apps: Stop depending on chrome_switches.h

apps/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 APPS_PREF_NAMES_H_
-#define APPS_PREF_NAMES_H_
+#ifndef APPS_SWITCHES_H_
+#define APPS_SWITCHES_H_
 
 namespace apps {
+namespace switches {
 
-namespace prefs {
+extern const char kShowAppListShortcut[];
 
-extern const char kAppLauncherIsEnabled[];
-
-}  // namespace prefs
-
+}  // namespace switches
 }  // namespace apps
 
-#endif  // APPS_PREF_NAMES_H_
+#endif  // APPS_SWITCHES_H_