Tray elements behave appropriately on the multiple signin screen (more like lock screen)

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 14e1f9144cdffef725d80b85ce2509ac741efe46..0060a8cf0467becc97800624c3c09bedecde465b 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -400,6 +400,10 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
     return session_state_delegate_.get();
   }
 
+  // For testing only: set specific SessionStateDelegate
+  void SetSessionStateDelegateForTesting(
+      SessionStateDelegate* session_state_delegate);
+
   AccessibilityDelegate* accessibility_delegate() {
     return accessibility_delegate_.get();
   }