Add device port unmapping support to forwarder2.

tools/android/forwarder2/forwarder.cc

Index: tools/android/forwarder2/forwarder.cc
diff --git a/tools/android/forwarder2/forwarder.cc b/tools/android/forwarder2/forwarder.cc
index f1aef15bc3457b4bd85fb5511d55b98122b75da7..d82bb0c3d6fa885f29eb11201f9b8b91d3cf6fe7 100644
--- a/tools/android/forwarder2/forwarder.cc
+++ b/tools/android/forwarder2/forwarder.cc
@@ -94,16 +94,9 @@ Forwarder::Forwarder(scoped_ptr<Socket> socket1, scoped_ptr<Socket> socket2)
       socket2_(socket2.Pass()) {
   DCHECK(socket1_.get());
   DCHECK(socket2_.get());
-  // The forwarder thread doesn't need to listen to notifications. It can be
-  // keept alive until either the conenction is broken or the program exit.
-  socket1_->reset_exit_notifier_fd();
-  socket2_->reset_exit_notifier_fd();
 }
 
-Forwarder::~Forwarder() {
-  socket1_->Close();
-  socket2_->Close();
-}
+Forwarder::~Forwarder() {}
 
 void Forwarder::Run() {
   const int nfds = Socket::GetHighestFileDescriptor(*socket1_, *socket2_) + 1;