Make sure the google wallet in-app payment support app is always installed.

chrome/browser/extensions/external_component_loader.cc

+// Copyright (c) 2013 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_component_loader.h"
+
+#include "base/values.h"
+#include "chrome/common/extensions/extension_constants.h"
+
+namespace extensions {
+
+ExternalComponentLoader::ExternalComponentLoader() {}
+
+ExternalComponentLoader::~ExternalComponentLoader() {}
+
+void ExternalComponentLoader::StartLoading() {
+  prefs_.reset(new base::DictionaryValue());
+  std::string appId = extension_misc::kInAppPaymentsSupportAppId;
+  prefs_->SetString(appId + ".external_update_url",
+                    extension_urls::GetWebstoreUpdateUrl().spec());
+  LoadFinished();
+}
+
+}  // namespace extensions