Histograms.xml python script housekeeping

tools/metrics/common/path_util.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.
+
+"""Utility functions for resolving file paths in histograms scripts."""
+
+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__), '..', '..', '..']
+  path = os.path.join(*(depth + src_relative_file_path.split('/')))
+  return os.path.abspath(path)