Add Windows, Mac, Android support to low bandwidth audio test

tools-webrtc/download_tools.py

 #!/usr/bin/env python
 # Copyright (c) 2016 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.
 
 """Downloads precompiled tools.
 
 These are checked into the repository as SHA-1 hashes (see *.sha1 files in
 subdirectories). Note that chrome-webrtc-resources is a Google-internal bucket,
 so please download and compile these tools manually if this script fails.
 """
 
 import os
 import subprocess
 import sys
 
 
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+# Needed to properly resolve PATH and executable extensions on Windows.

[kjellander_webrtc, 2017/03/27 09:05:10]

Skip the "and executable extensions" part in this script, since it's not used.

[oprypin_webrtc, 2017/03/27 09:19:07]

I think it is actually still relevant to resolve the extension for
download_from_google_storage.bat - I read somewhere that only .exe are resolved
automatically but can't find that reference anymore.

[kjellander_webrtc, 2017/03/27 09:46:51]

Ah, I see now. I somehow confused this in my head with that you would append
extensions, but you're talking about using the shell to auto-resolve extensions.
I'm sure windows cmd.exe auto-resolves .bat, so yes let's  keep this as is.

+USE_SHELL = sys.platform == 'win32'
 
 
 def main(directories):
   if not directories:
     directories = [SCRIPT_DIR]
 
   for path in directories:
     cmd = [
       'download_from_google_storage',
       '--directory',
       '--num_threads=10',
       '--bucket', 'chrome-webrtc-resources',
       '--auto_platform',
       '--recursive',
       path,
     ]
     print 'Downloading precompiled tools...'
-    subprocess.check_call(cmd)
+    subprocess.check_call(cmd, shell=USE_SHELL)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))