base: Fix/add header #ifndef guards.

base/allocator/allocator_extension_thunks.h

 // Copyright (c) 2012 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_ALLOCATOR_ALLOCATOR_THUNKS_EXTENSION_H
-#define BASE_ALLOCATOR_ALLOCATOR_THUNKS_EXTENSION_H
+#ifndef BASE_ALLOCATOR_ALLOCATOR_EXTENSION_THUNKS_H_
+#define BASE_ALLOCATOR_ALLOCATOR_EXTENSION_THUNKS_H_
 
 #include <stddef.h> // for size_t
 
 namespace base {
 namespace allocator {
 namespace thunks {
 
 // WARNING: You probably don't want to use this file unless you are routing a
 // new allocator extension from a specific allocator implementation to base.
 // See allocator_extension.h to see the interface that base exports.
 
 typedef bool (*GetAllocatorWasteSizeFunction)(size_t* size);
 void SetGetAllocatorWasteSizeFunction(
     GetAllocatorWasteSizeFunction get_allocator_waste_size_function);
 GetAllocatorWasteSizeFunction GetGetAllocatorWasteSizeFunction();
 
 typedef void (*GetStatsFunction)(char* buffer, int buffer_length);
 void SetGetStatsFunction(GetStatsFunction get_stats_function);
 GetStatsFunction GetGetStatsFunction();
 
 typedef void (*ReleaseFreeMemoryFunction)();
 void SetReleaseFreeMemoryFunction(
     ReleaseFreeMemoryFunction release_free_memory_function);
 ReleaseFreeMemoryFunction GetReleaseFreeMemoryFunction();
 
 }  // namespace thunks
 }  // namespace allocator
 }  // namespace base
 
-#endif
+#endif  // BASE_ALLOCATOR_ALLOCATOR_EXTENSION_THUNKS_H_