Author: <than@redhat.com>

Fix build error caused by python-3.9 on EL9

Traceback (most recent call last):
  File "/builddir/build/BUILD/chromium-143.0.7499.40/out/Release/../../tools/metrics/histograms/generate_allowlist_from_histograms_file.py", line 10, in <module>
    import extract_histograms
  File "/builddir/build/BUILD/chromium-143.0.7499.40/tools/metrics/histograms/extract_histograms.py", line 24, in <module>
    import xml_utils
  File "/builddir/build/BUILD/chromium-143.0.7499.40/tools/metrics/histograms/../common/xml_utils.py", line 14, in <module>
    DomTree = minidom.Element | minidom.Document
TypeError: unsupported operand type(s) for |: 'type' and 'type'

diff -up chromium-143.0.7499.40/tools/metrics/histograms/extract_histograms.py.python-3.9-ftbfs chromium-143.0.7499.40/tools/metrics/histograms/extract_histograms.py
--- chromium-143.0.7499.40/tools/metrics/histograms/extract_histograms.py.python-3.9-ftbfs	2025-11-19 22:40:05.000000000 +0100
+++ chromium-143.0.7499.40/tools/metrics/histograms/extract_histograms.py	2025-12-02 17:23:41.996802101 +0100
@@ -18,6 +18,7 @@ import re
 import sys
 from typing import TypedDict
 import xml.dom.minidom
+from typing import Optional, Union
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
 import xml_utils
@@ -84,7 +85,7 @@ class EnumDict(TypedDict, total=False):
   """A dict representing an enum."""
 
   name: str
-  type: str | None
+  type: Optional[str]
   buckets: list[_BucketDict]
   summary: str
 
@@ -108,7 +109,7 @@ def ExpandHistogramNameWithSuffixes(
     suffix_name: str,
     histogram_name: str,
     histogram_suffixes_node: xml.dom.minidom.Element,
-) -> tuple[str | None, ExtractionErrors]:
+) -> tuple[Optional[str], ExtractionErrors]:
   """Creates a new histogram name based on a histogram suffix.
 
   Args:
@@ -310,7 +311,7 @@ def _ExtractOwners(node: xml.dom.minidom
 
 def _ExtractImprovementDirection(
     histogram_node: xml.dom.minidom.Element,
-) -> tuple[str | None, ExtractionErrors]:
+) -> tuple[Union[str, None], ExtractionErrors]:
   """Extracts improvement direction from the given histogram element, if any.
 
   Args:
@@ -644,7 +645,7 @@ def ExtractVariantsFromXmlTree(
   return variants_dict, errors
 
 
-def _GetObsoleteReason(node: xml.dom.minidom.Element) -> str | None:
+def _GetObsoleteReason(node: xml.dom.minidom.Element) -> Optional[str]:
   """If the node's histogram is obsolete, returns a string explanation.
 
   Otherwise, returns None.
diff -up chromium-143.0.7499.40/tools/metrics/common/xml_utils.py.than chromium-143.0.7499.40/tools/metrics/common/xml_utils.py
--- chromium-143.0.7499.40/tools/metrics/common/xml_utils.py.than	2025-12-04 17:48:11.924111675 +0100
+++ chromium-143.0.7499.40/tools/metrics/common/xml_utils.py	2025-12-04 17:49:42.451979769 +0100
@@ -11,7 +11,8 @@ from xml.dom import minidom
 # The implementation of Node type is possible with extra runtime checks, however
 # using a more specific type makes the intent clearer and avoids potential
 # warnings about attributes like `tagName` not being present on all Node types.
-DomTree = minidom.Element | minidom.Document
+from typing import Union
+DomTree = Union[minidom.Element, minidom.Document]
 
 _ELEMENT_NODE = minidom.Node.ELEMENT_NODE