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

ui/message_center/views/notification_view_md.h

Index: ui/message_center/views/notification_view_md.h
diff --git a/ui/message_center/views/notification_view_md.h b/ui/message_center/views/notification_view_md.h
index 85a675b4280fa04906a506db94b878ec330deb32..35fdbbab839a45b4392dc4993021203c031e75a8 100644
--- a/ui/message_center/views/notification_view_md.h
+++ b/ui/message_center/views/notification_view_md.h
@@ -28,6 +28,7 @@ class ProportionalImageView;
 
 namespace {
 class CompactTitleMessageView;
+class ItemView;
 }
 
 // View that displays all current types of notification (web, basic, image, and
@@ -104,7 +105,7 @@ class MESSAGE_CENTER_EXPORT NotificationViewMD
   views::View* image_container_ = nullptr;
   ProportionalImageView* image_view_ = nullptr;
   std::vector<views::LabelButton*> action_buttons_;
-  std::vector<views::View*> item_views_;
+  std::vector<ItemView*> item_views_;
   views::ProgressBar* progress_bar_view_ = nullptr;
   CompactTitleMessageView* compact_title_message_view_ = nullptr;