Make it possible to keep the port allocator session running

webrtc/p2p/base/p2ptransportchannel.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 1052 matching lines @@
       break;
     }
   }
   set_receiving(receiving);
 }
 
 // We checked the status of our connections and we had at least one that
 // was writable, go into the writable state.
 void P2PTransportChannel::HandleWritable() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
-  if (!writable()) {
-    for (uint32 i = 0; i < allocator_sessions_.size(); ++i) {
-      if (allocator_sessions_[i]->IsGettingPorts()) {
-        allocator_sessions_[i]->StopGettingPorts();
-      }
+  if (writable()) {
+    return;
+  }
+
+  for (PortAllocatorSession* session : allocator_sessions_) {
+    if (!session->IsGettingPorts()) {
+      continue;
     }
+    // If gathering continually, keep the last session running so that it
+    // will gather candidates if the networks change.
+    if (gather_continually_ && session == allocator_sessions_.back()) {
+      session->ClearGettingPorts();
+      break;
+    }
+    session->StopGettingPorts();
   }
 
   was_writable_ = true;
   set_writable(true);
 }
 
 // Notify upper layer about channel not writable state, if it was before.
 void P2PTransportChannel::HandleNotWritable() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
   if (was_writable_) {
@@ skipping 256 matching lines @@
   }
 }
 
 void P2PTransportChannel::OnReadyToSend(Connection* connection) {
   if (connection == best_connection_ && writable()) {
     SignalReadyToSend(this);
   }
 }
 
 }  // namespace cricket