Enable SPDY 3.1 and 3.0 in UrlRequestContextBuilder by default

net/socket/next_proto.h

Index: net/socket/next_proto.h
diff --git a/net/socket/next_proto.h b/net/socket/next_proto.h
index 797c6ae863800d95c7860b028a81350fed85cad7..92ffee425c3801c9018e162b3912172ccaacb766 100644
--- a/net/socket/next_proto.h
+++ b/net/socket/next_proto.h
@@ -39,6 +39,10 @@ typedef std::vector<NextProto> NextProtoVector;
 
 NET_EXPORT NextProtoVector NextProtosHttpOnly();
 
+// Default values, which are subject to change over time.  Currently just
+// SPDY 3 and 3.1.
+NET_EXPORT NextProtoVector NextProtosDefaults();
+
 // All of these also enable QUIC.
 NET_EXPORT NextProtoVector NextProtosSpdy3();
 NET_EXPORT NextProtoVector NextProtosSpdy31();