Adds plumbing for QUIC early connection migration. No behavior change.

net/quic/quic_session.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.
 //
 // A QuicSession, which demuxes a single connection to individual streams.
 
 #ifndef NET_QUIC_QUIC_SESSION_H_
 #define NET_QUIC_QUIC_SESSION_H_
 
 #include <stddef.h>
@@ skipping 64 matching lines @@
   void OnSuccessfulVersionNegotiation(const QuicVersion& version) override;
   void OnCanWrite() override;
   void OnCongestionWindowChange(QuicTime /*now*/) override {}
   void OnConnectionMigration() override {}
   // Deletes streams that are safe to be deleted now that it's safe to do so (no
   // other operations are being done on the streams at this time).
   void PostProcessAfterData() override;
   bool WillingAndAbleToWrite() const override;
   bool HasPendingHandshake() const override;
   bool HasOpenDynamicStreams() const override;
+  void OnPathDegrading() override;
 
   // Called on every incoming packet. Passes |packet| through to |connection_|.
   virtual void ProcessUdpPacket(const IPEndPoint& self_address,
                                 const IPEndPoint& peer_address,
                                 const QuicEncryptedPacket& packet);
 
   // Called by streams when they want to write data to the peer.
   // Returns a pair with the number of bytes consumed from data, and a boolean
   // indicating if the fin bit was consumed.  This does not indicate the data
   // has been sent on the wire: it may have been turned into a packet and queued
@@ skipping 311 matching lines @@
   // The stream id which was last popped in OnCanWrite, or 0, if not under the
   // call stack of OnCanWrite.
   QuicStreamId currently_writing_stream_id_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicSession);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_SESSION_H_