Add browser test for new user CrOS login flow

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 2e7c0313c650d0f3aae5a009a1826314dcfec659..ae1bf73e9b1df2a651e933c457525e582f074d97 100644
--- a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h
+++ b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h
@@ -62,6 +62,7 @@ class LoginDisplayWebUIHandler {
   // Show sign-in screen for the given credentials.
   virtual void ShowSigninScreenForCreds(const std::string& username,
                                         const std::string& password) = 0;
+  virtual void SetGaiaOriginForTesting(const std::string& arg) = 0;
  protected:
   virtual ~LoginDisplayWebUIHandler() {}
 };
@@ -248,6 +249,7 @@ class SigninScreenHandler
   virtual void ShowErrorScreen(LoginDisplay::SigninError error_id) OVERRIDE;
   virtual void ShowSigninScreenForCreds(const std::string& username,
                                         const std::string& password) OVERRIDE;
+  virtual void SetGaiaOriginForTesting(const std::string& arg) OVERRIDE;
 
   // BrowsingDataRemover::Observer overrides.
   virtual void OnBrowsingDataRemoverDone() OVERRIDE;
@@ -434,6 +436,9 @@ class SigninScreenHandler
   // NOTIFICATION_AUTH_CANCELLED.
   bool has_pending_auth_ui_;
 
+  // Testing helper, specifies new value for gaia url.
+  std::string gaia_origin_for_test_;
+
   DISALLOW_COPY_AND_ASSIGN(SigninScreenHandler);
 };