Add a template to handle properly issuing completion callbacks. This fixes

ppapi/ppapi_shared.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': 'ppapi_shared',
       'type': 'static_library',
       'dependencies': [
@@ skipping 50 matching lines @@
         'shared_impl/webkit_forwarding.cc',
         'shared_impl/webkit_forwarding.h',
 
         'thunk/common.h',
         'thunk/common.cc',
         'thunk/enter.h',
         'thunk/ppb_audio_api.h',
         'thunk/ppb_audio_config_api.h',
         'thunk/ppb_audio_config_thunk.cc',
         'thunk/ppb_audio_thunk.cc',
-        'thunk/ppb_audio_trusted_api.h',
         'thunk/ppb_audio_trusted_thunk.cc',
         'thunk/ppb_broker_api.h',
         'thunk/ppb_broker_thunk.cc',
         'thunk/ppb_buffer_api.h',
         'thunk/ppb_buffer_thunk.cc',
         'thunk/ppb_buffer_trusted_api.h',
         'thunk/ppb_buffer_trusted_thunk.cc',
         'thunk/ppb_char_set_api.h',
         'thunk/ppb_char_set_thunk.cc',
         'thunk/ppb_context_3d_api.h',
@@ skipping 58 matching lines @@
         'thunk/ppb_video_layer_api.h',
         'thunk/ppb_video_layer_thunk.cc',
         'thunk/ppb_widget_api.h',
         'thunk/ppb_widget_thunk.cc',
         'thunk/ppb_zoom_thunk.cc',
         'thunk/thunk.h',
       ],
     },
   ],
 }