Add CHECK in Job::DoInitConnectionComplete().

Bug: 819101
Change-Id: I4b48053ae5a972fc92491406d357c1b382b24ef8
Reviewed-on: https://chromium-review.googlesource.com/990493
Commit-Queue: Bence Béky <bnc@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547709}

net/http/http_stream_factory_impl_job.cc

@@ -1055,10 +1055,16 @@ int HttpStreamFactoryImpl::Job::DoInitConnectionComplete(int result) {
         net_log_.AddEvent(
             NetLogEventType::HTTP_STREAM_REQUEST_PROTO,
             base::Bind(&NetLogHttpStreamProtoCallback, negotiated_protocol_));
-        if (negotiated_protocol_ == kProtoHTTP2)
+        if (negotiated_protocol_ == kProtoHTTP2) {
+          // If request is WebSocket with no proxy, then HTTP/2 must not have
+          // been advertised in the TLS handshake.  The TLS layer must not have
+          // accepted the server choosing HTTP/2.
+          // TODO(bnc): Change to DCHECK once https://crbug.com/819101 is fixed.
+          CHECK(!(is_websocket_ && proxy_info_.is_direct()));
           using_spdy_ = true;
         }
       }
+    }
   } else if (proxy_info_.is_https() && connection_->socket() &&
         result == OK) {
     ProxyClientSocket* proxy_socket =