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

chrome/browser/extensions/external_registry_loader_win.cc

Index: chrome/browser/extensions/external_registry_loader_win.cc
diff --git a/chrome/browser/extensions/external_registry_loader_win.cc b/chrome/browser/extensions/external_registry_loader_win.cc
index 0f45a8a9b5ccc37fc59cedef4d75c224dbeefcdb..0b5a67f83687c838b7723790af6f0953dc435e9f 100644
--- a/chrome/browser/extensions/external_registry_loader_win.cc
+++ b/chrome/browser/extensions/external_registry_loader_win.cc
@@ -164,7 +164,7 @@
       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 << ".";