Land prep work to enable NaCl in the Linux x64 GN builds.

ppapi/thunk/BUILD.gn

 # Copyright 2015 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.
 
 source_set("thunk") {
   sources = [
     "enter.cc",
     "enter.h",
     "ppb_audio_api.h",
     "ppb_audio_buffer_api.h",
@@ skipping 102 matching lines @@
     "ppb_url_loader_api.h",
     "ppb_url_loader_thunk.cc",
     "ppb_url_loader_trusted_thunk.cc",
     "ppb_url_request_info_api.h",
     "ppb_url_request_info_thunk.cc",
     "ppb_url_response_info_api.h",
     "ppb_url_response_info_thunk.cc",
     "ppb_var_array_thunk.cc",
     "ppb_var_dictionary_thunk.cc",
     "ppb_video_capture_api.h",
-    "ppb_video_capture_thunk.cc",
     "ppb_video_decoder_api.h",
     "ppb_video_decoder_dev_api.h",
     "ppb_video_decoder_thunk.cc",
     "ppb_video_destination_private_api.h",
     "ppb_video_destination_private_thunk.cc",
     "ppb_video_encoder_api.h",
     "ppb_video_encoder_thunk.cc",
     "ppb_video_frame_api.h",
     "ppb_video_frame_thunk.cc",
     "ppb_video_source_private_api.h",
@@ skipping 28 matching lines @@
       "ppb_flash_fullscreen_thunk.cc",
       "ppb_flash_menu_thunk.cc",
       "ppb_flash_message_loop_thunk.cc",
       "ppb_flash_thunk.cc",
       "ppb_gles_chromium_texture_mapping_thunk.cc",
       "ppb_pdf_thunk.cc",
       "ppb_platform_verification_private_thunk.cc",
       "ppb_scrollbar_thunk.cc",
       "ppb_talk_private_thunk.cc",
       "ppb_url_util_thunk.cc",
+      "ppb_video_capture_thunk.cc",
       "ppb_video_decoder_dev_thunk.cc",
     ]
   }
 
   # We exclude a few more things for nacl_win64, to avoid pulling in more
   # dependencies.
   # TODO(GYP) this isn't correct. This should only be specifically for the
   # nacl_win64 build (cross-compiled for a 32-bit Chrome), rather than all
   # 64-bit builds.
   # See also //ppapi/shared_impl
   if (is_win && current_cpu == "x64" && current_toolchain != default_toolchain) {
     sources += [
       "ppb_graphics_3d_thunk.cc",
       "ppb_host_resolver_private_thunk.cc",
       "ppb_tcp_server_socket_private_thunk.cc",
       "ppb_tcp_socket_private_thunk.cc",
       "ppb_udp_socket_private_thunk.cc",
       "ppb_x509_certificate_private_thunk.cc",
     ]
   }
 
   defines = [ "PPAPI_THUNK_IMPLEMENTATION" ]
 }