We should use UserID object to identify users instead of username.

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 c1ba482f8700a591071a68b460737137f662102f..cd4da59e8c1bb8335efb6a5aede68d370952f33c 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
@@ -107,7 +107,7 @@ void EasyUnlockKeyManager::GetDeviceDataList(
 
 // static
 void EasyUnlockKeyManager::DeviceDataToRemoteDeviceDictionary(
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     const EasyUnlockDeviceKeyData& data,
     base::DictionaryValue* dict) {
   dict->SetString(kKeyBluetoothAddress, data.bluetooth_address);
@@ -119,7 +119,7 @@ void EasyUnlockKeyManager::DeviceDataToRemoteDeviceDictionary(
   dict->SetString(kKeyPermitType, kPermitTypeLicence);
   dict->SetString(kKeyPermitPermitId,
                   base::StringPrintf(kPermitPermitIdFormat,
-                                     user_id.c_str()));
+                                     user_id.GetUserEmail().c_str()));
 }
 
 // static
@@ -144,7 +144,7 @@ bool EasyUnlockKeyManager::RemoteDeviceDictionaryToDeviceData(
 
 // static
 void EasyUnlockKeyManager::DeviceDataListToRemoteDeviceList(
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     const EasyUnlockDeviceKeyDataList& data_list,
     base::ListValue* device_list) {
   device_list->Clear();