Able to reproduce the issue on reported chrome version 67.0.3379.0 using Mac 10.13.1.
Note: The issue is not seen on Windows 10 and on Ubuntu 14.04.

Bisect Information:
====================
Last Good Build: 67.0.3378.0
First Bad Build: 67.0.3379.0

You are probably looking for a change made after 544962 (known good), but no later than 544963 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/fae199abc147d925470e745e0fa2752775d4fa63..bd465948ea74fbf1d40c495832e4306c07c13406

Suspecting: https://chromium.googlesource.com/chromium/src/+/bd465948ea74fbf1d40c495832e4306c07c13406
Review URL: https://chromium-review.googlesource.com/961722 

@Ahmed Fakhry: Please help us in assigning it to the right owner if this is not related to your change.
Note: Removing Needs-Bisect label.

Thanks!

++ Adding RB-Stable as this seems to be a recent regression, Please remove if not applicable.

Thanks!

And this one too, Sorry! :)

They all can be fixed in a single small CL, I think. Feel free to dup them all into one bug. ( bug 825157 ,  bug 825782 , this bug, and  bug 792593  you are already working on).

M67 Stable promotion is coming soon. Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge into the release branch ASAP. Thank you.

*** Bulk Edit ***
M67 Stable promotion is coming soon. Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge into the release branch ASAP. 

If fix is already merged to M67 and nothing else is pending, pls mark the bug as fixed. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e132a7eb3c39e5839444aff108d783c2a68b92c2

commit e132a7eb3c39e5839444aff108d783c2a68b92c2
Author: spqchan <spqchan@chromium.org>
Date: Thu May 03 15:24:19 2018

[Mac] Fix padding in browser actions container

The horizontal padding around the browser actions
container was incorrectly reduced.

This causes issues where you can't resize the
omnibox (because the extensions now overlap the gripper)
or drag the extensions into the wrench menu

Bug:  825378 ,  825782 
Change-Id: I66061a67546fab679c280a8d816b78dbe19b876e
Reviewed-on: https://chromium-review.googlesource.com/1040914
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Sarah Chan <spqchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555740}
[modify] https://crrev.com/e132a7eb3c39e5839444aff108d783c2a68b92c2/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm

Hi spqchan@: Thanks for fixing this issue. I checked the latest Snapshot #555746 and it seems that your change has broken to show the hidden extension icon in the Wrench Menu (CocoaBrowser-Mode). Please find enclosed a screencast. Should I file a separate bugreport for it or do you want to wait until your change lands in Canary (tomorrow?) and fix it then within this report?

Regression range: https://chromium.googlesource.com/chromium/src/+log/a6594bc815d7d1d12e59730de3afc8f1416e4b9d..7971e79592788e8cd99bb387c2674518f0a69562

Thanks :-)
Mehmet

Deleted: screencast.mov 3.9 MB

	screencast.mov 3.9 MB View Download

Aw dang it :(
Thanks for looking into this! I'll work on a fix.

Okay, great, thanks :-)

Able to reproduce this issue on reported version hence verifying the fix on latest canary 68.0.3419.0 using Mac 10.13.1.

As per cl in comment#8 issue is fixed on 68.0.3419.0. i.e; Now able to drag/ resize omnibox content to hide extensions. Hence fix is working as expected.

But as mentioned in comment#9 hided extensions are not visible in wrench menu. Will verify the fix once this issue is fixed.

Thanks!

Deleted: 825378_M-68.mp4 543 KB

	825378_M-68.mp4 543 KB View Download

*** Bulk Edit ***
M67 Stable promotion is coming VERY soon. Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge into the release branch ASAP. 

If fix is already merged to M67 and nothing else is pending, pls mark the bug as fixed. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1c6d105674d79b345f23686eed134a6e744eb9d3

commit 1c6d105674d79b345f23686eed134a6e744eb9d3
Author: spqchan <spqchan@chromium.org>
Date: Tue May 08 16:13:57 2018

[Mac] Fix extension overflow menu

The extension icons don't show up properly in the
wrench menu. This CL fixes the issue by removing
incorrect size calculations

Bug:  825378 ,  840658 
Change-Id: I79de5e0b8bf0de4bc681418d6d7698b7b81e4164
Reviewed-on: https://chromium-review.googlesource.com/1048047
Commit-Queue: Sarah Chan <spqchan@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556817}
[modify] https://crrev.com/1c6d105674d79b345f23686eed134a6e744eb9d3/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm

Verified the fix on Mac 10.13.1 using Chrome version #68.0.3425.0 as per the comment #0.
Attaching screen cast for reference.
We are able to resize the omnibox in order to hide the extensions.
Hence, the fix is working as expected. 
Adding the verified labels.
Note: Able to reproduce the issue on chrome version with out fix.

Thanks...!!

Requesting merge for #8 and #14. The changes have be verified on Canary and have a low risk

This bug requires manual review: M67 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), kbleicher@(ChromeOS), govind@(Desktop)

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

Approving merge to M67 branch 3396 based on comment #17. Pls merge ASAP and mark bug as fixed if nothing else is pending after the merge. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ba01abd5b57c78d4e1259428d7e8dfe3ca3fc6e4

commit ba01abd5b57c78d4e1259428d7e8dfe3ca3fc6e4
Author: spqchan <spqchan@chromium.org>
Date: Wed May 09 18:21:50 2018

[Mac] Fix padding in browser actions container

The horizontal padding around the browser actions
container was incorrectly reduced.

This causes issues where you can't resize the
omnibox (because the extensions now overlap the gripper)
or drag the extensions into the wrench menu

(cherry picked from commit e132a7eb3c39e5839444aff108d783c2a68b92c2)

Bug:  825378 ,  825782 
Change-Id: I66061a67546fab679c280a8d816b78dbe19b876e
Reviewed-on: https://chromium-review.googlesource.com/1040914
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Sarah Chan <spqchan@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#555740}
Reviewed-on: https://chromium-review.googlesource.com/1052670
Reviewed-by: Sarah Chan <spqchan@chromium.org>
Cr-Commit-Position: refs/branch-heads/3396@{#536}
Cr-Branched-From: 9ef2aa869bc7bc0c089e255d698cca6e47d6b038-refs/heads/master@{#550428}
[modify] https://crrev.com/ba01abd5b57c78d4e1259428d7e8dfe3ca3fc6e4/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm

Cl listed at #14 still need a merge to M67, correct Sarah?

Sorry, I merged the CLs together into one. They're both merged :)
Closing this

No worries, marking as fixed per comment #22. Thank you.

Able to reproduce this issue on reported version 67.0.3379.0 hence verifying the fix on latest beta 67.0.3396.48 using Mac 10.13.3.

As per cl in comment#8 and comment#14 issue is fixed on 67.0.3396.48. i.e; Now able to drag/ resize omnibox content to hide extensions and hided extension is visible in wrench menu. Hence fix is working as expected.

As fix is working as expected adding TE-Verified labels.

Thanks!