Revert of Delete SignalThread class.

webrtc/examples/peerconnection/client/peer_connection_client.cc

 /*
  *  Copyright 2012 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.
  */
 
 #include "webrtc/examples/peerconnection/client/peer_connection_client.h"
 
 #include "webrtc/examples/peerconnection/client/defaults.h"
 #include "webrtc/rtc_base/checks.h"
 #include "webrtc/rtc_base/logging.h"
 #include "webrtc/rtc_base/nethelpers.h"
 #include "webrtc/rtc_base/stringutils.h"
-#include "webrtc/rtc_base/thread.h"
 
 #ifdef WIN32
 #include "webrtc/rtc_base/win32socketserver.h"
 #endif
 
 using rtc::sprintfn;
 
 namespace {
 
 // This is our magical hangup signal.
@@ skipping 476 matching lines @@
       Close();
       callback_->OnDisconnected();
     }
   }
 }
 
 void PeerConnectionClient::OnMessage(rtc::Message* msg) {
   // ignore msg; there is currently only one supported message ("retry")
   DoConnect();
 }