[Sync] Replace typedef with using.

components/sync/base/cryptographer.h

 // Copyright 2012 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_BASE_CRYPTOGRAPHER_H_
 #define COMPONENTS_SYNC_BASE_CRYPTOGRAPHER_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 167 matching lines @@
 
   // Returns a serialized sync_pb::NigoriKey version of current default
   // encryption key.
   std::string GetDefaultNigoriKeyData() const;
 
   // Generates a new Nigori from |serialized_nigori_key|, and if successful
   // installs the new nigori as the default key.
   bool ImportNigoriKey(const std::string& serialized_nigori_key);
 
  private:
-  typedef std::map<std::string, linked_ptr<const Nigori>> NigoriMap;
+  using NigoriMap = std::map<std::string, linked_ptr<const Nigori>>;
 
   // Helper method to instantiate Nigori instances for each set of key
   // parameters in |bag|.
   // Does not update the default nigori.
   void InstallKeyBag(const sync_pb::NigoriKeyBag& bag);
 
   // Helper method to add a nigori to the keybag, optionally making it the
   // default as well.
   bool AddKeyImpl(std::unique_ptr<Nigori> nigori, bool set_as_default);
 
@@ skipping 10 matching lines @@
   std::string default_nigori_name_;
 
   std::unique_ptr<sync_pb::EncryptedData> pending_keys_;
 
   DISALLOW_ASSIGN(Cryptographer);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_BASE_CRYPTOGRAPHER_H_