The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/12953e1967cb2a1168535f4ba21283910c1621dc

commit 12953e1967cb2a1168535f4ba21283910c1621dc
Author: Yuki Awano <yawano@chromium.org>
Date: Tue Sep 26 01:55:54 2017

Support android notification via chrome.automation

- Add support for elements inside android notification via
  chrome.automation.

      ChromeVox.

Bug:  763318 
Test: Confirm that user can navigate elements on android notification by
Change-Id: Iee057986596202f2e95c3db6b313cc21939e98bc
Reviewed-on: https://chromium-review.googlesource.com/656751
Commit-Queue: Yuki Awano <yawano@chromium.org>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504259}
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/chrome/browser/chromeos/arc/accessibility/arc_accessibility_helper_bridge.cc
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/chrome/browser/chromeos/arc/accessibility/arc_accessibility_helper_bridge.h
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/chrome/browser/chromeos/arc/accessibility/ax_tree_source_arc.cc
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/chrome/browser/chromeos/arc/accessibility/ax_tree_source_arc.h
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/components/arc/common/accessibility_helper.mojom
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/ui/arc/notification/arc_notification_content_view.cc
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/ui/arc/notification/arc_notification_surface.h
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/ui/arc/notification/arc_notification_surface_impl.cc
[modify] https://crrev.com/12953e1967cb2a1168535f4ba21283910c1621dc/ui/arc/notification/arc_notification_surface_impl.h

I believe feature work is done.