Fix md5_check.py crashing when adding a new zip file

build/android/gyp/util/md5_check.py

 # Copyright 2013 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.
 
 import difflib
 import hashlib
 import itertools
 import json
 import os
 import sys
@@ skipping 322 matching lines @@
     ret = self._GetEntry(path, subpath)
     return ret and ret['tag']
 
   def IterPaths(self):
     """Returns a generator for all top-level paths."""
     return (e['path'] for e in self._files)
 
   def IterSubpaths(self, path):
     """Returns a generator for all subpaths in the given zip.
 
-    If the given path is not a zip file, returns an empty generator.
+    If the given path is not a zip file or doesn't exist, returns an empty
+    iterable.
     """
     outer_entry = self._GetEntry(path)
+    if not outer_entry:
+      return ()
     subentries = outer_entry.get('entries', [])
     return (entry['path'] for entry in subentries)
 
 
 def _UpdateMd5ForFile(md5, path, block_size=2**16):
   with open(path, 'rb') as infile:
     while True:
       data = infile.read(block_size)
       if not data:
         break
@@ skipping 33 matching lines @@
 
 def _ExtractZipEntries(path):
   """Returns a list of (path, CRC32) of all files within |path|."""
   entries = []
   with zipfile.ZipFile(path) as zip_file:
     for zip_info in zip_file.infolist():
       # Skip directories and empty files.
       if zip_info.CRC:
         entries.append((zip_info.filename, zip_info.CRC))
   return entries