Consistently use namespaced base::Version in extensions code.

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 9b660b2e3701e58cc3ccc869eabe2cb3320a6664..ca6c10565b9f13c2a58428580853ca1dec4a7691 100644
--- a/chrome/browser/extensions/external_registry_loader_win.cc
+++ b/chrome/browser/extensions/external_registry_loader_win.cc
@@ -164,7 +164,7 @@ ExternalRegistryLoader::LoadPrefsOnFileThread() {
       continue;
     }
 
-    Version version(base::UTF16ToASCII(extension_version));
+    base::Version version(base::UTF16ToASCII(extension_version));
     if (!version.IsValid()) {
       LOG(ERROR) << "Invalid version value " << extension_version
                  << " for key " << key_path << ".";