Chrome Version: 62.0.3202.8
OS: ChromeOS Caroline

What steps will reproduce the problem?
(1) Open GMail.
(2) Find a non-trivial email (one that has content to scroll to).
(3) Try scrolling up and down with trackpad. 

What is the expected result?

Expect that you can scroll up and down the email smoothly.

What happens instead?

Scrolling is janky and sometimes just stops until you move much further, as though there is some threshold being mis-applied.