Update app list search box menu when Users changes

ui/app_list/views/search_box_view.cc

 // Copyright (c) 2012 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/views/search_box_view.h"
 
 #include <algorithm>
 
 #include "grit/ui_resources.h"
 #include "ui/app_list/app_list_model.h"
@@ skipping 54 matching lines @@
   AddChildView(menu_button_);
 #endif
 
   search_box_->RemoveBorder();
   search_box_->SetFont(rb.GetFont(ui::ResourceBundle::MediumFont));
   search_box_->set_placeholder_text_color(kHintTextColor);
   search_box_->SetController(this);
   AddChildView(search_box_);
 
   model_->search_box()->AddObserver(this);
+  view_delegate_->AddObserver(this);
+
   IconChanged();
   SpeechRecognitionButtonPropChanged();
   HintTextChanged();
 }
 
 SearchBoxView::~SearchBoxView() {
   model_->search_box()->RemoveObserver(this);
+  view_delegate_->RemoveObserver(this);
 }
 
 bool SearchBoxView::HasSearch() const {
   return !search_box_->text().empty();
 }
 
 void SearchBoxView::ClearSearch() {
   search_box_->SetText(base::string16());
   // Updates model and fires query changed manually because SetText() above
   // does not generate ContentsChanged() notification.
@@ skipping 142 matching lines @@
 
 void SearchBoxView::SelectionModelChanged() {
   search_box_->SelectSelectionModel(model_->search_box()->selection_model());
 }
 
 void SearchBoxView::TextChanged() {
   search_box_->SetText(model_->search_box()->text());
   NotifyQueryChanged();
 }
 
+void SearchBoxView::OnUsersChanged() {
+  InvalidateMenu();
+}
+
 }  // namespace app_list