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

webrtc/libjingle/xmllite/xmlnsstack.h

Index: webrtc/libjingle/xmllite/xmlnsstack.h
diff --git a/webrtc/libjingle/xmllite/xmlnsstack.h b/webrtc/libjingle/xmllite/xmlnsstack.h
new file mode 100644
index 0000000000000000000000000000000000000000..64e2f6ee66ff9149d68f884715109a1ae462508b
--- /dev/null
+++ b/webrtc/libjingle/xmllite/xmlnsstack.h
@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2004 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.
+ */
+
+#ifndef WEBRTC_LIBJINGLE_XMLLITE_XMLNSSTACK_H_
+#define WEBRTC_LIBJINGLE_XMLLITE_XMLNSSTACK_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+#include "webrtc/libjingle/xmllite/qname.h"
+
+namespace buzz {
+
+class XmlnsStack {
+public:
+  XmlnsStack();
+  ~XmlnsStack();
+
+  void AddXmlns(const std::string& prefix, const std::string& ns);
+  void RemoveXmlns();
+  void PushFrame();
+  void PopFrame();
+  void Reset();
+
+  std::pair<std::string, bool> NsForPrefix(const std::string& prefix);
+  bool PrefixMatchesNs(const std::string & prefix, const std::string & ns);
+  std::pair<std::string, bool> PrefixForNs(const std::string& ns, bool isAttr);
+  std::pair<std::string, bool> AddNewPrefix(const std::string& ns, bool isAttr);
+  std::string FormatQName(const QName & name, bool isAttr);
+
+private:
+
+  std::unique_ptr<std::vector<std::string> > pxmlnsStack_;
+  std::unique_ptr<std::vector<size_t> > pxmlnsDepthStack_;
+};
+}
+
+#endif  // WEBRTC_LIBJINGLE_XMLLITE_XMLNSSTACK_H_