Remove content/public/plugin and chrome/plugin

chrome/chrome_plugin.gypi

-# Copyright 2014 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.
-
-{
-  'targets': [
-    {
-      'target_name': 'plugin',
-      'type': 'static_library',
-      'variables': { 'enable_wexit_time_destructors': 1, },
-      'dependencies': [
-        '../base/base.gyp:base',
-        '../gin/gin.gyp:gin',
-        'chrome_features.gyp:chrome_common_features',
-        'chrome_resources.gyp:chrome_strings',
-      ],
-      'include_dirs': [
-        '..',
-        '<(grit_out_dir)',
-      ],
-      'sources': [
-        'plugin/chrome_content_plugin_client.cc',
-        'plugin/chrome_content_plugin_client.h',
-      ],
-    },
-  ],
-}