content: Remove odd and unused forward declaration in plugin_service_impl.h

content/browser/plugin_service_impl.h

 // 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.
 
 // This class responds to requests from renderers for the list of plugins, and
 // also a proxy object for plugin instances.
 
 #ifndef CONTENT_BROWSER_PLUGIN_SERVICE_IMPL_H_
 #define CONTENT_BROWSER_PLUGIN_SERVICE_IMPL_H_
 
@@ skipping 23 matching lines @@
 #endif
 
 #if defined(OS_POSIX) && !defined(OS_OPENBSD) && !defined(OS_ANDROID)
 #include "base/files/file_path_watcher.h"
 #endif
 
 namespace base {
 class MessageLoopProxy;
 }
 
-namespace webkit {
-namespace npapi {
-class PluginList;
-}
-}
-
 namespace content {
 class BrowserContext;
 class PluginDirWatcherDelegate;
 class PluginLoaderPosix;
 class PluginServiceFilter;
 class ResourceContext;
 struct PepperPluginInfo;
 
 // base::Bind() has limited arity, and the filter-related methods tend to
 // surpass that limit.
@@ skipping 185 matching lines @@
 
   // Used to detect if a given plug-in is crashing over and over.
   std::map<base::FilePath, std::vector<base::Time> > crash_times_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginServiceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_PLUGIN_SERVICE_IMPL_H_