/material_ui.dart for exactly two symbols: Colors.white and Colors.black87. Everything else it renders — DecoratedBox, BoxDecoration, Center, Column, Padding, Text, TextStyle, FlutterLogo — is already exported by package:flutter/widgets.dart (FlutterLogo at packages/flutter/lib/widgets.dart:59). Replacing those two colours with local Color constants drops the dependency with no change to the rendered output.

This follows the examples/flutter_view conversion in #190377 — local const Color declarations at the top of main.dart. splash needs no WidgetsApp because it never had a MaterialApp, which is what makes it the smallest self-contained unit to start with.

Changes

• examples/splash/lib/main.dart — import package:flutter/widgets.dart; add const Color _white = Color(0xFFFFFFFF) and const Color _black87 = Color(0xDD000000) (values taken from packages/flutter/lib/src/material/colors.dart:396 and :310) and use them in place of Colors.white / Colors.black87. The widget tree, sizes, padding and text are otherwise unchanged.
• examples/splash/test/splash_test.dart — same import swap, moved above flutter_test to satisfy directives_ordering. The existing Displays flutter logo and message test is untouched. Adds one test pinning the two colour values, since swapping Colors.* for literals is the one way this refactor could silently change rendering.
• examples/splash/pubspec.yaml — remove material_ui: ^0.0.2 and update the # PUBSPEC CHECKSUM: line.

pubspec.lock is deliberately unchanged: material_ui is still a direct dependency of image_list, layers, multiple_windows, platform_channel, platform_channel_swift and platform_view, so its root lock entry is still required.

Scope

This is one example, not the whole issue. 27 package:material_ui imports remain across those six examples, and examples/texture/lib/main.dart is still on package:flutter/material.dart — the only examples/ entry left in knownExamplesCrossImports. Note that removing that one also means deleting its allowlist line in the same commit, since the checker fails when a known cross import disappears. Happy to take the rest in follow-ups if the shape here looks right to you.

One thing worth flagging

dev/bots/check_examples_cross_imports.dart does not catch any of these. LibraryCrossImportStatementType in dev/bots/cross_imports_checker_utils.dart matches only the literal strings import 'package:flutter/material.dart' and import 'package:flutter/cupertino.dart', so material_ui / cupertino_ui imports are invisible to the cross-imports-examples validation today — anything cleaned up can regress silently. I have not touched the checker here. Whether it should learn about the package imports, and whether that lands before or after the conversions, seems like your call rather than something to fold into a cleanup PR — the utils file is shared with check_tests_cross_imports.dart, so it is not a mechanical change.

Part of #190305
Part of #177028

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the AI contribution guidelines and understand my responsibilities, or I am not using AI tools.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• I followed the breaking change policy and added Data Driven Fixes where supported.
• All existing and new tests are passing.

NOT PART OF THE PR BODY — author pre-flight (delete before posting)

Nothing above the separator has been published. The diff is uncommitted on branch fix/190305-minimize-cross-imports-in-examples in workspaces/flutter__flutter__issue-190305. Three things must happen before this is opened:

1. Post the claim comment and get a reply first. #190305 was filed by justinmc (Flutter team) under team-framework / P2 as part of #177028, with no good first issue or help wanted label, and the team is actively landing adjacent PRs (#190237, #190248, #190377). The assessment sets maintainer_alignment_required: true. The drafted claim comment in reports/flutter__flutter__190305/assessment.json is unposted. Sending an unsolicited PR into in-flight team work is the main risk here, not the code.

2. Run the tests. None have been run. Docker is permission-gated in this pipeline, so every command below is unexecuted and the checklist boxes above are all unchecked for that reason. Run these in the configured runner (ghcr.io/cirruslabs/flutter:stable), then tick the boxes:

python3 scripts/safe_project.py --workspace workspaces/flutter__flutter__issue-190305 --stack flutter --image ghcr.io/cirruslabs/flutter:stable --network on  -- bin/flutter update-packages
python3 scripts/safe_project.py --workspace workspaces/flutter__flutter__issue-190305 --stack flutter --image ghcr.io/cirruslabs/flutter:stable --network off -- bin/flutter test examples/splash
python3 scripts/safe_project.py --workspace workspaces/flutter__flutter__issue-190305 --stack flutter --image ghcr.io/cirruslabs/flutter:stable --network off -- bin/flutter analyze --no-pub examples/splash
python3 scripts/safe_project.py --workspace workspaces/flutter__flutter__issue-190305 --stack flutter --image ghcr.io/cirruslabs/flutter:stable --network off -- bin/cache/dart-sdk/bin/dart format --output=none --set-exit-if-changed examples/splash
python3 scripts/safe_project.py --workspace workspaces/flutter__flutter__issue-190305 --stack flutter --image ghcr.io/cirruslabs/flutter:stable --network off -- bin/cache/dart-sdk/bin/dart --enable-asserts dev/bots/check_examples_cross_imports.dart

3. Settle the checksum. # PUBSPEC CHECKSUM: 60tfp7 was derived by inference, not generated by the tool. _computeChecksum (packages/flutter_tools/lib/src/commands/update_packages.dart:535) hashes only the sorted dependency map, and splash's post-change set (flutter + flutter_test) is now byte-identical to dev/manual_tests and dev/benchmarks/imitation_game_flutter, both of which carry 60tfp7 — verified in-tree. bin/flutter update-packages confirms it in one run; if it reports a mismatch, rerun with --update-hashes and take the corrected line.

Open items for the author

• The second test is optional. The orchestrator asked for regression coverage; acceptance criterion 3 asked for an import-line-only change to the test file. Both were honoured by adding a test rather than editing the existing one. Drop the Uses the original splash palette block if maintainers prefer the minimal diff. It relies on find.byType(DecoratedBox).first being the app background — correct because FlutterLogo builds its own DecoratedBox via AnimatedContainer (packages/flutter/lib/src/widgets/flutter_logo.dart:72-77) as a descendant, and finders traverse in pre-order — but this is a static argument, not an observed pass.
• material_ui was not read directly. It is an external pub package (^0.0.2); Colors.white / Colors.black87 were verified against the repo's own packages/flutter/lib/src/material/colors.dart, not the package source, which lives outside the workspace.
• This partially walks back Migrate examples/splash to package:material_ui #190248 (Migrate examples/splash to package:material_ui), which is the intended direction per Minimize cross imports in examples #190305 but worth naming if a reviewer asks why splash changed twice.
• Precedent attribution: the conversion pattern comes from Refactor flutter_view example to not use material #190377 (Refactor flutter_view example to not use material). Migrate layers example to material_ui #190237 is the layers migration whose review thread prompted the issue — they are different PRs.