VideoCaptureDeviceFactory: Change device enumeration to callback + QTKit enumerates in UI thread.

media/video/capture/file_video_capture_device_factory.h

 // Copyright 2014 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.
 
 #ifndef MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_FACTORY_H_
 #define MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_FACTORY_H_
 
 #include "media/video/capture/video_capture_device_factory.h"
 
 namespace media {
 
 // Extension of VideoCaptureDeviceFactory to create and manipulate file-backed
 // fake devices. These devices play back video-only files as video capture
 // input.
 class MEDIA_EXPORT FileVideoCaptureDeviceFactory :
     public VideoCaptureDeviceFactory {
  public:
   FileVideoCaptureDeviceFactory() {}
   virtual ~FileVideoCaptureDeviceFactory() {}
 
   virtual scoped_ptr<VideoCaptureDevice> Create(
-      scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
       const VideoCaptureDevice::Name& device_name) OVERRIDE;
   virtual void GetDeviceNames(VideoCaptureDevice::Names* device_names) OVERRIDE;
   virtual void GetDeviceSupportedFormats(
       const VideoCaptureDevice::Name& device,
       VideoCaptureFormats* supported_formats) OVERRIDE;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_FACTORY_H_