Make PassphraseType a "enum class" instead of "enum".

components/sync/engine/sync_status.cc

 // Copyright (c) 2012 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 "components/sync/engine/sync_status.h"
 
 namespace syncer {
 
 SyncStatus::SyncStatus()
     : notifications_enabled(false),
       notifications_received(0),
       encryption_conflicts(0),
       hierarchy_conflicts(0),
       server_conflicts(0),
       committed_count(0),
       syncing(false),
       updates_received(0),
       reflected_updates_received(0),
       tombstone_updates_received(0),
       num_commits_total(0),
       num_local_overwrites_total(0),
       num_server_overwrites_total(0),
       nudge_source_notification(0),
       nudge_source_local(0),
       nudge_source_local_refresh(0),
       cryptographer_ready(false),
       crypto_has_pending_keys(false),
       has_keystore_key(false),
-      passphrase_type(IMPLICIT_PASSPHRASE),
+      passphrase_type(PassphraseType::IMPLICIT_PASSPHRASE),
       num_entries_by_type(MODEL_TYPE_COUNT, 0),
       num_to_delete_entries_by_type(MODEL_TYPE_COUNT, 0) {}
 
 SyncStatus::SyncStatus(const SyncStatus& other) = default;
 
 SyncStatus::~SyncStatus() {}
 
 }  // namespace syncer