Unable to reproduce the issue on chrome reported version# 69.0.3497.42 using Windows-7 & 10 with steps mentioned below:
1) Launched chrome reported version and in the omni-box typed 'faceb' and clicked on Enter
2) Able to see page navigated to "https://www.facebook.com"

@Reporter: Please find the attached screencast for your reference and let us know if we missed anything in reproducing the issue. Try to test this issue by creating new person with no apps and extensions in it and let us know if the issue still persists.

Thanks!

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After more investigation, I found one bookmark in mobile device to m.facebook.com.
Before omnibox display FQDN, now I can see difference between https://www.facebook.com and https://m.facebook.com

and it's same with new bookmark manager,I can't see URL without edit it. It's 2 regression. One solution to display FQDN ? and return to previous bookmark manager?

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Thank you for providing more feedback. Adding the requester to the cc list.

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

As per screencast provided in comment# 3, it seems like 'm.facebook.com' has been bookmarked and it has been bookmarked in other bookmarks folder, so when you typed 'faceb' in Omnibox and selected the suggestion below which was bookmarked, so it directly navigated to 'm.facebook.com'.

@Reporter: Please find the attached screencast for your reference and let us know if we missed anything in reproducing the issue.

Thanks!

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	875669.mp4 7.5 MB View Download

yes this is the problem. Omnibox not display FQDN for www. or m.
If type facebook  it display facebook.com  instead of displaying www.facebook.com and m.facebook.com


for other subdomain no problem found. example with nas.domain.com and wifi.domain.com  if type domain.com Omnybox display the 2 FQDN and can choice the correct.

Thank you for providing more feedback. Adding the requester to the cc list.

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

We've discussed eliding 'm' only on mobile, and leaving it on Desktop.

This seems to be a concrete complaint about it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ed2c4514bdbd17ee1e65bfefd150510a079c71ea

commit ed2c4514bdbd17ee1e65bfefd150510a079c71ea
Author: Tommy C. Li <tommycli@chromium.org>
Date: Mon Aug 27 21:11:16 2018

Omnibox UI: Don't elide "m" subdomains on Desktop.

Eliding the "m" subdomain on Desktop can be confusing, since users
would generally want to know if they are unintentionally on the mobile
site on Desktop.

After this CL, we only elide the "m" subdomain on Android and iOS.

Bug:  875669 
Change-Id: Ifededfce720444e5c9e85ffc97c92c8cee530937
Reviewed-on: https://chromium-review.googlesource.com/1185904
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586416}
[modify] https://crrev.com/ed2c4514bdbd17ee1e65bfefd150510a079c71ea/chrome/browser/ui/toolbar/toolbar_model_unittest.cc
[modify] https://crrev.com/ed2c4514bdbd17ee1e65bfefd150510a079c71ea/components/history/core/browser/history_backend_unittest.cc
[modify] https://crrev.com/ed2c4514bdbd17ee1e65bfefd150510a079c71ea/components/omnibox/browser/autocomplete_match_unittest.cc
[modify] https://crrev.com/ed2c4514bdbd17ee1e65bfefd150510a079c71ea/components/url_formatter/url_formatter.cc
[modify] https://crrev.com/ed2c4514bdbd17ee1e65bfefd150510a079c71ea/components/url_formatter/url_formatter_unittest.cc

Requesting merge to M69 due to high user impact as per https://bugs.chromium.org/p/chromium/issues/detail?id=881410 .