[EasyUnlock] Serialize and store BeaconSeeds along as cryptohome key metadata.

chrome/browser/chromeos/login/easy_unlock/easy_unlock_types.cc

 // 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.
 
 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_types.h"
 
 namespace chromeos {
 
 const char kEasyUnlockKeyMetaNameBluetoothAddress[] = "eu.btaddr";
 const char kEasyUnlockKeyMetaNameBluetoothType[] = "eu.bttype";
 const char kEasyUnlockKeyMetaNamePsk[] = "eu.psk";
 const char kEasyUnlockKeyMetaNamePubKey[] = "eu.pubkey";
 const char kEasyUnlockKeyMetaNameChallenge[] = "eu.C";
 const char kEasyUnlockKeyMetaNameWrappedSecret[] = "eu.WUK";
+const char kEasyUnlockKeyMetaNameSerializedBeaconSeeds[] = "eu.BS";
 
 EasyUnlockDeviceKeyData::EasyUnlockDeviceKeyData()
     : bluetooth_type(BLUETOOTH_CLASSIC) {}
 
 EasyUnlockDeviceKeyData::EasyUnlockDeviceKeyData(
     const EasyUnlockDeviceKeyData& other) = default;
 
 EasyUnlockDeviceKeyData::~EasyUnlockDeviceKeyData() {
 }
 
 }  // namespace chromeos