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

ash/common/system/web_notification/web_notification_tray.cc

Index: ash/common/system/web_notification/web_notification_tray.cc
diff --git a/ash/common/system/web_notification/web_notification_tray.cc b/ash/common/system/web_notification/web_notification_tray.cc
index feba9fffdf06e91fba9d42e6d2c0e151a1782607..299479afc26ecd3d31df829d14ccc9f05ba1480c 100644
--- a/ash/common/system/web_notification/web_notification_tray.cc
+++ b/ash/common/system/web_notification/web_notification_tray.cc
@@ -9,6 +9,7 @@
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
+#include "ash/common/shelf/wm_shelf_observer.h"
 #include "ash/common/shelf/wm_shelf_util.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/system/tray/system_tray.h"
@@ -205,8 +206,9 @@ class WebNotificationButton : public views::CustomButton {
 
 WebNotificationTray::WebNotificationTray(WmShelf* shelf,
                                          WmWindow* status_area_window,
-                                         SystemTray* system_tray)
-    : TrayBackgroundView(shelf),
+                                         SystemTray* system_tray,
+                                         WmShelfObserver* wm_shelf_observer)
+    : TrayBackgroundView(shelf, wm_shelf_observer),
       status_area_window_(status_area_window),
       system_tray_(system_tray),
       button_(nullptr),
@@ -222,7 +224,6 @@ WebNotificationTray::WebNotificationTray(WmShelf* shelf,
   tray_container()->AddChildView(button_);
   button_->SetFocusBehavior(FocusBehavior::NEVER);
   SetContentsBackground();
-  tray_container()->SetBorder(views::Border::NullBorder());
   message_center_tray_.reset(new message_center::MessageCenterTray(
       this, message_center::MessageCenter::Get()));
   popup_alignment_delegate_.reset(new AshPopupAlignmentDelegate(shelf));
@@ -234,6 +235,7 @@ WebNotificationTray::WebNotificationTray(WmShelf* shelf,
   popup_alignment_delegate_->StartObserving(display::Screen::GetScreen(),
                                             display);
   OnMessageCenterTrayChanged();
+  SetSeparatorVisibility(true);
 }
 
 WebNotificationTray::~WebNotificationTray() {
@@ -349,7 +351,6 @@ void WebNotificationTray::SetShelfAlignment(ShelfAlignment alignment) {
   if (alignment == shelf_alignment())
     return;
   TrayBackgroundView::SetShelfAlignment(alignment);
-  tray_container()->SetBorder(views::Border::NullBorder());
   // Destroy any existing bubble so that it will be rebuilt correctly.
   message_center_tray_->HideMessageCenterBubble();
   message_center_tray_->HidePopupBubble();