Move message_center::CustomNotificationView to arc::ArcNotificationView

ui/arc/notification/arc_notification_delegate.h

Index: ui/arc/notification/arc_notification_delegate.h
diff --git a/ui/arc/notification/arc_notification_delegate.h b/ui/arc/notification/arc_notification_delegate.h
index 787010b2d49c7fc7f6ca07b07697e89c41d1baaf..c27f6807e6774079def09e428099ce3371c5e7ed 100644
--- a/ui/arc/notification/arc_notification_delegate.h
+++ b/ui/arc/notification/arc_notification_delegate.h
@@ -9,6 +9,14 @@
 #include "base/memory/weak_ptr.h"
 #include "ui/message_center/notification_delegate.h"
 
+namespace message_center {
+
+class MessageCenterController;
+class MessageView;
+class Notification;
+
+}  // namespace message_center
+
 namespace arc {
 
 class ArcNotificationItem;
@@ -21,7 +29,9 @@ class ArcNotificationDelegate : public message_center::NotificationDelegate {
   explicit ArcNotificationDelegate(base::WeakPtr<ArcNotificationItem> item);
 
   // message_center::NotificationDelegate overrides:
-  std::unique_ptr<message_center::CustomContent> CreateCustomContent() override;
+  std::unique_ptr<message_center::MessageView> CreateCustomMessageView(
+      message_center::MessageCenterController* controller,
+      const message_center::Notification& notification) override;
   void Close(bool by_user) override;
   void Click() override;