[Findit] Initial code of findit for crash. Add scorers to apply heuristic rules.

appengine/findit/common/dependency.py

 # 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.
 
 import collections
 
+
 class Dependency(object):
   """Represents a dependency in Chrome, like blink, v8, pdfium, etc."""
   def __init__(self, path, repo_url, revision, deps_file='DEPS'):
     self.path = path
     self.repo_url = repo_url
     self.revision = revision
     self.deps_file = deps_file
     self.parent = None
     self.children = dict()
 
@@ skipping 21 matching lines @@
 class DependencyRoll(collections.namedtuple(
     'DependencyRoll', ('path', 'repo_url', 'old_revision', 'new_revision'))):
   """Represents a dependency roll (revision update) in chromium.
 
   Note: It is possible that the DEPS roll is a revert so that ``new_revision``
   is actually older than ``old_revision`` in the dependency.
   """
 
   def ToDict(self):
     return self._asdict()