Fix some make_expectations.py issues.

tools/perf_expectations/make_expectations.py

 #!/usr/bin/python
 # Copyright (c) 2010 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 math
 import optparse
 import re
 import simplejson
 import subprocess
 import sys
 import time
 import urllib2
 
 
 __version__ = '1.0'
 DEFAULT_EXPECTATIONS_FILE = 'perf_expectations.json'
 DEFAULT_VARIANCE = 0.05
 USAGE = ''
 
 
 def ReadFile(filename):
   try:
     file = open(filename, 'r')
   except IOError, e:
     print >> sys.stderr, ('I/O Error reading file %s(%s): %s' %
-                         (filename, e.errno, e.strerror))
+                          (filename, e.errno, e.strerror))
     raise e
-  if not file:
-    return None
   contents = file.read()
   file.close()
   return contents
 
 
 def ConvertJsonIntoDict(string):
   """Read a JSON string and convert its contents into a Python datatype."""
   if len(string) == 0:
     print >> sys.stderr, ('Error could not parse empty string')
     raise Exception('JSON data missing')
@@ skipping 188 matching lines @@
   if write_new_expectations:
     print 'writing expectations... ',
     WriteJson(DEFAULT_EXPECTATIONS_FILE, perf, perfkeys)
     print 'done'
   else:
     print 'no updates made'
 
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv))