Remove old downloads UI; Material Design version is now the default.

chrome/browser/ui/webui/downloads_ui.h

-// 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.
-
-#ifndef CHROME_BROWSER_UI_WEBUI_DOWNLOADS_UI_H_
-#define CHROME_BROWSER_UI_WEBUI_DOWNLOADS_UI_H_
-
-#include "base/macros.h"
-#include "content/public/browser/web_ui_controller.h"
-#include "ui/base/layout.h"
-
-namespace base {
-class RefCountedMemory;
-}
-
-class DownloadsUI : public content::WebUIController {
- public:
-  explicit DownloadsUI(content::WebUI* web_ui);
-
-  static base::RefCountedMemory* GetFaviconResourceBytes(
-      ui::ScaleFactor scale_factor);
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(DownloadsUI);
-};
-
-#endif  // CHROME_BROWSER_UI_WEBUI_DOWNLOADS_UI_H_