Add a benchmarking_extension API to call TCMalloc's HeapProfilerDump().

content/renderer/memory_benchmarking_extension.h

+// Copyright (c) 2013 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 CONTENT_RENDERER_MEMORY_BENCHMARKING_EXTENSION_H_
+#define CONTENT_RENDERER_MEMORY_BENCHMARKING_EXTENSION_H_
+
+#include "v8/include/v8.h"
+
+namespace content {
+
+class MemoryBenchmarkingExtension {
+ public:
+  static v8::Extension* Get();
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEMORY_BENCHMARKING_EXTENSION_H_