diff -up chromium-78.0.3904.70/net/quic/platform/impl/quic_default_proof_providers_impl.cc.vtable-symbol-undefined chromium-78.0.3904.70/net/quic/platform/impl/quic_default_proof_providers_impl.cc
--- chromium-78.0.3904.70/net/quic/platform/impl/quic_default_proof_providers_impl.cc.vtable-symbol-undefined	2019-10-23 09:12:08.754351798 -0400
+++ chromium-78.0.3904.70/net/quic/platform/impl/quic_default_proof_providers_impl.cc	2019-10-23 09:19:28.278431430 -0400
@@ -18,6 +18,7 @@
 #include "net/quic/crypto/proof_verifier_chromium.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_flags.h"
 #include "net/third_party/quiche/src/quic/platform/api/quic_ptr_util.h"
+#include "net/quic/platform/impl/quic_flags_impl.cc"
 
 DEFINE_QUIC_COMMAND_LINE_FLAG(
     bool,