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

chrome/browser/extensions/external_registry_loader_win.cc

 // 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.
 
 #include "chrome/browser/extensions/external_registry_loader_win.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
@@ skipping 146 matching lines @@
 
     base::string16 extension_version;
     if (key.ReadValue(kRegistryExtensionVersion, &extension_version)
         != ERROR_SUCCESS) {
       // TODO(erikkay): find a way to get this into about:extensions
       LOG(ERROR) << "Missing value " << kRegistryExtensionVersion
                  << " for key " << key_path << ".";
       continue;
     }
 
-    base::Version version(base::UTF16ToASCII(extension_version));
+    Version version(base::UTF16ToASCII(extension_version));
     if (!version.IsValid()) {
       LOG(ERROR) << "Invalid version value " << extension_version
                  << " for key " << key_path << ".";
       continue;
     }
 
     prefs->SetString(
         MakePrefName(id, ExternalProviderImpl::kExternalVersion),
         base::UTF16ToASCII(extension_version));
     prefs->SetString(
         MakePrefName(id, ExternalProviderImpl::kExternalCrx),
         extension_path_str);
     prefs->SetBoolean(
         MakePrefName(id, ExternalProviderImpl::kMayBeUntrusted),
         true);
   }
 
   prefs_.reset(prefs.release());
   LOCAL_HISTOGRAM_TIMES("Extensions.ExternalRegistryLoaderWin",
                         base::TimeTicks::Now() - start_time);
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&ExternalRegistryLoader::LoadFinished, this));
 }
 
 }  // namespace extensions