Update includes to new header locations.

chrome/renderer/plugins/missing_plugin.h

 // 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.
 
 #ifndef CHROME_RENDERER_PLUGINS_MISSING_PLUGIN_H_
 #define CHROME_RENDERER_PLUGINS_MISSING_PLUGIN_H_
 #pragma once
 
 #include "base/string16.h"
 #include "chrome/renderer/plugins/plugin_placeholder.h"
-#include "third_party/WebKit/Source/WebKit/chromium/public/WebString.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
 
 namespace content {
 class RenderThread;
 }
 
 class MissingPlugin : public PluginPlaceholder {
  public:
   // Creates a new WebViewPlugin with a MissingPlugin as a delegate.
   static webkit::WebViewPlugin* Create(
       content::RenderView* render_view,
@@ skipping 31 matching lines @@
   // |routing_id()| is the routing ID of our associated RenderView, but we have
   // a separate routing ID for messages specific to this placeholder.
   int32 placeholder_routing_id_;
 
   string16 message_;
 
   DISALLOW_COPY_AND_ASSIGN(MissingPlugin);
 };
 
 #endif  // CHROME_RENDERER_PLUGINS_MISSING_PLUGIN_H_