[Chromoting] Implement HostExperimentSessionPlugin

remoting/protocol/session_plugin.cc

+// 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 "base/logging.h"
+#include "remoting/protocol/session_plugin.h"
+
+namespace remoting {
+namespace protocol {
+
+SessionPlugin::SessionPlugin(
+    const base::Callback<std::unique_ptr<buzz::XmlElement>()>& new_attachments)
+    : new_attachments_(new_attachments) {
+  DCHECK(new_attachments_);
+}
+
+SessionPlugin::~SessionPlugin() = default;
+
+}  // namespace protocol
+}  // namespace remoting