The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0ecdd928638ff0a284fce728d16c2a138297dc8b

commit 0ecdd928638ff0a284fce728d16c2a138297dc8b
Author: Dominic Mazzoni <dmazzoni@chromium.org>
Date: Wed Dec 05 23:21:59 2018

Introduce class to override aura window hierarchy for accessibility.

In particular, we want to make it possible to jump from an aura
Window in the ash tree to a proxy window's corresponding client window
in the client tree.

Bug:  911945 

Change-Id: I7713ed0f808f5b5a79804eb7c50510a148639edf
Reviewed-on: https://chromium-review.googlesource.com/c/1362013
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614167}
[modify] https://crrev.com/0ecdd928638ff0a284fce728d16c2a138297dc8b/ui/views/BUILD.gn
[add] https://crrev.com/0ecdd928638ff0a284fce728d16c2a138297dc8b/ui/views/accessibility/ax_aura_window_utils.cc
[add] https://crrev.com/0ecdd928638ff0a284fce728d16c2a138297dc8b/ui/views/accessibility/ax_aura_window_utils.h
[add] https://crrev.com/0ecdd928638ff0a284fce728d16c2a138297dc8b/ui/views/accessibility/ax_aura_window_utils_unittest.cc
[modify] https://crrev.com/0ecdd928638ff0a284fce728d16c2a138297dc8b/ui/views/accessibility/ax_window_obj_wrapper.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a15d7535017f58556cb996cb75328512d91efe5d

commit a15d7535017f58556cb996cb75328512d91efe5d
Author: James Cook <jamescook@chromium.org>
Date: Fri Dec 07 01:02:42 2018

Fix double-parenting in AXWindowObjWrapper under mash

Under mus/mash both the WindowTreeHost's root aura::Window and the content
aura::Window will return the same Widget for GetWidgetForNativeView(). Only
return the Widget for the content window, not the root, since otherwise
we'll end up with two children in the AX node tree that have the same
parent.

This allows AXAuraWindowUtilsTest to run under views_mus_unittests and
unblocks some future tests.

Bug:  911945 ,  911776 
Test: views_unittests, views_mus_unittests
Change-Id: I554c77e0dca90f1901a42d3331bca0a05e7bbd88
Reviewed-on: https://chromium-review.googlesource.com/c/1365986
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614515}
[modify] https://crrev.com/a15d7535017f58556cb996cb75328512d91efe5d/ui/views/BUILD.gn
[modify] https://crrev.com/a15d7535017f58556cb996cb75328512d91efe5d/ui/views/accessibility/ax_window_obj_wrapper.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9285350cba540a5b5677541c955747c7ee9fd550

commit 9285350cba540a5b5677541c955747c7ee9fd550
Author: Dominic Mazzoni <dmazzoni@chromium.org>
Date: Wed Dec 12 18:28:13 2018

Add a checker to help find bugs in an AXTreeSource.

Bug:  911945 
Change-Id: I64af0f02733e46bf1cd6df73d4ed0735d662c1b3
Reviewed-on: https://chromium-review.googlesource.com/c/1364159
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615973}
[modify] https://crrev.com/9285350cba540a5b5677541c955747c7ee9fd550/ui/accessibility/BUILD.gn
[add] https://crrev.com/9285350cba540a5b5677541c955747c7ee9fd550/ui/accessibility/ax_tree_source_checker.h
[modify] https://crrev.com/9285350cba540a5b5677541c955747c7ee9fd550/ui/views/BUILD.gn
[modify] https://crrev.com/9285350cba540a5b5677541c955747c7ee9fd550/ui/views/accessibility/ax_aura_window_utils_unittest.cc
[modify] https://crrev.com/9285350cba540a5b5677541c955747c7ee9fd550/ui/views/accessibility/ax_widget_obj_wrapper.cc
[modify] https://crrev.com/9285350cba540a5b5677541c955747c7ee9fd550/ui/views/accessibility/ax_window_obj_wrapper.cc

Fixed with above CLs and https://chromium-review.googlesource.com/c/1366280. See  issue 911776