Implement automatic load of composed/embedded automation trees

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 276 matching lines @@
     // Relationships between this element and other elements.
     title_ui_element,
     activedescendant_id,
 
     // Color value for AX_ROLE_COLOR_WELL, each component is 0..255
     color_value_red,
     color_value_green,
     color_value_blue,
 
     // Inline text attributes.
-    text_direction
+    text_direction,
+
+    // Internal only; do not expose to platform APIs.

[dmazzoni, 2014/10/29 06:53:30]

I don't think we should put these here.

Let's add ax_frame_id that specifies the frame id of an axtree, and
ax_child_frame_id that specifies the id of a child axtree contained within this
tree.

[aboxhall, 2014/10/29 19:29:11]

I'm confused by this. These are being now used as process_id and routing_id but
not named as such. Was that what you intended?

[David Tseng, 2014/10/29 20:35:30]

It is; the intent is to have us ultimately use abstracted frame/child frame id's
which we as accessibility keep track of. Added TODO.

[aboxhall, 2014/10/29 20:53:29]

I find this really confusing. Why not just put process_id and routing_id in here
while we're still using them? (This question as much for Dominic.)

+    // Only applicable to views::WebView.
+    process_id,
+    routing_id
   };
 
   [cpp_enum_prefix_override="ax_attr"] enum AXFloatAttribute {
     // Document attributes.
     doc_loading_progress,
 
     // Range attributes.
     value_for_range,
     min_value_for_range,
     max_value_for_range
@@ skipping 71 matching lines @@
     word_ends
   };
 
   [cpp_enum_prefix_override="ax"] enum AXTextDirection {
     text_direction_lr,
     text_direction_rl,
     text_direction_tb,
     text_direction_bt
   };
 };