Remove allocator_extension_thunks since this layer is not required

base/allocator/allocator_extension.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_EXTENSION_H_
 #define BASE_ALLOCATOR_ALLOCATOR_EXTENSION_H_
 
 #include <stddef.h> // for size_t
 
-#include "base/allocator/allocator_extension_thunks.h"
 #include "base/base_export.h"
 #include "build/build_config.h"
 
 namespace base {
 namespace allocator {
 
+typedef void (*ReleaseFreeMemoryFunction)();
+typedef bool (*GetNumericPropertyFunction)(const char* name, size_t* value);
+
 // Request that the allocator release any free memory it knows about to the
 // system.
 BASE_EXPORT void ReleaseFreeMemory();
 
+// Get the named property's |value|. Returns true if the property is known.
+// Returns false if the property is not a valid property name for the current
+// allocator implementation.
+// |name| or |value| cannot be NULL
+BASE_EXPORT bool GetNumericProperty(const char* name, size_t* value);
+
 // These settings allow specifying a callback used to implement the allocator
 // extension functions.  These are optional, but if set they must only be set
 // once.  These will typically called in an allocator-specific initialization
 // routine.
 //
 // No threading promises are made.  The caller is responsible for making sure
 // these pointers are set before any other threads attempt to call the above
 // functions.
 
 BASE_EXPORT void SetReleaseFreeMemoryFunction(
-    thunks::ReleaseFreeMemoryFunction release_free_memory_function);
+    ReleaseFreeMemoryFunction release_free_memory_function);
 
 BASE_EXPORT void SetGetNumericPropertyFunction(
-    thunks::GetNumericPropertyFunction get_numeric_property_function);
+    GetNumericPropertyFunction get_numeric_property_function);
 
 }  // namespace allocator
 }  // namespace base
 
 #endif  // BASE_ALLOCATOR_ALLOCATOR_EXTENSION_H_