Delete the NPAPI plugin browsertests.

content/test/plugin/plugin_windowed_test.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 CONTENT_TEST_PLUGIN_PLUGIN_WINDOWED_TEST_H_
-#define CONTENT_TEST_PLUGIN_PLUGIN_WINDOWED_TEST_H_
-
-#include "content/test/plugin/plugin_test.h"
-
-namespace NPAPIClient {
-
-// This class contains a list of windowed plugin tests. Please add additional
-// tests to this class.
-class WindowedPluginTest : public PluginTest {
- public:
-  WindowedPluginTest(NPP id, NPNetscapeFuncs *host_functions);
-  ~WindowedPluginTest() override;
-
- private:
-  static LRESULT CALLBACK WindowProc(
-      HWND window, UINT message, WPARAM wparam, LPARAM lparam);
-  static void CallJSFunction(WindowedPluginTest*, const char*);
-
-  NPError SetWindow(NPWindow* pNPWindow) override;
-  NPError Destroy() override;
-
-  HWND window_;
-  bool done_;
-};
-
-}  // namespace NPAPIClient
-
-#endif  // CONTENT_TEST_PLUGIN_PLUGIN_WINDOWED_TEST_H_