Use PluginPrefs in ChromePluginServiceFilter to check whether a plugin is enabled.

content/content_browser.gypi

 # Copyright (c) 2011 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': 'content_browser',
       'type': 'static_library',
       'dependencies': [
@@ skipping 243 matching lines @@
         'browser/power_save_blocker_win.cc',
         'browser/ppapi_plugin_process_host.cc',
         'browser/ppapi_plugin_process_host.h',
         'browser/ppapi_broker_process_host.cc',
         'browser/ppapi_broker_process_host.h',
         'browser/plugin_process_host.cc',
         'browser/plugin_process_host.h',
         'browser/plugin_process_host_mac.cc',
         'browser/plugin_service.cc',
         'browser/plugin_service.h',
+        'browser/plugin_service_filter.h',
         'browser/quota_permission_context.h',
         'browser/renderer_host/accelerated_surface_container_mac.cc',
         'browser/renderer_host/accelerated_surface_container_mac.h',
         'browser/renderer_host/accelerated_surface_container_manager_mac.cc',
         'browser/renderer_host/accelerated_surface_container_manager_mac.h',
         'browser/renderer_host/async_resource_handler.cc',
         'browser/renderer_host/async_resource_handler.h',
         'browser/renderer_host/backing_store.cc',
         'browser/renderer_host/backing_store.h',
         'browser/renderer_host/backing_store_mac.h',
@@ skipping 263 matching lines @@
             'mac_bundle_resources': [
               'browser/gpu.sb',
               'browser/worker.sb',
             ],
           },
         }],
       ],
     },
   ],
 }