Add support for threadsafe completion callback factory.

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.
 
 {
   'target_defaults': {
     'variables': {
       'ppapi_proxy_target': 0,
     },
     'target_conditions': [
@@ skipping 125 matching lines @@
           'proxy/ppp_printing_proxy.cc',
           'proxy/ppp_printing_proxy.h',
           'proxy/ppp_text_input_proxy.cc',
           'proxy/ppp_text_input_proxy.h',
           'proxy/ppp_video_decoder_proxy.cc',
           'proxy/ppp_video_decoder_proxy.h',
           'proxy/proxy_array_output.cc',
           'proxy/proxy_array_output.h',
           'proxy/proxy_channel.cc',
           'proxy/proxy_channel.h',
+          'proxy/proxy_completion_callback_factory.h',
           'proxy/proxy_module.cc',
           'proxy/proxy_module.h',
           'proxy/proxy_object_var.cc',
           'proxy/proxy_object_var.h',
           'proxy/resource_creation_proxy.cc',
           'proxy/resource_creation_proxy.h',
           'proxy/resource_message_params.cc',
           'proxy/resource_message_params.h',
           'proxy/serialized_flash_menu.cc',
           'proxy/serialized_flash_menu.h',
@@ skipping 39 matching lines @@
               'proxy/ppp_instance_private_proxy.cc',
               'proxy/ppp_video_decoder_proxy.cc',
               'proxy/serialized_flash_menu.cc',
             ],
           }],
         ],
       }],
     ],
   },
 }