Create Login UI for Demo User.

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h

Index: chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h
diff --git a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h
index 4f589db78171c70a9b0036133bcf4eed0fd229ad..271f9354b6e81b6873a92468f3886447ad573f36 100644
--- a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h
+++ b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h
@@ -63,6 +63,9 @@ class SigninScreenHandlerDelegate {
   virtual void Login(const std::string& username,
                      const std::string& password) = 0;
 
+  // Sign in into a demo user session.
+  virtual void LoginAsDemoUser() = 0;
+
   // Sign in into Guest session.
   virtual void LoginAsGuest() = 0;
 
@@ -183,6 +186,9 @@ class SigninScreenHandler : public BaseScreenHandler,
   // Handles authentication request when signing in an existing user.
   void HandleAuthenticateUser(const base::ListValue* args);
 
+  // Handles entering as the demo user.
+  void HandleLaunchDemoUser(const base::ListValue* args);
+
   // Handles entering bwsi mode request.
   void HandleLaunchIncognito(const base::ListValue* args);