HostResolver is exposed to plugin.

ppapi/ppapi_proxy.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.
 
 {
   'targets': [
     {
       'target_name': 'ppapi_proxy',
       'type': '<(component)',
       'dependencies': [
@@ skipping 79 matching lines @@
         'proxy/ppb_flash_menu_proxy.cc',
         'proxy/ppb_flash_menu_proxy.h',
         'proxy/ppb_flash_message_loop_proxy.cc',
         'proxy/ppb_flash_message_loop_proxy.h',
         'proxy/ppb_flash_net_connector_proxy.cc',
         'proxy/ppb_flash_net_connector_proxy.h',
         'proxy/ppb_graphics_2d_proxy.cc',
         'proxy/ppb_graphics_2d_proxy.h',
         'proxy/ppb_graphics_3d_proxy.cc',
         'proxy/ppb_graphics_3d_proxy.h',
+        'proxy/ppb_host_resolver_private_proxy.cc',
+        'proxy/ppb_host_resolver_private_proxy.h',
         'proxy/ppb_image_data_proxy.cc',
         'proxy/ppb_image_data_proxy.h',
         'proxy/ppb_instance_proxy.cc',
         'proxy/ppb_instance_proxy.h',
         'proxy/ppb_message_loop_proxy.cc',
         'proxy/ppb_message_loop_proxy.h',
         'proxy/ppb_pdf_proxy.cc',
         'proxy/ppb_pdf_proxy.h',
         'proxy/ppb_tcp_socket_private_proxy.cc',
         'proxy/ppb_tcp_socket_private_proxy.h',
@@ skipping 46 matching lines @@
         'proxy/serialized_var.cc',
         'proxy/serialized_var.h',
         'proxy/var_serialization_rules.h',
       ],
       'defines': [
         'PPAPI_PROXY_IMPLEMENTATION',
       ],
     },
   ],
 }