--- breadcrumbs: - - /teams - Teams - - /teams/animations - Animations Team - - /teams/animations/highlights-archive - Highlights Archive page_name: september-2021---new-features-testing-code-health-interop-fixes-and-more title: September 2021 - New features, testing, code health, interop fixes and more! ---

September 2021 | Chrome Interactions Highlights | Archives: go/interactions-team-highlights

| Chapter I: New features |
|

Capability Delegation mustaq@ has been working on the spec proposal for the capability delegation. We got official signal from Mozilla (annevk@): useful/reasonable. Mozilla also started bugs & enhancements discussions. For payment capability delegation, the origin trial is now ready for partners. Composite BG-color animation xidachen@ launched the finch study for the feature CompositeBGColorAnimation on Beta channel, with 50% control vs 50% enabled. The preliminary result looks very positive (Note that currently we have < 7 days of data). Here are some highlights of the result: We do see performance improvement on Animations Smoothness metrics. There is no memory regression on Android There is no regression on FirstContentfulPaint and LargestContenfulPaint. Elastic Overscroll flackr@ made great progress on launching elastic overscroll. The feature is now on by default on tip of tree. Merged reduce stretch amount and prefers-reduce-motion behavior back to M93. Finch min version updated to include two recent merges and launched to 1% stable. Launch to 100% out for review.

Chapter II: Testing

Composite BG-color animation xidachen@ fixed some very flaky paint worklet tests. Given that these are flaky tests, the auto bisect tool doesn’t work. We have to manually bisect it to find out that it is due to the launch of this new feature that makes navigation faster. With many times of try and error, it seems that the combination of paint worklet test + a simple div in ref.html somehow caused the crash. The root cause is unknown yet. Cross-platform scroll-timeline tests kevers@fixed some scroll-timeline tests. The issues are: Error tolerances were too tight. Sensitive to scrollbar width (platform specific) Magic numbers in tests (tough to infer correctness at a glance) Misleading calculations (e.g. scrollheight - clientHeight to compute scroll range in both directions) Mixup of logical units in RTL tests. The issues were discovered when testing via polyfill implementation. A significant number of near misses in test failures. The solutions are: Compute error tolerance for percentage calculations based on a half pixel error in the scroll position. Hide scrollbars to ensure that scroll-range is consistent across platforms. Chapter III: Code Health

Triage scroll unification failing web tests skobes@ triaged failing web tests for scroll unification and the details are captured here. At this moment, there are 30 failing tests 13 failures from 4 functional regressions (3 P1s, 1 P2), bugs filed Cannot touch-drag custom scrollbars, resize corners Re-latch when scroller removed from DOM Scollbar arrow click scrolls by only 1px 12 failures from bad test (waitForCompositorCommit, rebaseline, etc) 5 requiring more investigation (3 plugin related)

Chapter IV: Interop fixes

Scroll-timeline polyfill kevers@ made more progress on scroll-timeline polyfill. Proxied AnimationEffect to override timing calculations Custom AnimationPlaybackEvents to report percentage based times Removed time-range from scroll timeline proxy Conversion between percents for API and times for internal use Two problematic tests remain with high failure rates, reminder average over 90% pass rate. The remaining work includes update timing and event phase.

Chapter V: Bug Updates Our team lost a bit of ground in P2s && P3s, but kept the P1s in check.

Chrome Interactions Highlights | September 2021 | go/interactions-team