Add a basic demo mode browser test.

chrome/browser/chromeos/login/authenticator.h

Index: chrome/browser/chromeos/login/authenticator.h
diff --git a/chrome/browser/chromeos/login/authenticator.h b/chrome/browser/chromeos/login/authenticator.h
index 079fb61e09ce76ee2b36b2a9650cbdce14000564..b1d38df31d932a56902a75436764af18cf2ec422 100644
--- a/chrome/browser/chromeos/login/authenticator.h
+++ b/chrome/browser/chromeos/login/authenticator.h
@@ -58,9 +58,10 @@ class Authenticator : public base::RefCountedThreadSafe<Authenticator> {
 
   // Initiates login into kiosk mode account identified by |app_user_id|.
   // The |app_user_id| is a generated username for the account.
-  // |force_ephemeral| specifies whether to force the session to be ephemeral.
-  virtual void LoginAsKioskAccount(
-      const std::string& app_user_id, bool force_ephemeral) = 0;
+  // |use_guest_mount| specifies whether to force the session to use a
+  // guest mount. If this is false, we use mount a public cryptohome.
+  virtual void LoginAsKioskAccount(const std::string& app_user_id,
+                                   bool use_guest_mount) = 0;
 
   // Completes retail mode login.
   virtual void OnRetailModeLoginSuccess() = 0;