PRESUBMIT doesn't need to check for old callback system

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index e6ef99b612efef5db337604e25f2acb53409b30c..d0305eea199bf2f8dc333f80b3f85b4424a9e4fb 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -182,35 +182,6 @@ def _CheckNoFRIEND_TEST(input_api, output_api):
       'FRIEND_TEST_ALL_PREFIXES() instead.\n' + '\n'.join(problems))]
 
 
-def _CheckNoNewOldCallback(input_api, output_api):
-  """Checks to make sure we don't introduce new uses of old callbacks."""
-
-  def HasOldCallbackKeywords(line):
-    """Returns True if a line of text contains keywords that indicate the use
-    of the old callback system.
-    """
-    return ('NewRunnableMethod' in line or
-            'NewCallback' in line or
-            input_api.re.search(r'\bCallback\d<', line) or
-            input_api.re.search(r'\bpublic Task\b', line) or
-            'public CancelableTask' in line)
-
-  problems = []
-  file_filter = lambda f: f.LocalPath().endswith(('.cc', '.h'))
-  for f in input_api.AffectedFiles(file_filter=file_filter):
-    if not any(HasOldCallbackKeywords(line) for line in f.NewContents()):
-      continue
-    for line_num, line in f.ChangedContents():
-      if HasOldCallbackKeywords(line):
-        problems.append('    %s:%d' % (f.LocalPath(), line_num))
-
-  if not problems:
-    return []
-  return [output_api.PresubmitPromptWarning('The old callback system is '
-      'deprecated. If possible, use base::Bind and base::Callback instead.\n' +
-      '\n'.join(problems))]
-
-
 def _CommonChecks(input_api, output_api):
   """Checks common to both upload and commit."""
   results = []
@@ -224,7 +195,6 @@ def _CommonChecks(input_api, output_api):
   results.extend(_CheckNoNewWStrings(input_api, output_api))
   results.extend(_CheckNoDEPSGIT(input_api, output_api))
   results.extend(_CheckNoFRIEND_TEST(input_api, output_api))
-  results.extend(_CheckNoNewOldCallback(input_api, output_api))
   return results