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

net/quic/core/quic_stream_sequencer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_stream_sequencer.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 #include <utility>
@@ skipping 179 matching lines @@
     return;
   }
   ignore_read_data_ = true;
   FlushBufferedFrames();
 }
 
 void QuicStreamSequencer::ReleaseBuffer() {
   buffered_frames_.ReleaseWholeBuffer();
 }
 
+void QuicStreamSequencer::ReleaseBufferIfEmpty() {
+  if (FLAGS_quic_release_crypto_stream_buffer && buffered_frames_.Empty()) {
+    buffered_frames_.ReleaseWholeBuffer();
+  }
+}
+
 void QuicStreamSequencer::FlushBufferedFrames() {
   DCHECK(ignore_read_data_);
   size_t bytes_flushed = buffered_frames_.FlushBufferedFrames();
   DVLOG(1) << "Flushing buffered data at offset "
            << buffered_frames_.BytesConsumed() << " length " << bytes_flushed
            << " for stream " << stream_->id();
   stream_->AddBytesConsumed(bytes_flushed);
   MaybeCloseStream();
 }
 
@@ skipping 11 matching lines @@
          "\n  bytes buffered: " + IntToString(NumBytesBuffered()) +
          "\n  bytes consumed: " + IntToString( NumBytesConsumed()) +
          "\n  has bytes to read: " +  (HasBytesToRead() ? "true" : "false") +
          "\n  frames received: " + IntToString(num_frames_received()) +
          "\n  close offset bytes: " + IntToString( close_offset_) +
          "\n  is closed: " + (IsClosed() ? "true" : "false");
   // clang-format on
 }
 
 }  // namespace net