Refactor allocator_interception_mac to use {Store,Replace}ZoneFunctions.

base/allocator/allocator_interception_mac.h

 // Copyright 2017 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_INTERCEPTION_MAC_H_
 #define BASE_ALLOCATOR_ALLOCATOR_INTERCEPTION_MAC_H_
 
+#include <malloc/malloc.h>
 #include <stddef.h>
 
+#include "third_party/apple_apsl/malloc.h"
+
 namespace base {
 namespace allocator {
 
+typedef void* (*malloc_type)(struct _malloc_zone_t* zone, size_t size);
+typedef void* (*calloc_type)(struct _malloc_zone_t* zone,
+                             size_t num_items,
+                             size_t size);
+typedef void* (*valloc_type)(struct _malloc_zone_t* zone, size_t size);
+typedef void (*free_type)(struct _malloc_zone_t* zone, void* ptr);
+typedef void* (*realloc_type)(struct _malloc_zone_t* zone,
+                              void* ptr,
+                              size_t size);
+typedef void* (*memalign_type)(struct _malloc_zone_t* zone,
+                               size_t alignment,
+                               size_t size);
+
+struct MallocZoneFunctions {
+  malloc_type malloc = nullptr;
+  calloc_type calloc = nullptr;
+  valloc_type valloc = nullptr;
+  free_type free = nullptr;
+  realloc_type realloc = nullptr;
+  memalign_type memalign = nullptr;
+};
+
+// Saves the function pointers currently used by |zone| into |functions|.
+void StoreZoneFunctions(ChromeMallocZone* zone, MallocZoneFunctions* functions);
+
+// Updates the malloc zone to use the functions specified by |functions|.
+void ReplaceZoneFunctions(ChromeMallocZone* zone,
+                          const MallocZoneFunctions* functions);
+
 // Calls the original implementation of malloc/calloc prior to interception.
 bool UncheckedMallocMac(size_t size, void** result);
 bool UncheckedCallocMac(size_t num_items, size_t size, void** result);
 
 // Intercepts calls to default and purgeable malloc zones. Intercepts Core
 // Foundation and Objective-C allocations.
 void InterceptAllocationsMac();
 }  // namespace allocator
 }  // namespace base
 
 #endif  // BASE_ALLOCATOR_ALLOCATOR_INTERCEPTION_MAC_H_