[Chromoting] Add SessionPlugin in JingleSession

remoting/protocol/session_plugin.cc

Index: remoting/protocol/session_plugin.cc
diff --git a/remoting/protocol/session_plugin.cc b/remoting/protocol/session_plugin.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a9e35fab7685a964bde65400cae27520e3f875bd
--- /dev/null
+++ b/remoting/protocol/session_plugin.cc
@@ -0,0 +1,30 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/base/constants.h"
+#include "remoting/protocol/session_plugin.h"
+
+using buzz::QName;
+using buzz::XmlElement;
+
+namespace remoting {
+namespace protocol {
+
+SessionPlugin::SessionPlugin() = default;
+
+SessionPlugin::~SessionPlugin() = default;
+
+// static
+const XmlElement* SessionPlugin::FindAttachments(const buzz::XmlElement& tag) {
+  return tag.FirstNamed(QName(kChromotingXmlNamespace, "attachments"));
+}
+
+// static
+std::unique_ptr<XmlElement> SessionPlugin::NewAttachments() {
+  return std::unique_ptr<XmlElement>(new XmlElement(
+      QName(kChromotingXmlNamespace, "attachments")));
+}
+
+}  // namespace protocol
+}  // namespace remoting