Release read buffer of QuicCryptoStream when incoming message become less frequent. Protected by --…

net/quic/core/quic_stream_sequencer.h

Index: net/quic/core/quic_stream_sequencer.h
diff --git a/net/quic/core/quic_stream_sequencer.h b/net/quic/core/quic_stream_sequencer.h
index 9b373664345ac29b7224dd2e210eadae2fe76cac..38a8e8cf17677afc373e8687fa6f122ead9bcfc3 100644
--- a/net/quic/core/quic_stream_sequencer.h
+++ b/net/quic/core/quic_stream_sequencer.h
@@ -82,6 +82,9 @@ class NET_EXPORT_PRIVATE QuicStreamSequencer {
   // Free the memory of underlying buffer.
   void ReleaseBuffer();
 
+  // Free the memory of underlying buffer when no bytes remain in it.
+  void ReleaseBufferIfEmpty();
+
   // Number of bytes in the buffer right now.
   size_t NumBytesBuffered() const;