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

components/update_client/crx_update_item.h

 // Copyright 2014 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 COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_
 #define COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 67 matching lines @@
   std::string id;
   CrxComponent component;
 
   base::Time last_check;
 
   // A component can be made available for download from several urls.
   std::vector<GURL> crx_urls;
   std::vector<GURL> crx_diffurls;
 
   // The from/to version and fingerprint values.
-  base::Version previous_version;
-  base::Version next_version;
+  Version previous_version;
+  Version next_version;
   std::string previous_fp;
   std::string next_fp;
 
   // True if the current update check cycle is on-demand.
   bool on_demand;
 
   // True if the differential update failed for any reason.
   bool diff_update_failed;
 
   // The error information for full and differential updates.
@@ skipping 22 matching lines @@
     bool operator()(CrxUpdateItem* item) const { return item->id == id_; }
 
    private:
     const std::string& id_;
   };
 };
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_