New copyright boilerplate policy for presubmit: don't require the current year

presubmit_canned_checks.py

 # Copyright (c) 2012 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.
 
 """Generic presubmit checks that can be reused by other presubmit checks."""
 
 import os as _os
 _HERE = _os.path.dirname(_os.path.abspath(__file__))
 
 
@@ skipping 864 matching lines @@
     project_name: What is the name of the project as it appears in the license.
   Returns:
     A list of warning or error objects.
   """
   excluded_paths = tuple(excluded_paths or [])
   text_files = tuple(text_files or (
       r'.+\.txt$',
       r'.+\.json$',
   ))
   project_name = project_name or 'Chromium'
+
+  # Accept any year number from 2006 to the current year, or the special
+  # 2006-2008 string used on the oldest files. 2006-2008 is deprecated, but
+  # tolerate it until it's removed from all files.
+  current_year = int(input_api.time.strftime('%Y'))
+  allowed_years = (str(s) for s in reversed(xrange(2006, current_year + 1)))
+  years_re = '(' + '|'.join(allowed_years) + '|2006-2008)'
+
+  # The (c) is deprecated, but tolerate it until it's removed from all files.
   license_header = license_header or (
-      r'.*? Copyright \(c\) %(year)s The %(project)s Authors\. '
+      r'.*? Copyright (\(c\) )?%(year)s The %(project)s Authors\. '
         r'All rights reserved\.\n'
       r'.*? Use of this source code is governed by a BSD-style license that '
         r'can be\n'
       r'.*? found in the LICENSE file\.(?: \*/)?\n'
   ) % {
-      'year': input_api.time.strftime('%Y'),
+      'year': years_re,
       'project': project_name,
   }
 
   results = []
   # This code loads the default black list (e.g. third_party, experimental, etc)
   # and add our black list (breakpad, skia and v8 are still not following
   # google style and are not really living this repository).
   # See presubmit_support.py InputApi.FilterSourceFile for the (simple) usage.
   black_list = input_api.DEFAULT_BLACK_LIST + excluded_paths
   white_list = input_api.DEFAULT_WHITE_LIST + text_files
@@ skipping 42 matching lines @@
     results.extend(input_api.canned_checks.CheckSvnForCommonMimeTypes(
         input_api, output_api))
     snapshot("checking license")
     results.extend(input_api.canned_checks.CheckLicense(
         input_api, output_api, license_header, source_file_filter=sources))
     snapshot("checking was uploaded")
     results.extend(input_api.canned_checks.CheckChangeWasUploaded(
         input_api, output_api))
   snapshot("done")
   return results