I believe this is a problem with the touch action filter and fling controller supressing the events but not calling the client API that they are discarding an event.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e0c27aa594d4584e9dff30a0b6e3604089ad9a0c

commit e0c27aa594d4584e9dff30a0b6e3604089ad9a0c
Author: Dave Tapuska <dtapuska@chromium.org>
Date: Wed Dec 20 22:50:56 2017

Fix input latency async trace events that don't end.

TouchAction and Touch Screen suppression failed to ack the event
back to the client which caused latency info objects not to be
terminated.

BUG= 796630 

Change-Id: I0768d0cc83b346612ecc72a3f8e75d46874194cf
Reviewed-on: https://chromium-review.googlesource.com/837470
Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#525501}
[modify] https://crrev.com/e0c27aa594d4584e9dff30a0b6e3604089ad9a0c/content/browser/renderer_host/input/gesture_event_queue.cc
[modify] https://crrev.com/e0c27aa594d4584e9dff30a0b6e3604089ad9a0c/content/browser/renderer_host/input/gesture_event_queue.h
[modify] https://crrev.com/e0c27aa594d4584e9dff30a0b6e3604089ad9a0c/content/browser/renderer_host/input/input_router_impl.cc