UserAgent: Mozilla/5.0 (X11; CrOS x86_64 9765.85.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.140 Safari/537.36
Platform: not official build

Steps to reproduce the problem:
1. Attach to external monitor (via hdmi, usb-c)
2. Move task bar on external display to vertical (left or right)
3. Open notifications menu (does not matter if empty or not)

What is the expected behavior?
Notifications menu should show available notifications, or should show as empty (see first attached screenshot).

What went wrong?
Notification menu is cut off on external display, whether empty or full of notifications (see second attached screenshot).

Did this work before? N/A 

Chrome version: 61.0.3163.140  Channel: stable
OS Version: 9765.85.0
Flash Version: Shockwave Flash 20180109.1 r999

My screenshots come from a CloudReady build of v61 running on PC, but this issue reproduced on Chromebooks running v63 stable.
 

Deleted: empty-notifications-built-in-monitor.png 3.2 MB

	empty-notifications-built-in-monitor.png 3.2 MB View Download

Deleted: cut-off-empty-notifications-external-monitor.png 1.1 MB

	cut-off-empty-notifications-external-monitor.png 1.1 MB View Download