Over to rameier@ as a starter bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3361a1016e0dffc8ffe7f76771588d7395118442

commit 3361a1016e0dffc8ffe7f76771588d7395118442
Author: Ryan Meier <rameier@chromium.org>
Date: Fri Aug 03 21:21:00 2018

Disable automatically modifying tab padding while a tab is closing

Adds checks before modifying whether or not a tab uses extra padding to
ensure that padding doesn't get changed while the tab is closing.
Without these checks, tab titles would suddenly jump several pixels to
the left near the end of the tab's closing animation.

Found while reproducing/fixing
Bug:  859321 

Change-Id: Id7db4b160530535af520cdfaf99202aa863a019a
Reviewed-on: https://chromium-review.googlesource.com/1162359
Commit-Queue: Ryan Meier <rameier@chromium.org>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580652}
[modify] https://crrev.com/3361a1016e0dffc8ffe7f76771588d7395118442/chrome/browser/ui/views/tabs/tab.cc

Tried checking the issue on latest canary 70.0.3514.0 using Mac 10.13.1 with the below mentioned steps.
1. Launched chrome
2. Opened multiple tabs
3. Selected few tabs out of them(Shift+click)
After hitting Cmd+W, all the selected tabs were closed. Similar behaviour is seen in 69.0.3480.0(expecting this version without fix)

@Ryan Meier: As we are not very clear about the expected and actual behaviour could you please let us know if we have missed anything and requesting you to help us in verifying the fix.

Thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c799f6a78b865699d08fb2c3bc9c90794039e30b

commit c799f6a78b865699d08fb2c3bc9c90794039e30b
Author: Ryan Meier <rameier@chromium.org>
Date: Tue Aug 07 17:32:22 2018

Update tab's active state when removed from view model

TabStrip now calls ActiveStateChanged() on tabs when they are removed
from the view model, giving them a chance to update any relevant state
(such as background/text color, etc).

Bug:  859321 
Change-Id: Iaad9d3dfa2d378c708a648315e5bdef9e2f2ff5f
Reviewed-on: https://chromium-review.googlesource.com/1162429
Commit-Queue: Ryan Meier <rameier@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581272}
[modify] https://crrev.com/c799f6a78b865699d08fb2c3bc9c90794039e30b/chrome/browser/ui/views/tabs/tab.cc
[modify] https://crrev.com/c799f6a78b865699d08fb2c3bc9c90794039e30b/chrome/browser/ui/views/tabs/tab.h
[modify] https://crrev.com/c799f6a78b865699d08fb2c3bc9c90794039e30b/chrome/browser/ui/views/tabs/tab_strip.cc