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

chrome/browser/extensions/api/runtime/chrome_runtime_api_delegate.cc

 // 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.
 
 #include "chrome/browser/extensions/api/runtime/chrome_runtime_api_delegate.h"
 
 #include <string>
 #include <utility>
 
 #include "base/location.h"
@@ skipping 233 matching lines @@
   if (!browser)
     return false;
   return extensions::ExtensionTabUtil::OpenOptionsPage(extension, browser);
 }
 
 void ChromeRuntimeAPIDelegate::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   DCHECK(type == extensions::NOTIFICATION_EXTENSION_UPDATE_FOUND);
-  typedef const std::pair<std::string, base::Version> UpdateDetails;
+  typedef const std::pair<std::string, Version> UpdateDetails;
   const std::string& id = content::Details<UpdateDetails>(details)->first;
-  const base::Version& version =
-      content::Details<UpdateDetails>(details)->second;
+  const Version& version = content::Details<UpdateDetails>(details)->second;
   if (version.IsValid()) {
     CallUpdateCallbacks(
         id, UpdateCheckResult(true, kUpdateFound, version.GetString()));
   }
 }
 
 void ChromeRuntimeAPIDelegate::UpdateCheckComplete(
     const std::string& extension_id) {
   ExtensionSystem* system = ExtensionSystem::Get(browser_context_);
   ExtensionService* service = system->extension_service();
@@ skipping 13 matching lines @@
     const UpdateCheckResult& result) {
   UpdateCallbackList callbacks = pending_update_checks_[extension_id];
   pending_update_checks_.erase(extension_id);
   for (UpdateCallbackList::const_iterator iter = callbacks.begin();
        iter != callbacks.end();
        ++iter) {
     const UpdateCheckCallback& callback = *iter;
     callback.Run(result);
   }
 }