Use continual gathering to restore backup connections

webrtc/p2p/base/p2ptransportchannel.h

Index: webrtc/p2p/base/p2ptransportchannel.h
diff --git a/webrtc/p2p/base/p2ptransportchannel.h b/webrtc/p2p/base/p2ptransportchannel.h
index fc22b2089af49e7ca972fbfdb9a1355bf1af5479..3baa5a9dfc944566fde38969e0bf2fe250af0916 100644
--- a/webrtc/p2p/base/p2ptransportchannel.h
+++ b/webrtc/p2p/base/p2ptransportchannel.h
@@ -260,8 +260,12 @@ class P2PTransportChannel : public TransportChannelImpl,
   void AddConnection(Connection* connection);
 
   void OnPortReady(PortAllocatorSession *session, PortInterface* port);
+  void OnPortsRemoved(PortAllocatorSession* session,
+                      const std::vector<PortInterface*>& ports);
   void OnCandidatesReady(PortAllocatorSession *session,
                          const std::vector<Candidate>& candidates);
+  void OnCandidatesRemoved(PortAllocatorSession* session,
+                           const std::vector<Candidate>& candidates);
   void OnCandidatesAllocationDone(PortAllocatorSession* session);
   void OnUnknownAddress(PortInterface* port,
                         const rtc::SocketAddress& addr,
@@ -269,8 +273,12 @@ class P2PTransportChannel : public TransportChannelImpl,
                         IceMessage* stun_msg,
                         const std::string& remote_username,
                         bool port_muxed);
+
+  // When a port is destroyed, remove it from both lists |ports_|
+  // and |removed_ports_|.
   void OnPortDestroyed(PortInterface* port);
-  void OnPortNetworkInactive(PortInterface* port);
+  // When removing a port, move it from |ports_| to |removed_ports_|.
+  bool RemovePort(PortInterface* port);
   void OnRoleConflict(PortInterface* port);
 
   void OnConnectionStateChange(Connection* connection);
@@ -285,6 +293,7 @@ class P2PTransportChannel : public TransportChannelImpl,
   void OnMessage(rtc::Message* pmsg) override;
   void OnSort();
   void OnCheckAndPing();
+  void OnRegatherOnFailedNetworks();
 
   // Returns true if the new_connection should be selected for transmission.
   bool ShouldSwitchSelectedConnection(Connection* new_connection) const;