Add roleDescription to DumpAccessibilityTree for mac.

content/browser/accessibility/dump_accessibility_tree_helper_mac.mm

Index: content/browser/accessibility/dump_accessibility_tree_helper_mac.mm
diff --git a/content/browser/accessibility/dump_accessibility_tree_helper_mac.mm b/content/browser/accessibility/dump_accessibility_tree_helper_mac.mm
index 6105adc55f7e9dee5e95ddb8d58e43b8ba9bac4f..50c40cdf9b14144a3ab40c4c97c722726a0ebfc2 100644
--- a/content/browser/accessibility/dump_accessibility_tree_helper_mac.mm
+++ b/content/browser/accessibility/dump_accessibility_tree_helper_mac.mm
@@ -17,10 +17,15 @@ 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];