Send QUIC ping packets when there are draining streams, even if there are no open streams.

net/quic/quic_chromium_client_session.cc

Index: net/quic/quic_chromium_client_session.cc
diff --git a/net/quic/quic_chromium_client_session.cc b/net/quic/quic_chromium_client_session.cc
index b85f248955874cc43ea435096dca8fa5593f7b73..1ef60a6229fd3fab71cb359effd1ba1f4e6062ed 100644
--- a/net/quic/quic_chromium_client_session.cc
+++ b/net/quic/quic_chromium_client_session.cc
@@ -938,6 +938,11 @@ void QuicChromiumClientSession::OnPathDegrading() {
   }
 }
 
+bool QuicChromiumClientSession::HasOpenDynamicStreams() const {
+  return QuicSession::HasOpenDynamicStreams() ||
+         GetNumDrainingOutgoingStreams() > 0;
+}
+
 void QuicChromiumClientSession::OnProofValid(
     const QuicCryptoClientConfig::CachedState& cached) {
   DCHECK(cached.proof_valid());