Looks similar to crbug.com/872705, could you help triage?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dfa4c566937074580ab6b4abfcbe547210cb8283

commit dfa4c566937074580ab6b4abfcbe547210cb8283
Author: gogerald <gogerald@google.com>
Date: Mon Aug 13 23:51:36 2018

Set virtual/user-activation-v2/fast/events/autoscroll-iframe-no-scrolling.html timeout pass

TBR: hayato@chromium.org
Bug:  873829 
Change-Id: I321d85a63971b1f9b01bb42d4b5d93db44125c92
Reviewed-on: https://chromium-review.googlesource.com/1173437
Commit-Queue: Ganggui Tang <gogerald@chromium.org>
Reviewed-by: Ganggui Tang <gogerald@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582752}
[modify] https://crrev.com/dfa4c566937074580ab6b4abfcbe547210cb8283/third_party/WebKit/LayoutTests/TestExpectations

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/17eaa39ff7ecaafaf98f73054431dd3e12b80b27

commit 17eaa39ff7ecaafaf98f73054431dd3e12b80b27
Author: jonross <jonross@chromium.org>
Date: Tue Aug 21 15:57:07 2018

Set virtual/mouseevent_fractional/fast/events/autoscroll-iframe-no-scrolling.html timeout pass

Similar to https://chromium-review.googlesource.com/c/chromium/src/+/1173437
this patch updates autoscroll-iframe-no-scrolling.html to have timeout pass as
expectations.

TBR=hayato@chromium.org

Bug:  873829 
Change-Id: Ib534bc8d45b487888c6f75033241786aba768878
Reviewed-on: https://chromium-review.googlesource.com/1183461
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584760}
[modify] https://crrev.com/17eaa39ff7ecaafaf98f73054431dd3e12b80b27/third_party/WebKit/LayoutTests/TestExpectations