Log the sync communication that happens between client and server.

chrome/browser/sync/protocol/proto_enum_conversions.h

Index: chrome/browser/sync/protocol/proto_enum_conversions.h
diff --git a/chrome/browser/sync/protocol/proto_enum_conversions.h b/chrome/browser/sync/protocol/proto_enum_conversions.h
index 76a912e91f6f2df45e024f1d21964bf7fdcff76f..35789d791eb0deca7990d40d666dca9bba29276e 100644
--- a/chrome/browser/sync/protocol/proto_enum_conversions.h
+++ b/chrome/browser/sync/protocol/proto_enum_conversions.h
@@ -32,6 +32,14 @@ const char* GetPageTransitionQualifierString(
 const char* GetUpdatesSourceString(
     sync_pb::GetUpdatesCallerInfo::GetUpdatesSource updates_source);
 
+const char* GetResponseTypeString(
+    sync_pb::CommitResponse::ResponseType response_type);
+
+const char* GetErrorTypeString(sync_pb::SyncEnums::ErrorType error_type);
+
+const char* GetActionString(
+   sync_pb::ClientToServerResponse::Error::Action action);
+
 const char* GetDeviceTypeString(
     sync_pb::SessionHeader::DeviceType device_type);