Block NPAPI plug-ins in Metro mode instead of not loading them at all.

chrome/browser/plugins/plugin_finder.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.
 
 #ifndef CHROME_BROWSER_PLUGINS_PLUGIN_FINDER_H_
 #define CHROME_BROWSER_PLUGINS_PLUGIN_FINDER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 33 matching lines @@
   // language tag, i.e. en-US). If found, sets |installer| to the
   // corresponding PluginInstaller and |plugin_metadata| to a copy of the
   // corresponding PluginMetadata.
   bool FindPlugin(const std::string& mime_type,
                   const std::string& language,
                   PluginInstaller** installer,
                   scoped_ptr<PluginMetadata>* plugin_metadata);
 
   // Finds the plug-in with the given identifier. If found, sets |installer|
   // to the corresponding PluginInstaller and |plugin_metadata| to a copy
-  // of the corresponding PluginMetadata.
+  // of the corresponding PluginMetadata. |installer| may be NULL.
   bool FindPluginWithIdentifier(const std::string& identifier,
                                 PluginInstaller** installer,
                                 scoped_ptr<PluginMetadata>* plugin_metadata);
 #endif
 
   // Returns the plug-in name with the given identifier.
   string16 FindPluginNameWithIdentifier(const std::string& identifier);
 
   // Gets plug-in metadata using |plugin|.
   scoped_ptr<PluginMetadata> GetPluginMetadata(
@@ skipping 22 matching lines @@
   std::map<std::string, PluginMetadata*> identifier_plugin_;
 
   // Synchronization for the above member variables is
   // required since multiple threads can be accessing them concurrently.
   base::Lock mutex_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginFinder);
 };
 
 #endif  // CHROME_BROWSER_PLUGINS_PLUGIN_FINDER_H_