Use continual gathering to restore backup connections

webrtc/p2p/base/port.cc

Index: webrtc/p2p/base/port.cc
diff --git a/webrtc/p2p/base/port.cc b/webrtc/p2p/base/port.cc
index ca162b86faa2c92d4028b06408e30c2521391d5e..2018fbbf4c67661a6a46f0ed5deef3ada94718b7 100644
--- a/webrtc/p2p/base/port.cc
+++ b/webrtc/p2p/base/port.cc
@@ -195,7 +195,6 @@ void Port::Construct() {
     ice_username_fragment_ = rtc::CreateRandomString(ICE_UFRAG_LENGTH);
     password_ = rtc::CreateRandomString(ICE_PWD_LENGTH);
   }
-  network_->SignalInactive.connect(this, &Port::OnNetworkInactive);

[pthatcher1, 2016/06/29 18:53:27]

Why do we no longer listen to a network being inactive?

[honghaiz3, 2016/06/29 20:19:22]

Because when a network becomes inactive, it will be detected in the session. 
The whole purpose of SignalNetworkInactive is to remove ports and remote
candidates. 
Doing that in the basicportallocatorsession allows a more uniform processing. 
Plus, doing that from the session avoids a potential leakage of IP address when
sending candidate removals as Taylor pointed out. 

   network_->SignalTypeChanged.connect(this, &Port::OnNetworkTypeChanged);
   network_cost_ = network_->GetCost();
 
@@ -652,11 +651,6 @@ void Port::OnMessage(rtc::Message *pmsg) {
   }
 }
 
-void Port::OnNetworkInactive(const rtc::Network* network) {
-  ASSERT(network == network_);
-  SignalNetworkInactive(this);
-}
-
 void Port::OnNetworkTypeChanged(const rtc::Network* network) {
   ASSERT(network == network_);