[SPDY] Add flag and about:flags entry for SPDY/4 alpha 1

net/spdy/spdy_session.cc

Index: net/spdy/spdy_session.cc
diff --git a/net/spdy/spdy_session.cc b/net/spdy/spdy_session.cc
index fede4ce89f8d21e53dff4dcad45051d6a4336eb3..5e2860651c771bb560d46972d596d564be27e2e6 100644
--- a/net/spdy/spdy_session.cc
+++ b/net/spdy/spdy_session.cc
@@ -53,6 +53,21 @@ const SpdyStreamId kFirstStreamId = 1;
 // Minimum seconds that unclaimed pushed streams will be kept in memory.
 const int kMinPushedStreamLifetimeSeconds = 300;
 
+int NPNToSpdyVersion(NextProto next_proto) {
+  switch (next_proto) {
+    case kProtoSPDY2:
+      return kSpdyVersion2;
+    case kProtoSPDY3:
+    case kProtoSPDY31:
+      return kSpdyVersion3;
+    case kProtoSPDY4a1:
+      return kSpdyVersion4;
+    default:
+      NOTREACHED();
+  }
+  return kSpdyVersion2;
+}
+
 base::Value* NetLogSpdySynCallback(const SpdyHeaderBlock* headers,
                                    bool fin,
                                    bool unidirectional,
@@ -404,10 +419,7 @@ net::Error SpdySession::InitializeWithSocket(
                                             host_port_pair().ToString()));
   }
 
-  DCHECK_GE(protocol, kProtoSPDY2);
-  DCHECK_LE(protocol, kProtoSPDY31);
-  int version = (protocol >= kProtoSPDY3) ? kSpdyVersion3 : kSpdyVersion2;
-  if (protocol >= kProtoSPDY31) {
+  if (protocol >= kProtoSPDY4a1) {
     flow_control_state_ = FLOW_CONTROL_STREAM_AND_SESSION;
     session_send_window_size_ = kSpdySessionInitialWindowSize;
     session_recv_window_size_ = kSpdySessionInitialWindowSize;
@@ -417,8 +429,8 @@ net::Error SpdySession::InitializeWithSocket(
     flow_control_state_ = FLOW_CONTROL_NONE;
   }
 
-  buffered_spdy_framer_.reset(new BufferedSpdyFramer(version,
-                                                     enable_compression_));
+  buffered_spdy_framer_.reset(
+      new BufferedSpdyFramer(NPNToSpdyVersion(protocol), enable_compression_));
   buffered_spdy_framer_->set_visitor(this);
   SendInitialSettings();
   UMA_HISTOGRAM_ENUMERATION("Net.SpdyVersion", protocol, kProtoMaximumVersion);