PPAPI: Make CompletionCallbacks work right on background threads.

ppapi/ppapi_shared.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': {
     'conditions': [
       ['inside_chromium_build==0', {
         'webkit_src_dir': '../../../..',
       },{
@@ skipping 52 matching lines @@
           'shared_impl/ppb_gamepad_shared.h',
           'shared_impl/ppb_graphics_3d_shared.cc',
           'shared_impl/ppb_graphics_3d_shared.h',
           'shared_impl/ppb_image_data_shared.cc',
           'shared_impl/ppb_image_data_shared.h',
           'shared_impl/ppb_input_event_shared.cc',
           'shared_impl/ppb_input_event_shared.h',
           'shared_impl/ppb_instance_shared.cc',
           'shared_impl/ppb_instance_shared.h',
           'shared_impl/ppb_memory_shared.cc',
+          'shared_impl/ppb_message_loop_shared.cc',
+          'shared_impl/ppb_message_loop_shared.h',
           'shared_impl/ppb_network_list_private_shared.cc',
           'shared_impl/ppb_network_list_private_shared.h',
           'shared_impl/ppb_opengles2_shared.cc',
           'shared_impl/ppb_opengles2_shared.h',
           'shared_impl/ppb_resource_array_shared.cc',
           'shared_impl/ppb_resource_array_shared.h',
           'shared_impl/ppb_url_util_shared.cc',
           'shared_impl/ppb_url_util_shared.h',
           'shared_impl/ppb_var_shared.cc',
           'shared_impl/ppb_var_shared.h',
@@ skipping 231 matching lines @@
               'thunk/ppb_tcp_socket_private_thunk.cc',
               'thunk/ppb_udp_socket_private_thunk.cc',
               'thunk/ppb_x509_certificate_private_thunk.cc',
             ],
           }],
         ],
       }],
     ],
   },
 }