The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/412d2b44a7ad91dbe8e9cd554b4660c3d415e604

commit 412d2b44a7ad91dbe8e9cd554b4660c3d415e604
Author: Hiroshi Ichikawa <ichikawa@chromium.org>
Date: Thu Jan 18 02:17:37 2018

Make CWVScrollView.contentOffset KVO compliant

Bug:  768725 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ib084b6cb0cc0871398e861b45ee8d10ac094ff67
Reviewed-on: https://chromium-review.googlesource.com/856476
Commit-Queue: Hiroshi Ichikawa <ichikawa@chromium.org>
Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530017}
[modify] https://crrev.com/412d2b44a7ad91dbe8e9cd554b4660c3d415e604/ios/web_view/internal/cwv_scroll_view.mm
[modify] https://crrev.com/412d2b44a7ad91dbe8e9cd554b4660c3d415e604/ios/web_view/public/cwv_scroll_view.h
[modify] https://crrev.com/412d2b44a7ad91dbe8e9cd554b4660c3d415e604/ios/web_view/test/BUILD.gn
[add] https://crrev.com/412d2b44a7ad91dbe8e9cd554b4660c3d415e604/ios/web_view/test/scroll_view_kvo_inttest.mm