Disable next compatibility mode for ChromeVox on dev channel

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 308 matching lines @@
     subtree_created,
     node_changed,
     node_removed
   };
 
   [cpp_enum_prefix_override="ax_attr"] enum AXStringAttribute {
     access_key,
     // Only used when invalid_state == invalid_state_other.
     aria_invalid_value,
     auto_complete,
+    chrome_channel,  // Automation only.
     container_live_relevant,
     container_live_status,
     description,
     display,
     // Only present when different from parent.
     font_family,
     html_tag,
     image_data_url,
     // Only present when different from parent.
     language,
@@ skipping 306 matching lines @@
     // First node is before the second one.
     before,
 
     // Nodes are the same.
     equal,
 
     // First node is after the second one.
     after
   };
 };