Add roleDescription to DumpAccessibilityTree for mac.

content/browser/accessibility/dump_accessibility_tree_helper_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/dump_accessibility_tree_helper.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/file_path.h"
 #include "base/utf_string_conversions.h"
 #include "content/browser/accessibility/browser_accessibility_cocoa.h"
 #include "content/browser/accessibility/browser_accessibility_mac.h"
 
 void DumpAccessibilityTreeHelper::Initialize() {}
 
 string16 DumpAccessibilityTreeHelper::ToString(BrowserAccessibility* node,
                                                char* prefix) {
   BrowserAccessibilityCocoa* cocoa_node = node->toBrowserAccessibilityCocoa();
   NSString* dump =
-      [NSString stringWithFormat:@"%s%@ subrole=%@ title='%@' value='%@'\n",
+      [NSString stringWithFormat:@"%s%@ "
+                                  "subrole=%@ "
+                                  "roleDescription='%@' "
+                                  "title='%@' "
+                                  "value='%@'\n",
        prefix,
        [cocoa_node role],
        [cocoa_node subrole],
+       [cocoa_node roleDescription],
        [cocoa_node title],
        [cocoa_node value]];
   std::string tempVal = [dump cStringUsingEncoding:NSUTF8StringEncoding];
 
   return UTF8ToUTF16(tempVal);
 }
 
 const FilePath::StringType DumpAccessibilityTreeHelper::GetActualFileSuffix()
     const {
   return FILE_PATH_LITERAL("-actual-mac.txt");
 }
 
 const FilePath::StringType DumpAccessibilityTreeHelper::GetExpectedFileSuffix()
     const {
   return FILE_PATH_LITERAL("-expected-mac.txt");
 }