Add presubmit check and automatic update script for ExtensionPermission enum.

tools/metrics/histograms/update_extension_permission.py

-# Copyright 2013 The Chromium Authors. All rights reserved.
+# Copyright 2014 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
-extension_function_histogram_value.h.
+'''Updates ExtensionPermission enum in histograms.xml file with values read from

[Jeffrey Yasskin, 2014/02/20 19:07:36]

Try to share the code between this file and the one you copied it from.

+permission_message.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'
+PERMISSION_MESSAGE_PATH = \
+  '../../../extensions/common/permissions/permission_message.h'
 
-EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH = \
-  '../../../chrome/browser/extensions/extension_function_histogram_value.h'
-ENUM_START_MARKER = "^enum HistogramValue {"
-ENUM_END_MARKER = "^ENUM_BOUNDARY"
+ENUM_NAME = 'ExtensionPermission'
+ENUM_START_MARKER = "^enum ID {"
+ENUM_END_MARKER = "^kEnumBoundary"
 
 
 class UserError(Exception):
   def __init__(self, message):
     Exception.__init__(self, message)
 
   @property
   def message(self):
     return self.args[0]
 
+def StyleLabel(label):
+  '''Transforms labels of form "kLabelName" to "LABEL_NAME"
+  '''
+  return label[1] + re.sub('([A-Z])', r'_\1', label[2:]).upper()

[Jeffrey Yasskin, 2014/02/20 19:07:36]

Probably assert that label.startswith('k') and label[1].isupper().

+
 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.
+  Reads the permission_message.h file, locates the
+  ID 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))
+          result.append((StyleLabel(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|.
+  """Sets the children of <enum name="ExtensionPermission" ...> node in
+  |document| to values generated from (label, value) pairs contained in
+  |histogram_values|.
 
   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
+        ID_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)
+  while ID_enum_node.hasChildNodes():
+    ID_enum_node.removeChild(
+      ID_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))
+    PERMISSION_MESSAGE_PATH)
+  ID_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)
+    ID_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))
+      % (PERMISSION_MESSAGE_PATH))
   histogram_values = ReadHistogramValues(
-    EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
+    PERMISSION_MESSAGE_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.')
 
 
 if __name__ == '__main__':
   main()