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

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

Index: chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
index b79b766c58b54ac0e20bb39f7f071ed3694b0c35..a42c5c82b42c10b5b03cd0ab743717c9fb2d27e6 100644
--- a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
@@ -38,6 +38,7 @@
 #include "chrome/browser/chromeos/login/error_screens_histogram_helper.h"
 #include "chrome/browser/chromeos/login/hwid_checker.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/quick_unlock/pin_storage.h"
 #include "chrome/browser/chromeos/login/quick_unlock/pin_storage_factory.h"
 #include "chrome/browser/chromeos/login/reauth_stats.h"
@@ -1231,8 +1232,9 @@ void SigninScreenHandler::HandleAccountPickerReady() {
 
 void SigninScreenHandler::HandleWallpaperReady() {
   if (ScreenLocker::default_screen_locker()) {
-    ScreenLocker::default_screen_locker()->delegate()->
-        OnLockBackgroundDisplayed();
+    ScreenLocker::default_screen_locker()
+        ->web_ui()
+        ->OnLockBackgroundDisplayed();
   }
 }
 
@@ -1450,10 +1452,6 @@ void SigninScreenHandler::CancelPasswordChangedFlowInternal() {
   }
 }
 
-OobeUI* SigninScreenHandler::GetOobeUI() const {
-  return static_cast<OobeUI*>(web_ui()->GetController());
-}
-
 bool SigninScreenHandler::IsGaiaVisible() const {
   return IsSigninScreen(GetCurrentScreen()) &&
       ui_state_ == UI_STATE_GAIA_SIGNIN;