[Findit] Add skeleton code for delta test script.

appengine/findit/crash/findit_for_chromecrash.py

 # Copyright 2016 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.
 
 import logging
 from collections import namedtuple
 
 from common import chromium_deps
 from crash import detect_regression_range
 from crash import findit_for_crash
 from crash.chromecrash_parser import ChromeCrashParser
 from crash.project_classifier import ProjectClassifier
 from crash.component_classifier import Component
 from crash.component_classifier import ComponentClassifier
 from model.crash.crash_config import CrashConfig
 
 # TODO(katesonia): Remove the default value after adding validity check to
 # config.
 _DEFAULT_TOP_N = 7
 
 
 # TODO(wrengr): move this to its own file, so it can be shared. When we do
 # so, we'll need to also pass in the 'solution' argument for the tag_dict.
 class Culprit(namedtuple('Culprit',
     ['project', 'components', 'cls', 'regression_range'])):
 
+  @property
+  def fields(self):
+    return self._fields
+
   # TODO(wrengr): better name for this method.
   def ToDicts(self):
     """Convert this object to a pair of anonymous dicts for JSON.
 
     Returns:
       (analysis_result_dict, tag_dict)
       The analysis result is a dict like below:
       {
           # Indicate if Findit found any suspects_cls, project,
           # components or regression_range.
@@ skipping 171 matching lines @@
 
     crash_stack = stacktrace.crash_stack
     suspected_project = self.project_classifier.Classify(
         suspected_cls, crash_stack)
 
     suspected_components = self.component_classifier.Classify(
         suspected_cls, crash_stack)
 
     return Culprit(suspected_project, suspected_components, suspected_cls,
         regression_range)