Able to reproduce the issue on windows 7 using chrome version 55.0.2873.0.the same is working fine on Mac 10.11.6.

Using the per-revision bisect providing the bisect results,
Good build: 55.0.2868.0 (Revision: 420217).
Bad build: 55.0.2870.0 (Revision: 420804).

You are probably looking for a change made after 420666 (known good), but no later than 420667 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/d9adeff125559612a223819de5fce36c5e337b4f..1c77b2b6c04efe4e5d5d3ec5688616d65b8d0138


@ellyjones -- Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to concern owner.
Thank You.

Adding beta blocker as this is recent regression.Please feel free to adjust if not required.

https://codereview.chromium.org/2373403002/

Blink doesn't affect omonibox.

This bug is reported as M55 Beta blocker.Please try to resolve this before M55 branch on Oct 6th,2016 so it has enough baking time in Dev.

ellyjones@: Could you please take a look into the CL review under progress and if possible, land the fix before M-55 branch as per C#6.

A friendly reminder that M55 Beta launch is coming soon! Your bug is labelled as Beta ReleaseBlock, pls make sure to land the fix ASAP. Thank you.

@kathrelkeld: Katherine, when this change lands could you do a quick check on Chrome OS that the Omnibox text editing doesn't seem to regress? Things to check might be ChromeVox feedback and cursor highlighting as you select with the mouse or keyboard, or cut and paste text. Hopefully nothing should have changed.

Thanks!

(I am worried, for example, about getting extra spurious announcements of text changes from ChromeVox.)

#9: We'll be sure to double check this during our FullRelease test pass next week.

**** Bulk edit -  please ignore if not applicable ****

This bug  is reported as M55 Beta blocker and we're getting closer to M55 Beta promotion. 
Please plan to have fix ready and merged to M55 branch (2883) by 5:00 PM PT, Monday(10/10) so it has enough baking time in Dev before Beta promotion. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cb06e3bec608cfc5f294d4aaa1a2c2e983017f05

commit cb06e3bec608cfc5f294d4aaa1a2c2e983017f05
Author: ellyjones <ellyjones@chromium.org>
Date: Fri Oct 07 19:33:00 2016

views: call UpdateAfterChange() in Textfield::InsertOrReplaceText().

The Omnibox uses InsertOrReplaceText() to implement its own paste handling that bypasses Textfield::OnPaste(), but the cursor still needs to be kept in sync with pastes.

BUG= 651016 

Review-Url: https://codereview.chromium.org/2399863002
Cr-Commit-Position: refs/heads/master@{#423930}

[modify] https://crrev.com/cb06e3bec608cfc5f294d4aaa1a2c2e983017f05/ui/views/controls/textfield/textfield.cc
[modify] https://crrev.com/cb06e3bec608cfc5f294d4aaa1a2c2e983017f05/ui/views/controls/textfield/textfield.h
[modify] https://crrev.com/cb06e3bec608cfc5f294d4aaa1a2c2e983017f05/ui/views/controls/textfield/textfield_test_api.h
[modify] https://crrev.com/cb06e3bec608cfc5f294d4aaa1a2c2e983017f05/ui/views/controls/textfield/textfield_unittest.cc

Please request a merge to M55 if change is baked/verified in Canary and safe to merge. Thank you.

Your change meets the bar and is auto-approved for M55 (branch: 2883)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b2d6905a80d1603373c401558a145e195714938d

commit b2d6905a80d1603373c401558a145e195714938d
Author: Elly Fong-Jones <ellyjones@chromium.org>
Date: Wed Oct 12 20:36:26 2016

views: call UpdateAfterChange() in Textfield::InsertOrReplaceText().

The Omnibox uses InsertOrReplaceText() to implement its own paste handling that bypasses Textfield::OnPaste(), but the cursor still needs to be kept in sync with pastes.

BUG= 651016 

Review-Url: https://codereview.chromium.org/2399863002
Cr-Commit-Position: refs/heads/master@{#423930}
(cherry picked from commit cb06e3bec608cfc5f294d4aaa1a2c2e983017f05)

Review URL: https://codereview.chromium.org/2413043002 .

Cr-Commit-Position: refs/branch-heads/2883@{#71}
Cr-Branched-From: 614d31daee2f61b0180df403a8ad43f20b9f6dd7-refs/heads/master@{#423768}

[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield.cc
[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield.h
[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield_test_api.h
[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield_unittest.cc

Merge complete to 2883.

Verified the issue on Windows-10 and Linux ubuntu 14.04 using chrome version 55.0.2883.11 with the steps mentioned above. Fix is working fine. Please find the attached screencast.

Deleted: Win-651016.mp4 450 KB

	Win-651016.mp4 450 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b2d6905a80d1603373c401558a145e195714938d

commit b2d6905a80d1603373c401558a145e195714938d
Author: Elly Fong-Jones <ellyjones@chromium.org>
Date: Wed Oct 12 20:36:26 2016

views: call UpdateAfterChange() in Textfield::InsertOrReplaceText().

The Omnibox uses InsertOrReplaceText() to implement its own paste handling that bypasses Textfield::OnPaste(), but the cursor still needs to be kept in sync with pastes.

BUG= 651016 

Review-Url: https://codereview.chromium.org/2399863002
Cr-Commit-Position: refs/heads/master@{#423930}
(cherry picked from commit cb06e3bec608cfc5f294d4aaa1a2c2e983017f05)

Review URL: https://codereview.chromium.org/2413043002 .

Cr-Commit-Position: refs/branch-heads/2883@{#71}
Cr-Branched-From: 614d31daee2f61b0180df403a8ad43f20b9f6dd7-refs/heads/master@{#423768}

[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield.cc
[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield.h
[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield_test_api.h
[modify] https://crrev.com/b2d6905a80d1603373c401558a145e195714938d/ui/views/controls/textfield/textfield_unittest.cc

[Automated comment] removing mislabelled merge-merged-2840