+msw@ for cl review context.
I will upload a change soon.

I'm guessing KSH == KSV (Keyboard Shortcut Viewer), what does 'H' stand for?
Posting before and after pictures, and a comparison with the wallpaper picker would be nice.

"H" stands for "helper", which is used by PM and UX.
I uploaded two pictures before/after changes and compared with wallpaper picker.

But it seems it still do not match exactly after the changes.

Deleted: KSV_before_compare.png 63.6 KB

	KSV_before_compare.png 63.6 KB View Download

Deleted: KSV_after_compare.png 63.6 KB

	KSV_after_compare.png 63.6 KB View Download

Uploaded another image to make it more obvious of the misalignment.

Deleted: KSV_after_compare2.png 74.9 KB

	KSV_after_compare2.png 74.9 KB View Download

I changed to spacing 9px, and it is matched.

wzang@, could you please double check wallpaper? Thanks!

Deleted: KSV_after_compre_spacing9px.png 75.0 KB

	KSV_after_compre_spacing9px.png 75.0 KB View Download

wzang@ will fix the alignment in another bug 889655.

I will change the spacing to 8px.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/423ec1531c590cc828dd43a6a3c36990b857b329

commit 423ec1531c590cc828dd43a6a3c36990b857b329
Author: wutao <wutao@chromium.org>
Date: Thu Sep 27 22:27:03 2018

Revise tab spacing in vertical mode

This cl revises the tab spacing in vertical mode to match the spacing in
the wallpaper picker.

Images before and after changes are uploaded in the bug.

Bug:  889559 
Test: manual.
Change-Id: I33a73809a9c674b009c5fdf1f9367645d395af87
Reviewed-on: https://chromium-review.googlesource.com/1249818
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Tao Wu <wutao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594896}
[modify] https://crrev.com/423ec1531c590cc828dd43a6a3c36990b857b329/ui/views/controls/tabbed_pane/tabbed_pane.cc