Revert "Add histograms_index file to record all available histograms xmls"

This reverts commit 91d6b1a9.

Reason for revert: Suspecting this CL for closing the tree
Unfortunately the compile error log is not very descriptive
https://ci.chromium.org/p/chromium/builders/ci/win32-archive-rel/15804?

Original change's description:
> Add histograms_index file to record all available histograms xmls
> 
> This histograms_index file provides a convenient way for a job to know
> all of the histogram files without having to search for them. As we
> split up histograms, we need a way to locate all available histograms
> xmls and thus we need this index file.
> 
> This cl also adds a PRESUBMIT check to make sure this index file is
> up-to-date.
> 
> Bug: 1116807
> Change-Id: Ifc55e421092448b5cecaa573f02e651a098428bf
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359234
> Reviewed-by: Steven Holte <holte@chromium.org>
> Reviewed-by: Brian White <bcwhite@chromium.org>
> Commit-Queue: Weilun Shi <sweilun@chromium.org>
> Auto-Submit: Weilun Shi <sweilun@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#800357}

TBR=bcwhite@chromium.org,holte@chromium.org,sweilun@chromium.org

Change-Id: Ia072d6f1f0bc23e73f9281631659ba1f6d52bb12
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1116807
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2368416Reviewed-by: Charlene Yan <cyan@chromium.org>
Commit-Queue: Charlene Yan <cyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800369}

tools/metrics/common/path_util.py

@@ -7,6 +7,15 @@
 import os.path
 
 
+def GetHistogramsFile():
+  """Returns the path to histograms.xml.
+
+  Prefer using this function instead of just open("histograms.xml"), so that
+  scripts work properly even if run from outside the histograms directory.
+  """
+  return GetInputFile('tools/metrics/histograms/histograms.xml')
+
+
 def GetInputFile(src_relative_file_path):
   """Converts a src/-relative file path into a path that can be opened."""
   depth = [os.path.dirname(__file__), '..', '..', '..']

tools/metrics/histograms/histogram_paths.py

-#!/usr/bin/env python
-# Copyright 2020 The Chromium Authors. All rights reserved.
+# 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.
 
@@ -12,29 +11,28 @@ sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
 import path_util
 
 
-def _FindHistogramsXmlFiles():
-  """Gets a list relative path to all histograms xmls under histograms_xml/."""
+def _FindHistogramsXmlFiles(base_dir):
+  """Gets a list of all histograms.xml files under the directory tree, prefixed
+  with tools/metrics/histograms/."""
   file_list = []
-  for dirName, _, fileList in os.walk(PATH_TO_HISTOGRAMS_XML_DIR):
+  for dirName, _, fileList in os.walk(base_dir):
     for filename in fileList:
-      if filename == 'histograms.xml' or filename == 'histogram_suffixes.xml':
-        # Compute the relative path of the histograms xml file.
-        filepath = os.path.relpath(
-          os.path.join(dirName, filename), PATH_TO_HISTOGRAMS_XML_DIR)
-        file_list.append(os.path.join('tools/metrics/histograms/', filepath))
+      if filename == 'histograms.xml':
+        filepath = os.path.join('tools/metrics/histograms/', dirName, filename)
+        file_list.append(filepath)
   return file_list
 
 
 ENUMS_XML_RELATIVE = 'tools/metrics/histograms/enums.xml'
-# The absolute path to the histograms_xml folder.
-PATH_TO_HISTOGRAMS_XML_DIR = path_util.GetInputFile(
-    'tools/metrics/histograms/histograms_xml')
+# This file path accounts for cases where the script is executed from other
+# metrics-related directories.
+PATH_TO_HISTOGRAMS_XML_DIR = os.path.join('..', 'histograms/histograms_xml')
 # In the middle state, histogram paths include both the large histograms.xml
 # file as well as the split up files.
 # TODO: Improve on the current design to avoid calling `os.walk()` at the time
 # of module import.
 HISTOGRAMS_XMLS_RELATIVE = (['tools/metrics/histograms/histograms.xml'] +
-                            _FindHistogramsXmlFiles())
+                            _FindHistogramsXmlFiles(PATH_TO_HISTOGRAMS_XML_DIR))
 OBSOLETE_XML_RELATIVE = ('tools/metrics/histograms/histograms_xml/'
                          'obsolete_histograms.xml')
 ALL_XMLS_RELATIVE = [ENUMS_XML_RELATIVE, OBSOLETE_XML_RELATIVE
@@ -44,7 +42,7 @@ ENUMS_XML = path_util.GetInputFile(ENUMS_XML_RELATIVE)
 UKM_XML = path_util.GetInputFile('tools/metrics/ukm/ukm.xml')
 HISTOGRAMS_XMLS = [path_util.GetInputFile(f) for f in HISTOGRAMS_XMLS_RELATIVE]
 OBSOLETE_XML = path_util.GetInputFile(OBSOLETE_XML_RELATIVE)
-ALL_XMLS = [path_util.GetInputFile(f) for f in ALL_XMLS_RELATIVE]
+ALL_XMLS = [ENUMS_XML, OBSOLETE_XML] + HISTOGRAMS_XMLS
 
 ALL_TEST_XMLS_RELATIVE = [
     'tools/metrics/histograms/test_data/enums.xml',
@@ -53,18 +51,3 @@ ALL_TEST_XMLS_RELATIVE = [
 ]
 ALL_TEST_XMLS = [path_util.GetInputFile(f) for f in ALL_TEST_XMLS_RELATIVE]
 TEST_ENUMS_XML, TEST_HISTOGRAMS_XML, TEST_UKM_XML = ALL_TEST_XMLS
-
-# The path to the `histogram_index` file.
-HISTOGRAMS_INDEX = path_util.GetInputFile(
-    'tools/metrics/histograms/histograms_index.txt')
-
-
-def main():
-  with open(HISTOGRAMS_INDEX, 'w+') as f:
-    f.write("\n".join(HISTOGRAMS_XMLS_RELATIVE))
-
-
-if __name__ == '__main__':
-  # Update the `histograms_index` file whenever histograms paths are updated.
-  # This file records all currently existing histograms.xml paths.
-  main()

tools/metrics/histograms/histograms_index.txt

-tools/metrics/histograms/histograms.xml
-tools/metrics/histograms/histogram_suffixes.xml
-tools/metrics/histograms/Fingerprint/histograms.xml
-tools/metrics/histograms/UMA/histograms.xml
\ No newline at end of file

tools/metrics/histograms/validate_histograms_index.py

-# Copyright 2020 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.
-"""Verify the `histograms_index` file is up-to-date."""
-
-import logging
-import os
-import sys
-
-import histogram_paths
-
-sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
-import path_util
-
-
-def main()
-  exit_code = 0
-  with open(histogram_paths.HISTOGRAMS_INDEX, 'r') as f:
-    histograms_paths = [line.strip() for line in f]
-    if histograms_paths != histogram_paths.HISTOGRAMS_XMLS_RELATIVE:
-      exit_code = 1
-      logging.error(
-        'histograms_index.txt is not up-to-date. Please run '
-        'python histogram_paths.py to update it.')
-
-  sys.exit(exit_code)
-
-
-if __name__ == '__main__':
-  main()
\ No newline at end of file