Mac a11y: Add RoleDescription and Value attributes to accessibility information.

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 1ae72bd2e30ef11ee400240645b91215f5f4c5e0..0dc20aab568ce3e2ce43ebfb96c4c7997641487c 100644
--- a/content/browser/accessibility/browser_accessibility_cocoa.mm
+++ b/content/browser/accessibility/browser_accessibility_cocoa.mm
@@ -1573,14 +1573,14 @@ bool InitializeAccessibilityTreeSearch(
   ui::AXRole browserAccessibilityRole = [self internalRole];
   if (browserAccessibilityRole == ui::AX_ROLE_TEXT_FIELD &&
       GetState(browserAccessibility_, ui::AX_STATE_PROTECTED)) {
-    return @"AXSecureTextField";
+    return NSAccessibilitySecureTextFieldSubrole;
   }
 
   if (browserAccessibilityRole == ui::AX_ROLE_DESCRIPTION_LIST)
-    return @"AXDefinitionList";
+    return NSAccessibilityDefinitionListSubrole;
 
   if (browserAccessibilityRole == ui::AX_ROLE_LIST)
-    return @"AXContentList";
+    return NSAccessibilityContentListSubrole;
 
   return [AXPlatformNodeCocoa nativeSubroleFromAXRole:browserAccessibilityRole];
 }