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

ash/common/system/chromeos/session/logout_button_tray.cc

Index: ash/common/system/chromeos/session/logout_button_tray.cc
diff --git a/ash/common/system/chromeos/session/logout_button_tray.cc b/ash/common/system/chromeos/session/logout_button_tray.cc
index 68aaef20c08544f2321b85fa197e8219446f551d..002667b159e60fc7d418781b3097fecc9ee0c2ab 100644
--- a/ash/common/system/chromeos/session/logout_button_tray.cc
+++ b/ash/common/system/chromeos/session/logout_button_tray.cc
@@ -9,6 +9,7 @@
 
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/shelf/shelf_types.h"
+#include "ash/common/shelf/wm_shelf_observer.h"
 #include "ash/common/system/chromeos/session/logout_confirmation_controller.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
 #include "ash/common/system/tray/system_tray_notifier.h"
@@ -98,8 +99,9 @@ LogoutButton::LogoutButton(views::ButtonListener* listener)
 
 LogoutButton::~LogoutButton() {}
 
-LogoutButtonTray::LogoutButtonTray(WmShelf* wm_shelf)
-    : TrayBackgroundView(wm_shelf),
+LogoutButtonTray::LogoutButtonTray(WmShelf* wm_shelf,
+                                   WmShelfObserver* wm_shelf_observer)
+    : TrayBackgroundView(wm_shelf, wm_shelf_observer),
       button_(nullptr),
       login_status_(LoginStatus::NOT_LOGGED_IN),
       show_logout_button_in_tray_(false) {
@@ -118,7 +120,6 @@ LogoutButtonTray::LogoutButtonTray(WmShelf* wm_shelf)
     button_ = new LogoutButton(this);
   }
   tray_container()->AddChildView(button_);
-  tray_container()->SetBorder(views::Border::NullBorder());
   WmShell::Get()->system_tray_notifier()->AddLogoutButtonObserver(this);
 }
 
@@ -128,7 +129,6 @@ LogoutButtonTray::~LogoutButtonTray() {
 
 void LogoutButtonTray::SetShelfAlignment(ShelfAlignment alignment) {
   TrayBackgroundView::SetShelfAlignment(alignment);
-  tray_container()->SetBorder(views::Border::NullBorder());
 }
 
 base::string16 LogoutButtonTray::GetAccessibleNameForTray() {