[Sync] Reimplement proto value conversions on top of field visitors.

components/sync/driver/about_sync_util.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/driver/about_sync_util.h"
 
 #include <string>
 #include <utility>
 
 #include "base/location.h"
@@ skipping 406 matching lines @@
     keystore_migration_time.SetValue(
         GetTimeStr(full_status.keystore_migration_time, "Not Migrated"));
     passphrase_type.SetValue(
         PassphraseTypeToString(full_status.passphrase_type));
   }
 
   if (snapshot.is_initialized()) {
     if (snapshot.legacy_updates_source() !=
         sync_pb::GetUpdatesCallerInfo::UNKNOWN) {
       session_source.SetValue(
-          GetUpdatesSourceString(snapshot.legacy_updates_source()));
+          ProtoEnumToString(snapshot.legacy_updates_source()));
     }
     get_key_result.SetValue(GetSyncerErrorString(
         snapshot.model_neutral_state().last_get_key_result));
     download_result.SetValue(GetSyncerErrorString(
         snapshot.model_neutral_state().last_download_updates_result));
     commit_result.SetValue(
         GetSyncerErrorString(snapshot.model_neutral_state().commit_result));
   }
 
   if (is_status_valid) {
@@ skipping 77 matching lines @@
   }
 
   about_info->Set("type_status", service->GetTypeStatusMap());
 
   return about_info;
 }
 
 }  // namespace sync_ui_util
 
 }  // namespace syncer