The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9604fdc3c149d50a99d2cfb92a8a6d4b8bac77b0

commit 9604fdc3c149d50a99d2cfb92a8a6d4b8bac77b0
Author: James Wallace-Lee <jamwalla@chromium.org>
Date: Fri Oct 19 21:11:18 2018

chrome://accessibility: list browser windows, get trees one at a time

In chrome://accessibility, the "Chrome Native UI" section behaves like
the "Pages" section. Browser windows are listed individually using the
.row class the Pages list uses.

-AccessibilityUIMessageHandler::RequestNativeUITree takes a session ID
as an argument and returns the accessibility tree for a single browser
window.
-The TargetDescriptor dictionary includes a field for a browser window's
session id, and a "type" field that is either "page" for a WebContents
or "browser" for a Browser.
-In accessibility.js, showTree and other functions handle both browser
windows and pages, since they can check |data|'s type field.
-Elements in a .row element are given ids based on the row's id + a
description of the element: '<id>:title', 'showTree', 'copyTree',
'hideTree', 'tree'.


Bug:  842895 
Change-Id: I7ef7b4edb884ff097fdaefc41ba97a813a7b49e1
Reviewed-on: https://chromium-review.googlesource.com/c/1260009
Commit-Queue: James Wallace-Lee <jamwalla@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601296}
[modify] https://crrev.com/9604fdc3c149d50a99d2cfb92a8a6d4b8bac77b0/chrome/browser/accessibility/accessibility_ui.cc
[modify] https://crrev.com/9604fdc3c149d50a99d2cfb92a8a6d4b8bac77b0/chrome/browser/resources/accessibility/accessibility.html
[modify] https://crrev.com/9604fdc3c149d50a99d2cfb92a8a6d4b8bac77b0/chrome/browser/resources/accessibility/accessibility.js

Able to reproduce the issue on chrome version build without fix #68.0.3848.0 on Surface Pro 4 Windows 10 by following steps as per comment #0.

Verified the fix on Surface Pro 4 Windows 10, as per comment#0 on latest chrome version #72.0.3588.0.
Attaching screen shot for reference.
Observed hide tree button button under chrome://accessbility on build with fix (72.0.3588.0).
Hence, the fix is working as expected.
Adding the verified labels.

Thanks...!!

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chrome: 72.0.3602.2 (Official Build) dev (64-bit) (cohort: Dev)