Switch the about:gpu implementation from an about handler to dom_ui....

chrome/browser/dom_ui/gpu_ui.h

+// Copyright (c) 2010 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 CHROME_BROWSER_DOM_UI_GPU_UI_H_
+#define CHROME_BROWSER_DOM_UI_GPU_UI_H_
+#pragma once
+
+#include "chrome/browser/dom_ui/dom_ui.h"
+
+class GpuUI : public DOMUI {
+ public:
+  explicit GpuUI(TabContents* contents);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(GpuUI);
+};
+
+#endif  // CHROME_BROWSER_DOM_UI_GPU_UI_H_