Finalize documentation for the automation extension API.

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/apis/automation.idl.
   enum AXEvent {
     activedescendantchanged,
     alert,
     aria_attribute_changed,
     autocorrection_occured,
     blur,
     checked_state_changed,
     children_changed,
     focus,
     hide,
@@ skipping 326 matching lines @@
     word_ends
   };
 
   [cpp_enum_prefix_override="ax"] enum AXTextDirection {
     text_direction_lr,
     text_direction_rl,
     text_direction_tb,
     text_direction_bt
   };
 };