Update the type and cost of existing networks if its type is found later by network monitor

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 a353dc2a2f0a75975af37fd2b1d5a2d3ae6cd93f..a443c8fb4f304b39af3d673374089a9304c87f78 100644
--- a/webrtc/p2p/base/port.cc
+++ b/webrtc/p2p/base/port.cc
@@ -75,7 +75,7 @@ const int RTT_RATIO = 3;  // 3 : 1
 
 // The delay before we begin checking if this port is useless.
 const int kPortTimeoutDelay = 30 * 1000;  // 30 seconds
-}
+}  // namespace
 
 namespace cricket {
 
@@ -196,11 +196,10 @@ void Port::Construct() {
     password_ = rtc::CreateRandomString(ICE_PWD_LENGTH);
   }
   network_->SignalInactive.connect(this, &Port::OnNetworkInactive);
-  // TODO(honghaiz): Make it configurable from user setting.
-  network_cost_ =
-      (network_->type() == rtc::ADAPTER_TYPE_CELLULAR) ? kMaxNetworkCost : 0;
+  network_->SignalNetworkTypeChanged.connect(this, &Port::OnNetworkTypeChanged);
+  network_cost_ = network_->GetCost();
 
-  LOG_J(LS_INFO, this) << "Port created";
+  LOG_J(LS_INFO, this) << "Port created with network cost " << network_cost_;
 }
 
 Port::~Port() {
@@ -632,6 +631,12 @@ void Port::OnNetworkInactive(const rtc::Network* network) {
   SignalNetworkInactive(this);
 }
 
+void Port::OnNetworkTypeChanged(const rtc::Network* network) {
+  ASSERT(network == network_);
+
+  UpdateNetworkCost();
+}
+
 std::string Port::ToString() const {
   std::stringstream ss;
   ss << "Port[" << std::hex << this << std::dec << ":" << content_name_ << ":"
@@ -640,6 +645,27 @@ std::string Port::ToString() const {
   return ss.str();
 }
 
+// TODO(honghaiz): Make the network cost configurable from user setting.
+void Port::UpdateNetworkCost() {
+  uint16_t new_cost = network_->GetCost();
+  if (network_cost_ == new_cost) {
+    return;
+  }
+  LOG(LS_INFO) << "Network cost changed from " << network_cost_
+               << " to " << new_cost
+               << ". Number of candidates created: " << candidates_.size()
+               << ". Number of connections created: " << connections_.size();
+  network_cost_ = new_cost;
+  for (cricket::Candidate& candidate : candidates_) {
+    candidate.set_network_cost(network_cost_);
+  }
+  // Network cost change will affect the connection selection criteria.
+  // Signal the network cost change if any connection has been created.
+  if (!connections_.empty()) {
+    SignalNetworkCostChanged(this);
+  }
+}
+
 void Port::EnablePortPackets() {
   enable_port_packets_ = true;
 }
@@ -995,6 +1021,19 @@ void Connection::HandleBindingRequest(IceMessage* msg) {
       SignalNominated(this);
     }
   }
+  // Set the remote cost if the network_info attribute is available.
+  const StunUInt32Attribute* network_attr =
+      msg->GetUInt32(STUN_ATTR_NETWORK_INFO);
+  if (network_attr) {
+    uint32_t network_info = network_attr->value();
+    uint16_t network_cost = static_cast<uint16_t>(network_info);
+    if (network_cost != remote_candidate_.network_cost()) {
+      remote_candidate_.set_network_cost(network_cost);
+      // Network cost change will affect the connection ranking, so signal
+      // state change so that the transport channel will re-sort connections.
+      SignalStateChange(this);

[pthatcher1, 2016/05/17 21:23:11]

If we always send the cost, then this could cause issues when packets get
reordered.  It's not a very big deal, but we should note it.

[honghaiz3, 2016/05/18 07:41:47]

Added note at the beginning of the added code. 

+    }
+  }
 }
 
 void Connection::OnReadyToSend() {
@@ -1165,7 +1204,7 @@ std::string Connection::ToDebugId() const {
 
 uint32_t Connection::ComputeNetworkCost() const {
   // TODO(honghaiz): Will add rtt as part of the network cost.
-  return local_candidate().network_cost() + remote_candidate_.network_cost();
+  return port()->network_cost() + remote_candidate_.network_cost();
 }
 
 std::string Connection::ToString() const {