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

net/quic/quic_headers_stream.h

Index: net/quic/quic_headers_stream.h
diff --git a/net/quic/quic_headers_stream.h b/net/quic/quic_headers_stream.h
index 95066b66aa80bd4b388962747eaa0ad3f8e299c1..7a97c9efdee211540666016c0e6f8e3e5953423a 100644
--- a/net/quic/quic_headers_stream.h
+++ b/net/quic/quic_headers_stream.h
@@ -37,9 +37,13 @@ class NET_EXPORT_PRIVATE QuicHeadersStream : public ReliableQuicStream {
   uint32 ProcessRawData(const char* data, uint32 data_len) override;
   QuicPriority EffectivePriority() const override;
 
+  void OnSuccessfulVersionNegotiation(QuicVersion version);
+
  private:
   class SpdyFramerVisitor;
 
+  void InitializeFramer(QuicVersion version);
+
   // The following methods are called by the SimpleVisitor.
 
   // Called when a SYN_STREAM frame has been received.
@@ -71,7 +75,7 @@ class NET_EXPORT_PRIVATE QuicHeadersStream : public ReliableQuicStream {
   bool fin_;
   size_t frame_len_;
 
-  SpdyFramer spdy_framer_;
+  scoped_ptr<SpdyFramer> spdy_framer_;
   scoped_ptr<SpdyFramerVisitor> spdy_framer_visitor_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicHeadersStream);