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

base/bind.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
 $$ can be found here:
 $$
 $$ http://code.google.com/p/googletest/wiki/PumpManual
 $$
 
 $$
 $$ MAX_ARITY controls the number of arguments that Bind() supports.
 $$ The amount of code, and more importantly, the number of template types
@@ skipping 13 matching lines @@
 $$ See http://crbug.com/98542 for more context.
 $$
 $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.
 
 #ifndef BASE_BIND_H_
 #define BASE_BIND_H_
-#pragma once
 
 #include "base/bind_internal.h"
 #include "base/callback_internal.h"
 
 // See base/callback.h for how to use these functions. If reading the
 // implementation, before proceeding further, you should read the top
 // comment of base/bind_internal.h for a definition of common terms and
 // concepts.
 //
 // IMPLEMENTATION NOTE
@@ skipping 89 matching lines @@
   return Callback<typename BindState::UnboundRunType>(
       new BindState(internal::MakeRunnable(functor)[[]]
 $if ARITY > 0 [[, ]] $for ARG , [[p$(ARG)]]));
 }
 
 ]]  $$ for ARITY
 
 }  // namespace base
 
 #endif  // BASE_BIND_H_