Add the last_sent_packet_id to the candidate pair change signal

webrtc/p2p/base/transportchannel.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 137 matching lines @@
   sigslot::signal2<TransportChannel*, const rtc::SentPacket&> SignalSentPacket;
 
   // Deprecated by SignalSelectedCandidatePairChanged
   // This signal occurs when there is a change in the way that packets are
   // being routed, i.e. to a different remote location. The candidate
   // indicates where and how we are currently sending media.
   sigslot::signal2<TransportChannel*, const Candidate&> SignalRouteChange;
 
   // Signalled when the current selected candidate pair has changed.
   // The first parameter is the transport channel that signals the event.
-  // The second parameter is the new selected candidate pair.
-  sigslot::signal2<TransportChannel*, CandidatePairInterface*>
+  // The second parameter is the new selected candidate pair. The third
+  // parameter is the last packet id sent on the previous candidate pair.
+  sigslot::signal3<TransportChannel*, CandidatePairInterface*, int>
       SignalSelectedCandidatePairChanged;
 
   // Invoked when the channel is being destroyed.
   sigslot::signal1<TransportChannel*> SignalDestroyed;
 
   // Debugging description of this transport channel.
   std::string ToString() const;
 
  protected:
   // Sets the writable state, signaling if necessary.
@@ skipping 12 matching lines @@
   bool writable_;
   bool receiving_;
   DtlsTransportState dtls_state_ = DTLS_TRANSPORT_NEW;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(TransportChannel);
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_TRANSPORTCHANNEL_H_