Remove #pragma once. Just from base/ for now.

base/bind_internal.h.pump

 $$ This is a pump file for generating file templates.  Pump is a python
 $$ script that is part of the Google Test suite of utilities.  Description
 $$ can be found here:
 $$
 $$ http://code.google.com/p/googletest/wiki/PumpManual
 $$
 
 $$ See comment for MAX_ARITY in base/bind.h.pump.
 $var MAX_ARITY = 7
 $range ARITY 0..MAX_ARITY
 
 // Copyright (c) 2011 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 BASE_BIND_INTERNAL_H_
 #define BASE_BIND_INTERNAL_H_
-#pragma once
 
 #include "base/bind_helpers.h"
 #include "base/callback_internal.h"
 #include "base/memory/raw_scoped_refptr_mismatch_checker.h"
 #include "base/memory/weak_ptr.h"
 #include "base/template_util.h"
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include "base/bind_internal_win.h"
@@ skipping 456 matching lines @@
 
 ]]
 };
 
 ]] $$ for ARITY
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_BIND_INTERNAL_H_