[Win] Unbreak the user manager tuturial that I broke in r259326.

chrome/browser/profiles/profile_window.cc

Index: chrome/browser/profiles/profile_window.cc
diff --git a/chrome/browser/profiles/profile_window.cc b/chrome/browser/profiles/profile_window.cc
index a3ac27a70f610762a51ad61f7ef7e50c3f69eb7f..f6ed167e2bff00de546b70efa87ad85b2a933baa 100644
--- a/chrome/browser/profiles/profile_window.cc
+++ b/chrome/browser/profiles/profile_window.cc
@@ -271,7 +271,8 @@ void CreateGuestProfileForUserManager(
 }
 
 void ShowUserManagerMaybeWithTutorial(Profile* profile) {
-  if (!profile) {
+  // Guest users cannot appear in the User Manager, nor display a tutorial.
+  if (!profile || profile->IsGuestSession()) {
     chrome::ShowUserManager(base::FilePath());
     return;
   }