Create a UKM descriptions XML file

tools/metrics/ukm/model.py

Index: tools/metrics/ukm/model.py
diff --git a/tools/metrics/ukm/model.py b/tools/metrics/ukm/model.py
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+++ b/tools/metrics/ukm/model.py
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+# Copyright 2017 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.
+# """Model objects for ukm.xml contents."""
+
+import os
+import sys
+
+sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
+import models
+
+# Model definitions for ukm.xml content
+_OBSOLETE_TYPE = models.TextNodeType('obsolete')
+_OWNER_TYPE = models.TextNodeType('owner', single_line=True)
+_SUMMARY_TYPE = models.TextNodeType('summary')
+
+_LOWERCASE_NAME_FN = lambda n: n.attributes['name'].value.lower()
+
+_METRIC_TYPE =  models.ObjectNodeType(
+    'metric',
+    attributes=[('name', unicode)],
+    children=[
+        models.ChildType('obsolete', _OBSOLETE_TYPE, False),
+        models.ChildType('owners', _OWNER_TYPE, True),
+        models.ChildType('summary', _SUMMARY_TYPE, False),
+    ])
+
+_EVENT_TYPE =  models.ObjectNodeType(
+    'event',
+    alphabetization=('metric', _LOWERCASE_NAME_FN),
+    attributes=[('name', unicode)],
+    extra_newlines=(1, 1, 1),
+    children=[
+        models.ChildType('obsolete', _OBSOLETE_TYPE, False),
+        models.ChildType('owners', _OWNER_TYPE, True),
+        models.ChildType('summary', _SUMMARY_TYPE, False),
+        models.ChildType('metrics', _METRIC_TYPE, True),
+    ])
+
+_UKM_CONFIGURATION_TYPE = models.ObjectNodeType(
+    'ukm-configuration',
+    extra_newlines=(2, 1, 1),
+    indent=False,
+    children=[
+        models.ChildType('events', _EVENT_TYPE, True),
+    ])
+
+UKM_XML_TYPE = models.DocumentType(_UKM_CONFIGURATION_TYPE)
+
+def UpdateXML(original_xml):
+  """Parses the original xml and return a pretty printed version.
+
+  Args:
+    original_xml: A string containing the original xml file contents.
+
+  Returns:
+    A pretty-printed xml string, or None if the config contains errors.
+  """
+  config = UKM_XML_TYPE.Parse(original_xml)
+
+  return UKM_XML_TYPE.PrettyPrint(config)