Add the "virtual" keyword on method overrides that are missing it.

webkit/glue/plugins/pepper_file_chooser.h

 // Copyright (c) 2010 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 WEBKIT_GLUE_PLUGINS_PEPPER_FILE_CHOOSER_H_
 #define WEBKIT_GLUE_PLUGINS_PEPPER_FILE_CHOOSER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 11 matching lines @@
  public:
   FileChooser(PluginInstance* instance,
               const PP_FileChooserOptions_Dev* options);
   virtual ~FileChooser();
 
   // Returns a pointer to the interface implementing PPB_FileChooser that is
   // exposed to the plugin.
   static const PPB_FileChooser_Dev* GetInterface();
 
   // Resource overrides.
-  FileChooser* AsFileChooser() { return this; }
+  virtual FileChooser* AsFileChooser();
 
   // Stores the list of selected files.
   void StoreChosenFiles(const std::vector<std::string>& files);
 
   // PPB_FileChooser implementation.
   int32_t Show(PP_CompletionCallback callback);
   scoped_refptr<FileRef> GetNextChosenFile();
 
  private:
   PluginDelegate* delegate_;
   PP_FileChooserMode_Dev mode_;
   std::string accept_mime_types_;
   PP_CompletionCallback completion_callback_;
   std::vector< scoped_refptr<FileRef> > chosen_files_;
   size_t next_chosen_file_index_;
 };
 
 }  // namespace pepper
 
 #endif  // WEBKIT_GLUE_PLUGINS_PEPPER_FILE_CHOOSER_H_