added gpu_benchmarking_extension boilerplate and hooked it up to a new switch.

content/renderer/gpu/gpu_benchmarking_extension.cc

+// 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.
+
+#include "content/renderer/gpu/gpu_benchmarking_extension.h"
+
+#include "v8/include/v8.h"
+
+const char kGpuBenchmarkingExtensionName[] = "v8/GpuBenchmarking";
+
+namespace content {
+
+class GpuBenchmarkingWrapper : public v8::Extension {
+ public:
+  GpuBenchmarkingWrapper() :
+      v8::Extension(kGpuBenchmarkingExtensionName,
+          "if (typeof(chrome) == 'undefined') {"
+          "  chrome = {};"
+          "};"
+          "if (typeof(chrome.gpuBenchmarking) == 'undefined') {"
+          "  chrome.gpuBenchmarking = {};"
+          "};") {}
+
+  virtual v8::Handle<v8::FunctionTemplate> GetNativeFunction(
+      v8::Handle<v8::String> name) {
+    return v8::Handle<v8::FunctionTemplate>();
+  }
+};
+
+v8::Extension* GpuBenchmarkingExtension::Get() {
+  return new GpuBenchmarkingWrapper();
+}
+
+}  // namespace content