relnote: Allow individual QUIC writers to limit the maximum packet size.

net/quic/quic_packet_writer.h

 // Copyright 2013 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_PACKET_WRITER_H_
 #define NET_QUIC_QUIC_PACKET_WRITER_H_
 
 #include "net/base/ip_endpoint.h"
+#include "net/quic/quic_protocol.h"
 
 namespace net {
 
 struct WriteResult;
 
 // An interface between writers and the entity managing the
 // socket (in our case the QuicDispatcher).  This allows the Dispatcher to
 // control writes, and manage any writers who end up write blocked.
 class NET_EXPORT_PRIVATE QuicPacketWriter {
  public:
@@ skipping 12 matching lines @@
   // when an attempt to write results in the underlying socket becoming
   // write blocked.
   virtual bool IsWriteBlockedDataBuffered() const = 0;
 
   // Returns true if the network socket is not writable.
   virtual bool IsWriteBlocked() const = 0;
 
   // Records that the socket has become writable, for example when an EPOLLOUT
   // is received or an asynchronous write completes.
   virtual void SetWritable() = 0;
+
+  // Returns the maximum size of the packet which can be written using this
+  // writer for the supplied peer address.  This size may actually exceed the
+  // size of a valid QUIC packet.
+  virtual QuicByteCount GetMaxPacketSize(
+      const IPEndPoint& peer_address) const = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PACKET_WRITER_H_