Make //crypto factories return std::unique_ptr<>s

chrome/browser/chromeos/settings/token_encryptor.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_CHROMEOS_SETTINGS_TOKEN_ENCRYPTOR_H_
 #define CHROME_BROWSER_CHROMEOS_SETTINGS_TOKEN_ENCRYPTOR_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 29 matching lines @@
   explicit CryptohomeTokenEncryptor(const std::string& system_salt);
   ~CryptohomeTokenEncryptor() override;
 
   // TokenEncryptor overrides:
   std::string EncryptWithSystemSalt(const std::string& token) override;
   std::string DecryptWithSystemSalt(
       const std::string& encrypted_token_hex) override;
 
  private:
   // Converts |passphrase| to a SymmetricKey using the given |salt|.
-  crypto::SymmetricKey* PassphraseToKey(const std::string& passphrase,
-                                        const std::string& salt);
+  std::unique_ptr<crypto::SymmetricKey> PassphraseToKey(
+      const std::string& passphrase,
+      const std::string& salt);
 
   // Encrypts (AES) the token given |key| and |salt|.
   std::string EncryptTokenWithKey(crypto::SymmetricKey* key,
                                   const std::string& salt,
                                   const std::string& token);
 
   // Decrypts (AES) hex encoded encrypted token given |key| and |salt|.
   std::string DecryptTokenWithKey(crypto::SymmetricKey* key,
                                   const std::string& salt,
                                   const std::string& encrypted_token_hex);
 
   // The cached system salt passed to the constructor, originally coming
   // from cryptohome daemon.
   std::string system_salt_;
 
   // A key based on the system salt.  Useful for encrypting device-level
   // data for which we have no additional credentials.
   std::unique_ptr<crypto::SymmetricKey> system_salt_key_;
 
   DISALLOW_COPY_AND_ASSIGN(CryptohomeTokenEncryptor);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_SETTINGS_TOKEN_ENCRYPTOR_H_