Revert 180055: Very likely caused http://crbug.com/173885

content/browser/tracing/tracing_ui.h

-// Copyright (c) 2011 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_BROWSER_TRACING_UI_H_
-#define CONTENT_BROWSER_TRACING_UI_H_
-
-#include "content/public/browser/web_ui_controller.h"
-
-namespace content {
-
-// The C++ back-end for the chrome://tracing webui page.
-class TracingUI : public WebUIController {
- public:
-  explicit TracingUI(WebUI* web_ui);
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(TracingUI);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_TRACING_UI_H_