Enable shadow DOM-based "missing plugin" placeholder.

chrome/chrome_renderer.gypi

 # 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.
 
 {
   'variables': {
     'chrome_renderer_sources': [
       'renderer/benchmarking_extension.cc',
       'renderer/benchmarking_extension.h',
       'renderer/isolated_world_ids.h',
@@ skipping 43 matching lines @@
       'renderer/content_settings_observer.h',
       'renderer/custom_menu_commands.h',
       'renderer/external_extension.cc',
       'renderer/external_extension.h',
       'renderer/page_load_histograms.cc',
       'renderer/page_load_histograms.h',
       'renderer/plugins/chrome_plugin_placeholder.cc',
       'renderer/plugins/chrome_plugin_placeholder.h',
       'renderer/plugins/plugin_uma.cc',
       'renderer/plugins/plugin_uma.h',
+      'renderer/plugins/shadow_dom_plugin_placeholder.cc',
+      'renderer/plugins/shadow_dom_plugin_placeholder.h',
       'renderer/prefetch_helper.cc',
       'renderer/prefetch_helper.h',
       'renderer/prerender/prerender_dispatcher.cc',
       'renderer/prerender/prerender_dispatcher.h',
       'renderer/prerender/prerender_extra_data.cc',
       'renderer/prerender/prerender_extra_data.h',
       'renderer/prerender/prerender_helper.cc',
       'renderer/prerender/prerender_helper.h',
       'renderer/prerender/prerenderer_client.cc',
       'renderer/prerender/prerenderer_client.h',
@@ skipping 328 matching lines @@
               'export_dependent_settings': [
                 '<(allocator_target)',
               ],
             }],
           ],
         }],
       ],
     },
   ],
 }