Fix python scripts in src/tools/

tools/symsrc/img_fingerprint.py

 #!/usr/bin/env python
-
-# Copyright (c) 2008 The Chromium Authors. All rights reserved.
+# Copyright (c) 2011 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.
 
-"""This will retrieve an image's "fingerprint".  This is used when retrieving
-the image from the symbol server.  The .dll (or cab compressed .dl_) or .exe
-is expected at a path like:
- foo.dll/FINGERPRINT/foo.dll"""
+"""Retrieves an image's "fingerprint".
+
+This is used when retrieving the image from the symbol server.  The .dll (or cab
+compressed .dl_) or .exe is expected at a path like:
+  foo.dll/FINGERPRINT/foo.dll
+"""
 
 import sys
 import pefile
 
+
 def GetImgFingerprint(filename):
   """Returns the fingerprint for an image file"""
-
   pe = pefile.PE(filename)
   return "%08X%06x" % (
     pe.FILE_HEADER.TimeDateStamp, pe.OPTIONAL_HEADER.SizeOfImage)
 
 
-if __name__ == '__main__':
+def main():
   if len(sys.argv) != 2:
     print "usage: file.dll"
-    sys.exit(1)
+    return 1
 
   print GetImgFingerprint(sys.argv[1])
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())