Revert of Remove webrtc/libjingle/{xmllite,xmpp}

webrtc/libjingle/xmpp/pubsubstateclient.cc

+/*
+ *  Copyright 2011 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/libjingle/xmpp/pubsubstateclient.h"
+
+namespace buzz {
+
+std::string PublishedNickKeySerializer::GetKey(
+    const std::string& publisher_nick, const std::string& published_nick) {
+  return published_nick;
+}
+
+std::string PublisherAndPublishedNicksKeySerializer::GetKey(
+    const std::string& publisher_nick, const std::string& published_nick) {
+  return publisher_nick + ":" + published_nick;
+}
+
+}  // namespace buzz