AXSubrole and AXRoleDescription is not exposed for HTML form element.

content/browser/accessibility/browser_accessibility_cocoa.mm

 // Copyright (c) 2012 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.
 
 #include <execinfo.h>
 
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
 
 #include <map>
 
@@ skipping 578 matching lines @@
         IDS_AX_ROLE_BANNER));
   case ui::AX_ROLE_COMPLEMENTARY:
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_COMPLEMENTARY));
   case ui::AX_ROLE_CONTENT_INFO:
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_ADDRESS));
   case ui::AX_ROLE_FOOTER:
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_FOOTER));
+  case ui::AX_ROLE_FORM:
+    return base::SysUTF16ToNSString(content_client->GetLocalizedString(
+        IDS_AX_ROLE_FORM));
   case ui::AX_ROLE_MAIN:
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_MAIN_CONTENT));
   case ui::AX_ROLE_NAVIGATION:
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_NAVIGATIONAL_LINK));
   case ui::AX_ROLE_REGION:
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_REGION));
   case ui::AX_ROLE_SPIN_BUTTON:
@@ skipping 865 matching lines @@
     return [super hash];
   return browserAccessibility_->GetId();
 }
 
 - (BOOL)accessibilityShouldUseUniqueId {
   return YES;
 }
 
 @end