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

components/browser_sync/browser/profile_sync_service.cc

Index: components/browser_sync/browser/profile_sync_service.cc
diff --git a/components/browser_sync/browser/profile_sync_service.cc b/components/browser_sync/browser/profile_sync_service.cc
index de2967759da13acf4d8862d9d13fac1583130f68..ee3c25a206b44c3969da263a72133f2a1728a6a4 100644
--- a/components/browser_sync/browser/profile_sync_service.cc
+++ b/components/browser_sync/browser/profile_sync_service.cc
@@ -1731,8 +1731,9 @@ syncer::ModelTypeSet ProfileSyncService::GetRegisteredDataTypes() const {
 
 bool ProfileSyncService::IsUsingSecondaryPassphrase() const {
   syncer::PassphraseType passphrase_type = GetPassphraseType();
-  return passphrase_type == syncer::FROZEN_IMPLICIT_PASSPHRASE ||
-         passphrase_type == syncer::CUSTOM_PASSPHRASE;
+  return passphrase_type ==
+             syncer::PassphraseType::FROZEN_IMPLICIT_PASSPHRASE ||
+         passphrase_type == syncer::PassphraseType::CUSTOM_PASSPHRASE;
 }
 
 std::string ProfileSyncService::GetCustomPassphraseKey() const {