Add custom action support

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.
 
 // TODO(nektar): Migrate entire file to Mojoq.
 // 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 four enums, also add to
@@ skipping 229 matching lines @@
     vertical,
     visited
   };
 
   // An action to be taken on an accessibility node.
   // In contrast to |AXDefaultActionVerb|, these describe what happens to the
   // object, e.g. "FOCUS".
   enum AXAction {
     blur,
 
+    custom_action,
+
     // Decrement a slider or range control by one step value.
     decrement,
 
     // Do the default action for an object, typically this means "click".
     do_default,
 
     focus,
 
     // Return the content of this image object in the image_data attribute.
     get_image_data,
@@ skipping 264 matching lines @@
 
     // Used for caching. Do not read directly. Use
     // |AXNode::GetOrComputeLineStartOffsets|
     // For all text fields and content editable roots: A list of the start
     // offsets of each line inside this object.
     cached_line_starts,
 
     // For inline text. These int lists must be the same size; they represent
     // the start and end character offset of each word within this text.
     word_starts,
-    word_ends
+    word_ends,
+
+    custom_action_ids

[dmazzoni, 2017/06/06 03:06:00]

Add a comment for this. You could mention that they're currently only used
on Android and give a good example of a custom action there.

[yawano, 2017/06/08 09:25:29]

Done.

+  };
+
+  [cpp_enum_prefix_override="ax_attr"] enum AXStringListAttribute {
+    custom_action_descriptions
   };
 
   enum AXMarkerType {
     // Assignments are ignored by the parser, but are kept here for clarity.
     spelling = 1,
     grammar = 2,
     spelling_grammar = 3,
     text_match = 4,
     spelling_text_match = 5,
     grammar_text_match = 6,
@@ skipping 117 matching lines @@
     // First node is before the second one.
     before,
 
     // Nodes are the same.
     equal,
 
     // First node is after the second one.
     after
   };
 };