Allocator shim skeleton + Linux impl behind a build flag

base/allocator/allocator_shim_default_dispatch_to_tcmalloc.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 "base/allocator/allocator_shim_internals.h"
+#include "third_party/tcmalloc/chromium/src/config.h"
+#include "third_party/tcmalloc/chromium/src/gperftools/tcmalloc.h"
+
+namespace {
+
+using base::allocator::AllocatorDispatch;
+
+void* TCMalloc(const AllocatorDispatch*, size_t size) {
+  return tc_malloc(size);
+}
+
+void* TCCalloc(const AllocatorDispatch*, size_t n, size_t size) {
+  return tc_calloc(n, size);
+}
+
+void* TCMemalign(const AllocatorDispatch*, size_t alignment, size_t size) {
+  return tc_memalign(alignment, size);
+}
+
+void* TCRealloc(const AllocatorDispatch*, void* address, size_t size) {
+  return tc_realloc(address, size);
+}
+
+void TCFree(const AllocatorDispatch*, void* address) {
+  tc_free(address);
+}
+
+}  // namespace
+
+const AllocatorDispatch AllocatorDispatch::default_dispatch = {
+    &TCMalloc,   /* alloc_function */
+    &TCCalloc,   /* alloc_zero_initialized_function */
+    &TCMemalign, /* alloc_aligned_function */
+    &TCRealloc,  /* realloc_function */
+    &TCFree,     /* free_function */
+    nullptr,     /* next */
+};
+
+// In the case of tcmalloc we have also to route the diagnostic symbols,
+// which are not part of the unified shim layer, to tcmalloc for consistency.
+
+extern "C" {
+
+SHIM_ALWAYS_EXPORT void malloc_stats(void) __THROW {
+  return tc_malloc_stats();
+}
+
+SHIM_ALWAYS_EXPORT int mallopt(int cmd, int value) __THROW {
+  return tc_mallopt(cmd, value);
+}
+
+#ifdef HAVE_STRUCT_MALLINFO
+SHIM_ALWAYS_EXPORT struct mallinfo mallinfo(void) __THROW {
+  return tc_mallinfo();
+}
+#endif
+
+SHIM_ALWAYS_EXPORT size_t malloc_size(void* address) __THROW {
+  return tc_malloc_size(address);
+}
+
+#if defined(__ANDROID__)
+SHIM_ALWAYS_EXPORT size_t malloc_usable_size(const void* address) __THROW {
+#else
+SHIM_ALWAYS_EXPORT size_t malloc_usable_size(void* address) __THROW {
+#endif
+  return tc_malloc_size(address);
+}
+
+}  // extern "C"