Protect AppListItemList Add/Remove and fix sync bugs

ash/shell/app_list.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 <string>
 
 #include "ash/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell/example_factory.h"
 #include "ash/shell/toplevel_window.h"
@@ skipping 180 matching lines @@
  private:
   WindowTypeLauncherItem::Type type_;
 
   DISALLOW_COPY_AND_ASSIGN(ExampleSearchResult);
 };
 
 class ExampleAppListViewDelegate : public app_list::AppListViewDelegate {
  public:
   ExampleAppListViewDelegate()
       : model_(new app_list::AppListModel) {
-    PopulateApps(model_->item_list());
+    PopulateApps();
     DecorateSearchBox(model_->search_box());
   }
 
  private:
-  void PopulateApps(app_list::AppListItemList* item_list) {
+  void PopulateApps() {
     for (int i = 0;
          i < static_cast<int>(WindowTypeLauncherItem::LAST_TYPE);
          ++i) {
       WindowTypeLauncherItem::Type type =
           static_cast<WindowTypeLauncherItem::Type>(i);
       std::string id = base::StringPrintf("%d", i);
-      item_list->AddItem(new WindowTypeLauncherItem(id, type));
+      model_->AddItem(new WindowTypeLauncherItem(id, type));
     }
   }
 
   gfx::ImageSkia CreateSearchBoxIcon() {
     const base::string16 icon_text = base::ASCIIToUTF16("ash");
     const gfx::Size icon_size(32, 32);
 
     gfx::Canvas canvas(icon_size, 1.0f, false /* is_opaque */);
     canvas.DrawStringInt(icon_text,
                          gfx::Font(),
@@ skipping 142 matching lines @@
 };
 
 }  // namespace
 
 app_list::AppListViewDelegate* CreateAppListViewDelegate() {
   return new ExampleAppListViewDelegate;
 }
 
 }  // namespace shell
 }  // namespace ash