components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/custom_allocator.cc

Index: third_party/tcmalloc/chromium/src/custom_allocator.cc
diff --git a/third_party/tcmalloc/chromium/src/custom_allocator.cc b/third_party/tcmalloc/chromium/src/custom_allocator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e1fed44dd27fe125bbe0b379838388e0949e3be6
--- /dev/null
+++ b/third_party/tcmalloc/chromium/src/custom_allocator.cc
@@ -0,0 +1,52 @@
+// 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.
+
+#include <gperftools/custom_allocator.h>
+
+#include "base/low_level_alloc.h"
+
+static LowLevelAlloc::Arena* g_arena = nullptr;
+
+bool g_is_initalized_for_unit_test = false;
+
+// static
+void CustomAllocator::Initialize() {
+  g_arena = LowLevelAlloc::NewArena(0, LowLevelAlloc::DefaultArena());
+}
+
+// static
+bool CustomAllocator::Shutdown() {
+  if (!g_is_initalized_for_unit_test)
+    return LowLevelAlloc::DeleteArena(g_arena);
+  g_is_initalized_for_unit_test = false;
+  return true;
+}
+
+// static
+bool CustomAllocator::IsInitialized() {
+  return g_arena || g_is_initalized_for_unit_test;
+}
+
+void CustomAllocator::InitializeForUnitTest() {
+  g_is_initalized_for_unit_test = true;
+}
+
+// static
+void* CustomAllocator::Allocate(size_t size) {
+  if (g_is_initalized_for_unit_test)
+    return new char[size];
+
+  if (!g_arena)
+    return nullptr;
+
+  return LowLevelAlloc::AllocWithArena(size, g_arena);
+}
+
+// static
+void CustomAllocator::Free(void* ptr, size_t /* size */) {
+  if (g_is_initalized_for_unit_test)
+    delete [] reinterpret_cast<char*>(ptr);
+  else
+    LowLevelAlloc::Free(ptr);
+}