Mac QTKit Video Capture: Run QTCaptureSession teardown in UI thread, clean up -stopCapture use.

media/video/capture/mac/video_capture_device_mac.mm

 // Copyright (c) 2012 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.
 
 #include "media/video/capture/mac/video_capture_device_mac.h"
 
 #include <IOKit/IOCFPlugIn.h>
 #include <IOKit/usb/IOUSBLib.h>
 #include <IOKit/usb/USBSpec.h>
 
@@ skipping 422 matching lines @@
     SetErrorState("Could not start capture device.");
     return;
   }
 
   state_ = kCapturing;
 }
 
 void VideoCaptureDeviceMac::StopAndDeAllocate() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(state_ == kCapturing || state_ == kError) << state_;
-  [capture_device_ stopCapture];
 
   [capture_device_ setCaptureDevice:nil];
   [capture_device_ setFrameReceiver:nil];
   client_.reset();
   state_ = kIdle;
   tried_to_square_pixels_ = false;
 }
 
 bool VideoCaptureDeviceMac::Init(
     VideoCaptureDevice::Name::CaptureApiType capture_api_type) {
@@ skipping 121 matching lines @@
   if (![capture_device_ setCaptureHeight:capture_format_.frame_size.height()
                                    width:capture_format_.frame_size.width()
                                frameRate:capture_format_.frame_rate]) {
     ReceiveError("Could not configure capture device.");
     return false;
   }
   return true;
 }
 
 } // namespace media