Remove platform_video_capturing_mac and the callback thread checker in VideoCaptureDeviceAVFoundati…

media/capture/video/mac/video_capture_device_avfoundation_mac.mm

 // Copyright 2013 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 "media/capture/video/mac/video_capture_device_avfoundation_mac.h"
 
 #import <CoreMedia/CoreMedia.h>
 #import <CoreVideo/CoreVideo.h>
 #include <stddef.h>
 #include <stdint.h>
@@ skipping 233 matching lines @@
       setSampleBufferDelegate:self
                         queue:dispatch_get_global_queue(
                                   DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)];
   [captureSession_ addOutput:captureVideoDataOutput_];
   return YES;
 }
 
 - (BOOL)setCaptureHeight:(int)height
                    width:(int)width
                frameRate:(float)frameRate {
-  // Check if either of VideoCaptureDeviceMac::AllocateAndStart() or
-  // VideoCaptureDeviceMac::ReceiveFrame() is calling here, depending on the
-  // running state. VCDM::ReceiveFrame() calls here to change aspect ratio.
-  DCHECK((![captureSession_ isRunning] &&
-          main_thread_checker_.CalledOnValidThread()) ||
-         callback_thread_checker_.CalledOnValidThread());
+  DCHECK(![captureSession_ isRunning] &&
+         main_thread_checker_.CalledOnValidThread());
 
   frameWidth_ = width;
   frameHeight_ = height;
   frameRate_ = frameRate;
 
   FourCharCode best_fourcc = kCVPixelFormatType_422YpCbCr8;
   const bool prefer_mjpeg =
       width > kMjpegWidthThreshold || height > kMjpegHeightThreshold;
   for (CrAVCaptureDeviceFormat* format in captureDevice_.formats) {
     const FourCharCode fourcc =
@@ skipping 73 matching lines @@
 - (void)stopCapture {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   if ([captureSession_ isRunning])
     [captureSession_ stopRunning];  // Synchronous.
   [[NSNotificationCenter defaultCenter] removeObserver:self];
 }
 
 #pragma mark Private methods
 
 // |captureOutput| is called by the capture device to deliver a new frame.
+// AVFoundation calls from a number of threads, depending on, at least, if
+// Chrome is on foreground or background.
 - (void)captureOutput:(CrAVCaptureOutput*)captureOutput
 didOutputSampleBuffer:(CoreMediaGlue::CMSampleBufferRef)sampleBuffer
        fromConnection:(CrAVCaptureConnection*)connection {
-  // AVFoundation calls from a number of threads, depending on, at least, if
-  // Chrome is on foreground or background. Sample the actual thread here.
-  callback_thread_checker_.DetachFromThread();
-  CHECK(callback_thread_checker_.CalledOnValidThread());
-
   const CoreMediaGlue::CMFormatDescriptionRef formatDescription =
       CoreMediaGlue::CMSampleBufferGetFormatDescription(sampleBuffer);
   const FourCharCode fourcc =
       CoreMediaGlue::CMFormatDescriptionGetMediaSubType(formatDescription);
   const CoreMediaGlue::CMVideoDimensions dimensions =
       CoreMediaGlue::CMVideoFormatDescriptionGetDimensions(formatDescription);
   const media::VideoCaptureFormat captureFormat(
       gfx::Size(dimensions.width, dimensions.height), frameRate_,
       FourCCToChromiumPixelFormat(fourcc));
 
@@ skipping 56 matching lines @@
 }
 
 - (void)sendErrorString:(NSString*)error {
   DLOG(ERROR) << [error UTF8String];
   base::AutoLock lock(lock_);
   if (frameReceiver_)
     frameReceiver_->ReceiveError(FROM_HERE, [error UTF8String]);
 }
 
 @end