Make it possible to keep the port allocator session running

webrtc/p2p/client/basicportallocator.cc

Index: webrtc/p2p/client/basicportallocator.cc
diff --git a/webrtc/p2p/client/basicportallocator.cc b/webrtc/p2p/client/basicportallocator.cc
index 982025279d7322102add345e7c897145599233bb..38ab52b7c4f1ad9411c68763f3d9734e881bf395 100644
--- a/webrtc/p2p/client/basicportallocator.cc
+++ b/webrtc/p2p/client/basicportallocator.cc
@@ -189,9 +189,9 @@ void BasicPortAllocatorSession::StartGettingPorts() {
     network_thread_->PostDelayed(ShakeDelay(), this, MSG_SHAKE);
 }
 
-void BasicPortAllocatorSession::StopGettingPorts() {
+void BasicPortAllocatorSession::StopGettingPorts(bool keep_session_running) {
   ASSERT(rtc::Thread::Current() == network_thread_);
-  running_ = false;
+  running_ = keep_session_running;
   network_thread_->Clear(this, MSG_ALLOCATE);
   for (uint32 i = 0; i < sequences_.size(); ++i)
     sequences_[i]->Stop();