Add presubmit check and automatic update script for ExtensionPermission enum.

tools/metrics/histograms/update_extension_functions.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.
 
-"""Updates ExtensionFunctions enum in histograms.xml file with values read from
+'''Updates ExtensionFunctions enum in histograms.xml file with values read from

[Jeffrey Yasskin, 2014/03/10 20:53:23]

Double quotes for multi-line strings are an order of magnitude more common than
single quotes. You should avoid changing this instance.

 extension_function_histogram_value.h.
 
 If the file was pretty-printed, the updated version is pretty-printed too.
-"""
+'''
 
-import logging
-import re
-import sys
-
-from xml.dom import minidom
-
-from diffutil import PromptUserToAcceptDiff
-from pretty_print import PrettyPrintNode
-
-HISTOGRAMS_PATH = 'histograms.xml'
-ENUM_NAME = 'ExtensionFunctions'
-
-EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH = \
-  '../../../chrome/browser/extensions/extension_function_histogram_value.h'
-ENUM_START_MARKER = "^enum HistogramValue {"
-ENUM_END_MARKER = "^ENUM_BOUNDARY"
-
-
-class UserError(Exception):
-  def __init__(self, message):
-    Exception.__init__(self, message)
-
-  @property
-  def message(self):
-    return self.args[0]
-
-def ExtractRegexGroup(line, regex):
-    m = re.match(regex, line)
-    if m:
-      return m.group(1)
-    else:
-      return None
-
-
-def ReadHistogramValues(filename):
-  """Returns a list of pairs (label, value) corresponding to HistogramValue.
-
-  Reads the extension_functions_histogram_value.h file, locates the
-  HistogramValue enum definition and returns a pair for each entry.
-  """
-
-  # Read the file as a list of lines
-  with open(filename) as f:
-    content = f.readlines()
-
-  # Locate the enum definition and collect all entries in it
-  inside_enum = False # We haven't found the enum definition yet
-  result = []
-  for line in content:
-    line = line.strip()
-    if inside_enum:
-      # Exit condition: we reached last enum value
-      if re.match(ENUM_END_MARKER, line):
-        inside_enum = False
-      else:
-        # Inside enum: generate new xml entry
-        label = ExtractRegexGroup(line.strip(), "^([\w]+)")
-        if label:
-          result.append((label, enum_value))
-          enum_value += 1
-    else:
-      if re.match(ENUM_START_MARKER, line):
-        inside_enum = True
-        enum_value = 0 # Start at 'UNKNOWN'
-  return result
-
-
-def UpdateHistogramDefinitions(histogram_values, document):
-  """Sets the children of <enum name="ExtensionFunctions" ...> node in
-  |document| to values generated from policy ids contained in
-  |policy_templates|.
-
-  Args:
-    histogram_values: A list of pairs (label, value) defining each extension
-                      function
-    document: A minidom.Document object representing parsed histogram
-              definitions XML file.
-
-  """
-  # Find ExtensionFunctions enum.
-  for enum_node in document.getElementsByTagName('enum'):
-    if enum_node.attributes['name'].value == ENUM_NAME:
-        extension_functions_enum_node = enum_node
-        break
-  else:
-    raise UserError('No policy enum node found')
-
-  # Remove existing values.
-  while extension_functions_enum_node.hasChildNodes():
-    extension_functions_enum_node.removeChild(
-      extension_functions_enum_node.lastChild)
-
-  # Add a "Generated from (...)" comment
-  comment = ' Generated from {0} '.format(
-    EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
-  extension_functions_enum_node.appendChild(document.createComment(comment))
-
-  # Add values generated from policy templates.
-  for (label, value) in histogram_values:
-    node = document.createElement('int')
-    node.attributes['value'] = str(value)
-    node.attributes['label'] = label
-    extension_functions_enum_node.appendChild(node)
-
-def Log(message):
-  logging.info(message)
-
-def main():
-  if len(sys.argv) > 1:
-    print >>sys.stderr, 'No arguments expected!'
-    sys.stderr.write(__doc__)
-    sys.exit(1)
-
-  Log('Reading histogram enum definition from "%s".'
-      % (EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH))
-  histogram_values = ReadHistogramValues(
-    EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
-
-  Log('Reading existing histograms from "%s".' % (HISTOGRAMS_PATH))
-  with open(HISTOGRAMS_PATH, 'rb') as f:
-    histograms_doc = minidom.parse(f)
-    f.seek(0)
-    xml = f.read()
-
-  Log('Comparing histograms enum with new enum definition.')
-  UpdateHistogramDefinitions(histogram_values, histograms_doc)
-
-  Log('Writing out new histograms file.')
-  new_xml = PrettyPrintNode(histograms_doc)
-  if PromptUserToAcceptDiff(xml, new_xml, 'Is the updated version acceptable?'):
-    with open(HISTOGRAMS_PATH, 'wb') as f:
-      f.write(new_xml)
-
-  Log('Done.')
-
+from update_histogram_enum import UpdateHistogramEnum
 
 if __name__ == '__main__':
-  main()
+  UpdateHistogramEnum(histogram_enum_name='ExtensionFunctions',
+                      source_enum_path=('../../../chrome/browser/extensions/'
+                                        'extension_function_histogram_value.h'),
+                      start_marker='^enum HistogramValue {',
+                      end_marker='^ENUM_BOUNDARY')