It looks like there's a bug in how we filter out the trace-events: we ignore all trace-events that happen before or after SyntheticGestureController::running trace-events (which stops when the gesture-event generation ends), but it is possible for the scroll-event generation (in the browser-process) to have ended, but the event-processing (in renderer/viz) to still continue afterwards.

The following revision refers to this bug:
  https://chromium.googlesource.com/catapult/+/22c3e6c8fd7fe8ce1adad2425595796d7362193a

commit 22c3e6c8fd7fe8ce1adad2425595796d7362193a
Author: Ehsan Chiniforooshan <chiniforooshan@chromium.org>
Date: Fri Oct 12 16:53:38 2018

Telemetry: process all rendering pipeline events

This CL processes all rendering pipeline events that are
associated with frames initiated during animations. Some of
these events can arrive after the animation segment.

Bug:  chromium:893199 
Change-Id: I5e44ccf058616e25037b0513bedf01654178f8d2
Reviewed-on: https://chromium-review.googlesource.com/c/1276745
Commit-Queue: Ehsan Chiniforooshan <chiniforooshan@chromium.org>
Reviewed-by: Ben Hayden <benjhayden@chromium.org>

[modify] https://crrev.com/22c3e6c8fd7fe8ce1adad2425595796d7362193a/tracing/tracing/metrics/rendering/pipeline.html
[modify] https://crrev.com/22c3e6c8fd7fe8ce1adad2425595796d7362193a/tracing/tracing/metrics/rendering/pipeline_test.html

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bb11cbc66e56a475bdf0f5bf3d962cf80c3afe27

commit bb11cbc66e56a475bdf0f5bf3d962cf80c3afe27
Author: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Date: Fri Oct 12 22:54:58 2018

Roll src/third_party/catapult c8b97e37ec9c..99b88b0a2d58 (21 commits)

https://chromium.googlesource.com/catapult.git/+log/c8b97e37ec9c..99b88b0a2d58


git log c8b97e37ec9c..99b88b0a2d58 --date=short --no-merges --format='%ad %ae %s'
2018-10-12 simonhatch@chromium.org Pinpoint - Merge bugs with same root cause.
2018-10-12 benjhayden@chromium.org Change deprecation warnings in /api/alerts to errors.
2018-10-12 benjhayden@chromium.org Cache report names, test suites, and descriptors in v2spa service worker
2018-10-12 chiniforooshan@chromium.org Telemetry: process all rendering pipeline events
2018-10-12 benjhayden@chromium.org Cache session ids in v2spa service worker.
2018-10-12 benjhayden@chromium.org Fix links in rollback.md
2018-10-12 benjhayden@chromium.org Add KeyValueCacheRequest for v2spa service worker.
2018-10-12 benjhayden@chromium.org Add ts_mon metrics to common/timing.py
2018-10-12 benjhayden@chromium.org Add CacheRequestBase for v2spa service worker.
2018-10-12 nednguyen@google.com [Telemetry] Add --test-filter flag that support exact matching of multiple tests
2018-10-12 sadrul@chromium.org rendering: Generate metrics at the 95%ile.
2018-10-12 pasko@chromium.org androidStartupMetric: re-introduce First Contentful Paint
2018-10-12 chrishtr@chromium.org Clean up categories to match current tracing in Blink.
2018-10-11 jbudorick@chromium.org Revert "Enable orderfile memory optimization in benchmarks"
2018-10-11 benjhayden@chromium.org Add task queue for v2spa service worker.
2018-10-11 benjhayden@chromium.org Remove unnecessary file dashboard/test/index.html
2018-10-11 perezju@chromium.org [soundwave] Allow points with missing r_chromium
2018-10-11 chiniforooshan@chromium.org Telemetry: migrate frame_times & percentage_smooth
2018-10-11 ulan@chromium.org [tracing] Restore the minimum mutator utilization metric.
2018-10-11 seanmccullough@chromium.org [chromeperf] add prefix to wct script so tests get found.
2018-10-11 pasko@chromium.org Enable orderfile memory optimization in benchmarks


Created with:
  gclient setdep -r src/third_party/catapult@99b88b0a2d58

The AutoRoll server is located here: https://autoroll.skia.org/r/catapult-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel

BUG=chromium:840872, chromium:893199 ,chromium:867060,chromium:894261,chromium:894287, chromium:886621 ,chromium:893514,chromium:758566, chromium:879526 , chromium:890757 , chromium:892385 , chromium:877660 ,chromium:758566
TBR=sullivan@chromium.org

Change-Id: I469ed20d66790fa12e290ad65e2ea51c16cfdba7
Reviewed-on: https://chromium-review.googlesource.com/c/1279078
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#599392}
[modify] https://crrev.com/bb11cbc66e56a475bdf0f5bf3d962cf80c3afe27/DEPS

This is not happening anymore after the fix landed:
https://ci.chromium.org/p/chrome/builders/luci.chrome.ci/Android%20Nexus5%20Perf/2722

(However, the bot is still failing, due to other errors.)