A couple fixes to find_unmapped_histograms.py.

tools/metrics/histograms/find_unmapped_histograms.py

 # Copyright 2013 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 for histograms that are absent from histograms.xml.
 
 This is a heuristic scan, so a clean run of this script does not guarantee that
 all histograms in the Chromium source are properly mapped.  Notably, field
 trials are entirely ignored by this script.
 
@@ skipping 20 matching lines @@
     (\w*::)?  # Optional namespace
     k[A-Z]    # Match a constant identifier: 'k' followed by an uppercase letter
     \w*       # Match the rest of the constant identifier
     $         # Make sure there's only the identifier, nothing else
     """, re.VERBOSE)
 HISTOGRAM_REGEX = re.compile(r"""
     UMA_HISTOGRAM  # Match the shared prefix for standard UMA histogram macros
     \w*            # Match the rest of the macro name, e.g. '_ENUMERATION'
     \(             # Match the opening parenthesis for the macro
     \s*            # Match any whitespace -- especially, any newlines
-    ([^,]*)        # Capture the first parameter to the macro
+    ([^,\)]*)      # Capture the first parameter to the macro

[Ilya Sherman, 2014/08/26 00:27:24]

Hmm, do you really need to escape the paren within a [] range?  Seems
surprising.

[Alexei Svitkine (slow), 2014/08/29 22:42:11]

You're right, it wasn't necessary. Done.

     ,              # Match the comma that delineates the first parameter

[Ilya Sherman, 2014/08/26 00:27:24]

Does this not need to be updated to allow for a paren as well?

[Alexei Svitkine (slow), 2014/08/29 22:42:11]

Done.

     """, re.VERBOSE)
 
 
 class DirectoryNotFoundException(Exception):
   """Base class to distinguish locally defined exceptions from standard ones."""
   def __init__(self, msg):
     self.msg = msg
 
   def __str__(self):
     return self.msg
@@ skipping 53 matching lines @@
                '"FakeHistogram" + variant'
 
   Returns:
     None
   """
   # Ignore histogram macros, which typically contain backslashes so that they
   # can be formatted across lines.
   if '\\' in histogram:
     return
 
-  # Field trials are unique within a session, so are effectively constants.
-  if histogram.startswith('base::FieldTrial::MakeName'):
-    return
-
   # Ignore histogram names that have been pulled out into C++ constants.
   if CONSTANT_REGEX.match(histogram):
     return
 
   # TODO(isherman): This is still a little noisy... needs further filtering to
   # reduce the noise.
   logging.warning('%s contains non-literal histogram name <%s>', filename,
                   histogram)
 
 
@@ skipping 121 matching lines @@
     logging.info('Histograms in Chromium but not in XML files:')
     logging.info('-------------------------------------------------')
     for histogram in sorted(unmapped_histograms):
       logging.info('  %s - %s', histogram, hashHistogramName(histogram))
   else:
     logging.info('Success!  No unmapped histograms found.')
 
 
 if __name__ == '__main__':
   main()