Add a basic demo mode browser test.

chrome/browser/chromeos/login/parallel_authenticator.h

Index: chrome/browser/chromeos/login/parallel_authenticator.h
diff --git a/chrome/browser/chromeos/login/parallel_authenticator.h b/chrome/browser/chromeos/login/parallel_authenticator.h
index 8ea765a59372a76e1ef6a656d20e3f4ffb95c599..d6c25e2829c8d62e510a754703391209f4fb43e7 100644
--- a/chrome/browser/chromeos/login/parallel_authenticator.h
+++ b/chrome/browser/chromeos/login/parallel_authenticator.h
@@ -132,10 +132,12 @@ class ParallelAuthenticator : public Authenticator,
   virtual void LoginAsPublicAccount(const std::string& username) OVERRIDE;
 
   // Initiates login into the kiosk mode account identified by |app_user_id|.
-  // Mounts an public but non-ephemeral cryptohome and notifies consumer on the
-  // success/failure.
-  virtual void LoginAsKioskAccount(
-      const std::string& app_user_id, bool force_ephemeral) OVERRIDE;
+  // Mounts an public and notifies consumer on the success/failure. If

[bartfab (slow), 2014/03/20 13:22:29]

"Mounts an public" is missing a few words :).

[rkc, 2014/03/20 21:45:01]

Done.

+  // |force_guest| is true, instead we mount a guest mount (which is

[bartfab (slow), 2014/03/20 13:22:29]

"If [...], instead we [...], otherwise the mount [...]." is both grammatically
wrong (change of subject mid-sentence) and very hard to follow. Why not say
something like:

If |force_ephemeral| is true, the mount is always ephemeral. Otherwise, the
mount is ephemeral iff the |DeviceEphemeralUsersEnabled| policy is enabled.

[rkc, 2014/03/20 21:45:01]

Changed the comment around to make it clearer.

+  // ephemeral), otherwise the mount is non-ephemeral (unless specified
+  // by enterprise policy that it should be ephemeral).
+  virtual void LoginAsKioskAccount(const std::string& app_user_id,
+                                   bool force_guest) OVERRIDE;
 
   // These methods must be called on the UI thread, as they make DBus calls
   // and also call back to the login UI.