Adds CryptoHandshakeMessage::HasStringPiece method.

net/quic/core/crypto/crypto_handshake_message_test.cc

Index: net/quic/core/crypto/crypto_handshake_message_test.cc
diff --git a/net/quic/core/crypto/crypto_handshake_message_test.cc b/net/quic/core/crypto/crypto_handshake_message_test.cc
index 65b064b14e49630a473aa09be494d1ea9f338e64..7032a23969d67991c5bdbdbcaf09c8e0b7fe758c 100644
--- a/net/quic/core/crypto/crypto_handshake_message_test.cc
+++ b/net/quic/core/crypto/crypto_handshake_message_test.cc
@@ -117,6 +117,13 @@ TEST(CryptoHandshakeMessageTest, ServerDesignatedConnectionId) {
   EXPECT_EQ(str, message5.DebugString());
 }
 
+TEST(CryptoHandshakeMessageTest, HasStringPiece) {
+  CryptoHandshakeMessage message;
+  EXPECT_FALSE(message.HasStringPiece(kRCID));
+  message.SetStringPiece(kRCID, "foo");
+  EXPECT_TRUE(message.HasStringPiece(kRCID));
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace net