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 76faffec2e4899b1dd29a01a82c27c3f72d8d1a0..cb4a81aa046a405aaf0b85dc5a8d481ce49b9335 100644
--- a/chrome/browser/ui/webui/signin/login_ui_service.cc
+++ b/chrome/browser/ui/webui/signin/login_ui_service.cc
@@ -33,18 +33,17 @@ 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(
@@ -55,10 +54,6 @@ void LoginUIService::SyncConfirmationUIClosed(
       OnSyncConfirmationUIClosed(result));
 }
 
-void LoginUIService::UntrustedLoginUIShown() {
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnUntrustedLoginUIShown());
-}
-
 void LoginUIService::ShowLoginPopup() {
 #if defined(OS_CHROMEOS)
   NOTREACHED();