Add SessionStateObserver with ActiveUserChanged()

chrome/browser/ui/ash/session_state_delegate_chromeos.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.h"
 
 #include "base/logging.h"
 #include "chrome/browser/chromeos/login/screen_locker.h"
+#include "chrome/browser/chromeos/login/user.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/session_manager_client.h"
 
 SessionStateDelegate::SessionStateDelegate() {
+  chromeos::UserManager::Get()->AddSessionStateObserver(this);
 }
 
 SessionStateDelegate::~SessionStateDelegate() {
 }
 
 int SessionStateDelegate::GetMaximumNumberOfLoggedInUsers() const {
   return 3;
 }
 
 int SessionStateDelegate::NumberOfLoggedInUsers() const {
@@ skipping 55 matching lines @@
   for (chromeos::UserList::const_iterator it = logged_in_users.begin();
        it != logged_in_users.end(); ++it) {
     const chromeos::User* user = (*it);
     users->push_back(user->email());
   }
 }
 
 void SessionStateDelegate::SwitchActiveUser(const std::string& email) {
   chromeos::UserManager::Get()->SwitchActiveUser(email);
 }
+
+void SessionStateDelegate::AddSessionStateObserver(
+    ash::SessionStateObserver* observer) {
+  session_state_observer_list_.AddObserver(observer);
+}
+
+void SessionStateDelegate::RemoveSessionStateObserver(
+    ash::SessionStateObserver* observer) {
+  session_state_observer_list_.RemoveObserver(observer);
+}
+
+void SessionStateDelegate::ActiveUserChanged(
+    const chromeos::User* active_user) {
+  FOR_EACH_OBSERVER(ash::SessionStateObserver,
+                    session_state_observer_list_,
+                    ActiveUserChanged(active_user->email()));
+}