Route calls to tcmalloc MallocExtension through allocator agnostic interface

base/allocator/allocator_extension_thunks.cc

Index: base/allocator/allocator_extension_thunks.cc
diff --git a/base/allocator/allocator_extension_thunks.cc b/base/allocator/allocator_extension_thunks.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f8985a26826993d98df4ec3a170fd8c65595df79
--- /dev/null
+++ b/base/allocator/allocator_extension_thunks.cc
@@ -0,0 +1,42 @@
+// 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.
+
+#include "base/allocator/allocator_extension_thunks.h"
+
+#include <cstddef> // for NULL
+
+namespace base {
+namespace allocator {
+namespace thunks {
+
+// This slightly odd translation unit exists because of the peculularity of how
+// allocator_unittests works on windows.  That target has to perform
+// tcmalloc-specific initialization on windows, but it cannot depend on base
+// otherwise.  This target sits in the middle - both libbase and
+// allocator_unittests can depend on it.
+// This file can't depend on anything else in base, including logging.
+
+static GetStatsFunction* g_get_stats_function = NULL;
+static ReleaseFreeMemoryFunction* g_release_free_memory_function = NULL;
+
+void SetGetStatsFunction(GetStatsFunction* get_stats_function) {
+  g_get_stats_function = get_stats_function;
+}
+
+GetStatsFunction* GetGetStatsFunction() {
+  return g_get_stats_function;
+}
+
+void SetReleaseFreeMemoryFunction(
+      ReleaseFreeMemoryFunction* release_free_memory_function) {
+  g_release_free_memory_function = release_free_memory_function;
+}
+
+ReleaseFreeMemoryFunction* GetReleaseFreeMemoryFunction() {
+  return g_release_free_memory_function;
+}
+
+}  // namespace thunks
+}  // namespace allocator
+}  // namespace base