Tested the issue on Windows 7, Mac 10.10.5, Ubuntu 14.04 using 51.0.2682.0, latest canary 51.0.2686.0 with below steps:

1.Open URL:http://www.httpwatch.com/httpgallery/authentication/ in chrome.
2.Clicked on the button "DISPLAY IMAGE" at the bottom of the page.
3.Filled HTTP Basic Auth dialog form with some random values and submitted the form.
4.Form does not submit and auth dialog box remained.
5.Not observed any prompt for save user login information.

Please find attached screencast and update if anything missed here in triaging the issue.

iceman@Could you please provide the actual and expected behavior screencast for better understanding the issue to triage it further.

Deleted: 596513.mp4 1.2 MB

596513.mp4 1.2 MB Download

OK, I'll make a screencast for that.
Did you navigate to http://www.httpwatch.com/ after submitting auth form?
It seems important for the bug reproducing.

Thank you for providing more feedback. Assigning to requester "ssamanoori@chromium.org" for another review.

For more details visit https://sites.google.com/a/chromium.org/dev/issue-tracking/autotriage - Your friendly Sheriffbot

Here is my screencast, hope that it will help.

Deleted: Screencast 2016-03-22.mp4 4.9 MB

Screencast 2016-03-22.mp4 4.9 MB Download

Able to reproduce the issue on Windows 7, Ubuntu 14.04 using 51.2682.0, latest canary 51.0.2692.0 as per process in screencast(comment #5).

This is non regression issue seen from M-30(30.0.1549.0).Hence, marking it as untriaged.

Could anyone from dev team look into this issue please.

Not sure who owns the UI code here.  Real bug that should ideally be fixed.

This is UI>Browser>Password, adding to the queue and under the corresponding meta-bug.