Move UserScript and Extension switches to top-level extensions/.

extensions/common/switches.h

+// Copyright 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.
+
+#ifndef EXTENSIONS_COMMON_SWITCHES_H_
+#define EXTENSIONS_COMMON_SWITCHES_H_
+
+// All switches in alphabetical order. The switches should be documented
+// alongside the definition of their values in the .cc file.
+namespace extensions {
+
+namespace switches {
+
+extern const char kAllowLegacyExtensionManifests[];
+extern const char kAllowScriptingGallery[];
+extern const char kExtensionsOnChromeURLs[];
+extern const char kShowComponentExtensionOptions[];
+
+}  // namespace switches
+
+}  // namespace extensions
+
+#endif // EXTENSIONS_COMMON_SWITCHES_H_