Disable HTTP/2 over NPN (with OpenSSL).

net/http/http_network_session.cc

Index: net/http/http_network_session.cc
diff --git a/net/http/http_network_session.cc b/net/http/http_network_session.cc
index 777d721e7a229a784a07bb42c42b2e9770d45a58..d843e01f853f50dc460739789103a8ba5eb48f32 100644
--- a/net/http/http_network_session.cc
+++ b/net/http/http_network_session.cc
@@ -320,11 +320,20 @@ bool HttpNetworkSession::IsProtocolEnabled(AlternateProtocol protocol) const {
       protocol - ALTERNATE_PROTOCOL_MINIMUM_VALID_VERSION];
 }
 
-void HttpNetworkSession::GetNextProtos(NextProtoVector* next_protos) const {
+void HttpNetworkSession::GetAlpnProtos(NextProtoVector* alpn_protos) const {
   if (HttpStreamFactory::spdy_enabled()) {
-    *next_protos = next_protos_;
+    *alpn_protos = next_protos_;
   } else {
-    next_protos->clear();
+    alpn_protos->clear();
+  }
+}
+
+void HttpNetworkSession::GetNpnProtos(NextProtoVector* npn_protos) const {
+  if (HttpStreamFactory::spdy_enabled()) {
+    *npn_protos = next_protos_;
+    DisableHTTP2(npn_protos);
+  } else {
+    npn_protos->clear();
   }
 }