Chrome Version: 58.0.3029.31 dev-channel
Chrome OS Version: 58.0.3029.31 dev-channel
Chrome OS Platform: 9334.18.0 dev-channel chell

Please specify Cr-* of the system to which this bug/feature applies (add
the label below).

Steps To Reproduce:
(1) Connect UDL2 with monitor attached and mouse to Chromebook.
(2) Close lid.

Expected Result:
Notification about entering dock mode should be shown to the user.

Actual Result:
No notification.

How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
Always.

What is the impact to the user, and is there a workaround? If so, what is
it?
No workaround. 

Please provide any additional information below. Attach a screen shot or
log if possible.
Issue is also affecting UDL3 devices.
Issue is not reproducible on stable channel 57.0.2987.123. This is a regression.
Issue is also reproducible on asuka chromebook.

For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.