Add GetDebugState() in SendAlgorithmInterface().

net/quic/core/congestion_control/pacing_sender.cc

Index: net/quic/core/congestion_control/pacing_sender.cc
diff --git a/net/quic/core/congestion_control/pacing_sender.cc b/net/quic/core/congestion_control/pacing_sender.cc
index 1d6394726e0052167c13cadf890471a30f032db5..a292103f4024711743812ef85f857a7bba0b60af 100644
--- a/net/quic/core/congestion_control/pacing_sender.cc
+++ b/net/quic/core/congestion_control/pacing_sender.cc
@@ -4,6 +4,8 @@
 
 #include "net/quic/core/congestion_control/pacing_sender.h"
 
+#include <string>
+
 #include "net/quic/core/quic_flags.h"
 
 using std::min;
@@ -208,4 +210,8 @@ CongestionControlType PacingSender::GetCongestionControlType() const {
   return sender_->GetCongestionControlType();
 }
 
+std::string PacingSender::GetDebugState() const {
+  return sender_->GetDebugState();
+}
+
 }  // namespace net