arc: Make ChromeVox read an ARC custom notification

ui/message_center/notification.cc

Index: ui/message_center/notification.cc
diff --git a/ui/message_center/notification.cc b/ui/message_center/notification.cc
index 2b248a006b435d256c9fe1e34f3a5240c80aaa3a..eed61df1763ac3ad02139abe877161366210f468 100644
--- a/ui/message_center/notification.cc
+++ b/ui/message_center/notification.cc
@@ -58,7 +58,8 @@ RichNotificationData::RichNotificationData(const RichNotificationData& other)
 #endif  // defined(OS_CHROMEOS)
       vibration_pattern(other.vibration_pattern),
       renotify(other.renotify),
-      silent(other.silent) {}
+      silent(other.silent),
+      accessible_name(other.accessible_name) {}
 
 RichNotificationData::~RichNotificationData() {}