The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/39f560255cec8088d951c863c30647c2f4374341

commit 39f560255cec8088d951c863c30647c2f4374341
Author: Aaron Leventhal <aleventhal@chromium.org>
Date: Fri Sep 29 20:42:36 2017

Prefer IAccessible* over BrowserAccessibility* to test Win AX tree

It's more reliable to test the actual interfaces that screen readers will
use, than to test with internal interfaces. Doing so has revealed a bug with 
HTML <meter> and the value interface.

Another advantage of using IAccessible* in the tree formatter is 
that it will be easier to reuse the tree formatting code to write IA2 debugging 
tools that work in with any IA2 app.

Bug:  770189 
Change-Id: I67e91fb437afb6fb225add10ef13fa4b10e84ef4
Reviewed-on: https://chromium-review.googlesource.com/691316
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505454}
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/BUILD.gn
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter.cc
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter.h
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_android.cc
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_auralinux.cc
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_blink.cc
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_blink.h
[add] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_browser.cc
[add] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_browser.h
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_mac.mm
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_stub.cc
[modify] https://crrev.com/39f560255cec8088d951c863c30647c2f4374341/content/browser/accessibility/accessibility_tree_formatter_win.cc