Chrome version : 71.0.3577.0 (Official Build) fc334a55a70eec12fc77853c53979f81e8496c21-refs/branch-heads/3577@{#1}(32/64 Bit)
OS :Mac(10.13.1,10.13.6,10.14.1) 

Pre-condition:
Enable following flags under chrome://flags
1.Force UI direction
2.Enable RTL
3.New Tab Page Background Selection 
4.Enable using the Google local NTP

Steps to reproduce:
1.Launch chrome and navigate to NTP.
2.Click on gear icon and select'chrome Backgrounds'
3.Under collection select any option Eg..Landscapes.
4.Press Tab And bring Focus on Landscapes options and observe.

Actual Result:Focus is seen misplaced(Shifted to RHS) on Tile present in 'chrome backgrounds'.
Expected Result:Focus should be seen at proper position on Tile present in 'chrome backgrounds'.

This is a regression issue broken in ‘M-71’ and  bisect information:
Good Build : 71.0.3558.0 (Revision : 593043)
Bad Build : 71.0.3559.0 (Revision : 593399)

You are probably looking for a change made after 593067 (known good), but no later than 593076 (first known bad).

CHANGE-LOG URL:

https://chromium.googlesource.com/chromium/src/+log/fe6e02d2be1c8bfe626db5a411d23d61165a6aca..3e4e10cf8afeff34ed2275d022a5fffae14904a2

Suspect:https://chromium.googlesource.com/chromium/src/+/c95c6af2d0d93f7cd103fd0282795fdc60d01bb4

@Weilun Shi: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.

Kindly refer the attached screen-cast.

https://drive.google.com/open?id=1KY9g884M0_hQ3JZv-Ec0px9b1n1TQDcL

Note:

1.Unable to provide 'per-revision' bisect as it shows "We don't have enough builds to bisect" error message.
2.Tried on other machines but still getting the same error again.
3.Hence provided suspect through 'Chromium bisect'.
4.Issue is also seen on latest canary #71.0.3577.0.
5.Issue is not seen on OS:Windows (7, 8, 8.1 ,10) and Linux 14.04 LTS

Thank you..!