Migrate Libsecret for OSCrypt to a new schema

components/os_crypt/key_storage_libsecret.h

 // Copyright 2016 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_OS_CRYPT_KEY_STORAGE_LIBSECRET_H_
 #define COMPONENTS_OS_CRYPT_KEY_STORAGE_LIBSECRET_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "components/os_crypt/key_storage_linux.h"
 
 // Specialisation of KeyStorageLinux that uses Libsecret.
 class KeyStorageLibsecret : public KeyStorageLinux {
  public:
   KeyStorageLibsecret() = default;
   ~KeyStorageLibsecret() override = default;
 
   // KeyStorageLinux
   std::string GetKey() override;
 
  protected:
   // KeyStorageLinux
   bool Init() override;
 
  private:
   std::string AddRandomPasswordInLibsecret();
 
+  // TODO(crbug.com/639298) Older Chromium releases stored passwords with a
+  // problematic schema. Detect password entries with the old schema and migrate
+  // them to the new schema. Returns the migrated password or an empty string if
+  // none we migrated.
+  std::string Migrate();
+
   DISALLOW_COPY_AND_ASSIGN(KeyStorageLibsecret);
 };
 
 #endif  // COMPONENTS_OS_CRYPT_KEY_STORAGE_LIBSECRET_H_