Unable to reproduce the issue on Win-10 using chrome reported version #61.0.3163.100, latest stable #62.0.3202.62 and latest canary #64.0.3247.0.

Attached a screen cast for reference.

Following are the steps followed to reproduce the issue.
------------
1. Opened the attached file "margin-auto-grid-example.html"
2. Observed a horizontal scrollbar at the bottom of the page.
3. Changed the grid element overflow back to `auto`.
4. Did not observe any horizontal scrollbar at the bottom of the page.

Reporter@ - Could you please verify the screen cast and please let us know if anything missed from our side and also please check the issue on latest canary #64.0.3247.0 by creating a new profile without any apps and extensions and please let us know if the issue still persist or not.

Thanks...!!

Deleted: 776581.webm 6.5 MB

	776581.webm 6.5 MB View Download

So if you are seeing the horizontal scrollbar at all, you are seeing the bug.

I've tweaked the file to show it a bit clearer. If you load this file, it should start with no horizontal scrollbar, only a vertical one. Clicking hide scrollbars adds `overflow: hidden` to the body, and clicking the show button removes that style. After clicking the show button, there is now a horizontal scrollbar when there shouldn't be.

The `margin: auto` on the div element resizes to larger when the scrollbars go away. However, when the scrollbars come back, the margin is not recalculated so it's width is too wide and it creates a horizontal scroll as it overflows the page.

Deleted: margin-auto-grid-example.html 1.1 KB

margin-auto-grid-example.html 1.1 KB View Download

Thank you for providing more feedback. Adding requester "krajshree@chromium.org" to the cc list and removing "Needs-Feedback" label.

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

Able to reproduce the issue on windows 10 , Mac os 10.12.6 and ubuntu 14.04 using chrome M62 #62.0.3202.62 and M64 #64.0.3249.0 .

This is a Non-Regression issue seen from M57 and the behavior is different earlier to M57 .


Marking it as untraiged for further inputs on this.

Thanks!

I've been able to reproduce the issue on linux chrome 63.0.3239.9

Fix is coming: https://crrev.com/c/751262

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d84d88fc4d3223c89148ef62bc2785410e77fa2e

commit d84d88fc4d3223c89148ef62bc2785410e77fa2e
Author: Javier Fernandez <jfernandez@igalia.com>
Date: Sat Nov 04 10:06:43 2017

[css-grid] Ignore auto-margins in the track sizing algorithm

We resolve any auto-margin during the execution of the Grid logic.
Even though we compute them again if there is any change requiring to
perform a new layout, the previously resolved auto-margins may affect
the track sizing computation for content-sized (eg. auto) tracks.

We must ignore any 'auto' margin during the track sizing algorithm,
so I added additional logic to the utility functions we already have
in order to ignore any previously computed 'auto' margin.

Bug:  776581 
Change-Id: I3a18819feed44d856c3a80d15e387721872b5f98
Reviewed-on: https://chromium-review.googlesource.com/751262
Commit-Queue: Javier Fernandez <jfernandez@igalia.com>
Reviewed-by: Manuel Rego Casasnovas <rego@igalia.com>
Cr-Commit-Position: refs/heads/master@{#514042}
[add] https://crrev.com/d84d88fc4d3223c89148ef62bc2785410e77fa2e/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-container-scroll-accounts-for-auto-margin-expected.html
[add] https://crrev.com/d84d88fc4d3223c89148ef62bc2785410e77fa2e/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-container-scroll-accounts-for-auto-margin.html
[modify] https://crrev.com/d84d88fc4d3223c89148ef62bc2785410e77fa2e/third_party/WebKit/Source/core/layout/GridLayoutUtils.cpp
[modify] https://crrev.com/d84d88fc4d3223c89148ef62bc2785410e77fa2e/third_party/WebKit/Source/core/layout/GridTrackSizingAlgorithm.cpp

This issue should be FIXED now, please, verify.