This issue has existed for a very long time. Quite annoying, and surprised it hasn't been fixed yet.

Steps to reproduce:
1: Make sure you are using a browser that has lots of bookmarks added, so that they don't all appear at once (> 23 on 1366 x 768 res)

2: Click the three dots button in top right hand corner of screen ("Customise and control Google Chrome")

3: Move mouse pointer to Bookmarks menu item

4: Move mouse pointer over Bookmarks menu and try to scroll wheel up and down

Problem still exists in latest version of Chrome (67.0.3396.62).

Specially, the erratic behaviour is that it scrolls down just one bookmark item, and then jumps back up again when attempting to scroll down further, while viewing the top-most bookmarks items in the list.

The scroll behaviour briefly returns to normal after the small downwards triangle arrow at the very bottom of the menu is used, or the down arrow on the keyboard is used to go past the last visible bookmark item. The erratic behaviour returns when you scroll/navigate back to the top of the Bookmarks menu again.

*** UI Mass Triage***
Seems bug is valid, hence tagging with appropriate label for expert review.

But we are unable to repro this issue as per C#1 steps on Windows 10 using chrome latest canary.

Scrolling issue still happening on Google Chrome 73.0.3677.0, using Windows 8.1

Two users have posted video clips of the behaviour in another ticket (https://bugs.chromium.org/p/chromium/issues/detail?id=820042). Suggest merging the two tickets together.