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

chrome/browser/ui/webui/downloads_ui_browsertest.h

-// Copyright 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 CHROME_BROWSER_UI_WEBUI_DOWNLOADS_UI_BROWSERTEST_H_
-#define CHROME_BROWSER_UI_WEBUI_DOWNLOADS_UI_BROWSERTEST_H_
-
-#include "base/macros.h"
-#include "chrome/test/base/web_ui_browser_test.h"
-
-// This is a helper class used by downloads_ui_browsertest.js.
-class DownloadsUIBrowserTest : public WebUIBrowserTest {
- public:
-  DownloadsUIBrowserTest();
-  ~DownloadsUIBrowserTest() override;
-
-  // WebUIBrowserTest:
-  void SetUpCommandLine(base::CommandLine* command_line) override;
-
- protected:
-  // Sets the pref to allow or prohibit deleting history entries.
-  void SetDeleteAllowed(bool allowed);
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(DownloadsUIBrowserTest);
-};
-
-#endif  // CHROME_BROWSER_UI_WEBUI_DOWNLOADS_UI_BROWSERTEST_H_