Rename the aura_shell namespace to ash

ash/app_list/app_list_model.cc

 // Copyright (c) 2011 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 "ash/app_list/app_list_model.h"
 
-namespace aura_shell {
+namespace ash {
 
 AppListModel::AppListModel() {
 }
 
 AppListModel::~AppListModel() {
 }
 
 void AppListModel::AddGroup(AppListItemGroupModel* group) {
   groups_.Add(group);
 }
 
 AppListItemGroupModel* AppListModel::GetGroup(int index) {
   DCHECK(index >= 0 && index < group_count());
   return groups_.item_at(index);
 }
 
 void AppListModel::AddObserver(ui::ListModelObserver* observer) {
   groups_.AddObserver(observer);
 }
 
 void AppListModel::RemoveObserver(ui::ListModelObserver* observer) {
   groups_.RemoveObserver(observer);
 }
 
-}  // namespace aura_shell
+}  // namespace ash