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

base/bind_internal_win.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
 
 // 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.
 
 // Specializations of RunnableAdapter<> for Windows specific calling
 // conventions.  Please see base/bind_internal.h for more info.
 
 #ifndef BASE_BIND_INTERNAL_WIN_H_
 #define BASE_BIND_INTERNAL_WIN_H_
-#pragma once
 
 // In the x64 architecture in Windows, __fastcall, __stdcall, etc, are all
 // the same as __cdecl which would turn the following specializations into
 // multiple definitions.
 #if !defined(ARCH_CPU_X86_64)
 
 namespace base {
 namespace internal {
 
 template <typename Functor>
@@ skipping 42 matching lines @@
 };
 
 ]]  $$for ARITY
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // !defined(ARCH_CPU_X86_64)
 
 #endif  // BASE_BIND_INTERNAL_WIN_H_