Cache the value of GetMaxPlaintextSize in QuicPacketCreator. No functional change.

net/quic/quic_packet_creator.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.
 //
 // Accumulates frames for the next packet until more frames no longer fit or
 // it's time to create a packet from them.  Also provides packet creation of
 // FEC packets based on previously created packets.
 
 #ifndef NET_QUIC_QUIC_PACKET_CREATOR_H_
 #define NET_QUIC_QUIC_PACKET_CREATOR_H_
@@ skipping 173 matching lines @@
   }
 
   void set_connection_id_length(QuicConnectionIdLength length) {
     connection_id_length_ = length;
   }
 
   QuicByteCount max_packet_length() const {
     return max_packet_length_;
   }
 
-  void set_max_packet_length(QuicByteCount length) {
-    // |max_packet_length_| should not be changed mid-packet or mid-FEC group.
-    DCHECK(fec_group_.get() == nullptr && queued_frames_.empty());
-    max_packet_length_ = length;
-  }
+  // Sets the encrypter to use for the encryption level and updates the max
+  // plaintext size.
+  void SetEncrypter(EncryptionLevel level, QuicEncrypter* encrypter);
+
+  // Sets the maximum packet length.
+  void SetMaxPacketLength(QuicByteCount length);
 
   // Returns current max number of packets covered by an FEC group.
   size_t max_packets_per_fec_group() const {
       return max_packets_per_fec_group_;
   }
 
   // Sets creator's max number of packets covered by an FEC group.
   // Note: While there are no constraints on |max_packets_per_fec_group|,
   // this setter enforces a min value of kLowestMaxPacketsPerFecGroup.
   // To turn off FEC protection, use StopFecProtectingPackets().
@@ skipping 49 matching lines @@
   // a packet or FEC group boundary, when the creator's sequence_number_length_
   // can be changed to this new value.
   QuicSequenceNumberLength next_sequence_number_length_;
   // Sequence number length for the current packet and for the current FEC group
   // when FEC is enabled. Mutable so PacketSize() can adjust it when the packet
   // is empty.
   mutable QuicSequenceNumberLength sequence_number_length_;
   // packet_size_ is mutable because it's just a cache of the current size.
   // packet_size should never be read directly, use PacketSize() instead.
   mutable size_t packet_size_;
+  mutable size_t max_plaintext_size_;
   QuicFrames queued_frames_;
   scoped_ptr<RetransmittableFrames> queued_retransmittable_frames_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicPacketCreator);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PACKET_CREATOR_H_