Finish implementation and tests of 5 ARIA 1.1 attributes.

content/browser/accessibility/browser_accessibility_cocoa.mm

Index: content/browser/accessibility/browser_accessibility_cocoa.mm
diff --git a/content/browser/accessibility/browser_accessibility_cocoa.mm b/content/browser/accessibility/browser_accessibility_cocoa.mm
index 9b1017d4519e1d5ed90ea6854a9bb09d3d0b2d96..868319e645e37f82dd076f0360eec35172865d23 100644
--- a/content/browser/accessibility/browser_accessibility_cocoa.mm
+++ b/content/browser/accessibility/browser_accessibility_cocoa.mm
@@ -1337,6 +1337,13 @@ NSString* const NSAccessibilityRequiredAttribute = @"AXRequired";
 - (NSString*)roleDescription {
   if (![self instanceActive])
     return nil;
+
+  if (browserAccessibility_->HasStringAttribute(
+      ui::AX_ATTR_ROLE_DESCRIPTION)) {
+    return NSStringForStringAttribute(
+        browserAccessibility_, ui::AX_ATTR_ROLE_DESCRIPTION);
+  }
+
   NSString* role = [self role];
 
   ContentClient* content_client = content::GetContentClient();