Unable to narrow down the range using tool as this issue is not reproducible on chromium builds, hence providing the suspect from change log.

Change log URL : 
https://chromium.googlesource.com/chromium/src/+log/56.0.2908.0..56.0.2909.0?pretty=fuller&n=10000

Suspecting : r 429658 or 429665 ? from Change log.

@spqchan : Please take a look.

Note : Issue is not seen on Windows and Linux OS.

Stable blocker (visual regression), probably not beta blocker though I'm open to discussion. 

I am seeing this e.g. as well with the i-icon and the magnifying glass icon. Screenshots are attached. I am using a non-retina Macbook Air.

Deleted: i-icon.png 7.7 KB

	i-icon.png 7.7 KB View Download

Deleted: magnifying glass icon.png 7.2 KB

	magnifying glass icon.png 7.2 KB View Download

It's likely that this is caused by r429658

I'll look into this

 Issue 663682  has been merged into this issue.

Friendly ping to get an update on this issue.

Thanks,

Fix in review: https://codereview.chromium.org/2503713002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f1b792a63088465603c079e7dc1037acb2b67427

commit f1b792a63088465603c079e7dc1037acb2b67427
Author: spqchan <spqchan@chromium.org>
Date: Fri Nov 18 20:16:11 2016

[Mac] Fix for omnibox lock icon
- Align the permission bubble to be below the Lock Icon
- Fix blurry lock icon

BUG= 662411 ,  662365 

Review-Url: https://codereview.chromium.org/2503713002
Cr-Commit-Position: refs/heads/master@{#433283}

[modify] https://crrev.com/f1b792a63088465603c079e7dc1037acb2b67427/chrome/browser/ui/cocoa/location_bar/image_decoration.mm
[modify] https://crrev.com/f1b792a63088465603c079e7dc1037acb2b67427/chrome/browser/ui/cocoa/location_bar/image_decoration_unittest.mm
[modify] https://crrev.com/f1b792a63088465603c079e7dc1037acb2b67427/chrome/browser/ui/cocoa/location_bar/security_state_bubble_decoration.mm

[Auto-generated comment by a script] We noticed that this issue is targeted for M-56; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-56 label, otherwise remove Merge-TBD label. Thanks.

Your change meets the bar and is auto-approved for M56 (branch: 2924)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d4f0c7b3e73f274c4606f201385539d328e1f5da

commit d4f0c7b3e73f274c4606f201385539d328e1f5da
Author: spqchan <spqchan@chromium.org>
Date: Mon Nov 21 18:55:56 2016

[Mac] Fix for omnibox lock icon

- Align the permission bubble to be below the Lock Icon
- Fix blurry lock icon

BUG= 662411 ,  662365 

Review-Url: https://codereview.chromium.org/2503713002
Cr-Commit-Position: refs/heads/master@{#433283}
(cherry picked from commit f1b792a63088465603c079e7dc1037acb2b67427)

Review URL: https://codereview.chromium.org/2521033002 .

Cr-Commit-Position: refs/branch-heads/2924@{#32}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}

[modify] https://crrev.com/d4f0c7b3e73f274c4606f201385539d328e1f5da/chrome/browser/ui/cocoa/location_bar/image_decoration.mm
[modify] https://crrev.com/d4f0c7b3e73f274c4606f201385539d328e1f5da/chrome/browser/ui/cocoa/location_bar/image_decoration_unittest.mm
[modify] https://crrev.com/d4f0c7b3e73f274c4606f201385539d328e1f5da/chrome/browser/ui/cocoa/location_bar/security_state_bubble_decoration.mm

Already merged, removing TBD.

This bug requires manual review: No test file found in commits.
Please contact the milestone owner if you have questions.
Owners: amineer@(clank), cmasso@(bling), gkihumba@(cros), bustamante@(desktop)

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

This bug requires manual review: No test file found in commits.
Please contact the milestone owner if you have questions.
Owners: amineer@(clank), cmasso@(bling), gkihumba@(cros), bustamante@(desktop)

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

[Automated comment] removing mislabelled Merge-Review-56, Hotlist-Merge-Review