Revert of base: Remove using:: declaration from version.h header.

chrome/browser/plugins/plugin_metadata.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_METADATA_H_
 #define CHROME_BROWSER_PLUGINS_PLUGIN_METADATA_H_
 
 #include <map>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 51 matching lines @@
   // URL to open when the user clicks on the "Problems installing?" link.
   const GURL& help_url() const { return help_url_; }
 
   const std::string& language() const { return language_; }
 
   bool HasMimeType(const std::string& mime_type) const;
   void AddMimeType(const std::string& mime_type);
   void AddMatchingMimeType(const std::string& mime_type);
 
   // Adds information about a plugin version.
-  void AddVersion(const base::Version& version, SecurityStatus status);
+  void AddVersion(const Version& version, SecurityStatus status);
 
   // Checks if |plugin| mime types match all |matching_mime_types_|.
   // If there is no |matching_mime_types_|, |group_name_matcher_| is used
   // for matching.
   bool MatchesPlugin(const content::WebPluginInfo& plugin);
 
   // If |status_str| describes a valid security status, writes it to |status|
   // and returns true, else returns false and leaves |status| unchanged.
   static bool ParseSecurityStatus(const std::string& status_str,
                                   SecurityStatus* status);
 
   // Returns the security status for the given plugin (i.e. whether it is
   // considered out-of-date, etc.)
   SecurityStatus GetSecurityStatus(const content::WebPluginInfo& plugin) const;
 
   scoped_ptr<PluginMetadata> Clone() const;
 
  private:
   struct VersionComparator {
-    bool operator() (const base::Version& lhs, const base::Version& rhs) const;
+    bool operator() (const Version& lhs, const Version& rhs) const;
   };
 
   std::string identifier_;
   base::string16 name_;
   base::string16 group_name_matcher_;
   bool url_for_display_;
   GURL plugin_url_;
   GURL help_url_;
   std::string language_;
-  std::map<base::Version, SecurityStatus, VersionComparator> versions_;
+  std::map<Version, SecurityStatus, VersionComparator> versions_;
   std::vector<std::string> all_mime_types_;
   std::vector<std::string> matching_mime_types_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginMetadata);
 };
 
 #endif  // CHROME_BROWSER_PLUGINS_PLUGIN_METADATA_H_