a11y: Exclude children of nested keyboard accessible controls from a11y tree.

ui/views/cocoa/bridged_content_view.mm

 // 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.
 
 #import "ui/views/cocoa/bridged_content_view.h"
 
 #include "base/logging.h"
 #import "base/mac/mac_util.h"
 #import "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #include "skia/ext/skia_utils_mac.h"
+#import "ui/accessibility/platform/ax_platform_node_mac.h"
 #include "ui/base/cocoa/cocoa_base_utils.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_mac.h"
 #include "ui/base/ime/input_method.h"
 #include "ui/base/ime/text_edit_commands.h"
 #include "ui/base/ime/text_input_client.h"
 #include "ui/compositor/canvas_painter.h"
 #import "ui/events/cocoa/cocoa_event_utils.h"
 #include "ui/events/keycodes/dom/dom_code.h"
 #import "ui/events/keycodes/keyboard_code_conversion_mac.h"
@@ skipping 1322 matching lines @@
            endedAtPoint:(NSPoint)screenPoint
               operation:(NSDragOperation)operation {
   views::DragDropClientMac* client = [self dragDropClient];
   if (client)
     client->EndDrag();
 }
 
 // NSAccessibility informal protocol implementation.
 
 - (id)accessibilityAttributeValue:(NSString*)attribute {
-  if ([attribute isEqualToString:NSAccessibilityChildrenAttribute]) {
-    return @[ hostedView_->GetNativeViewAccessible() ];
-  }
+  if ([attribute isEqualToString:NSAccessibilityChildrenAttribute])
+    return [((AXPlatformNodeCocoa*)hostedView_->GetNativeViewAccessible())
+        accessibilityAttributeValue:attribute];
+  else if ([attribute isEqualToString:NSAccessibilityParentAttribute])
+    // BridgedContentView is the top level for Views in a Widget.
+    return self;
+  else if ([attribute isEqualToString:NSAccessibilityRoleAttribute])
+    return NSAccessibilityWindowRole;
 
   return [super accessibilityAttributeValue:attribute];
 }
 
 - (id)accessibilityHitTest:(NSPoint)point {
   return [hostedView_->GetNativeViewAccessible() accessibilityHitTest:point];
 }
 
 @end