new_contents: #!/usr/bin/env python
  #  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  #
  #  Use of this source code is governed by a BSD-style license
  #  that can be found in the LICENSE file in the root of the source
  #  tree. An additional intellectual property rights grant can be found
  #  in the file PATENTS.  All contributing project authors may
  #  be found in the AUTHORS file in the root of the source tree.
  
  """Checks if a virtual webcam is running and starts it if not.
  
  Returns a non-zero return code if the webcam could not be started.
  
  Prerequisites:
  * Python must have the psutil package installed.
  * Windows: a scheduled task named 'ManyCam' must exist and be configured to
    launch ManyCam preconfigured to auto-play the test clip.
  * Mac: ManyCam must be installed in the default location and be preconfigured
    to auto-play the test clip.
  * Linux: The v4l2loopback must be loaded to the kernel already (with the
    devices=2 argument) and the v4l2_file_player application must be compiled and
    put in the location specified below.
  """
  
  import psutil
  import subprocess
  import sys
  
  
  WEBCAM_WIN = ['schtasks', '/run', '/tn', 'ManyCam']
  WEBCAM_MAC = ['open', '/Applications/ManyCam/ManyCam.app']
  WEBCAM_LINUX = (
      '$HOME/fake-webcam-driver/linux/v4l2_file_player/v4l2_file_player '
      '$HOME/webrtc_video_quality/reference_video.yuv 640 480 /dev/video1 &')
  
  
  def IsWebCamRunning():
    if sys.platform == 'win32':
      process_name = 'ManyCam.exe'
    elif sys.platform.startswith('darwin'):
      process_name = 'ManyCam'
    elif sys.platform.startswith('linux'):
      process_name = 'v4l2_file_player'
    else:
      raise Exception('Unsupported platform: %s' % sys.platform)
    for p in psutil.get_process_list():
      if process_name == p.name:
        print 'Found a running virtual webcam (%s with PID %s)' % (p.name, p.pid)
        return True
    return False
  
  
  def Main():
    if IsWebCamRunning():
      return 0
  
    try:
      if sys.platform == 'win32':
        subprocess.check_call(WEBCAM_WIN)
      elif sys.platform.startswith('darwin'):
        subprocess.check_call(WEBCAM_MAC)
      elif sys.platform.startswith('linux'):
        subprocess.check_call(WEBCAM_LINUX, shell=True)
  
      print 'Successfully launched virtual webcam.'
      return 0
  
    except Exception as e:
      print 'Failed to launch virtual webcam: %s' % e
  
  
  if __name__ == '__main__':
    sys.exit(Main())
  
subject: Add script to ensure virtual webcam is running.