[cros,de-hack] Get rid of singleton for the WebUILoginScreen.

chrome/browser/chromeos/login/existing_user_controller.cc

Index: chrome/browser/chromeos/login/existing_user_controller.cc
diff --git a/chrome/browser/chromeos/login/existing_user_controller.cc b/chrome/browser/chromeos/login/existing_user_controller.cc
index 94c724b9ef34183fa31d5b777cd7b830306fb2d5..84630bfb4c6b32b4e780327c083b8376d60abed7 100644
--- a/chrome/browser/chromeos/login/existing_user_controller.cc
+++ b/chrome/browser/chromeos/login/existing_user_controller.cc
@@ -80,6 +80,7 @@ ExistingUserController* ExistingUserController::current_controller_ = NULL;
 ExistingUserController::ExistingUserController(LoginDisplayHost* host)
     : login_status_consumer_(NULL),
       host_(host),
+      login_display_(host_->CreateLoginDisplay(this)),
       num_login_attempts_(0),
       user_settings_(new UserCrosSettingsProvider),
       weak_factory_(this),
@@ -87,8 +88,6 @@ ExistingUserController::ExistingUserController(LoginDisplayHost* host)
   DCHECK(current_controller_ == NULL);
   current_controller_ = this;
 
-  login_display_ = host_->CreateLoginDisplay(this);
-
   registrar_.Add(this,
                  chrome::NOTIFICATION_LOGIN_USER_IMAGE_CHANGED,
                  content::NotificationService::AllSources());
@@ -144,9 +143,7 @@ ExistingUserController::~ExistingUserController() {
   } else {
     NOTREACHED() << "More than one controller are alive.";
   }
-  DCHECK(login_display_ != NULL);
-  login_display_->Destroy();
-  login_display_ = NULL;
+  DCHECK(login_display_.get());
 }
 
 ////////////////////////////////////////////////////////////////////////////////