PPAPI: Refactor MessageChannel to prep for sync postMessae

chrome/renderer/pepper/pepper_helper.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 "chrome/renderer/pepper/pepper_helper.h"
 
 #include "chrome/renderer/pepper/chrome_renderer_pepper_host_factory.h"
 #include "chrome/renderer/pepper/pepper_shared_memory_message_filter.h"
 #include "content/public/renderer/renderer_ppapi_host.h"
 #include "ppapi/host/ppapi_host.h"
 
 PepperHelper::PepperHelper(content::RenderFrame* render_frame)
     : RenderFrameObserver(render_frame) {}
 
 PepperHelper::~PepperHelper() {}
 
 void PepperHelper::DidCreatePepperPlugin(content::RendererPpapiHost* host) {
   // TODO(brettw) figure out how to hook up the host factory. It needs some
   // kind of filter-like system to allow dynamic additions.
   host->GetPpapiHost()->AddHostFactoryFilter(
       scoped_ptr<ppapi::host::HostFactory>(
           new ChromeRendererPepperHostFactory(host)));
   host->GetPpapiHost()->AddInstanceMessageFilter(
       scoped_ptr<ppapi::host::InstanceMessageFilter>(
           new PepperSharedMemoryMessageFilter(host)));
+
+  // The Native Client plugin is a host for external plugins.
+  if (host->GetPluginName() == "Native Client")
+    host->SetToExternalPluginHost();
 }