Allocator shim skeleton + Linux impl behind a build flag

base/allocator/allocator_shim_override_libc_symbols.h

+// 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.
+
+// Its purpose is to SHIM_ALIAS_SYMBOL the Libc symbols for malloc/new to the
+// shim layer entry points.
+
+#ifdef BASE_ALLOCATOR_ALLOCATOR_SHIM_OVERRIDE_LIBC_SYMBOLS_H_
+#error This header is meant to be included only once by allocator_shim.cc
+#endif
+#define BASE_ALLOCATOR_ALLOCATOR_SHIM_OVERRIDE_LIBC_SYMBOLS_H_
+
+#include <malloc.h>
+
+#include "base/allocator/allocator_shim_internals.h"
+
+extern "C" {
+
+SHIM_ALWAYS_EXPORT void* malloc(size_t size) __THROW
+    SHIM_ALIAS_SYMBOL(ShimMalloc);
+
+SHIM_ALWAYS_EXPORT void free(void* ptr) __THROW
+    SHIM_ALIAS_SYMBOL(ShimFree);
+
+SHIM_ALWAYS_EXPORT void* realloc(void* ptr, size_t size) __THROW
+    SHIM_ALIAS_SYMBOL(ShimRealloc);
+
+SHIM_ALWAYS_EXPORT void* calloc(size_t n, size_t size) __THROW
+    SHIM_ALIAS_SYMBOL(ShimCalloc);
+
+SHIM_ALWAYS_EXPORT void cfree(void* ptr) __THROW
+    SHIM_ALIAS_SYMBOL(ShimFree);
+
+SHIM_ALWAYS_EXPORT void* memalign(size_t align, size_t s) __THROW
+    SHIM_ALIAS_SYMBOL(ShimMemalign);
+
+SHIM_ALWAYS_EXPORT void* valloc(size_t size) __THROW
+    SHIM_ALIAS_SYMBOL(ShimValloc);
+
+SHIM_ALWAYS_EXPORT void* pvalloc(size_t size) __THROW
+    SHIM_ALIAS_SYMBOL(ShimPvalloc);
+
+SHIM_ALWAYS_EXPORT int posix_memalign(void** r, size_t a, size_t s) __THROW
+    SHIM_ALIAS_SYMBOL(ShimPosixMemalign);
+
+// The default dispatch translation unit has to define also the following
+// symbols (unless they are ultimately routed to the system symbols):
+//   void malloc_stats(void);
+//   int mallopt(int, int);
+//   struct mallinfo mallinfo(void);
+//   size_t malloc_size(void*);
+//   size_t malloc_usable_size(const void*);
+
+}  // extern "C"