Implement Non-Closable Notification

ui/message_center/notification.h

Index: ui/message_center/notification.h
diff --git a/ui/message_center/notification.h b/ui/message_center/notification.h
index 491943d6e07529f1399d54440aef7c64a799d89f..237de3985b292923ca8f3eecf5a11191a268d75d 100644
--- a/ui/message_center/notification.h
+++ b/ui/message_center/notification.h
@@ -53,6 +53,7 @@ class MESSAGE_CENTER_EXPORT RichNotificationData {
   std::vector<ButtonInfo> buttons;
   bool should_make_spoken_feedback_for_popup_updates;
   bool clickable;
+  bool closable;
   std::vector<int> vibration_pattern;
   bool silent;
 };
@@ -206,6 +207,9 @@ class MESSAGE_CENTER_EXPORT Notification {
     optional_fields_.clickable = clickable;
   }
 
+  bool closable() const { return optional_fields_.closable; }
+  void set_closable(bool closable) { optional_fields_.closable = closable; }
+
   NotificationDelegate* delegate() const { return delegate_.get(); }
 
   const RichNotificationData& rich_notification_data() const {