Add functionality to explicitly set SNI in the QUIC test client

net/tools/quic/test_tools/quic_test_client.h

Index: net/tools/quic/test_tools/quic_test_client.h
diff --git a/net/tools/quic/test_tools/quic_test_client.h b/net/tools/quic/test_tools/quic_test_client.h
index a25a842d5cb1d5d1040149ace721009930feb4ab..b76d1cfce204ded52e609cd540194aecef020b2a 100644
--- a/net/tools/quic/test_tools/quic_test_client.h
+++ b/net/tools/quic/test_tools/quic_test_client.h
@@ -202,6 +202,13 @@ class QuicTestClient : public test::SimpleClient,
 
   size_t num_responses() const { return num_responses_; }
 
+  // Explicitly set the SNI value for this client, overriding the default
+  // behavior which extracts the SNI value from the request URL.
+  void OverrideSni(const std::string& sni) {
+    override_sni_set_ = true;
+    override_sni_ = sni;
+  }
+
  protected:
   QuicTestClient();
 
@@ -274,6 +281,11 @@ class QuicTestClient : public test::SimpleClient,
   size_t num_requests_;
   size_t num_responses_;
 
+  // If set, this value is used for the connection SNI, overriding the usual
+  // logic which extracts the SNI from the request URL.
+  bool override_sni_set_ = false;
+  std::string override_sni_;
+
   DISALLOW_COPY_AND_ASSIGN(QuicTestClient);
 };