Moves QuicTag typedefs, and QuicTag utility methods to quic_tag.{h,cc}. 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 7ebff6b3436a400e4dc2064b02e17422df9171b2..74a6d3d52335b15d1d054840a3d8a8f9e12f8c57 100644
--- a/net/quic/core/quic_protocol.h
+++ b/net/quic/core/quic_protocol.h
@@ -49,14 +49,6 @@ class QuicAckListenerInterface;
 // stored in memory as a little endian uint32_t, we need
 // to reverse the order of the bytes.
 
-// MakeQuicTag returns a value given the four bytes. For example:
-//   MakeQuicTag('C', 'H', 'L', 'O');
-NET_EXPORT_PRIVATE QuicTag MakeQuicTag(char a, char b, char c, char d);
-
-// Returns true if the tag vector contains the specified tag.
-NET_EXPORT_PRIVATE bool ContainsQuicTag(const QuicTagVector& tag_vector,
-                                        QuicTag tag);
-
 // Size in bytes of the data packet header.
 NET_EXPORT_PRIVATE size_t GetPacketHeaderSize(QuicVersion version,
                                               const QuicPacketHeader& header);