Protect AppListItemList Add/Remove and fix sync bugs

ui/app_list/app_list_item.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_item.h"
 
 #include "base/logging.h"
 #include "ui/app_list/app_list_item_observer.h"
 
 namespace app_list {
@@ skipping 70 matching lines @@
   return app_type;
 }
 
 ui::MenuModel* AppListItem::GetContextMenuModel() {
   return NULL;
 }
 
 bool AppListItem::CompareForTest(const AppListItem* other) const {
   return id_ == other->id_ &&
       title_ == other->title_ &&
+      GetItemType() == other->GetItemType() &&
       position_.Equals(other->position_);
 }
 
 std::string AppListItem::ToDebugString() const {
   return id_.substr(0, 8) + " '" + title_ + "'"
       + " [" + position_.ToDebugString() + "]";
 }
 
 }  // namespace app_list