Tested the issue in Android and able to reproduce the issue. 

Steps Followed:
1. Launch Chrome.
2. Navigate to any URL - https://www.w3.org/TR/pointerevents/#the-touch-action-css-property
3. Scroll down.
4. Observed that black patch is displayed in the bottom of the page

Chrome versions tested:
66.0.3359.181(Stable), 68.0.3441.0(Canary)

OS:
Android 8.1.0

Android Devices:
Pixel 2 XL

Using the per-revision bisect providing the bisect results,
Good Build - 68.0.3436.0
Bad Build - 68.0.3437.0

You are looking for a change made after 560163(GOOD), but before 560175(BAD).

As the script didn't provide the exact suspect, providing possible suspect details manually from the given range:

CHANGELOG URL:
The script might not always return single CL as suspect as some perf builds might get missing due to failure.
https://chromium.googlesource.com/chromium/src/+/b0f91240e080da87de885feeb6e6392fecc10f5b

@skobes:  Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to owner concerned.

Please navigate to below link for log's and screen cast --
go/chrome-androidlogs/847220

@pdr -- Could you also take a look for the below CL:
https://chromium.googlesource.com/chromium/src/+/028845b7d0d8981909144c8a6aa33262ed469b80

Note: 
1. This issue is not observed in Desktop.
2. This issue is not observed in FireFox mobile version.

Thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a49126b324ee7632e799a4ba22d84263820075f7

commit a49126b324ee7632e799a4ba22d84263820075f7
Author: Steve Kobes <skobes@chromium.org>
Date: Tue May 29 16:19:11 2018

Restore LayoutView::LocalVisualRectIgnoringVisibility.

This was removed in http://crrev.com/560172, but turns out to be
necessary.

Bug:  847220 
Change-Id: I311e35d8e5dca32e3a42f63c9389d52b4cdee7c0
Reviewed-on: https://chromium-review.googlesource.com/1076387
Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562452}
[modify] https://crrev.com/a49126b324ee7632e799a4ba22d84263820075f7/third_party/blink/renderer/core/exported/web_frame_test.cc
[modify] https://crrev.com/a49126b324ee7632e799a4ba22d84263820075f7/third_party/blink/renderer/core/layout/layout_view.cc
[modify] https://crrev.com/a49126b324ee7632e799a4ba22d84263820075f7/third_party/blink/renderer/core/layout/layout_view.h

I could repro this issue on Pixel 2 XL/P and S5 Mini/M on the test page mentioned but not on any page so far. This issue appears to be there in last week's dev also so marking it RBB. Please let us know if it affects more pages, so that we can adjust labels accordingly. Thanks!

Also we need to get this fix merged to M68.

This should be fixed at r562452.  I'll request merge once it's in canary.

Verified in 69.0.3445.0

Your change meets the bar and is auto-approved for M68. Please go ahead and merge the CL to branch 3440 manually. Please contact milestone owner if you have questions.
Owners: cmasso@(Android), kariahda@(iOS), bhthompson@(ChromeOS), abdulsyed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Please merge as soon as possible.

This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

If all merges have been completed, please remove any remaining Merge-Approved labels from this issue.

Thanks for your time! To disable nags, add the Disable-Nags label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fdbecdc7107686686457e2ff81c20d33eda137b9

commit fdbecdc7107686686457e2ff81c20d33eda137b9
Author: Steve Kobes <skobes@chromium.org>
Date: Mon Jun 04 20:08:12 2018

Restore LayoutView::LocalVisualRectIgnoringVisibility.

This was removed in http://crrev.com/560172, but turns out to be
necessary.

TBR=skobes@chromium.org

(cherry picked from commit a49126b324ee7632e799a4ba22d84263820075f7)

Bug:  847220 
Change-Id: I311e35d8e5dca32e3a42f63c9389d52b4cdee7c0
Reviewed-on: https://chromium-review.googlesource.com/1076387
Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Steve Kobes <skobes@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#562452}
Reviewed-on: https://chromium-review.googlesource.com/1085998
Reviewed-by: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/branch-heads/3440@{#164}
Cr-Branched-From: 010ddcfda246975d194964ccf20038ebbdec6084-refs/heads/master@{#561733}
[modify] https://crrev.com/fdbecdc7107686686457e2ff81c20d33eda137b9/third_party/blink/renderer/core/exported/web_frame_test.cc
[modify] https://crrev.com/fdbecdc7107686686457e2ff81c20d33eda137b9/third_party/blink/renderer/core/layout/layout_view.cc
[modify] https://crrev.com/fdbecdc7107686686457e2ff81c20d33eda137b9/third_party/blink/renderer/core/layout/layout_view.h

This issue is now not reproducible on latest M68-68.0.3440.25 and M69-69.0.3457.0, verified on Pixel 2/OPM1.0180608.001