Get rid of view_messages.h includes in chrome\renderer.

chrome/renderer/extensions/chrome_v8_extension_handler.cc

 // Copyright (c) 2011 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/extensions/chrome_v8_extension_handler.h"
 
 #include "base/logging.h"
 #include "chrome/renderer/extensions/chrome_v8_context.h"
 #include "content/public/renderer/render_thread.h"
-#include "content/common/view_messages.h"
 
 using content::RenderThread;
 
 ChromeV8ExtensionHandler::ChromeV8ExtensionHandler(ChromeV8Context* context)
     : context_(context), routing_id_(MSG_ROUTING_NONE) {
 }
 
 ChromeV8ExtensionHandler::~ChromeV8ExtensionHandler() {
   if (routing_id_ != MSG_ROUTING_NONE)
     RenderThread::Get()->RemoveRoute(routing_id_);
 }
 
 int ChromeV8ExtensionHandler::GetRoutingId() {
   if (routing_id_ == MSG_ROUTING_NONE) {
-    RenderThread* render_thread = RenderThread::Get();
-    CHECK(render_thread);
-    render_thread->Send(new ViewHostMsg_GenerateRoutingID(&routing_id_));
-    render_thread->AddRoute(routing_id_, this);
+    routing_id_ = RenderThread::Get()->GenerateRoutingID();
+    RenderThread::Get()->AddRoute(routing_id_, this);
   }
 
   return routing_id_;
 }
 
 void ChromeV8ExtensionHandler::Send(IPC::Message* message) {
   RenderThread::Get()->Send(message);
 }