components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/gperftools/custom_allocator.h

+// Copyright 2015 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 CUSTOM_ALLOCATOR_H_
+#define CUSTOM_ALLOCATOR_H_
+
+#include <stddef.h>
+
+// PERFTOOLS_DLL_DECL is unnecessary, as it is Windows specific.
+
+// A container class for using LowLevelAlloc with STL_Allocator. The functions
+// Allocate() and Free() must match the specificiations in STL_Allocator.
+class CustomAllocator {

[jar (doing other things), 2015/08/21 02:48:43]

Why are we using a class, rather than a namespace?

[Simon Que, 2015/08/21 05:44:05]

This is required as a template type for STL_Allocator. Is it possible to pass a
namespace as a template type? I didn't think it is possible.

[jar (doing other things), 2015/08/21 17:32:31]

I see.  SGTM.

+ public:
+  // This is a stateless class, but there is static data within the module that
+  // needs to be created and deleted.
+  static void Initialize();
+  static bool Shutdown();
+  static bool IsInitialized();
+
+  static void* Allocate(size_t size);
+  static void Free(void* ptr, size_t size);
+};
+
+#endif  // CUSTOM_ALLOCATOR_H_