Removed unused ScreenObserver::OnSetUsernamePassword() method.

chrome/browser/chromeos/login/wizard_controller.cc

Index: chrome/browser/chromeos/login/wizard_controller.cc
diff --git a/chrome/browser/chromeos/login/wizard_controller.cc b/chrome/browser/chromeos/login/wizard_controller.cc
index 5ed4fcc116093219aeea0a8688c242b3e2adaa34..8945f3ce79639a6ec7b0f30d6be9384df67ab38e 100644
--- a/chrome/browser/chromeos/login/wizard_controller.cc
+++ b/chrome/browser/chromeos/login/wizard_controller.cc
@@ -1019,12 +1019,6 @@ void WizardController::OnExit(ExitCodes exit_code) {
   }
 }
 
-void WizardController::OnSetUserNamePassword(const std::string& username,
-                                             const std::string& password) {
-  username_ = username;
-  password_ = password;
-}
-
 void WizardController::ShowErrorScreen() {
   VLOG(1) << "Showing error screen.";
   SetCurrentScreen(GetScreen(kErrorScreenName));