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

chrome/browser/parsers/metadata_parser_filebase.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 CHROME_BROWSER_PARSERS_METADATA_PARSER_FILEBASE_H_
 #define CHROME_BROWSER_PARSERS_METADATA_PARSER_FILEBASE_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/hash_tables.h"
 #include "chrome/browser/parsers/metadata_parser.h"
 
 typedef base::hash_map<std::string, std::string> PropertyMap;
 
 // Parser for the file type. Allows for parsing of files, and gets
 // properties associated with files.
 class FileMetadataParser : public MetadataParser {
  public:
   explicit FileMetadataParser(const FilePath& path);
 
   virtual ~FileMetadataParser();
 
   // Implementation of MetadataParser
   virtual bool Parse();
   virtual bool GetProperty(const std::string& key, std::string* value);
 
-  MetadataPropertyIterator* GetPropertyIterator();
+  virtual MetadataPropertyIterator* GetPropertyIterator();
 
  protected:
   PropertyMap properties_;
   FilePath path_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FileMetadataParser);
 };
 
 class FileMetadataPropertyIterator : public MetadataPropertyIterator {
  public:
   explicit FileMetadataPropertyIterator(PropertyMap& properties);
 
   virtual ~FileMetadataPropertyIterator();
 
   // Implementation of MetadataPropertyIterator
   virtual bool GetNext(std::string* key, std::string* value);
   virtual int Length();
   virtual bool IsEnd();
 
  private:
   PropertyMap& properties_;
   PropertyMap::iterator it;
 
   DISALLOW_COPY_AND_ASSIGN(FileMetadataPropertyIterator);
 };
 
 #endif  // CHROME_BROWSER_PARSERS_METADATA_PARSER_FILEBASE_H_