Mac a11y: Add Help, TopLevelUIElement, and Window accessibility attributes.

ui/accessibility/ax_enums.idl

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // These should be kept in sync with third_party/WebKit/public/web/WebAXEnums.h
 // until the Chromium and Blink trees are merged.
 [camel_case_enum_to_string=true] namespace ui {
 
   // For new entries to the following three enums, also add to
   // chrome/common/extensions/api/automation.idl.
@@ skipping 224 matching lines @@
   };
 
   [cpp_enum_prefix_override="ax_attr"] enum AXStringAttribute {
     access_key,
     action,
     // Only used when invalid_state == invalid_state_other.
     aria_invalid_value,
     auto_complete,
     container_live_relevant,
     container_live_status,
     description,

[dmazzoni, 2016/07/26 22:26:56]

It's not obvious at all, but "description" maps to the AXHelp attribute on Mac.
We use this convention because on the web, the primary and secondary accessible
text for an object are called "name" and "description", so we map those to the
primary and secondary on Mac, which is AXTitle/AXDescription (primary) and
AXHelp (secondary). In newer versions of OS X it's AXLabel instead of
AXTitle/AXDescription.

[Patti Lor, 2016/07/27 02:59:00]

Done - this involved rewriting the AXRoleDescription selector to only generate a
role description from the role and subrole though (this is what it currently
does now if AX_ATTR_DESCRIPTION isn't populated). Thanks!

     display,
     // Only present when different from parent.
     font_family,
+    help_text,
     html_tag,
     // Only present when different from parent.
     language,
     name,
     live_relevant,
     live_status,
     placeholder,
     role,
     shortcut,
     url,
@@ skipping 246 matching lines @@
     swipe_left_3,
     swipe_up_3,
     swipe_right_3,
     swipe_down_3,
     swipe_left_4,
     swipe_up_4,
     swipe_right_4,
     swipe_down_4
   };
 };