Script to populate the XML for the CSS property UseCounter.

tools/metrics/histograms/update_histogram_enum.py

 # 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 enums in histograms.xml file with values read from provided C++ enum.
 
 If the file was pretty-printed, the updated version is pretty-printed too.
 """
 
 import logging
@@ skipping 118 matching lines @@
     new_children.append(
         CreateEnumItemNode(document, value, source_enum_values[value]))
 
   # Update |enum_node|.
   while enum_node.hasChildNodes():
     enum_node.removeChild(enum_node.lastChild)
   for child in new_children:
     enum_node.appendChild(child)
 
 
-def UpdateHistogramEnum(histogram_enum_name, source_enum_path,
-                        start_marker, end_marker):
+def UpdateHistogramFromDict(histogram_enum_name, source_enum_values,
+                            source_enum_path):
   """Updates |histogram_enum_name| enum in histograms.xml file with values
-  read from |source_enum_path|, where |start_marker| and |end_marker| indicate
-  the beginning and end of the source enum definition, respectively.
+  from the {value: 'key'} dictionary |source_enum_values|. A comment is added
+  to histograms.xml citing that the values in |histogram_enum_name| were
+  sourced from |source_enum_path|.
   """
   # TODO(ahernandez.miralles): The line below is present in nearly every
   # file in this directory; factor out into a central location
   HISTOGRAMS_PATH = 'histograms.xml'
 
-  Log('Reading histogram enum definition from "{0}".'.format(source_enum_path))
-  source_enum_values = ReadHistogramValues(source_enum_path, start_marker,
-                                           end_marker)
-
   Log('Reading existing histograms from "{0}".'.format(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_enum_name, source_enum_values,
                              source_enum_path, histograms_doc)
 
   Log('Writing out new histograms file.')
   new_xml = print_style.GetPrintStyle().PrettyPrintNode(histograms_doc)
   if not PromptUserToAcceptDiff(
       xml, new_xml, 'Is the updated version acceptable?'):
     Log('Cancelled.')
     return
 
   with open(HISTOGRAMS_PATH, 'wb') as f:
     f.write(new_xml)
 
   Log('Done.')
+
+
+def UpdateHistogramEnum(histogram_enum_name, source_enum_path,
+                        start_marker, end_marker):
+  """Updates |histogram_enum_name| enum in histograms.xml file with values
+  read from |source_enum_path|, where |start_marker| and |end_marker| indicate
+  the beginning and end of the source enum definition, respectively.
+  """
+
+  Log('Reading histogram enum definition from "{0}".'.format(source_enum_path))
+  source_enum_values = ReadHistogramValues(source_enum_path, start_marker,
+                                           end_marker)
+
+  UpdateHistogramFromDict(histogram_enum_name, source_enum_values,
+      source_enum_path)