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

chrome/browser/extensions/webstore_installer.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_EXTENSIONS_WEBSTORE_INSTALLER_H_
 #define CHROME_BROWSER_EXTENSIONS_WEBSTORE_INSTALLER_H_
 
 #include <list>
 #include <string>
 
@@ skipping 140 matching lines @@
     // Used to show the install dialog.
     ExtensionInstallPrompt::ShowDialogCallback show_dialog_callback;
 
     // The icon to use to display the extension while it is installing.
     gfx::ImageSkia installing_icon;
 
     // A dummy extension created from |manifest|;
     scoped_refptr<Extension> dummy_extension;
 
     // Required minimum version.
-    scoped_ptr<base::Version> minimum_version;
+    scoped_ptr<Version> minimum_version;
 
     // Ephemeral apps are transiently installed.
     bool is_ephemeral;
 
     // The authuser index required to download the item being installed. May be
     // the empty string, in which case no authuser parameter is used.
     std::string authuser;
 
    private:
     Approval();
@@ skipping 113 matching lines @@
   std::list<SharedModuleInfo::ImportInfo> pending_modules_;
   // Total extension modules we need download and install (the main module and
   // depedences).
   int total_modules_;
   bool download_started_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_WEBSTORE_INSTALLER_H_