[Chromoting] Use HostExperimentSessionPlugin in host

remoting/protocol/fake_session.cc

 // Copyright (c) 2012 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/protocol/fake_session.h"
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "remoting/protocol/fake_authenticator.h"
@@ skipping 86 matching lines @@
                               base::Passed(&transport_info)),
         signaling_delay_);
   }
 }
 
 void FakeSession::ProcessTransportInfo(
     std::unique_ptr<buzz::XmlElement> transport_info) {
   transport_->ProcessTransportInfo(transport_info.get());
 }
 
-// TODO(zijiehe): Supports SessionPlugin in FakeSession.
 void FakeSession::AddPlugin(SessionPlugin* plugin) {
-  NOTIMPLEMENTED();
+  DCHECK(plugin);
+  for (const auto& message : attachments_) {
+    if (message.attachments) {
+      plugin->OnIncomingMessage(*(message.attachments));
+    }
+  }
+}
+
+void FakeSession::SetAttachment(size_t round,
+                                std::unique_ptr<buzz::XmlElement> attachment) {
+  while (attachments_.size() <= round) {
+    attachments_.emplace_back();
+  }
+  attachments_[round].AddAttachment(std::move(attachment));
 }
 
 }  // namespace protocol
 }  // namespace remoting