[web] Add opt-in raw samples, measured sample count and warm-up phase hook to the web benchmark recorder - #195118

flutter/flutter@d4c8577...0c2473c

2026-10-28 [email protected] Roll Packages from a8549ae to 13d38e0 (9 revisions) (flutter/flutter#195488)
2026-10-28 [email protected] Use int.oneBitCount in PersistentHashMap and scope 53-bit caps to JS (flutter/flutter#195005)
2026-10-28 [email protected] Roll pub packages (flutter/flutter#195483)
2026-10-28 [email protected] [iPhone Duo] Use the correct UIScreen to report the display size and update when fold/unfold (flutter/flutter#195199)
2026-10-28 [email protected] [fuchsia] Fix portable_ui_test.h includes for newer Fuchsia SDKs (flutter/flutter#195420)
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2026-10-27 [email protected] Revert: Reland square corners fix (flutter/flutter#195436)
2026-10-27 [email protected] [flutter_tools] Add DeviceService app launch and flutter run support for tool extensions (flutter/flutter#194589)
2026-10-27 [email protected] [engine] Honor targetWidth/targetHeight for animated images (flutter/flutter#194615)
2026-10-27 [email protected] [Android][a11y] Set visibleToUser=false for hidden semantics nodes (flutter/flutter#194411)
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2026-10-27 [email protected] [web] Capture pointers to the Flutter view so drags survive platform view iframes (flutter/flutter#195187)
2026-10-27 [email protected] [web] Add opt-in raw samples, measured sample count and warm-up phase hook to the web benchmark recorder (flutter/flutter#195118)
2026-10-27 [email protected] Link migration guide in deprecation messages (flutter/flutter#195361)
2026-10-27 [email protected] Pin basic_material_app_macos__compile to macOS 26 (flutter/flutter#195429)
2026-10-27 [email protected] Add benchmark for warmed pipeline usage (flutter/flutter#195001)
2026-10-27 [email protected] [flutter_tools] Add device log streaming support to DeviceService and ExtensionBackedDevice (flutter/flutter#194964)
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… hook to the web benchmark recorder (flutter#195118)

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Adds three opt-in, compile-time `--dart-define`s to the web
macrobenchmarks recorder (`dev/benchmarks/macrobenchmarks`). They let a
local benchmark host compute frame-time percentiles and start a CPU
profiler exactly when warm-up ends, without forking the app's reporting
protocol:

- `BENCHMARK_REPORT_SAMPLES=true`: `Profile.toJson` also reports two
flat lists of raw sample magnitudes (in microseconds, in recording
order) for each series, so `/profile-data` carries per-frame data:
`<series>.samples` (the measured samples) and `<series>.warmUpSamples`
(the warm-up samples). `scoreKeys` and the existing statistics are
unchanged.
- `BENCHMARK_MEASURED_SAMPLES=<n>`: overrides the number of measured
samples, which defaults to 100. `kDefaultTotalSampleCount` follows.
- `BENCHMARK_REPORT_PHASES=true`: installs a new static
`Profile.phaseListener`, which `Profile.stopWarmingUp()` calls with
`'measure'` at the warm-up → measure switch. `web_benchmarks.dart` uses
it to send a fire-and-forget `POST benchmark-phase` to the benchmark
server. The request is not awaited and is deferred with `Timer.run`, so
the frame loop and the first measured frame are not affected.

With none of the defines set, the output is the same as today, so CI and
the dashboards are unaffected. To check this, I ran `dart
dev/devicelab/bin/run.dart -t web_benchmarks_canvaskit` with
`BENCHMARK_TARGETS=draw_rect` on this branch and on its `master` base.
Both runs produced the same 13 `ResultData` keys and the same
`BenchmarkScoreKeys`. The devicelab host is not changed in this PR.

The new tests are in
`dev/benchmarks/macrobenchmarks/test/web/recorder_test.dart`. They
check:
- the exact legacy key set when sample reporting is off;
- that `<series>.samples` has only the measured samples and
`<series>.warmUpSamples` only the warm-up samples, in order, with
outliers kept, for reported and unreported series, and with each series
split at its own warm-up boundary;
- that `extraData` still merges last;
- that `phaseListener` fires exactly once with `'measure'`, after the
warm-up flag flips, on both automatic and manual warm-up;
- that nothing is called when no listener is set;
- that samples, warm-up samples, the scalar statistics and `scoreKeys`
survive a `jsonEncode`/`jsonDecode` round trip (compared numerically,
since the JS and Wasm encoders print doubles differently), and that the
decoded key set is still the legacy one when reporting is off.

`dev/bots` does not run the macrobenchmarks package tests, so I ran them
manually from `dev/benchmarks/macrobenchmarks` with `flutter test
--platform chrome test/web/recorder_test.dart` and `flutter test
--platform chrome --wasm test/web/recorder_test.dart` (11 tests pass on
both).

Part of flutter#191316

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