Modal window in user session not blocks user adding screen.

chrome/browser/ui/ash/session_state_delegate_views.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/ash/session_state_delegate_views.h"
 
 #include "base/logging.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/gfx/image/image_skia.h"
@@ skipping 28 matching lines @@
 bool SessionStateDelegate::IsScreenLocked() const {
   return false;
 }
 
 void SessionStateDelegate::LockScreen() {
 }
 
 void SessionStateDelegate::UnlockScreen() {
 }
 
+bool SessionStateDelegate::IsUserSessionBlocked() const {
+  return false;
+}
+
 const base::string16 SessionStateDelegate::GetUserDisplayName(
     ash::MultiProfileIndex index) const {
   NOTIMPLEMENTED();
   return UTF8ToUTF16("");
 }
 
 const std::string SessionStateDelegate::GetUserEmail(
     ash::MultiProfileIndex index) const {
   NOTIMPLEMENTED();
   return "";
@@ skipping 16 matching lines @@
 
 void SessionStateDelegate::AddSessionStateObserver(
     ash::SessionStateObserver* observer) {
   NOTIMPLEMENTED();
 }
 
 void SessionStateDelegate::RemoveSessionStateObserver(
     ash::SessionStateObserver* observer) {
   NOTIMPLEMENTED();
 }