old_contents: #!/usr/bin/env python
  # Copyright 2017 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.
  
  from __future__ import print_function
  
  import argparse
  import os
  import subprocess
  import sys
  
  
  # This function is inspired from the one in src/tools/vim/ninja-build.vim in the
  # Chromium repository.
  def path_to_source_root(path):
    """Returns the absolute path to the chromium source root."""
    candidate = os.path.dirname(path)
    # This is a list of directories that need to identify the src directory. The
    # shorter it is, the more likely it's wrong (checking for just
    # "build/common.gypi" would find "src/v8" for files below "src/v8", as
    # "src/v8/build/common.gypi" exists). The longer it is, the more likely it is
    # to break when we rename directories.
    fingerprints = ['chrome', 'net', 'v8', 'build', 'skia']
    while candidate and not all(
        [os.path.isdir(os.path.join(candidate, fp)) for fp in fingerprints]):
      new_candidate = os.path.dirname(candidate)
      if new_candidate == candidate:
        raise Exception("Couldn't find source-dir from %s" % path)
      candidate = os.path.dirname(candidate)
    return candidate
  
  
  def main():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '--file-path',
        help='The file path, could be absolute or relative to the current '
             'directory.',
        required=True)
    parser.add_argument(
        '--build-dir',
        help='The build directory, relative to the source directory.',
        required=True)
  
    options = parser.parse_args()
  
    src_dir = path_to_source_root(os.path.abspath(options.file_path))
    abs_build_dir = os.path.join(src_dir, options.build_dir)
    src_relpath = os.path.relpath(options.file_path, abs_build_dir)
  
    print('Building %s' % options.file_path)
  
    ninja_exec = 'ninja'
    carets = '^'
    # We need to make sure that we call the ninja executable, calling |ninja|
    # directly might end up calling a wrapper script that'll remove the caret
    # characters.
    if sys.platform == 'win32':
      ninja_exec = 'ninja.exe'
      # The caret character has to be escaped on Windows as it's an escape
      # character.
      carets = '^^'
  
    command = [
        ninja_exec,
        '-C', abs_build_dir,
        '%s%s' % (src_relpath, carets)
    ]
    # |shell| should be set to True on Windows otherwise the carets characters
    # get dropped from the command line.
    return subprocess.call(command, shell=sys.platform=='win32')
  
  
  if __name__ == '__main__':
    sys.exit(main())
  
new_contents: #!/usr/bin/env python
  # Copyright 2017 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.
  
  from __future__ import print_function
  
  import argparse
  import os
  import subprocess
  import sys
  
  
  # This function is inspired from the one in src/tools/vim/ninja-build.vim in the
  # Chromium repository.
  def path_to_source_root(path):
    """Returns the absolute path to the chromium source root."""
    candidate = os.path.dirname(path)
    # This is a list of directories that need to identify the src directory. The
    # shorter it is, the more likely it's wrong (checking for just
    # "build/common.gypi" would find "src/v8" for files below "src/v8", as
    # "src/v8/build/common.gypi" exists). The longer it is, the more likely it is
    # to break when we rename directories.
    fingerprints = ['chrome', 'net', 'v8', 'build', 'skia']
    while candidate and not all(
        [os.path.isdir(os.path.join(candidate, fp)) for fp in fingerprints]):
      new_candidate = os.path.dirname(candidate)
      if new_candidate == candidate:
        raise Exception("Couldn't find source-dir from %s" % path)
      candidate = os.path.dirname(candidate)
    return candidate
  
  
  def main():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '--file-path',
        help='The file path, could be absolute or relative to the current '
             'directory.',
        required=True)
    parser.add_argument(
        '--build-dir',
        help='The build directory, relative to the source directory. Jumbo '
             'builds aren\'t supported but you can create a non-jumbo build '
             'config just for this script and keep using jumbo in your regular '
             'builds.',
        required=True)
  
    options = parser.parse_args()
  
    src_dir = path_to_source_root(os.path.abspath(options.file_path))
    abs_build_dir = os.path.join(src_dir, options.build_dir)
    src_relpath = os.path.relpath(options.file_path, abs_build_dir)
  
    print('Building %s' % options.file_path)
  
    ninja_exec = 'ninja'
    carets = '^'
    # We need to make sure that we call the ninja executable, calling |ninja|
    # directly might end up calling a wrapper script that'll remove the caret
    # characters.
    if sys.platform == 'win32':
      ninja_exec = 'ninja.exe'
      # The caret character has to be escaped on Windows as it's an escape
      # character.
      carets = '^^'
  
    command = [
        ninja_exec,
        '-C', abs_build_dir,
        '%s%s' % (src_relpath, carets)
    ]
    # |shell| should be set to True on Windows otherwise the carets characters
    # get dropped from the command line.
    return subprocess.call(command, shell=sys.platform=='win32')
  
  
  if __name__ == '__main__':
    sys.exit(main())
  
subject: Make it clear that compile_single_file.py doesn't support Jumbo builds