SPDY: Use SpdyMajorVersion rather than ints for SPDY version number.

net/spdy/spdy_protocol.h

Index: net/spdy/spdy_protocol.h
diff --git a/net/spdy/spdy_protocol.h b/net/spdy/spdy_protocol.h
index 4f84ee9321d8cdc6d5d4fbd323897d15d5ebcbf4..236836a84b4f0ebf9b63a9b8187e6179d3ceb695 100644
--- a/net/spdy/spdy_protocol.h
+++ b/net/spdy/spdy_protocol.h
@@ -28,14 +28,15 @@ namespace net {
 
 // The major versions of SPDY. Major version differences indicate
 // framer-layer incompatibility, as opposed to minor version numbers
-// which indicate application-layer incompatibility. It is guaranteed
-// that the enum value SPDYn maps to the integer n.
+// which indicate application-layer incompatibility. Do not rely on
+// the mapping from enum value SPDYn to the integer n.
 enum SpdyMajorVersion {
   SPDY2 = 2,
   SPDY_MIN_VERSION = SPDY2,
   SPDY3 = 3,
   SPDY4 = 4,
-  SPDY_MAX_VERSION = SPDY4
+  SPDY5 = 5,
+  SPDY_MAX_VERSION = SPDY5
 };
 
 // A SPDY stream id is a 31 bit entity.
@@ -490,6 +491,12 @@ class NET_EXPORT_PRIVATE SpdyConstants {
   static size_t GetPrefixLength(SpdyFrameType type, SpdyMajorVersion version);
 
   static size_t GetFrameMaximumSize(SpdyMajorVersion version);
+
+  static SpdyMajorVersion ParseMajorVersion(int version_number);
+
+  static int SerializeMajorVersion(SpdyMajorVersion version);
+
+  static std::string GetVersionString(SpdyMajorVersion version);
 };
 
 class SpdyFrame;