Make it possible to keep the port allocator session running

webrtc/p2p/base/p2ptransportchannel.cc

Index: webrtc/p2p/base/p2ptransportchannel.cc
diff --git a/webrtc/p2p/base/p2ptransportchannel.cc b/webrtc/p2p/base/p2ptransportchannel.cc
index 15ac006872e9087bf8af8cbe1fde783fd29f1160..d1b2330c62e2f386374425153048e4476c7c3edb 100644
--- a/webrtc/p2p/base/p2ptransportchannel.cc
+++ b/webrtc/p2p/base/p2ptransportchannel.cc
@@ -1072,8 +1072,16 @@ void P2PTransportChannel::HandleWritable() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
   if (!writable()) {

[pthatcher1, 2015/09/28 23:34:00]

Can you make an early return here?

if (writable()) {
  return;
}

[honghaiz3, 2015/09/29 00:04:49]

Done.

     for (uint32 i = 0; i < allocator_sessions_.size(); ++i) {
-      if (allocator_sessions_[i]->IsGettingPorts()) {
-        allocator_sessions_[i]->StopGettingPorts();
+      PortAllocatorSession* session = allocator_sessions_[i];
+      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_ && (i + 1 == allocator_sessions_.size())) {
+        session->ClearGettingPorts();
+      } else {
+        session->StopGettingPorts();
       }

[pthatcher1, 2015/09/28 23:34:00]

I think this would be more readable like this:
 
  for (PortAllocactorSession* session : allocator_sessions_) {
    if (!session->IsGettingPorts()) {
      continue;
    }
    if (gather_continually && session == allocator_sessions_.back()) {
      // If gathering continually, keep the last session running so that it
      // will gather candidates if the networks change.
      session->ClearGettingPorts();
      continue;
    }
    session->StopGettingPorts();
  }

[honghaiz3, 2015/09/29 00:04:49]

Done. Replaced continue with break because that is the last session. 

     }
   }