Adds clearer function to create rtc::Thread without Physical SocketServer

Moves logic of default SocketServer from MessageQueue to SocketServer

Review-Url: https://codereview.webrtc.org/1891293002
Cr-Commit-Position: refs/heads/master@{#12541}

webrtc/base/nullsocketserver.cc

@@ -0,0 +1,49 @@
+/*
+ *  Copyright 2016 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/base/checks.h"
+#include "webrtc/base/nullsocketserver.h"
+
+namespace rtc {
+
+NullSocketServer::NullSocketServer() : event_(false, false) {}
+NullSocketServer::~NullSocketServer() {}
+
+bool NullSocketServer::Wait(int cms, bool process_io) {
+  event_.Wait(cms);
+  return true;
+}
+
+void NullSocketServer::WakeUp() {
+  event_.Set();
+}
+
+rtc::Socket* NullSocketServer::CreateSocket(int /* type */) {
+  RTC_NOTREACHED();
+  return nullptr;
+}
+
+rtc::Socket* NullSocketServer::CreateSocket(int /* family */, int /* type */) {
+  RTC_NOTREACHED();
+  return nullptr;
+}
+
+rtc::AsyncSocket* NullSocketServer::CreateAsyncSocket(int /* type */) {
+  RTC_NOTREACHED();
+  return nullptr;
+}
+
+rtc::AsyncSocket* NullSocketServer::CreateAsyncSocket(int /* family */,
+                                                      int /* type */) {
+  RTC_NOTREACHED();
+  return nullptr;
+}
+
+}  // namespace rtc