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

chrome/browser/chromeos/login/easy_unlock/easy_unlock_remove_keys_operation.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_remove_keys_operation.h"
 
 #include "base/bind.h"
 #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 {
 
 EasyUnlockRemoveKeysOperation::EasyUnlockRemoveKeysOperation(
     const UserContext& user_context,
     size_t start_index,
     const RemoveKeysCallback& callback)
     : user_context_(user_context),
       callback_(callback),
@@ skipping 20 matching lines @@
 
 void EasyUnlockRemoveKeysOperation::OnGetSystemSalt(
     const std::string& system_salt) {
   user_context_.GetKey()->Transform(Key::KEY_TYPE_SALTED_SHA256_TOP_HALF,
                                     system_salt);
   RemoveKey();
 }
 
 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());
 
   // TODO(xiyuan): Use ListKeyEx and delete by label instead of by index.
   cryptohome::HomedirMethods::GetInstance()->RemoveKeyEx(
       id,
       auth,
       EasyUnlockKeyManager::GetKeyLabel(key_index_),
       base::Bind(&EasyUnlockRemoveKeysOperation::OnKeyRemoved,
                  weak_ptr_factory_.GetWeakPtr()));
@@ skipping 13 matching lines @@
   if (return_code == cryptohome::MOUNT_ERROR_KEY_FAILURE) {
     callback_.Run(true);
   } else {
     LOG(ERROR) << "Easy unlock remove keys operation failed, code="
                << return_code;
     callback_.Run(false);
   }
 }
 
 }  // namespace chromeos