Remove some linked_ptr c/b/extension

chrome/browser/extensions/api/storage/sync_storage_backend.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_API_STORAGE_SYNC_STORAGE_BACKEND_H_
 #define CHROME_BROWSER_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_
 
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
-#include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "components/sync/model/syncable_service.h"
 #include "extensions/browser/api/storage/settings_observer.h"
 #include "extensions/browser/api/storage/settings_storage_quota_enforcer.h"
 #include "extensions/browser/value_store/value_store_factory.h"
 
 namespace syncer {
 class SyncErrorFactory;
 }
 
@@ skipping 53 matching lines @@
   const scoped_refptr<ValueStoreFactory> storage_factory_;
 
   // Quota limits (see SettingsStorageQuotaEnforcer).
   const SettingsStorageQuotaEnforcer::Limits quota_;
 
   // The list of observers to settings changes.
   const scoped_refptr<SettingsObserverList> observers_;
 
   // A cache of ValueStore objects that have already been created.
   // Ensure that there is only ever one created per extension.
-  typedef std::map<std::string, linked_ptr<SyncableSettingsStorage> >
-      StorageObjMap;
+  using StorageObjMap =
+      std::map<std::string, std::unique_ptr<SyncableSettingsStorage>>;
   mutable StorageObjMap storage_objs_;
 
   // Current sync model type. Either EXTENSION_SETTINGS or APP_SETTINGS.
   syncer::ModelType sync_type_;
 
   // Current sync processor, if any.
   std::unique_ptr<syncer::SyncChangeProcessor> sync_processor_;
 
   // Current sync error handler if any.
   std::unique_ptr<syncer::SyncErrorFactory> sync_error_factory_;
 
   syncer::SyncableService::StartSyncFlare flare_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncStorageBackend);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_