Expose internal treegrid role, do some cleanup for table/grid/treegrid handling

content/browser/accessibility/browser_accessibility_manager_mac.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 "content/browser/accessibility/browser_accessibility_manager_mac.h"
 
 #include "base/bind.h"
 #import "base/mac/mac_util.h"
 #import "base/mac/scoped_nsobject.h"
 #import "base/mac/sdk_forward_declarations.h"
@@ skipping 193 matching lines @@
       if (IsRootTree()) {
         mac_notification = NSAccessibilityLoadCompleteNotification;
       } else {
         mac_notification = NSAccessibilityLayoutCompleteNotification;
       }
       break;
     case ui::AX_EVENT_INVALID_STATUS_CHANGED:
       mac_notification = NSAccessibilityInvalidStatusChangedNotification;
       break;
     case ui::AX_EVENT_SELECTED_CHILDREN_CHANGED:
-      if (node->GetRole() == ui::AX_ROLE_GRID ||
-          node->GetRole() == ui::AX_ROLE_TABLE) {
+      if (node->IsTableLikeRole()) {
         mac_notification = NSAccessibilitySelectedRowsChangedNotification;
       } else {
         mac_notification = NSAccessibilitySelectedChildrenChangedNotification;
       }
       break;
     case ui::AX_EVENT_DOCUMENT_SELECTION_CHANGED: {
       mac_notification = NSAccessibilitySelectedTextChangedNotification;
       // WebKit fires a notification both on the focused object and the root.
       BrowserAccessibility* focus = GetFocus();
       if (!focus)
@@ skipping 254 matching lines @@
     NSAccessibilityTextChangeValues : changes,
     NSAccessibilityTextChangeElement : native_node
   };
 }
 
 NSView* BrowserAccessibilityManagerMac::GetParentView() {
   return delegate() ? delegate()->AccessibilityGetAcceleratedWidget() : nullptr;
 }
 
 }  // namespace content