Move message_center::CustomNotificationView to arc::ArcNotificationView

ui/message_center/notification_delegate_views.cc

Index: ui/message_center/notification_delegate_views.cc
diff --git a/ui/message_center/notification_delegate_views.cc b/ui/message_center/notification_delegate_views.cc
index 1d12a307f0813d5bdc52c49ea854d01987af809f..6f1bc726b1e27f7ff1c68126171e2413f6654727 100644
--- a/ui/message_center/notification_delegate_views.cc
+++ b/ui/message_center/notification_delegate_views.cc
@@ -4,11 +4,13 @@
 
 #include "ui/message_center/notification_delegate.h"
 
-#include "ui/views/view.h"
+#include "ui/message_center/views/message_view.h"
 
 namespace message_center {
 
-std::unique_ptr<CustomContent> NotificationDelegate::CreateCustomContent() {
+std::unique_ptr<MessageView> NotificationDelegate::CreateCustomMessageView(
+    MessageCenterController* controller,
+    const Notification& notification) {
   return nullptr;
 }