Retry npm calls since they seem a bit unreliable.

build_apprtc_closure.py

 #!/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.
 
 """Invokes the AppRTC closure compiler.
 
 The AppRTC javascript code must be closure-compiled. This script uses
 the node toolchain we downloaded earlier.
 """
 
 import os
 import shutil
-import subprocess
 import sys
 
 import utils
 
 
 def main():
   node_path = os.path.abspath('node')
   if not os.path.exists(node_path):
     return 'Expected node at %s.' % node_path
   samples_path = os.path.join('src', 'out', 'webrtc-samples')
   if not os.path.exists(samples_path):
     return 'Expected webrtc-samples at %s.' % os.path.abspath(samples_path)
 
   os.chdir(samples_path)
   
   if utils.GetPlatform() is 'win':
     npm_bin = os.path.join(node_path, 'npm.cmd')
     node_bin = os.path.join(node_path, 'node.exe')
   else:
     npm_bin = os.path.join(node_path, 'bin', 'npm')
     node_bin = os.path.join(node_path, 'bin', 'node')
 
-  subprocess.check_call([npm_bin, 'install'])
+  utils.RunSubprocessWithRetry([npm_bin, 'install'])
   local_grunt_bin = os.path.join('node_modules', 'grunt-cli', 'bin', 'grunt')
 
   if not os.path.exists(local_grunt_bin):
     return ('Missing grunt-cli in the webrtc-samples checkout; did '
             'npm install fail?')
 
-  subprocess.check_call([node_bin, local_grunt_bin, 'closurecompiler:debug'])
+  utils.RunSubprocessWithRetry([node_bin, local_grunt_bin,
+                               'closurecompiler:debug'])
 
 
 if __name__ == '__main__':
   sys.exit(main())