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

components/sync/engine/events/configure_get_updates_request_event.cc

Index: components/sync/engine/events/configure_get_updates_request_event.cc
diff --git a/components/sync/engine/events/configure_get_updates_request_event.cc b/components/sync/engine/events/configure_get_updates_request_event.cc
index 5ff5c83b5ee375aeae2cc3102a7b7c3fa66c19d7..a709c0235488dbe9087819001b0f13df494d58f1 100644
--- a/components/sync/engine/events/configure_get_updates_request_event.cc
+++ b/components/sync/engine/events/configure_get_updates_request_event.cc
@@ -27,7 +27,7 @@ std::string ConfigureGetUpdatesRequestEvent::GetType() const {
 }
 
 std::string ConfigureGetUpdatesRequestEvent::GetDetails() const {
-  return base::StringPrintf("Reason: %s", GetUpdatesOriginString(origin_));
+  return base::StringPrintf("Reason: %s", ProtoEnumToString(origin_));
 }
 
 std::unique_ptr<base::DictionaryValue>