Revert 187340 "PPAPI: Remove threading options; it's always on"

webkit/plugins/plugin_switches.cc

 // Copyright (c) 2010 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 "webkit/plugins/plugin_switches.h"
 
 namespace switches {
 
 // Dumps extra logging about plugin loading to the log file.
 const char kDebugPluginLoading[] = "debug-plugin-loading";
 
 // Disable Pepper3D.
 const char kDisablePepper3d[] = "disable-pepper-3d";
 
 // "Command-line" arguments for the PPAPI Flash; used for debugging options.
 const char kPpapiFlashArgs[] = "ppapi-flash-args";
 
+// Set to true to not allow threadsafety support in native Pepper plugins.
+const char kDisablePepperThreading[] = "disable-pepper-threading";
+
 #if defined(OS_WIN)
 // Used by the plugins_test when testing the older WMP plugin to force the new
 // plugin to not get loaded.
 extern const char kUseOldWMPPlugin[] = "use-old-wmp";
 #endif
 
 }  // namespace switches