Remove platform_video_capturing_mac and the callback thread checker in VideoCaptureDeviceAVFoundati…

media/capture.gypi

 # Copyright 2016 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.
 
 {
   'defines': [
     'MEDIA_IMPLEMENTATION',
   ],
   'variables': {
     # GN version: //media/capture:capture
@@ skipping 29 matching lines @@
       'capture/video/file_video_capture_device_factory.cc',
       'capture/video/file_video_capture_device_factory.h',
       'capture/video/linux/v4l2_capture_delegate.cc',
       'capture/video/linux/v4l2_capture_delegate.h',
       'capture/video/linux/video_capture_device_chromeos.cc',
       'capture/video/linux/video_capture_device_chromeos.h',
       'capture/video/linux/video_capture_device_factory_linux.cc',
       'capture/video/linux/video_capture_device_factory_linux.h',
       'capture/video/linux/video_capture_device_linux.cc',
       'capture/video/linux/video_capture_device_linux.h',
-      'capture/video/mac/platform_video_capturing_mac.h',
       'capture/video/mac/video_capture_device_avfoundation_mac.h',
       'capture/video/mac/video_capture_device_avfoundation_mac.mm',
       'capture/video/mac/video_capture_device_decklink_mac.h',
       'capture/video/mac/video_capture_device_decklink_mac.mm',
       'capture/video/mac/video_capture_device_factory_mac.h',
       'capture/video/mac/video_capture_device_factory_mac.mm',
       'capture/video/mac/video_capture_device_mac.h',
       'capture/video/mac/video_capture_device_mac.mm',
       'capture/video/video_capture_device.cc',
       'capture/video/video_capture_device.h',
@@ skipping 37 matching lines @@
     'conditions': [
       ['OS=="linux" and use_udev==1', {
         'capture_sources': [
           'capture/device_monitor_udev.cc',
           'capture/device_monitor_udev.h',
         ],
       }],
     ],
   },
 }