Route calls to tcmalloc MallocExtension through allocator agnostic interface

base/allocator/allocator_extension_thunks.h

Index: base/allocator/allocator_extension_thunks.h
diff --git a/base/allocator/allocator_extension_thunks.h b/base/allocator/allocator_extension_thunks.h
new file mode 100644
index 0000000000000000000000000000000000000000..7c9c23120808ef0fb55d4951b4d04fdda59b568e
--- /dev/null
+++ b/base/allocator/allocator_extension_thunks.h
@@ -0,0 +1,30 @@
+// 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.
+
+#ifndef BASE_ALLOCATOR_ALLOCATOR_THUNKS_EXTENSION_H
+#define BASE_ALLOCATOR_ALLOCATOR_THUNKS_EXTENSION_H
+#pragma once
+
+namespace base {
+namespace allocator {
+namespace thunks {
+
+// WARNING: You probably don't want to use this file unless you are routing a
+// new allocator extension from a specific allocator implementation to base.
+// See allocator_extension.h to see the interface that base exports.
+
+typedef void GetStatsFunction(char*, int);
+void SetGetStatsFunction(GetStatsFunction* get_stats_function);
+GetStatsFunction* GetGetStatsFunction();
+
+typedef void ReleaseFreeMemoryFunction();
+void SetReleaseFreeMemoryFunction(
+    ReleaseFreeMemoryFunction* release_free_memory_function);
+ReleaseFreeMemoryFunction* GetReleaseFreeMemoryFunction();
+
+}  // namespace thunks
+}  // namespace allocator
+}  // namespace base
+
+#endif