Fix audit_runtime_enabled_features now that omahaproxy has headers in their CSV

Source/build/scripts/audit_runtime_enabled_features.py

 #!/usr/bin/env python
 
 import requests
 import re
 from in_file import InFile
 
 BRANCH_FORMAT = "https://src.chromium.org/blink/branches/chromium/%s/%s"
 TRUNK_PATH = "Source/platform/RuntimeEnabledFeatures.in"
 TRUNK_URL = "https://src.chromium.org/blink/trunk/%s" % TRUNK_PATH
 
@@ skipping 29 matching lines @@
 
 
 def stable_features(in_file):
     return [feature['name'] for feature in in_file.name_dictionaries if feature['status'] == 'stable']
 
 
 def branch_from_version(version_string):
     # Format: 31.0.1650.63, the second digit was only ever used for M4
     # no clue what it's actually intended for.
     version_regexp = r"(?P<major>\d+)\.\d+\.(?P<branch>\d+)\.(?P<minor>\d+)"
-    return int(re.match(version_regexp, version_string).group('branch'))
+    match = re.match(version_regexp, version_string)
+    # if match == None, we'll blow up, so at least provide some debugging information:
+    if not match:
+        print version_string
+    return int(match.group('branch'))
 
 
 def print_feature_diff(added_features, removed_features):
     for feature in added_features:
         print "+ %s" % feature
     for feature in removed_features:
         print "- %s" % feature
 
 
 def historical_versions(os_string, channel):
     url_pattern = "http://omahaproxy.appspot.com/history?os=%s&channel=%s"
     url = url_pattern % (os_string, channel)
     releases_csv = requests.get(url).text.strip("\n")
     # Format: os,channel,version_string,date_string
-    return [line.split(',')[2] for line in releases_csv.split("\n")]
+    lines = releases_csv.split('\n')
+    # As of June 2014, omahaproxy is now including headers:
+    assert(lines[0] == 'os,channel,version,timestamp')
+    # FIXME: We could replace this with more generic CSV parsing now that we have headers.
+    return [line.split(',')[2] for line in lines[1:]]
 
 
 def feature_file_url_for_branch(branch):
     path = features_path(branch)
     if not path:
         return None
     return BRANCH_FORMAT % (branch, path)
 
 
 def feature_file_for_branch(branch):
@@ skipping 83 matching lines @@
     for version, feature_file in historical_tuples + active_tuples:
         auditor.add_version(version, feature_file)
 
     print "\nConsider for removal (have been stable for at least one release):"
     for feature in stale_features(historical_tuples):
         print feature
 
 
 if __name__ == "__main__":
     main()