(Unable to narrow down the range using per-revision bisect as getting all good chrome builds and in case of old script chromium builds doesn't has 'report an issue' button,hence providing cl)
CL:
https://chromium.googlesource.com/chromium/src/+log/69.0.3457.0..69.0.3460.0?pretty=fuller&n=10000

Suspecting: r567111 or r567027 ?

@afakhry: Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Adding release blocker label for this issue.Please reduce priority or remove if not the case.

Thank You!

I reverted locally r567027 and I can still reproduce the problem, so must be something else. Also note that only middle click fails for me. Normal clicking on the links works as expected.

@dgozman: Could r566969 be related since it affects how clicking on links works?

M69 branch is coming soon on July 19th, Your bug is marked as ReleaseBlock-Beta for M69. Please try to land the fix ASAP to trunk in order to prevent many merges going after M69 branch. This will also help us to branch M69 from high quality trunk. Thank you.

These links were introduced in https://chromium-review.googlesource.com/c/chromium/src/+/1100158. They point to "#", which is converted to chrome-extension://invalid here [1].

I think you should handle auxclick event (which fires for middle button click), and also call preventDefault() on the event parameter in onclick handlers (or else ctrl+click opens two new tabs).

r566969 seems to be unrelated.

[1] https://cs.chromium.org/chromium/src/chrome/browser/ui/browser_navigator.cc?rcl=627fd97ad671f7157584a311c6ad3f2cf49c4afe&l=464
[2] https://chromium-review.googlesource.com/c/chromium/src/+/1100158/3/chrome/browser/resources/feedback/js/feedback.js#452

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f548ad67a42891217d6b2926cc0c46559c859253

commit f548ad67a42891217d6b2926cc0c46559c859253
Author: Ahmed Fakhry <afakhry@google.com>
Date: Wed Jun 20 18:16:14 2018

Fix auxclick events in privacy links

call preventDefault() on auxclick events to avoid
opening an invalid URL since those links are href="#".

Also increase line height of the privacy note text per
UX feedback.

BUG= 853662 ,852387

Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ib1dd1d5c9cfe03d03de263b5b02c03052756a9ab
Reviewed-on: https://chromium-review.googlesource.com/1106638
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568930}
[modify] https://crrev.com/f548ad67a42891217d6b2926cc0c46559c859253/chrome/browser/resources/feedback/css/feedback.css
[modify] https://crrev.com/f548ad67a42891217d6b2926cc0c46559c859253/chrome/browser/resources/feedback/js/feedback.js

Should be fixed now. Please verify.