[Sync] Replace typedef with using.

components/sync/engine_impl/attachments/attachment_uploader_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 COMPONENTS_SYNC_ENGINE_IMPL_ATTACHMENTS_ATTACHMENT_UPLOADER_IMPL_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_ATTACHMENTS_ATTACHMENT_UPLOADER_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 63 matching lines @@
   // downloads.
   static void ConfigureURLFetcherCommon(
       net::URLFetcher* fetcher,
       const std::string& auth_token,
       const std::string& raw_store_birthday,
       ModelType model_type,
       net::URLRequestContextGetter* request_context_getter);
 
  private:
   class UploadState;
-  typedef std::string UniqueId;
-  typedef std::unordered_map<UniqueId, std::unique_ptr<UploadState>> StateMap;
+  using UniqueId = std::string;
+  using StateMap = std::unordered_map<UniqueId, std::unique_ptr<UploadState>>;
 
   void OnUploadStateStopped(const UniqueId& unique_id);
 
   GURL sync_service_url_;
   scoped_refptr<net::URLRequestContextGetter> url_request_context_getter_;
   std::string account_id_;
   OAuth2TokenService::ScopeSet scopes_;
   scoped_refptr<OAuth2TokenServiceRequest::TokenServiceProvider>
       token_service_provider_;
   std::string raw_store_birthday_;
   StateMap state_map_;
   ModelType model_type_;
 
   // Must be last data member.
   base::WeakPtrFactory<AttachmentUploaderImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AttachmentUploaderImpl);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_ATTACHMENTS_ATTACHMENT_UPLOADER_IMPL_H_