QBONE bonnet: Print the QBONE region on /statusz.

Protected by n/a, statusz handler only.

PiperOrigin-RevId: 448986574

quiche/quic/qbone/bonnet/mock_qbone_tunnel.h

diff --git a/quiche/quic/qbone/bonnet/mock_qbone_tunnel.h b/quiche/quic/qbone/bonnet/mock_qbone_tunnel.h
index 207ae29..409bc47 100644
--- a/quiche/quic/qbone/bonnet/mock_qbone_tunnel.h
+++ b/quiche/quic/qbone/bonnet/mock_qbone_tunnel.h
@@ -36,6 +36,8 @@
   MOCK_METHOD(State, state, ());
 
   MOCK_METHOD(std::string, HealthString, ());
+
+  MOCK_METHOD(std::string, ServerRegionString, ());
 };
 
 }  // namespace quic

quiche/quic/qbone/bonnet/qbone_tunnel_interface.h

diff --git a/quiche/quic/qbone/bonnet/qbone_tunnel_interface.h b/quiche/quic/qbone/bonnet/qbone_tunnel_interface.h
index deb3b37..c4bd7b4 100644
--- a/quiche/quic/qbone/bonnet/qbone_tunnel_interface.h
+++ b/quiche/quic/qbone/bonnet/qbone_tunnel_interface.h
@@ -61,6 +61,8 @@
   virtual State state() = 0;
 
   virtual std::string HealthString() = 0;
+
+  virtual std::string ServerRegionString() = 0;
 };
 
 }  // namespace quic