lazy allocation and early release memory in QuicStreamSequencerBuffer. Protected by --quic_reduce_s…

net/quic/core/quic_stream_sequencer.cc

Index: net/quic/core/quic_stream_sequencer.cc
diff --git a/net/quic/core/quic_stream_sequencer.cc b/net/quic/core/quic_stream_sequencer.cc
index 7dbdb97e9b9242e3aad5007d5159f2c901989aa9..a55568b24d6a7ac6cecfdc0cfa42914183d7974d 100644
--- a/net/quic/core/quic_stream_sequencer.cc
+++ b/net/quic/core/quic_stream_sequencer.cc
@@ -185,6 +185,10 @@ void QuicStreamSequencer::StopReading() {
   FlushBufferedFrames();
 }
 
+void QuicStreamSequencer::ReleaseBuffer() {
+  buffered_frames_.ReleaseWholeBuffer();
+}
+
 void QuicStreamSequencer::FlushBufferedFrames() {
   DCHECK(ignore_read_data_);
   size_t bytes_flushed = buffered_frames_.FlushBufferedFrames();