Add a build flag to configure bundling of HSTS preload list

net/http/transport_security_state_source.h

Index: net/http/transport_security_state_source.h
diff --git a/net/http/transport_security_state_source.h b/net/http/transport_security_state_source.h
index 206746d04bad4d331748605bf7b680881ffd404b..2c065db11843904afca0f1adb5738a50985a08be 100644
--- a/net/http/transport_security_state_source.h
+++ b/net/http/transport_security_state_source.h
@@ -5,8 +5,16 @@
 #ifndef NET_HTTP_TRANSPORT_SECURITY_STATE_SOURCE_H_
 #define NET_HTTP_TRANSPORT_SECURITY_STATE_SOURCE_H_
 
+#include <stddef.h>
+#include <stdint.h>
+
+#include "net/base/net_export.h"
+
 namespace net {
 
+// kNoReportURI is a placeholder for when a pinset does not have a report URI.
+NET_EXPORT_PRIVATE extern const char kNoReportURI[];
+
 struct TransportSecurityStateSource {
   struct Pinset {
     const char* const* const accepted_pins;