[Chrome OS MD] Draw a 1px separator between 2 tray items

ash/common/system/web_notification/web_notification_tray.h

Index: ash/common/system/web_notification/web_notification_tray.h
diff --git a/ash/common/system/web_notification/web_notification_tray.h b/ash/common/system/web_notification/web_notification_tray.h
index 6938498016b13a470ac9069fa7106f7aa32b32c9..f303b53d2cc7578dd37c6a67a217176ab80f0359 100644
--- a/ash/common/system/web_notification/web_notification_tray.h
+++ b/ash/common/system/web_notification/web_notification_tray.h
@@ -42,6 +42,7 @@ class MessagePopupCollection;
 namespace ash {
 class AshPopupAlignmentDelegate;
 class SystemTray;
+class ViewObserver;
 class WebNotificationBubbleWrapper;
 class WebNotificationButton;
 class WmWindow;
@@ -56,7 +57,8 @@ class ASH_EXPORT WebNotificationTray
  public:
   WebNotificationTray(WmShelf* shelf,
                       WmWindow* status_area_window,
-                      SystemTray* system_tray);
+                      SystemTray* system_tray,
+                      ViewObserver* view_observer);
   ~WebNotificationTray() override;
 
   // Sets the height of the system tray bubble (or legacy notification bubble)