[SPDY] Do not advertise SPDY/2 by default

net/http/http_stream_factory.h

Index: net/http/http_stream_factory.h
diff --git a/net/http/http_stream_factory.h b/net/http/http_stream_factory.h
index 2a58206cf2a3b481b775f5e168b773955303b30b..2e83b103bcbd490b79fa09a6df9b991c386f3a54 100644
--- a/net/http/http_stream_factory.h
+++ b/net/http/http_stream_factory.h
@@ -265,25 +265,24 @@ class NET_EXPORT HttpStreamFactory {
   // Sets http/1.1 as the only protocol supported via NPN or Alternate-Protocol.
   static void EnableNpnHttpOnly();
 
-  // Sets http/1.1, quic and spdy/2 (the default spdy protocol) as the protocols
-  // supported via NPN or Alternate-Protocol.
-  static void EnableNpnSpdy();
-
-  // Sets http/1.1, quic, spdy/2, and spdy/3 as the protocols supported via NPN
-  // or Alternate-Protocol.
+  // Sets http/1.1, quic, and spdy/3 as the protocols supported via
+  // NPN or Alternate-Protocol.
   static void EnableNpnSpdy3();
 
-  // Sets http/1.1, quic, spdy/2, spdy/3, and spdy/3.1 as the protocols
+  // Sets http/1.1, quic, spdy/3, and spdy/3.1 as the protocols
   // supported via NPN or Alternate-Protocol.
   static void EnableNpnSpdy31();
 
-  // Sets http/1.1, quic, spdy/2, spdy/3, spdy/3.1, and spdy/4a2 as
-  // the protocols supported via NPN or Alternate-Protocol.
+  // Sets http/1.1, quic, spdy/2, spdy/3, and spdy/3.1 as the
+  // protocols supported via NPN or Alternate-Protocol.
+  static void EnableNpnSpdy31WithSpdy2();
+
+  // Sets http/1.1, quic, spdy/3, spdy/3.1, and spdy/4a2 as the
+  // protocols supported via NPN or Alternate-Protocol.
   static void EnableNpnSpdy4a2();
 
-  // Sets http/1.1, quic, spdy/2, spdy/3, spdy/3.1, spdy/4a2, and
-  // http/2 draft 04 as the protocols supported via NPN or
-  // Alternate-Protocol.
+  // Sets http/1.1, quic, spdy/3, spdy/3.1, spdy/4a2, and http/2 draft
+  // 04 as the protocols supported via NPN or Alternate-Protocol.
   static void EnableNpnHttp2Draft04();
 
   // Sets the protocols supported by NPN (next protocol negotiation) during the