Adds QUIC_VERSION_24 which uses SPDY/4 header compression instead of SPDY/3.

net/quic/quic_protocol.h

Index: net/quic/quic_protocol.h
diff --git a/net/quic/quic_protocol.h b/net/quic/quic_protocol.h
index 9e74023f813044850b7fc19d276acf5710692320..cdf45c9144e0d4cb4ae6a8570480eed1d7892c5a 100644
--- a/net/quic/quic_protocol.h
+++ b/net/quic/quic_protocol.h
@@ -312,6 +312,7 @@ enum QuicVersion {
 
   QUIC_VERSION_22 = 22,  // Send Server Config Update messages on crypto stream.
   QUIC_VERSION_23 = 23,  // Timestamp in the ack frame.
+  QUIC_VERSION_24 = 24,  // SPDY/4 header compression.
 };
 
 // This vector contains QUIC versions which we currently support.
@@ -321,7 +322,8 @@ enum QuicVersion {
 //
 // IMPORTANT: if you are adding to this list, follow the instructions at
 // http://sites/quic/adding-and-removing-versions
-static const QuicVersion kSupportedQuicVersions[] = {QUIC_VERSION_23,
+static const QuicVersion kSupportedQuicVersions[] = {QUIC_VERSION_24,
+                                                     QUIC_VERSION_23,
                                                      QUIC_VERSION_22};
 
 typedef std::vector<QuicVersion> QuicVersionVector;