Simplify QUIC's encryption path now that FEC is gone. Protected by FLAG_quic_inplace_encryption.

net/quic/quic_protocol.cc

Index: net/quic/quic_protocol.cc
diff --git a/net/quic/quic_protocol.cc b/net/quic/quic_protocol.cc
index 60bd559a5a1d52d412041cfe08991b6db1b6ca44..438090ed6505801348087807a4f9f769a6bb0900 100644
--- a/net/quic/quic_protocol.cc
+++ b/net/quic/quic_protocol.cc
@@ -35,6 +35,10 @@ size_t GetPacketHeaderSize(QuicConnectionIdLength connection_id_length,
          kPrivateFlagsSize;
 }
 
+size_t GetStartOfEncryptedData(const QuicPacketHeader& header) {
+  return GetPacketHeaderSize(header) - kPrivateFlagsSize;
+}
+
 size_t GetStartOfEncryptedData(QuicConnectionIdLength connection_id_length,
                                bool include_version,
                                bool include_path_id,