old_contents: #!/usr/bin/python
  # Copyright 2015 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.
  
  """Pulls down the current dart sdk to third_party/dart-sdk/."""
  
  import os
  import subprocess
  import sys
  
  # Path constants. (All of these should be absolute paths.)
  THIS_DIR = os.path.abspath(os.path.dirname(__file__))
  CHROMIUM_DIR = os.path.abspath(os.path.join(THIS_DIR, '..', '..'))
  DART_SDK_DIR = os.path.join(CHROMIUM_DIR, 'third_party', 'dart-sdk')
  
  # TODO(erg): We might want 32 bit linux too? I don't know of anyone who still
  # uses that though. It looks like clang isn't built 32 bit.
  
  LINUX_64_SDK = ('http://gsdview.appspot.com/dart-archive/channels/dev/' +
                  'raw/43808/sdk/dartsdk-linux-x64-release.zip')
  
  OUTPUT_FILE = os.path.join(DART_SDK_DIR, 'dartsdk-linux-x64-release.zip')
  
  def RunCommand(command, fail_hard=True):
    """Run command and return success (True) or failure; or if fail_hard is
       True, exit on failure."""
  
    print 'Running %s' % (str(command))
    if subprocess.call(command, shell=False) == 0:
      return True
    print 'Failed.'
    if fail_hard:
      sys.exit(1)
    return False
  
  def main():
    # For version one, we don't actually redownload if the sdk is already
    # present. This will be replaced with download_from_google_storage once
    # it supports tarballs.
    #
    # You can explicitly redownload this by blowing away your
    # third_party/dart-sdk/ directory.
    if not os.path.exists(OUTPUT_FILE):
      wget_command = ['wget', '-N', '-c', LINUX_64_SDK, '-P', DART_SDK_DIR]
      if not RunCommand(wget_command, fail_hard=False):
        print "Failed to get dart sdk from server."
        return
  
      unzip_command = ['unzip', '-q', OUTPUT_FILE, '-d', DART_SDK_DIR]
      if not RunCommand(unzip_command, fail_hard=False):
        print "Failed to unzip the dart sdk."
  
  if __name__ == '__main__':
    sys.exit(main())
  
new_contents: #!/usr/bin/python
  # Copyright 2015 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.
  
  """Pulls down the current dart sdk to third_party/dart-sdk/.
  
  You can manually force this to run again by removing
  third_party/dart-sdk/STAMP_FILE, which contains the URL of the SDK that
  was downloaded. Rolling works by updating LINUX_64_SDK to a new URL.
  """
  
  import os
  import shutil
  import subprocess
  import sys
  
  # How to roll the dart sdk: Just change this url! We write this to the stamp
  # file after we download, and then check the stamp file for differences.
  LINUX_64_SDK = ('http://gsdview.appspot.com/dart-archive/channels/dev/' +
                  'raw/43903/sdk/dartsdk-linux-x64-release.zip')
  
  # Path constants. (All of these should be absolute paths.)
  THIS_DIR = os.path.abspath(os.path.dirname(__file__))
  CHROMIUM_DIR = os.path.abspath(os.path.join(THIS_DIR, '..', '..'))
  DART_SDK_DIR = os.path.join(CHROMIUM_DIR, 'third_party', 'dart-sdk')
  OUTPUT_FILE = os.path.join(DART_SDK_DIR, 'dartsdk-linux-x64-release.zip')
  STAMP_FILE = os.path.join(DART_SDK_DIR, 'STAMP_FILE')
  
  def RunCommand(command, fail_hard=True):
    """Run command and return success (True) or failure; or if fail_hard is
       True, exit on failure."""
  
    print 'Running %s' % (str(command))
    if subprocess.call(command, shell=False) == 0:
      return True
    print 'Failed.'
    if fail_hard:
      sys.exit(1)
    return False
  
  def main():
    # Only get the SDK if we don't have a stamp for or have an out of date stamp
    # file.
    get_sdk = False
    if not os.path.exists(STAMP_FILE):
      get_sdk = True
    else:
      # Get the contents of the stamp file.
      with open(STAMP_FILE, "r") as stamp_file:
        stamp_url = stamp_file.read().replace('\n', '')
        if stamp_url != LINUX_64_SDK:
          get_sdk = True
  
    if get_sdk:
      # Completely remove all traces of the previous SDK.
      shutil.rmtree(DART_SDK_DIR)
      os.mkdir(DART_SDK_DIR)
  
      wget_command = ['wget', '-N', '-c', LINUX_64_SDK, '-P', DART_SDK_DIR]
      if not RunCommand(wget_command, fail_hard=False):
        print "Failed to get dart sdk from server."
        return
  
      unzip_command = ['unzip', '-o', '-q', OUTPUT_FILE, '-d', DART_SDK_DIR]
      if not RunCommand(unzip_command, fail_hard=False):
        print "Failed to unzip the dart sdk."
  
      # Write our stamp file so we don't redownload the sdk.
      with open(STAMP_FILE, "w") as stamp_file:
        stamp_file.write(LINUX_64_SDK)
  
  if __name__ == '__main__':
    sys.exit(main())
  
subject: Update the script that downloads the dart sdk so we can roll it.