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[android] Isolate API-34 high contrast listener in AccessibilityBridge behind Api34Impl by gmackall · Pull Request #192502 · flutter/flutter · GitHub
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[android] Isolate API-34 high contrast listener in AccessibilityBridge behind Api34Impl - #192502

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gmackall:fix-192231-api34-high-contrast
Sep 11, 2026
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[android] Isolate API-34 high contrast listener in AccessibilityBridge behind Api34Impl#192502
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flutter:masterfrom
gmackall:fix-192231-api34-high-contrast

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@gmackall gmackall commented Sep 9, 2026

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Isolates API-34 UiModeManager.ContrastChangeListener and related contrast calls in AccessibilityBridge inside an @RequiresApi(API_LEVELS.API_34) static holder class (Api34Impl) with @DoNotInline.

Background / Root Cause

On Android 12 and 13 (API < 34), AccessibilityBridge previously evaluated a ternary merge point in <init> between a lambda cast to (ContrastChangedListener & UiModeManager.ContrastChangeListener) and a no-op fallback. D8 desugars this intersection cast into a synthetic class implementing UiModeManager.ContrastChangeListener. Because this ternary join occurs in <init>, the ART verifier attempts to resolve the synthetic class and its unimplemented interface when loading AccessibilityBridge, failing with NoClassDefFoundError: Failed resolution of: Lt2; (ClassNotFoundException: android.app.UiModeManager$ContrastChangeListener).

By moving all references to UiModeManager.ContrastChangeListener into Api34Impl and holding the observer as an Object reference on AccessibilityBridge, ART never attempts to load or verify the API-34 types on devices with API < 34.

Fixes #192231

Pre-launch Checklist

This pull request was generated with Gemini / AI assistance.

@gmackall
[android] Isolate API-34 high contrast listener in AccessibilityBridg…
9546100 
…e behind Api34Impl

Isolates API-34 UiModeManager.ContrastChangeListener references in AccessibilityBridge inside a static Api34Impl holder class to prevent ART class verification failures and NoClassDefFoundError crashes on pre-API 34 devices (Android 12/13).

Fixes flutter#192231
@gmackall gmackall added the CICD Run CI/CD label Sep 9, 2026
@github-actions github-actions Bot added platform-android Android applications specifically engine flutter/engine related. See also e: labels. team-android Owned by Android platform team and removed CICD Run CI/CD labels Sep 9, 2026
@gmackall gmackall added the CICD Run CI/CD label Sep 9, 2026
@gmackall
gmackall marked this pull request as ready for review September 9, 2026 19:48
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gmackall requested a review from a team as a code owner September 9, 2026 19:48
@gmackall
gmackall requested review from mboetger and removed request for a team September 9, 2026 19:48
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Code Review

This pull request refactors the high contrast observer in AccessibilityBridge.java to prevent class-verification errors on pre-API 34 devices. It isolates API 34-specific logic, including UiModeManager.ContrastChangeListener, inside a static nested class Api34Impl and stores the observer as a generic Object. Additionally, a unit test is added to AccessibilityBridgeTest.java to verify that the observer is unregistered upon release. There are no review comments, and I have no feedback to provide.

mboetger
mboetger approved these changes Sep 11, 2026
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LGTM

@gmackall gmackall added the autosubmit Merge PR when tree becomes green via auto submit App label Sep 11, 2026
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auto-submit Bot added this pull request to the merge queue Sep 11, 2026
Merged via the queue into flutter:master with commit 016b17b Sep 11, 2026
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@flutter-dashboard flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Sep 11, 2026
@Renzo-Olivares Renzo-Olivares mentioned this pull request Sep 11, 2026
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auto-submit Bot pushed a commit to flutter/packages that referenced this pull request Sep 12, 2026
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Roll Flutter from 63b9518f16bc to 2553f89be1ef (62 revisions) (#12855)
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Roll Flutter from 63b9518f16bc to 2553f89be1ef (62 revisions)

