components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/base/custom_allocator.cc

+// Copyright (c) 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.
+
+// ---
+// Author: Simon Que
+
+#include "base/custom_allocator.h"
+
+// static
+void CustomAllocator::SetArena(LowLevelAlloc::Arena* arena) {
+  arena_ = arena;
+}
+
+// static
+void* CustomAllocator::Allocate(size_t size) {
+  if (arena_)
+    return LowLevelAlloc::AllocWithArena(size, arena_);
+
+  return LowLevelAlloc::Alloc(size);
+}
+
+// static
+void CustomAllocator::Free(void* ptr, size_t /* size */) {
+  LowLevelAlloc::Free(ptr);
+}
+
+// static
+LowLevelAlloc::Arena* CustomAllocator::arena_ = NULL;