Allow embedder to use custom cryptography in Autofill table.

components/autofill/core/browser/webdata/system_encryptor.h

+// Copyright (c) 2017 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_AUTOFILL_CORE_BROWSER_WEBDATA_SYSTEM_ENCRYPTOR_H_
+#define COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_SYSTEM_ENCRYPTOR_H_
+
+#include "components/autofill/core/browser/webdata/autofill_table_encryptor.h"
+
+namespace autofill {
+// Default encryptor used in Autofill table.
+class SystemEncryptor : public AutofillTableEncryptor {
+ public:
+  bool EncryptString16(const base::string16& plaintext,
+                       std::string* ciphertext) const override;
+
+  bool DecryptString16(const std::string& ciphertext,
+                       base::string16* plaintext) const override;
+};
+
+}  // namespace autofill
+
+#endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_WEBDATA_SYSTEM_ENCRYPTOR_H_