Modified git cl format for distributed histograms

If files in histograms folder are changed, pretty_print.py will be run on every
XML file changed and it will take in an additional relative path argument since
histograms are split up by prefixes.

Change-Id: I6902de2079edbb3bf17858ea93fb26d49a28fb37
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2340139
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Wenhan (Han) Zhang <zwenhan@google.com>

git_cl.py

@@ -5031,16 +5031,36 @@ def CMDformat(parser, args):
   # whereas the top-level presubmit script merely issues a warning. Formatting
   # these files is somewhat slow, so it's important not to duplicate the work.
   if not opts.presubmit:
-    for xml_dir in GetDirtyMetricsDirs(diff_files):
+    for diff_xml in GetDiffXMLs(diff_files):
+      xml_dir = GetMetricsDirs(diff_xml)
+      if not xml_dir:
+        continue
+
       tool_dir = os.path.join(top_dir, xml_dir)
       pretty_print_tool = os.path.join(tool_dir, 'pretty_print.py')
       cmd = ['vpython', pretty_print_tool, '--non-interactive']
+
+      # If the XML file is histograms.xml or enums.xml, add the xml path to the
+      # command as pretty_print.py in histograms needs a relative path argument
+      # after splitting the histograms into multiple directories.
+      # For example, in tools/metrics/ukm, pretty-print could be run using:
+      #   $ python pretty_print.py
+      # But in tools/metrics/histogrmas, pretty-print should be run with an
+      # additional relative path argument, like:
+      #   $ python pretty_print.py histograms_xml/UMA/histograms.xml
+      #   $ python pretty_print.py enums.xml
+      if (diff_xml.endswith('histograms.xml')
+          or diff_xml.endswith('enums.xml')):
+        cmd.append(diff_xml)
+
       if opts.dry_run or opts.diff:
         cmd.append('--diff')
+
       # TODO(isherman): Once this file runs only on Python 3.3+, drop the
       # `shell` param and instead replace `'vpython'` with
       # `shutil.which('frob')` above: https://stackoverflow.com/a/32799942
-      stdout = RunCommand(cmd, cwd=top_dir,
+      stdout = RunCommand(cmd,
+                          cwd=top_dir,
                           shell=sys.platform.startswith('win32'))
       if opts.diff:
         sys.stdout.write(stdout)
@@ -5050,8 +5070,13 @@ def CMDformat(parser, args):
   return return_value
 
 
-def GetDirtyMetricsDirs(diff_files):
-  xml_diff_files = [x for x in diff_files if MatchingFileType(x, ['.xml'])]
+def GetDiffXMLs(diff_files):
+  return [
+      os.path.normpath(x) for x in diff_files if MatchingFileType(x, ['.xml'])
+  ]
+
+
+def GetMetricsDir(diff_xml):
   metrics_xml_dirs = [
     os.path.join('tools', 'metrics', 'actions'),
     os.path.join('tools', 'metrics', 'histograms'),
@@ -5060,9 +5085,9 @@ def GetDirtyMetricsDirs(diff_files):
     os.path.join('tools', 'metrics', 'ukm'),
   ]
   for xml_dir in metrics_xml_dirs:
-    if any(
-        os.path.normpath(file).startswith(xml_dir) for file in xml_diff_files):
-      yield xml_dir
+    if diff_xml.startswith(xml_dir):
+      return xml_dir
+  return None
 
 
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