Fix dangerous pointer use in UserScriptMaster

chrome/browser/extensions/extension_system_impl.h

 // Copyright 2014 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_EXTENSIONS_EXTENSION_SYSTEM_IMPL_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_SYSTEM_IMPL_H_
 
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/one_shot_event.h"
 
@@ skipping 92 matching lines @@
 
     // The services that are shared between normal and incognito profiles.
 
     scoped_ptr<StateStore> state_store_;
     scoped_ptr<StateStore> rules_store_;
     // LazyBackgroundTaskQueue is a dependency of
     // MessageService and EventRouter.
     scoped_ptr<LazyBackgroundTaskQueue> lazy_background_task_queue_;
     scoped_ptr<EventRouter> event_router_;
     scoped_ptr<NavigationObserver> navigation_observer_;
-    scoped_refptr<UserScriptMaster> user_script_master_;
+    scoped_ptr<UserScriptMaster> user_script_master_;
     scoped_ptr<Blacklist> blacklist_;
     // StandardManagementPolicyProvider depends on Blacklist.
     scoped_ptr<StandardManagementPolicyProvider>
         standard_management_policy_provider_;
     scoped_ptr<RuntimeData> runtime_data_;
     // ExtensionService depends on StateStore, Blacklist and RuntimeData.
     scoped_ptr<ExtensionService> extension_service_;
     scoped_ptr<ManagementPolicy> management_policy_;
     // extension_info_map_ needs to outlive process_manager_.
     scoped_refptr<InfoMap> extension_info_map_;
@@ skipping 23 matching lines @@
   // extension processes and those require access to the ResourceContext owned
   // by |io_data_|.
   scoped_ptr<ProcessManager> process_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionSystemImpl);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SYSTEM_IMPL_H_