Got Exception:

Traceback (most recent call last):
  File "upload_screenshots_unittest.py", line 21, in test_find_screenshots
    os.path.join(testdata_path, 'translation_expectations.pyl'))
  File "D:\src\win\src\tools\translation\upload_screenshots.py", line 102, in find_screenshots
    repo_root, list_grds_in_repository(repo_root), translation_expectations)
  File "D:\src\win\src\tools\translation\upload_screenshots.py", line 83, in list_grds_in_repository
    ['git', 'ls-files', '--', '*.grd'], cwd=repo_path)
  File "D:\src\depot_tools\win_tools-2_7_6_bin\python\bin\lib\subprocess.py", line 566, in check_output
    process = Popen(stdout=PIPE, *popenargs, **kwargs)
  File "D:\src\depot_tools\win_tools-2_7_6_bin\python\bin\lib\subprocess.py", line 709, in __init__
    errread, errwrite)
  File "D:\src\depot_tools\win_tools-2_7_6_bin\python\bin\lib\subprocess.py", line 957, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified

Same error when run the unittest.

Change line 82-83 to
  output = subprocess.check_output(
      ['git', 'ls-files', '--', '*.grd'], cwd=repo_path, shell=True)
resolve the problem.

But I'm not sure if that will break other platforms.