Add the --disable-off-store-extension-install switch.

chrome/common/extensions/switch_utils.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/common/extensions/switch_utils.h"
+
+#include "base/command_line.h"
+#include "chrome/common/chrome_switches.h"
+
+namespace extensions {
+
+namespace switch_utils {
+
+bool IsOffStoreInstallEnabled() {
+  return !CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kDisableOffStoreExtensionInstall);
+}
+
+}  // switch_utils
+
+}  // extensions