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

chromeos/tpm/tpm_token_info_getter.cc

Index: chromeos/tpm/tpm_token_info_getter.cc
diff --git a/chromeos/tpm/tpm_token_info_getter.cc b/chromeos/tpm/tpm_token_info_getter.cc
index 6f6dfe7b3b1fb3eb767422a8836cc780678b8bb3..a06cd454c23cb7e96ca9cdca268523edc220e4e5 100644
--- a/chromeos/tpm/tpm_token_info_getter.cc
+++ b/chromeos/tpm/tpm_token_info_getter.cc
@@ -41,7 +41,7 @@ TPMTokenInfo::~TPMTokenInfo() {}
 
 // static
 scoped_ptr<TPMTokenInfoGetter> TPMTokenInfoGetter::CreateForUserToken(
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     CryptohomeClient* cryptohome_client,
     const scoped_refptr<base::TaskRunner>& delayed_task_runner) {
   CHECK(!user_id.empty());
@@ -56,7 +56,7 @@ scoped_ptr<TPMTokenInfoGetter> TPMTokenInfoGetter::CreateForSystemToken(
     const scoped_refptr<base::TaskRunner>& delayed_task_runner) {
   return scoped_ptr<TPMTokenInfoGetter>(
       new TPMTokenInfoGetter(
-          TYPE_SYSTEM, std::string(), cryptohome_client, delayed_task_runner));
+          TYPE_SYSTEM, user_manager::UserID(std::string(), std::string()), cryptohome_client, delayed_task_runner));
 }
 
 TPMTokenInfoGetter::~TPMTokenInfoGetter() {}
@@ -73,7 +73,7 @@ void TPMTokenInfoGetter::Start(const TPMTokenInfoCallback& callback) {
 
 TPMTokenInfoGetter::TPMTokenInfoGetter(
     TPMTokenInfoGetter::Type type,
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     CryptohomeClient* cryptohome_client,
     const scoped_refptr<base::TaskRunner>& delayed_task_runner)
     : delayed_task_runner_(delayed_task_runner),