Create a UKM descriptions XML file

tools/metrics/common/models.py

 # Copyright 2015 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.
 """Types for building models of metric description xml files.
 
 UMA uses several XML files to allow clients to describe the metrics that they
 collect, e.g.
 https://chromium.googlesource.com/chromium/src/+/master/tools/metrics/rappor/rappor.xml
 
 These types can be used to build models that describe the canonical formatted
@@ skipping 58 matching lines @@
 
 class NodeType(object):
   """Base type for a type of XML node.
 
   Args:
     indent: True iff this node should have its children indented when pretty
         printing.
     extra_newlines: None or a triple of integers describing the number of
         newlines that should be printed (after_open, before_close, after_close)
     single_line: True iff this node may be squashed into a single line.
+    alphabetization: A (tag, keyfn) pair, which specifies the tag of the
+       children that should be sorted, and a function to get the sort key from
+       the xml node.
   """
   __metaclass__ = abc.ABCMeta
 
   def __init__(self, tag,
                indent=True,
                extra_newlines=None,
-               single_line=False):
+               single_line=False,
+               alphabetization=None):
     self.tag = tag
     self.indent = indent
     self.extra_newlines = extra_newlines
     self.single_line = single_line
+    self.alphabetization = alphabetization
 
   @abc.abstractmethod
   def Unmarshall(self, node):
     """Extracts the content of the node to an object.
 
     Args:
       node: The XML node to extract data from.
 
     Returns:
       An object extracted from the node.
@@ skipping 262 matching lines @@
     Returns:
       An XML style object.
     """
     types = self.root_type.GetNodeTypes()
     return pretty_print_xml.XmlStyle(
         attribute_order={t: types[t].GetAttributes() for t in types},
         tags_that_have_extra_newline={t: types[t].extra_newlines for t in types
                                       if types[t].extra_newlines},
         tags_that_dont_indent=[t for t in types if not types[t].indent],
         tags_that_allow_single_line=[t for t in types if types[t].single_line],
-        tags_alphabetization_rules={})
+        tags_alphabetization_rules={t: types[t].alphabetization for t in types
+                                    if types[t].alphabetization})
 
   def _ToXML(self, obj):
     """Converts an object into an XML document.
 
     Args:
       obj: An object to serialize to XML.
 
     Returns:
       An XML minidom Document object.
     """
     doc = minidom.Document()
     self.root_type.MarshallIntoNode(doc, doc, obj)
     return doc
 
   def PrettyPrint(self, obj):
     """Converts an object into pretty-printed XML as a string.
 
     Args:
       obj: An object to serialize to XML.
 
     Returns:
       A string containing pretty printed XML.
     """
-    return self.GetPrintStyle().PrettyPrintNode(self._ToXML(obj))
+    return self.GetPrintStyle().PrettyPrintXml(self._ToXML(obj))