Remove platform_video_capturing_mac and the callback thread checker in VideoCaptureDeviceAVFoundati…

media/capture/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 import("//media/media_options.gni")
 import("//testing/test.gni")
 
 source_set("capture") {
   sources = [
@@ skipping 27 matching lines @@
     "video/file_video_capture_device.h",
     "video/file_video_capture_device_factory.cc",
     "video/file_video_capture_device_factory.h",
     "video/linux/v4l2_capture_delegate.cc",
     "video/linux/video_capture_device_chromeos.cc",
     "video/linux/video_capture_device_chromeos.h",
     "video/linux/video_capture_device_factory_linux.cc",
     "video/linux/video_capture_device_factory_linux.h",
     "video/linux/video_capture_device_linux.cc",
     "video/linux/video_capture_device_linux.h",
-    "video/mac/platform_video_capturing_mac.h",
     "video/mac/video_capture_device_avfoundation_mac.h",
     "video/mac/video_capture_device_avfoundation_mac.mm",
     "video/mac/video_capture_device_decklink_mac.h",
     "video/mac/video_capture_device_decklink_mac.mm",
     "video/mac/video_capture_device_factory_mac.h",
     "video/mac/video_capture_device_factory_mac.mm",
     "video/mac/video_capture_device_mac.h",
     "video/mac/video_capture_device_mac.mm",
     "video/video_capture_device.cc",
     "video/video_capture_device.h",
@@ skipping 88 matching lines @@
 
   deps = [
     "//media/base:unittests",
     "//testing/gmock",
     "//testing/gtest",
   ]
 
   # TODO(mcasas): Fix size_t to int truncation warning-treated-as-errors.
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 }