Use PluginPrefs in ChromePluginServiceFilter to check whether a plugin is enabled.

content/renderer/render_view.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 CONTENT_RENDERER_RENDER_VIEW_H_
 #define CONTENT_RENDERER_RENDER_VIEW_H_
 #pragma once
 
 #include <deque>
 #include <map>
@@ skipping 67 matching lines @@
 struct ViewHostMsg_RunFileChooser_Params;
 struct ViewMsg_SwapOut_Params;
 struct ViewMsg_Navigate_Params;
 struct ViewMsg_StopFinding_Params;
 struct WebDropData;
 
 namespace base {
 class WaitableEvent;
 }
 
-namespace chrome {
-class ChromeContentRendererClient;
-}
-
 namespace gfx {
 class Point;
 class Rect;
 }
 
 namespace webkit {
 
-namespace npapi {
-class PluginGroup;
-}  // namespace npapi
-
 namespace ppapi {
 class PluginInstance;
 class PluginModule;
 }  // namespace ppapi
 
 }  // namespace webkit
 
 namespace webkit_glue {
 struct CustomContextMenuContext;
 class ImageResourceFetcher;
@@ skipping 1095 matching lines @@
   // bunch of stuff, you should probably create a helper class and put your
   // data and methods on that to avoid bloating RenderView more.  You can use
   // the Observer interface to filter IPC messages and receive frame change
   // notifications.
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(RenderView);
 };
 
 #endif  // CONTENT_RENDERER_RENDER_VIEW_H_