Add config to prune TURN ports

webrtc/p2p/base/portallocator.cc

Index: webrtc/p2p/base/portallocator.cc
diff --git a/webrtc/p2p/base/portallocator.cc b/webrtc/p2p/base/portallocator.cc
index f9f87b007f2b2e0ca19ba870f3ff754b6d21f6cd..9ee08a1476145922a200eaf024d4b1489944ad9f 100644
--- a/webrtc/p2p/base/portallocator.cc
+++ b/webrtc/p2p/base/portallocator.cc
@@ -32,11 +32,13 @@ PortAllocatorSession::PortAllocatorSession(const std::string& content_name,
 void PortAllocator::SetConfiguration(
     const ServerAddresses& stun_servers,
     const std::vector<RelayServerConfig>& turn_servers,
-    int candidate_pool_size) {
+    int candidate_pool_size,
+    bool prune_turn_ports) {
   bool ice_servers_changed =
       (stun_servers != stun_servers_ || turn_servers != turn_servers_);
   stun_servers_ = stun_servers;
   turn_servers_ = turn_servers;
+  prune_turn_ports_ = prune_turn_ports;
 
   // If ICE servers changed, throw away any existing pooled sessions and create
   // new ones.