cros: Cleanup lock screen and OOBE C++ backing code.

chrome/browser/chromeos/login/signin_screen_controller.cc

Index: chrome/browser/chromeos/login/signin_screen_controller.cc
diff --git a/chrome/browser/chromeos/login/signin_screen_controller.cc b/chrome/browser/chromeos/login/signin_screen_controller.cc
index 2ecc0ae983d7570c485203a8aa917211d456c283..9e62ba38258b0dff379f5310bce50e9761f872df 100644
--- a/chrome/browser/chromeos/login/signin_screen_controller.cc
+++ b/chrome/browser/chromeos/login/signin_screen_controller.cc
@@ -6,6 +6,7 @@
 
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/login/lock/screen_locker.h"
+#include "chrome/browser/chromeos/login/lock/webui_screen_locker.h"
 #include "chrome/browser/chromeos/login/screens/chrome_user_selection_screen.h"
 #include "chrome/browser/chromeos/login/ui/views/user_board_view.h"
 #include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
@@ -23,7 +24,7 @@ SignInScreenController::SignInScreenController(
   instance_ = this;
 
   gaia_screen_->SetScreenHandler(oobe_ui_->GetGaiaScreenActor());
-  std::string display_type = static_cast<OobeUI*>(oobe_ui)->display_type();
+  std::string display_type = oobe_ui->display_type();
   user_selection_screen_.reset(new ChromeUserSelectionScreen(display_type));
   user_selection_screen_->SetLoginDisplayDelegate(login_display_delegate);
 
@@ -51,9 +52,8 @@ void SignInScreenController::Init(const user_manager::UserList& users,
 void SignInScreenController::OnSigninScreenReady() {
   gaia_screen_->MaybePreloadAuthExtension();
   user_selection_screen_->InitEasyUnlock();
-  if (ScreenLocker::default_screen_locker()) {
-    ScreenLocker::default_screen_locker()->delegate()->OnLockWebUIReady();
-  }
+  if (ScreenLocker::default_screen_locker())
+    ScreenLocker::default_screen_locker()->web_ui()->OnLockWebUIReady();
 }
 
 void SignInScreenController::RemoveUser(const AccountId& account_id) {