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

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

Index: chrome/browser/chromeos/login/easy_unlock/easy_unlock_remove_keys_operation.cc
diff --git a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_remove_keys_operation.cc b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_remove_keys_operation.cc
index 795db23dbe99b2dfe0f4d76490e508801c6d47d8..1a75bb3db28cde4a41c3a3efc927486902401114 100644
--- a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_remove_keys_operation.cc
+++ b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_remove_keys_operation.cc
@@ -8,6 +8,7 @@
 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h"
 #include "chromeos/cryptohome/homedir_methods.h"
 #include "chromeos/cryptohome/system_salt_getter.h"
+#include "components/user_manager/user_id.h"
 #include "google_apis/gaia/gaia_auth_util.h"
 
 namespace chromeos {
@@ -48,8 +49,8 @@ void EasyUnlockRemoveKeysOperation::OnGetSystemSalt(
 
 void EasyUnlockRemoveKeysOperation::RemoveKey() {
   std::string canonicalized =
-      gaia::CanonicalizeEmail(user_context_.GetUserID());
-  cryptohome::Identification id(canonicalized);
+      gaia::CanonicalizeEmail(user_context_.GetUserID().GetUserEmail());
+  cryptohome::Identification id(user_manager::UserID(std::string() /* gaia_id */, canonicalized));

[Denis Kuznetsov (DE-MUC), 2015/06/10 16:50:45]

FromUserEmail()

   const Key* const auth_key = user_context_.GetKey();
   cryptohome::Authorization auth(auth_key->GetSecret(), auth_key->GetLabel());