Use continual gathering to restore backup connections

webrtc/p2p/base/portinterface.h

Index: webrtc/p2p/base/portinterface.h
diff --git a/webrtc/p2p/base/portinterface.h b/webrtc/p2p/base/portinterface.h
index e73861965e538e0ab8e09907d56b63241547c4b7..ef4f8af17faa0cd765bf2a11b587235f65d07658 100644
--- a/webrtc/p2p/base/portinterface.h
+++ b/webrtc/p2p/base/portinterface.h
@@ -78,6 +78,11 @@ class PortInterface {
 
   virtual const std::vector<Candidate>& Candidates() const = 0;
 
+  // A port is closed when it is not actively used. A closed port will not be
+  // used to create connections except when it receives stun requests from
+  // unknown addresses, although the connections on it may still be used.
+  virtual void Close() = 0;
+
   // Sends the given packet to the given address, provided that the address is
   // that of a connection or an address that has sent to us already.
   virtual int SendTo(const void* data, size_t size,
@@ -104,8 +109,9 @@ class PortInterface {
   // any usefulness.
   sigslot::signal1<PortInterface*> SignalDestroyed;
 
-  // Signaled when the network used by this port becomes inactive.
-  sigslot::signal1<PortInterface*> SignalNetworkInactive;
+  // A closed port will not be used to create new connections except when
+  // receiving stun ping from unknown address.
+  sigslot::signal1<PortInterface*> SignalClosed;
 
   // Signaled when Port discovers ice role conflict with the peer.
   sigslot::signal1<PortInterface*> SignalRoleConflict;
@@ -123,6 +129,8 @@ class PortInterface {
 
   virtual std::string ToString() const = 0;
 
+  virtual void FailAndDestroyConnections() = 0;
+
  protected:
   PortInterface() {}
 };