svndiff.py: add ability to compare before-and-after JSON files, not just raw images

tools/verify_images_for_gm_results.py

 #!/usr/bin/python
 
 # Copyright (c) 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.
 
 
 """ Look through skia-autogen, searching for all checksums which should have
 corresponding files in Google Storage, and verify that those files exist. """
 
 
 import json
 import posixpath
 import re
 import subprocess
 import sys
 
 
+# TODO(borenet): Replace some/all of these with constants from gm/gm_json.py
 AUTOGEN_URL = 'http://skia-autogen.googlecode.com/svn/gm-actual'
 GS_URL = 'gs://chromium-skia-gm/gm'
 TEST_NAME_PATTERN = re.compile('(\S+)_(\S+).png')
 
 
 def FileNameToGSURL(filename, hash_type, hash_value):
   """ Convert a file name given in a checksum file to the URL of the
   corresponding image file in Google Storage.
 
   filename: string; the file name to convert. Takes the form specified by
@@ skipping 123 matching lines @@
 def Main():
   urls = FindURLs(AUTOGEN_URL)
   missing = VerifyURLs(urls)
   if missing:
     print 'Found %d Missing files.' % len(missing)
     return 1
 
 
 if __name__ == '__main__':
   sys.exit(Main())