Can you please provide specific URLs where you are seeing this problem so we can reproduce?

Any urls.

For example;
http://strategy-council.com/files/schedule/en/1.pdf (from this page http://strategy-council.com/en/events/1)
or
http://w1.c1.rada.gov.ua/pls/zweb2/webproc34?id=&pf3511=53018&pf35401=320562 (from this page http://w1.c1.rada.gov.ua/pls/zweb2/webproc4_1?id=&pf3511=53018)
or any image

Thank you for providing more feedback. Adding requester "dahlke@chromium.org" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Unable to reproduce this issue on reported verison 62.0.3202.62 using Ubuntu 14.04 with below steps. Attaching screencast for reference.

1.Launched chrome and navigated to http://strategy-council.com/files/schedule/en/1.pdf and http://w1.c1.rada.gov.ua/pls/zweb2/webproc4_1?id=&pf3511=53018
2.Downloaded files and observed extensions as .pdf, .rtf, .docx

@Reporter: Could you please recheck the issue on fresh profile which doesn't have any apps or extensions added. And also please check the attached screencast and let us know if we miss anything from our end.

Thanks!

Deleted: Issue 778513.ogv 3.6 MB

	Issue 778513.ogv 3.6 MB View Download

I think this is a KDE-specific bug that happens when one's using the more recent KDE Frameworks 5-based kdialog. I was able to reproduce it here on Fedora 27 running Plasma.

Yes, this is KDE-specific, and almost certainly a dupe of  Issue 752375 .

Thanks for the FYI; I'm going to merge this issue into that one and point my CL to it.