UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3501.0 Safari/537.36

Steps to reproduce the problem:
1. Launch Chrome/Chromium
  * export ACCESSIBILITY_ENABLED=1, and
  * launch with --force-renderer-accessibility

2. Load "data:text/html,<h2>foo</h2>" in browser

3. Accerciser and use its Interface Viewer to examine the Attributes (under "Accessible")

What is the expected behavior?
The list of attributes would include "level:2".

What went wrong?
The list of attributes is empty.

Did this work before? No 

Chrome version: 70.0.3501.0  Channel: n/a
OS Version: 
Flash Version: 

Compare to: Firefox (with accessibility enabled), Epiphany

Documentation: https://developer.gnome.org/atk/stable/AtkObject.html#atk-object-get-attributes, also https://w3c.github.io/html-aam/#el-h1-h6 and https://rawgit.com/w3c/core-aam/master/#ariaLevelHeading

Impacts:

1. With respect to this specific test case (heading level), because the heading level is not exposed, Orca cannot present it. In addition, Orca's keyboard commands to navigate amongst headings at a given level (e.g. "1" for the next H1, "2" for the next H2") don't work.

2. In general, object attributes are used to expose things where the platform accessibility API lacks a better means. At the present time, this is true of heading level, but also of things like aria-posinset and aria-setsize. The fact that no object attributes are exposed at all means there's quite a bit of information that should be expose to Orca which is not. See the HTML-AAM and Core-AAM for additional examples.

3. For debugging and other purposes, other user agents have exposed things like the id of an element via object attributes (or the equivalent property on other platforms). If this were done in Chromium, it would be far easier to do automated accessibility testing for Chromium in Linux because we could tree dive looking for the accessible element with the specified id.

4. The good news: IAccessible2 uses object attributes in a very similar fashion and with very similar content. To my knowledge, IA2 clients are getting these attributes exposed to them by Chromium. Thus my guess is that it won't take much work to get the attribute names and values as that work has presumably already been done for IA2. That same information just needs to be exposed via ATK.