Add a missing QUICHE_EXPORT_PRIVATE to spdy_protocol.h
PiperOrigin-RevId: 441833368
diff --git a/quiche/spdy/core/spdy_protocol.h b/quiche/spdy/core/spdy_protocol.h
index 7f462a5..2368f9c 100644
--- a/quiche/spdy/core/spdy_protocol.h
+++ b/quiche/spdy/core/spdy_protocol.h
@@ -279,7 +279,7 @@
// Serialize RST_STREAM or GOAWAY frame error code to string
// for logging/debugging.
-const char* ErrorCodeToString(SpdyErrorCode error_code);
+QUICHE_EXPORT_PRIVATE const char* ErrorCodeToString(SpdyErrorCode error_code);
// Serialize |type| to string for logging/debugging.
QUICHE_EXPORT_PRIVATE const char* WriteSchedulerTypeToString(