Handling of different types of empty alt

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 589 matching lines @@
   enum AXSortDirection {
     unsorted,
     ascending,
     descending,
     other
   };
 
   enum AXNameFrom {
     uninitialized,
     attribute,
+    attribute_explicitly_empty,
     contents,
     placeholder,
     related_element,
     value
   };
 
   enum AXDescriptionFrom {
     uninitialized,
     attribute,
     contents,
@@ skipping 41 matching lines @@
     // First node is before the second one.
     before,
 
     // Nodes are the same.
     equal,
 
     // First node is after the second one.
     after
   };
 };