Remove allocator_extension_thunks since this layer is not required

base/allocator/allocator_extension_thunks.cc

-// 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.
-
-#include "base/allocator/allocator_extension_thunks.h"
-
-#include <cstddef> // for NULL
-
-namespace base {
-namespace allocator {
-namespace thunks {
-
-// This slightly odd translation unit exists because of the peculularity of how
-// allocator_unittests work on windows.  That target has to perform
-// tcmalloc-specific initialization on windows, but it cannot depend on base
-// otherwise. This target sits in the middle - base and allocator_unittests
-// can depend on it. This file can't depend on anything else in base, including
-// logging.
-
-static ReleaseFreeMemoryFunction g_release_free_memory_function = NULL;
-static GetNumericPropertyFunction g_get_numeric_property_function = NULL;
-
-void SetReleaseFreeMemoryFunction(
-    ReleaseFreeMemoryFunction release_free_memory_function) {
-  g_release_free_memory_function = release_free_memory_function;
-}
-
-ReleaseFreeMemoryFunction GetReleaseFreeMemoryFunction() {
-  return g_release_free_memory_function;
-}
-
-void SetGetNumericPropertyFunction(
-    GetNumericPropertyFunction get_numeric_property_function) {
-  g_get_numeric_property_function = get_numeric_property_function;
-}
-
-GetNumericPropertyFunction GetGetNumericPropertyFunction() {
-  return g_get_numeric_property_function;
-}
-
-}  // namespace thunks
-}  // namespace allocator
-}  // namespace base