Transfer responsibility for providing a close button for a notification to each implementation of M…

ui/message_center/notification_delegate.h

Index: ui/message_center/notification_delegate.h
diff --git a/ui/message_center/notification_delegate.h b/ui/message_center/notification_delegate.h
index a493c18e252eb43b99572acf3347be67e88dce3e..a35c478821a12a177a9b264f1d29c5bae500e314 100644
--- a/ui/message_center/notification_delegate.h
+++ b/ui/message_center/notification_delegate.h
@@ -7,6 +7,7 @@
 
 #include <memory>
 #include <string>
+#include <tuple>
 
 #include "base/callback.h"
 #include "base/macros.h"
@@ -15,6 +16,10 @@
 #include "ui/message_center/message_center_export.h"
 
 #if defined(TOOLKIT_VIEWS) && !defined(OS_MACOSX)
+#include "ui/message_center/views/custom_notification_content_view_delegate.h"
+#endif
+
+#if defined(TOOLKIT_VIEWS) && !defined(OS_MACOSX)
 namespace views {
 class View;
 }
@@ -59,7 +64,10 @@ class MESSAGE_CENTER_EXPORT NotificationDelegate
 #if defined(TOOLKIT_VIEWS) && !defined(OS_MACOSX)
   // To be called to construct the contents view of a popup for notifications
   // whose type is NOTIFICATION_TYPE_CUSTOM.
-  virtual std::unique_ptr<views::View> CreateCustomContent();
+  virtual std::tuple<
+      std::unique_ptr<views::View>,
+      std::unique_ptr<message_center::CustomNotificationContentViewDelegate>>
+  CreateCustomContent();
 #endif
 
   // Indicates whether this notification should be displayed when there is