Able to reproduce the issue on windows 7 , Mac Os 10.12.6 and ubuntu 14.04 using chrome M61 #61.0.3163.91 and M63 #63.0.3219.0 .

This is a regression issue broken in M61.

Using the per-revision bisect providing the bisect results,
Good build: 61.0.3137.0 (Revision: 481056).
Bad build: 61.0.3138.0 (Revision: 481386).

You are probably looking for a change made after 481207 (known good), but no later than 481208 (first known bad).

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/+log/148c2697ed43abbc96e517b0c65517ebcef171b7..4cef659a8009c5cb4f5708336ae37654d23653b3

From the CL above, assigning the issue to the concern owner 

@Dave Tapuska- Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Reviewed-on: https://chromium-review.googlesource.com/527917

Thanks!

It looks like you are using simplr-smoothscroll I think?

This library is broken against Chrome 61 and later.

See: https://github.com/simov/simplr-smoothscroll/issues/27

This is not my site, and it is not using simplr-smoothscroll from what I can tell (although I presume something similar is being used).  Neither jquery.simplr.smoothscroll.js nor jquery.simplr.smoothscroll.min.js are being used.  All I know is that this site was designed using best practices, it works in every browser but Chrome, and it worked in Chrome up until version 61. 

Is there a good reason why such a site should not work in Chrome?  Or has Chrome become the new Internet Explorer, using proprietary rules to accomplish nothing but annoy web designers (and to a lesser extent users)?

On the contrary if you look at the site provided you will see that it really isn't designed to best practices. Open the rendering section of devtools and select highlight scroll performance issues and see that the entire document is selected. This means that the entire document is likely using main thread scrolling which can be janky.

Secondly if you look at http://www.concadelsogno.it/script/default/jquery-plugins.js you will see it contains srSmoothScroll code (although not the license file). It appears someone added and bundled it inside the website.

This change was actually directly done to fix interop issues between Firefox and Chrome; we now actually use the same elements as the scrolling element. Code such as srSmoothScroll isn't really necessary because Chrome does smooth scrolling natively in releases in the past year and a half.

Ok.  I'm not sure I get the logic.  But thank you for taking the time to explain.

(I get that srSmoothScroll is likely no longer necessary.  I get that Google/Chromium wants smooth scrolling to be consistent across all sites.  I am also not sure why it should cause a problem to allow package based scrolling.  And while I read that Chrome now employs smooth-scrolling as default scroll behavior - but the current default scrolling behavior that I observe in Chrome is not remotely close to being as smooth and seamless as the scrolling experience offered by http://www.concadelsogno.it in other browsers.)

No this isn't about smooth scroll at all. Just an example of a library (srsmoothscroll) that does an explicit user agent check to work around a bug that has been in the platform for a long time. Now we finally fixed the bug and now all the code that does the user agent checks isn't doing the right thing. THere are ways to detect the correct behavior without doing a user-agent check but in fact using document.scrollingElement instead.

Suggest you check out https://dev.opera.com/articles/fixing-the-scrolltop-bug/

I presume you are taking the javascript from this site and reusing it. If you are doing that you should be able to just patch the srSmoothScroll function as detailed in the bug and be done with it.

I will look into it.  Thank you.

 Issue 768841  has been merged into this issue.

We've had 60+ feedback reports about mouse scroll not working in the past 48 hours. Adding our hotlist for tracking.

Do we know if these reports are from people having mouse gesture extensions installed or actual websites. Do we have a list of URIs?

 Issue 771161  has been merged into this issue.

 Issue 771542  has been merged into this issue.

 Issue 774872  has been merged into this issue.

 Issue 777533  has been merged into this issue.

 Issue 779987  has been merged into this issue.

 Issue 801834  has been merged into this issue.

 Issue 850898  has been merged into this issue.