Support presentational iframes and make use of them in the uber frame.

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 522 matching lines @@
     bool isAriaPressedDefined;
     bool isMixed;
     browserAccessibility_->GetAriaTristate("aria-pressed",
                                            &isAriaPressedDefined,
                                            &isMixed);
     if (isAriaPressedDefined)
       return NSAccessibilityCheckBoxRole;
     else
       return NSAccessibilityButtonRole;
   }
+
+  // If this is a web area for a presentational iframe, give it a role of
+  // something other than WebArea so that the fact that it's a separate doc
+  // is not exposed to AT.
+  if (browserAccessibility_->IsWebAreaForPresentationalIframe())
+    return NSAccessibilityGroupRole;
+
   return [AXPlatformNodeCocoa nativeRoleFromAXRole:role];
 }
 
 // Returns a string indicating the role description of this object.
 - (NSString*)roleDescription {
   NSString* role = [self role];
 
   ContentClient* content_client = content::GetContentClient();
 
   // The following descriptions are specific to webkit.
   if ([role isEqualToString:@"AXWebArea"]) {
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_WEB_AREA));
   }
 
   if ([role isEqualToString:@"NSAccessibilityLinkRole"]) {
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_LINK));
   }
 
   if ([role isEqualToString:@"AXHeading"]) {
     return base::SysUTF16ToNSString(content_client->GetLocalizedString(
         IDS_AX_ROLE_HEADING));
   }
 
-  if ([role isEqualToString:NSAccessibilityGroupRole] ||
-      [role isEqualToString:NSAccessibilityRadioButtonRole]) {
+  if (([role isEqualToString:NSAccessibilityGroupRole] ||
+       [role isEqualToString:NSAccessibilityRadioButtonRole]) &&
+      !browserAccessibility_->IsWebAreaForPresentationalIframe()) {
     std::string role;
     if (browserAccessibility_->GetHtmlAttribute("role", &role)) {
       ui::AXRole internalRole = [self internalRole];
       if ((internalRole != ui::AX_ROLE_GROUP &&
            internalRole != ui::AX_ROLE_LIST_ITEM) ||
           internalRole == ui::AX_ROLE_TAB) {
         // TODO(dtseng): This is not localized; see crbug/84814.
         return base::SysUTF8ToNSString(role);
       }
     }
@@ skipping 930 matching lines @@
     return [super hash];
   return browserAccessibility_->GetId();
 }
 
 - (BOOL)accessibilityShouldUseUniqueId {
   return YES;
 }
 
 @end