Tried testing the issue on reported chrome version #68.0.3440.106 using Windows 10, by following below steps.

Steps:
=====
1.Launched chrome.             
2.Navigated to " http://jsfiddle.net/ej0n7fwo/24/".
3.Tried scrollingg at red div, observed that the scrooling can be done.

Attached screencast for reference.
@reporter : Could you please review the attached screencast and let us know if anything is being missed here. If possible request you provide screencast of the issue, so that it would be really helpful for better triaging of the issue.

Thanks.!

Deleted: 879399.mp4 2.5 MB

	879399.mp4 2.5 MB View Download

Thanks for testing. I've tried that jsfiddle on several setups:

- Bad: 96-DPI external monitor connected to Win 10 laptop
- Bad: three different 96-DPI external monitors connected to Win 10 desktop
- Bad: unknown resolution external monitor connected to MacBook Pro (colleague)
- OK: high-DPI Win 10 laptop display
- OK: high-DPI/retina MacBook Pro laptop display

Disabling GPU acceleration does not fix it.

Screen cap attached. When my cursor is stopped over the red div, I'm wheeling the scroll wheel.

Deleted: wheel.gif 142 KB

	wheel.gif 142 KB View Download

Thank you for providing more feedback. Adding the requester to the cc list.

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

As per comment #3, Tested this issue on reported chrome 68.0.3440.106 and latest chrome stable 69.0.3497.81 using windows 10(Hi-dpi). Unable to provide 
screen-cast as we are using different screen sizes. 
Steps:
-----
1. Launched chrome
2. Enabled external monitors setup
As we are able to scroll at red div.

@Reporter: Could you please upgrade to latest chrome stable 69.0.3497.81, you can download latest chrome builds here:
" https://www.chromium.org/getting-involved/dev-channel ". Can you verify this issue with New Profile that is not having any extensions and apps or reset all the flags. Let us know whether issue still persists.

Thanks.!

Tested with 69.0.3497.81, problem still happens.

> Tested this issue ... using windows 10(Hi-dpi).

In the cases I've tested, this happens on non-hi-DPI screens (96-DPI). I've had three other people reproduce it on Windows and MacOS (included in my list in #3).

Thank you for providing more feedback. Adding the requester to the cc list.

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

I can repro. overflow-behavior shouldn't affect unscrollable regions so the expectation here is that it should always allow scrolling.

I'm guessing there's some precision issues that cause us to think there's overflow for the purposes of overscroll-behavior but not actually produce any overflow.

majidvp@ PTAL and triage it if you are not the proper owner.

assigning to sunyunjia@ to triage this. 

We have had bugs related to composited scrolling but comment #3 mentions that the issue persists even after disabling composited scrolling. So I think #6 is right about the potential cause and we need to investigate that.