Make CUS interface more resilient by returning a copy of the data

chrome/browser/component_updater/crx_update_item.h

 // 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.
 
 #ifndef CHROME_BROWSER_COMPONENT_UPDATER_CRX_UPDATE_ITEM_H_
 #define CHROME_BROWSER_COMPONENT_UPDATER_CRX_UPDATE_ITEM_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 37 matching lines @@
 //     |          |                 |                  |           |
 //     |          |   error         V                  |           |
 //     |          +---------<- kUpdatingDiff ->--------|-----------+ success
 //     |                                               |           |
 //     |              error                            V           |
 //     +----------------------------------------- kDownloading     |
 //     |                                               |           |
 //     |              error                            V           |
 //     +------------------------------------------ kUpdating ->----+ success
 //
-struct CrxUpdateItem {
+struct CrxUpdateItem : public base::SupportsWeakPtr<CrxUpdateItem> {
   enum Status {
     kNew,
     kChecking,
     kCanUpdate,
     kDownloadingDiff,
     kDownloading,
     kUpdatingDiff,
     kUpdating,
     kUpdated,
     kUpToDate,
@@ skipping 49 matching lines @@
   // Function object used to find a specific component.
   class FindById {
    public:
     explicit FindById(const std::string& id) : id_(id) {}
 
     bool operator()(CrxUpdateItem* item) const { return item->id == id_; }
 
    private:
     const std::string& id_;
   };
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CrxUpdateItem);
 };
 
 }  // namespace component_updater
 
 #endif  // CHROME_BROWSER_COMPONENT_UPDATER_CRX_UPDATE_ITEM_H_