[NOT FOR REVIEW] Basic allocator shim for macOS.

base/allocator/allocator_shim.cc

 // Copyright 2016 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_shim.h"
 
 #include <errno.h>
 
 #include <new>
 
@@ skipping 225 matching lines @@
     size = (size + GetCachedPageSize() - 1) & ~(GetCachedPageSize() - 1);
   }
   return ShimMemalign(GetCachedPageSize(), size);
 }
 
 void ShimFree(void* address) {
   const allocator::AllocatorDispatch* const chain_head = GetChainHead();
   return chain_head->free_function(chain_head, address);
 }
 
+size_t ShimGetSizeEstimate(const void* address) {
+  const allocator::AllocatorDispatch* const chain_head = GetChainHead();
+  // TODO: Fix get_size_estimate() to take 'const void*'.
+  return chain_head->get_size_estimate_function(
+      chain_head, const_cast<void*>(address));
+}
+
 }  // extern "C"
 
 #if !defined(OS_WIN)
 // Cpp symbols (new / delete) should always be routed through the shim layer
 // except on Windows where the malloc intercept is deep enough that it also
 // catches the cpp calls.
 #include "base/allocator/allocator_shim_override_cpp_symbols.h"
 #endif
 
 #if defined(OS_ANDROID)
 // Android does not support symbol interposition. The way malloc symbols are
 // intercepted on Android is by using link-time -wrap flags.
 #include "base/allocator/allocator_shim_override_linker_wrapped_symbols.h"
 #elif defined(OS_WIN)
 // On Windows we use plain link-time overriding of the CRT symbols.
 #include "base/allocator/allocator_shim_override_ucrt_symbols_win.h"
+#elif defined(OS_MACOSX)
+#include "base/allocator/allocator_shim_override_mac_symbols.h"
 #else
 #include "base/allocator/allocator_shim_override_libc_symbols.h"
 #endif
 
 // In the case of tcmalloc we also want to plumb into the glibc hooks
 // to avoid that allocations made in glibc itself (e.g., strdup()) get
 // accidentally performed on the glibc heap instead of the tcmalloc one.
 #if defined(USE_TCMALLOC)
 #include "base/allocator/allocator_shim_override_glibc_weak_symbols.h"
 #endif
 
 // Cross-checks.
 
 #if defined(MEMORY_TOOL_REPLACES_ALLOCATOR)
 #error The allocator shim should not be compiled when building for memory tools.
 #endif
 
 #if (defined(__GNUC__) && defined(__EXCEPTIONS)) || \
     (defined(_HAS_EXCEPTIONS) && _HAS_EXCEPTIONS)
 #error This code cannot be used when exceptions are turned on.
 #endif