Added include guards, which should be a big win on commonly included files like this one.

xpcom/base/nsIID.h

@@ -19,7 +19,9 @@
 #ifndef __nsIID_h
 #define __nsIID_h
 
+#ifndef nsID_h__
 #include "nsID.h"
+#endif
 
 /**
  * An "interface id" which can be used to uniquely identify a given

xpcom/public/nsIID.h

@@ -1,44 +0,0 @@
-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
- *
- * The contents of this file are subject to the Netscape Public License
- * Version 1.0 (the "NPL"); you may not use this file except in
- * compliance with the NPL.  You may obtain a copy of the NPL at
- * http://www.mozilla.org/NPL/
- *
- * Software distributed under the NPL is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
- * for the specific language governing rights and limitations under the
- * NPL.
- *
- * The Initial Developer of this code under the NPL is Netscape
- * Communications Corporation.  Portions created by Netscape are
- * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
- * Reserved.
- */
-
-#ifndef __nsIID_h
-#define __nsIID_h
-
-#include "nsID.h"
-
-/**
- * An "interface id" which can be used to uniquely identify a given
- * interface.
- */
-
-typedef nsID nsIID;
-
-/**
- * A macro shorthand for <tt>const nsIID&<tt>
- */
-
-#define REFNSIID const nsIID&
-
-/**
- * Define an IID (obsolete)
- */
- 
-#define NS_DEFINE_IID(_name, _iidspec) \
-  const nsIID _name = _iidspec
-
-#endif /* __nsIID_h */