Clean up LoginUIService. Remove Singleton behavior from PeopleHandler

chrome/browser/ui/webui/signin/login_ui_service.cc

Index: chrome/browser/ui/webui/signin/login_ui_service.cc
diff --git a/chrome/browser/ui/webui/signin/login_ui_service.cc b/chrome/browser/ui/webui/signin/login_ui_service.cc
index 042f6c72309d17ff903ff0f99d14a0c6de0ab2d7..1ebe33b2c9e6e1102a5417b3157b6209936979a8 100644
--- a/chrome/browser/ui/webui/signin/login_ui_service.cc
+++ b/chrome/browser/ui/webui/signin/login_ui_service.cc
@@ -17,7 +17,7 @@
 #include "components/signin/core/common/profile_management_switches.h"
 
 LoginUIService::LoginUIService(Profile* profile)
-    : ui_(NULL), profile_(profile) {
+    : profile_(profile) {
 }
 
 LoginUIService::~LoginUIService() {}
@@ -30,18 +30,17 @@ void LoginUIService::RemoveObserver(LoginUIService::Observer* observer) {
   observer_list_.RemoveObserver(observer);
 }
 
+LoginUIService::LoginUI* LoginUIService::current_login_ui() const {
+  return ui_list_.empty() ? nullptr : ui_list_.front();
+}
+
 void LoginUIService::SetLoginUI(LoginUI* ui) {
-  DCHECK(!current_login_ui() || current_login_ui() == ui);
-  ui_ = ui;
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnLoginUIShown(ui_));
+  ui_list_.remove(ui);
+  ui_list_.push_front(ui);
 }
 
 void LoginUIService::LoginUIClosed(LoginUI* ui) {
-  if (current_login_ui() != ui)
-    return;
-
-  ui_ = NULL;
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnLoginUIClosed(ui));
+  ui_list_.remove(ui);
 }
 
 void LoginUIService::SyncConfirmationUIClosed(
@@ -52,10 +51,6 @@ void LoginUIService::SyncConfirmationUIClosed(
       OnSyncConfirmationUIClosed(result));
 }
 
-void LoginUIService::UntrustedLoginUIShown() {
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnUntrustedLoginUIShown());
-}
-
 void LoginUIService::ShowLoginPopup() {
 #if defined(OS_CHROMEOS)
   NOTREACHED();