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

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

Index: chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
diff --git a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
index 94a5e8957b10df57231bcdc59fea14c2f896dc16..7ed4f274683fb116474283769a4a8c690e711ae5 100644
--- a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
+++ b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
@@ -29,6 +29,7 @@ const char kKeyPermitPermitId[] = "permitRecord.permitId";
 const char kKeyPermitData[] = "permitRecord.data";
 const char kKeyPermitType[] = "permitRecord.type";
 const char kKeyPsk[] = "psk";
+const char kKeySerializedBeaconSeeds[] = "serializedBeaconSeeds";
 
 const char kKeyLabelPrefix[] = "easy-unlock-";
 
@@ -125,6 +126,7 @@ void EasyUnlockKeyManager::DeviceDataToRemoteDeviceDictionary(
   dict->SetString(kKeyPermitPermitId,
                   base::StringPrintf(kPermitPermitIdFormat,
                                      account_id.GetUserEmail().c_str()));
+  dict->SetString(kKeySerializedBeaconSeeds, data.serialized_beacon_seeds);
 }
 
 // static
@@ -154,6 +156,14 @@ bool EasyUnlockKeyManager::RemoteDeviceDictionaryToDeviceData(
     }
   }
 
+  std::string serialized_beacon_seeds;
+  if (dict.GetString(kKeySerializedBeaconSeeds, &serialized_beacon_seeds)) {
+    data->serialized_beacon_seeds = serialized_beacon_seeds;
+  } else {
+    PA_LOG(ERROR) << "Failed to parse key data: "
+                  << "expected serialized_beacon_seeds.";
+  }
+
   data->bluetooth_address.swap(bluetooth_address);
   data->public_key.swap(public_key);
   data->psk.swap(psk);