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

chrome/browser/plugins/plugin_metadata.h

Index: chrome/browser/plugins/plugin_metadata.h
diff --git a/chrome/browser/plugins/plugin_metadata.h b/chrome/browser/plugins/plugin_metadata.h
index 1080bec905ec1f3704dfcd4a0aca2a896a79926c..99ed7d3202150e26a1c167c6b4f23467760180eb 100644
--- a/chrome/browser/plugins/plugin_metadata.h
+++ b/chrome/browser/plugins/plugin_metadata.h
@@ -69,7 +69,7 @@
   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
@@ -89,7 +89,7 @@
 
  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_;
@@ -99,7 +99,7 @@
   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_;