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

base/atomicops_internals_arm_gcc.h

 // Copyright (c) 2009 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.
 
 // This file is an internal atomic implementation, use base/atomicops.h instead.
 //
 // LinuxKernelCmpxchg and Barrier_AtomicIncrement are from Google Gears.
 
 #ifndef BASE_ATOMICOPS_INTERNALS_ARM_GCC_H_
 #define BASE_ATOMICOPS_INTERNALS_ARM_GCC_H_
-#pragma once
 
 namespace base {
 namespace subtle {
 
 // 0xffff0fc0 is the hard coded address of a function provided by
 // the kernel which implements an atomic compare-exchange. On older
 // ARM architecture revisions (pre-v6) this may be implemented using
 // a syscall. This address is stable, and in active use (hard coded)
 // by at least glibc-2.7 and the Android C library.
 typedef Atomic32 (*LinuxKernelCmpxchgFunc)(Atomic32 old_value,
@@ skipping 94 matching lines @@
 
 inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
   MemoryBarrier();
   return *ptr;
 }
 
 } // namespace base::subtle
 } // namespace base
 
 #endif  // BASE_ATOMICOPS_INTERNALS_ARM_GCC_H_