Histograms.xml python script housekeeping

tools/metrics/histograms/update_use_counter_feature_enum.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """Scans the Chromium source of UseCounter, formats the Feature enum for
 histograms.xml and merges it. This script can also generate a python code
 snippet to put in uma.py of Chromium Dashboard. Make sure that you review the
 output for correctness.
 """
 
 import optparse
 import os
 import sys
 
-sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))

[Ilya Sherman, 2015/05/27 00:12:24]

Why is this line no longer needed?  I believe that it was previously added to
allow the script to be run from any directory.

[ncarter (slow), 2015/05/29 23:01:10]

This statement would allow a script in tools/metrics/histogram to use the
"import" keyword to pull in a script from tools/metrics/common as a module. It
works by modifying the import search path. Other files in this directory did
this to pull in diff_util from common. It looks like it was just mistakenly
copied to this file, because no module from common is actually imported here.

In the new patch set I've changed how these scripts handle imports (they adjust
the search path to include 'tools/metrics' and then import relative from there).

-from update_histogram_enum import ReadHistogramValues
-from update_histogram_enum import UpdateHistogramEnum
+import update_histogram_enum
 
 
 def PrintEnumForDashboard(enum_dict):
   """Prints enum_items formatted for use in uma.py of Chromium dashboard."""
   for key in sorted(enum_dict.iterkeys()):
     print '  %d: \'%s\',' % (key, enum_dict[key])
 
 
 if __name__ == '__main__':
   parser = optparse.OptionParser()
   parser.add_option('--for-dashboard', action='store_true', dest='dashboard',
                     default=False,
                     help='Print enum definition formatted for use in uma.py of '
                     'Chromium dashboard developed at '
                     'https://github.com/GoogleChrome/chromium-dashboard')
   options, args = parser.parse_args()
 
-  source_path = \
-      '../../../third_party/WebKit/Source/core/frame/UseCounter.h'
+  source_path = 'third_party/WebKit/Source/core/frame/UseCounter.h'
 
   START_MARKER = '^enum Feature {'
   END_MARKER = '^NumberOfFeatures'
 
   if options.dashboard:
-    enum_dict = ReadHistogramValues(source_path, START_MARKER, END_MARKER)
+    enum_dict = update_histogram_enum.ReadHistogramValues(source_path,
+                                                          START_MARKER,
+                                                          END_MARKER)
     PrintEnumForDashboard(enum_dict)
   else:
-    UpdateHistogramEnum(
+    update_histogram_enum.UpdateHistogramEnum(
         histogram_enum_name='FeatureObserver',
         source_enum_path=source_path,
         start_marker=START_MARKER,
         end_marker=END_MARKER)