Introduce bad_message.h for chrome and NaCl.

extensions/browser/bad_message.h

 // Copyright 2015 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_BROWSER_BAD_MESSAGE_H_
 #define EXTENSIONS_BROWSER_BAD_MESSAGE_H_
 
 namespace content {
 class RenderProcessHost;
 }
@@ skipping 19 matching lines @@
   // reason.
   BAD_MESSAGE_MAX
 };
 
 // Called when the browser receives a bad IPC message from an extension process.
 // Logs the event, records a histogram metric for the |reason|, and terminates
 // the process for |host|.
 void ReceivedBadMessage(content::RenderProcessHost* host,
                         BadMessageReason reason);
 
-}  // bad_message
+}  // namespace bad_message
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_BAD_MESSAGE_H_