Delete out of date comment, and unused forward declaration. No behavior change.

net/quic/core/quic_protocol.h

Index: net/quic/core/quic_protocol.h
diff --git a/net/quic/core/quic_protocol.h b/net/quic/core/quic_protocol.h
index 89b4c6bc4fb3a5b0786ef5b3f2b070eb1c791e6e..e739747bbcea58839e06d4df115b481078c6ef84 100644
--- a/net/quic/core/quic_protocol.h
+++ b/net/quic/core/quic_protocol.h
@@ -40,14 +40,6 @@ namespace net {
 
 class QuicPacket;
 struct QuicPacketHeader;
-class QuicAckListenerInterface;
-
-// Version and Crypto tags are written to the wire with a big-endian
-// representation of the name of the tag.  For example
-// the client hello tag (CHLO) will be written as the
-// following 4 bytes: 'C' 'H' 'L' 'O'.  Since it is
-// stored in memory as a little endian uint32_t, we need
-// to reverse the order of the bytes.
 
 // Size in bytes of the data packet header.
 NET_EXPORT_PRIVATE size_t GetPacketHeaderSize(QuicVersion version,