Show number of hidden items in new-style list notification.

ui/message_center/message_center_style.h

Index: ui/message_center/message_center_style.h
diff --git a/ui/message_center/message_center_style.h b/ui/message_center/message_center_style.h
index 289903d35d2b5744d3224bdb9a6ff4983c33166e..3eee4aee016e35c053c987f43f1cc33cc5e57a5b 100644
--- a/ui/message_center/message_center_style.h
+++ b/ui/message_center/message_center_style.h
@@ -108,7 +108,9 @@ MESSAGE_CENTER_EXPORT gfx::Size GetImageSizeForContainerSize(
     const gfx::Size& container_size,
     const gfx::Size& image_size);
 
-const size_t kNotificationMaximumItems = 5;     // For list notifications.
+// For list notifications.
+// Not used when --enabled-new-style-notification is set.
+const size_t kNotificationMaximumItems = 5;
 
 // Timing.
 const int kAutocloseDefaultDelaySeconds = 8;