flutter/flutter@63b9518...2553f89

2026-09-12 chris@bracken.jp Roll clang to 07d67299a15ce03b053736e2d31a668ee0576987 (flutter/flutter#192607)
2026-09-12 engine-flutter-autoroll@skia.org Roll Dart SDK from b24b352c29db to 7863887acbfb (3 revisions) (flutter/flutter#192665)
2026-09-12 codefu@google.com fix(tree): et format --all (flutter/flutter#192669)
2026-09-12 matt.boetger@gmail.com Support activity-alias in Android launcher activity detection (flutter/flutter#187251)
2026-09-12 matt.boetger@gmail.com fix: regenerate gradle lockfiles for external_textures integration test (flutter/flutter#192657)
2026-09-12 engine-flutter-autoroll@skia.org Roll Skia from 51aa02b2c195 to e5e96533b732 (4 revisions) (flutter/flutter#192646)
2026-09-12 Rusino@users.noreply.github.com [WebParagraph] Fix text pixelation, glyph clipping, and snapping offsets to avoid subpixel raster caching (flutter/flutter#191736)
2026-09-12 codefu@google.com fix(tests): Add ruby dep to Mac windowing_test (flutter/flutter#192656)
2026-09-12 116356835+AbdeMohlbi@users.noreply.github.com Remove some `unawaited_futures` outdated ignores (flutter/flutter#192026)
2026-09-11 katelovett@google.com Bump Dart to 3.13, reformat, re-enable formatting check (flutter/flutter#192649)
2026-09-11 34871572+gmackall@users.noreply.github.com [android] Isolate API-34 high contrast listener in AccessibilityBridge behind Api34Impl (flutter/flutter#192502)
2026-09-11 katelovett@google.com Update style guide for Dart 3.13 (flutter/flutter#192639)
2026-09-11 codefu@google.com ci(bringups): remove bringup from these tests (flutter/flutter#192637)
2026-09-11 30870216+gaaclarke@users.noreply.github.com Unmark new_gallery_windows_impeller__transition_perf as bringup (flutter/flutter#192633)
2026-09-11 30870216+gaaclarke@users.noreply.github.com Unmark new_gallery_windows_skia__transition_perf as bringup (flutter/flutter#192635)
2026-09-11 engine-flutter-autoroll@skia.org Roll Skia from f446aec4ce9e to 51aa02b2c195 (2 revisions) (flutter/flutter#192631)
2026-09-11 codefu@google.com fix(ci): mac verify binaries still racing (flutter/flutter#192634)
2026-09-11 engine-flutter-autoroll@skia.org Roll Packages from 8a35b16 to 9caa77c (8 revisions) (flutter/flutter#192630)
2026-09-11 engine-flutter-autoroll@skia.org Roll Dart SDK from a76fee2722e0 to b24b352c29db (2 revisions) (flutter/flutter#192627)
2026-09-11 bkonyi@google.com [tool] Migrate PackagesCommand and Pub to modular dependency injection (flutter/flutter#192460)
2026-09-11 bkonyi@google.com [tool] Migrate Darwin framework commands to modular dependency injection (flutter/flutter#192252)
2026-09-11 bkonyi@google.com [tool] Migrate Upgrade, Downgrade, and UpdatePackages commands to modular dependency injection (flutter/flutter#190787)
2026-09-11 engine-flutter-autoroll@skia.org Roll Skia from b3fa80a0e168 to f446aec4ce9e (55 revisions) (flutter/flutter#192620)
2026-09-11 engine-flutter-autoroll@skia.org Roll Dart SDK from d20d59cfa664 to a76fee2722e0 (2 revisions) (flutter/flutter#192616)
2026-09-11 okorohelijah@google.com remove deeplink integration tests from bringup (flutter/flutter#192459)
2026-09-11 154381524+flutteractionsbot@users.noreply.github.com Revert: [devicelab] Clean up Chrome profile directories and trap abort signals in web benchmarks (flutter/flutter#192615)
2026-09-11 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from C0j8F-_Iy-OQZ6YyI... to m69nfK-wnHaMTe8P9... (flutter/flutter#192608)
2026-09-11 kevmoo@users.noreply.github.com Fix Wasm build cache mismatch in ResidentWebRunner and browser 404 fallbacks (flutter/flutter#190786)
2026-09-11 engine-flutter-autoroll@skia.org Roll Dart SDK from 3ce3116bc9ec to d20d59cfa664 (1 revision) (flutter/flutter#192588)
2026-09-11 robert.ancell@canonical.com [Linux] Keep the frame at the top of a resizing subsurface (flutter/flutter#192408)
2026-09-10 1961493+harryterkelsen@users.noreply.github.com [devicelab] Clean up Chrome profile directories and trap abort signals in web benchmarks (flutter/flutter#192584)
2026-09-10 1961493+harryterkelsen@users.noreply.github.com [web] Keep ImageSource alive until Picture disposal (flutter/flutter#192516)
2026-09-10 jhy03261997@gmail.com Remove the accessibility evaluations feature flag (flutter/flutter#192266)
2026-09-10 97480502+b-luk@users.noreply.github.com Promote Windows gradient benchmark tests to non-bringup (flutter/flutter#192581)
2026-09-10 116356835+AbdeMohlbi@users.noreply.github.com Remove commented out export in `text_input.dart` since the dart compiler has the correct behavior now (flutter/flutter#191539)
2026-09-10 bkonyi@google.com [flutter_tools] Do not mistake server-initiated requests for responses to client requests in AnalysisServer (flutter/flutter#192546)
2026-09-10 engine-flutter-autoroll@skia.org Roll Packages from 36e088a to 8a35b16 (12 revisions) (flutter/flutter#192550)
2026-09-10 137456488+flutter-pub-roller-bot@users.noreply.github.com Roll pub packages (flutter/flutter#192517)
2026-09-10 kevmoo@users.noreply.github.com feat(web): support --web-content-hash for entrypoint files (flutter/flutter#190153)
2026-09-10 zhongliu88889@gmail.com [web] Stop iOS auto-zoom by sizing semantic inputs at 16px (flutter/flutter#192328)
2026-09-10 engine-flutter-autoroll@skia.org Roll Dart SDK from 0d55b7a6a9ee to 3ce3116bc9ec (2 revisions) (flutter/flutter#192534)
2026-09-10 116356835+AbdeMohlbi@users.noreply.github.com Update more enum instances comparison to use equality == since dart has the correct behavior now (flutter/flutter#191788)
2026-09-10 bkonyi@google.com Fix specify_nonobvious_local_variable_types lints in luci_resultdb_test.dart (flutter/flutter#192543)
2026-09-10 engine-flutter-autoroll@skia.org Roll ICU from 8cc91d9b6ab9 to 6ebb40c59477 (1 revision) (flutter/flutter#192527)
2026-09-10 robert.ancell@canonical.com [Linux] Make the framebuffer depth/stencil buffer optional (flutter/flutter#192156)
2026-09-10 robert.ancell@canonical.com [Linux] Cancel input when events stop being delivered (flutter/flutter#192277)
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[Android] AccessibilityBridge's API-34 high-contrast lambda fails class verification on pre-34 devices (NoClassDefFoundError at launch)

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