Update app list search box menu when Users changes

ui/app_list/app_list_view_delegate.cc

 // Copyright 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 "ui/app_list/app_list_view_delegate.h"
 
+#include "ui/app_list/app_list_view_delegate_observer.h"
+
 namespace app_list {
 
 AppListViewDelegate::User::User() : active(false) {
 }
 
 AppListViewDelegate::User::~User() {
 }
 
+const AppListViewDelegate::Users& AppListViewDelegate::GetUsers() const {
+  return users_;
+}
+
+void AppListViewDelegate::AddObserver(AppListViewDelegateObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void AppListViewDelegate::RemoveObserver(
+    AppListViewDelegateObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void AppListViewDelegate::NotifyUsersChanged() {
+  FOR_EACH_OBSERVER(AppListViewDelegateObserver,
+                    observers_,
+                    OnUsersChanged());
+}
+
 }  // app_list