Checking again with flag disabled: 

70.0.3524.2 (Official Build) canary (64-bit)
Google_Eve.9584.160.0
#ash-keyboard-shortcut-viewer-app set to 'Disabled' 

Reproduces per steps above. Keeping bug open.

Sorry for the confusion, "mash" means the app version. If it still repros with the app disabled, it's not a "mash" problem.

@Laura, the important part here is whether ChromeVox reads the new item. The system focus is probably still actually on the text field. If ChromeVox does speak the new item, then I think this might be fine (perhaps ChromeVox should update the focus highlight). If ChromeVox does not speak, then it is an issue with the underlying UI.

Google Chrome	72.0.3593.0 (Official Build) dev (64-bit)
Firmware Version	Google_Caroline.7820.384.0

Re-testing as part of our assessment. Since it's been two milestones, I did not try changing the flag and just tested the UI out of the box. If that's an issue, please just let me know. 

Let me explain the exact issue a little more, it does appear to be a problem with the underlying UI: 

# Follow steps above to load ChromeVox and Keyboard Shortcuts 
# Focus lands on the search box 
# Press tab once. ChromeVox focus ring is still on the search box but the keyboard focus is now on "Popular Shortcuts." Nothing is spoken here. 
# Press the down arrow key to move to "Tabs and Windows" section. ChromeVox gets back in line with the keyboard focus, orange focus highlight moves to the Tabs and Windows section, Tabs and Windows is read. 

This bug is dependent specifically on the scenario where focus lands on the search box upon opening. If the focus landed upon any of the categories including "Popular Shortcuts" upon opening, the focus ring lines up with the keyboard focus and the category name is read. I'm not sure why focus is landing differently for me upon opening the app a second, third, etc. time, perhaps it's remembering where I left off? 

 Issue 894094  has been merged into this issue.

+dmazzoni@

How ChromeVox focus is determined? If I use "Tab", will ChromeVox focus change or I need to set the View focusable? 

I found the reason: the MdTab does not request focus as the Tab version in the OnFocus().

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e9600b8f2e705850ed701aff9283e22511e0ac3a

commit e9600b8f2e705850ed701aff9283e22511e0ac3a
Author: wutao <wutao@chromium.org>
Date: Fri Jan 11 18:22:35 2019

tabbed_pane: notify a11y event on focus

In MdTab::OnFocus, it does not notify a11y event of focus, which causes
the ChromeVox focus out of sync. This patch notifies the event as we do
in the Tab::OnFocus.

Bug:  876388 
Test: manual
Change-Id: I332c3dfa355d9ab41cf5848f549cde164d73b045
Reviewed-on: https://chromium-review.googlesource.com/c/1406196
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Tao Wu <wutao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622062}
[modify] https://crrev.com/e9600b8f2e705850ed701aff9283e22511e0ac3a/ui/views/controls/tabbed_pane/tabbed_pane.cc