Enable forced extension updates on NaCl arch mismatch.

chrome/browser/extensions/updater/extension_downloader_delegate.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/updater/extension_downloader_delegate.h"
 
 #include "base/logging.h"
 #include "base/version.h"
 
 namespace extensions {
@@ skipping 14 matching lines @@
     const std::string& id,
     ManifestFetchData::PingData* ping) {
   return false;
 }
 
 std::string ExtensionDownloaderDelegate::GetUpdateUrlData(
     const std::string& id) {
   return std::string();
 }
 
+bool ExtensionDownloaderDelegate::ShouldForceUpdate(
+    const std::string& id,
+    std::string* source) {
+  return false;
+}
+
 }  // namespace extensions