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

net/quic/core/quic_stream_sequencer.h

 // 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.
 
 #ifndef NET_QUIC_QUIC_STREAM_SEQUENCER_H_
 #define NET_QUIC_QUIC_STREAM_SEQUENCER_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 64 matching lines @@
   void SetBlockedUntilFlush();
 
   // Sets the sequencer to discard all incoming data itself and not call
   // |stream_->OnDataAvailable()|.  |stream_->OnFinRead()| will be called
   // automatically when the FIN is consumed (which may be immediately).
   void StopReading();
 
   // 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;
 
   // Number of bytes has been consumed.
   QuicStreamOffset NumBytesConsumed() const;
 
   int num_frames_received() const { return num_frames_received_; }
 
   int num_duplicate_frames_received() const {
     return num_duplicate_frames_received_;
@@ skipping 43 matching lines @@
 
   // If true, all incoming data will be discarded.
   bool ignore_read_data_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicStreamSequencer);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_STREAM_SEQUENCER_H_