Work around problem with corrupt npm cache on Mac.

build_apprtc_appengine_app.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 grunt build on AppRTC.
 
 The AppRTC javascript code must be closure-compiled. This script uses
 the node toolchain we downloaded earlier.
 """
 
 import fileinput
 import os
 import shutil
+import subprocess
 import sys
 
 import utils
 
 
 # Phantomjs generates very deep paths in the node_modules structure and
 # Windows can't deal with that, so just hack that out.
 def _WorkaroundPhantomJsOnWin(samples_path):
   if utils.GetPlatform() is 'win':
     package_json = os.path.join(samples_path, 'package.json')
     if not os.path.exists(package_json):
       raise Exception('Expected %s to exist.' % os.path.abspath(package_json))
 
     for line in fileinput.input(package_json, inplace=True):
       if not 'phantomjs' in line:
         sys.stdout.write(line)
 
 
+def _WorkAroundMacNpmCorruptedDataOnInstall(command):
+  print 'Wiping .npm folder and trying again...'
+  npm_storage = os.path.expanduser('~/.npm')
+  assert npm_storage.endswith('.npm')
+  shutil.rmtree(npm_storage, ignore_errors=True)
+  utils.RunSubprocessWithRetry(command)
+
+
 def main():
   node_path = os.path.abspath('node')
   if not os.path.exists(node_path):
     return 'Expected node at %s.' % node_path
   apprtc_path = os.path.join('src', 'out', 'apprtc')
   if not os.path.exists(apprtc_path):
     return 'Expected apprtc at %s.' % os.path.abspath(apprtc_path)
 
   _WorkaroundPhantomJsOnWin(apprtc_path)
   os.chdir(apprtc_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')
 
-  utils.RunSubprocessWithRetry([npm_bin, 'install'])
+  command = [npm_bin, 'install']
+  try:
+    utils.RunSubprocessWithRetry(command)
+  except subprocess.CalledProcessError:
+    if utils.GetPlatform() is not 'mac':
+      raise
+    _WorkAroundMacNpmCorruptedDataOnInstall(command)
+
   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 apprtc checkout; did '
             'npm install fail?')
 
   utils.RunSubprocessWithRetry([node_bin, local_grunt_bin, 'build'])
 
 
 if __name__ == '__main__':
   sys.exit(main())