Remove the Singleton<T> presubmit check from presubmit_canned_checks.py

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__))
 
 # Justifications for each filter:
@@ skipping 953 matching lines @@
       res_type = output_api.PresubmitPromptWarning
     else:
       res_type = output_api.PresubmitNotifyResult
     return [ res_type('|const NSClass*| is wrong, see ' +
                       'http://dev.chromium.org/developers/clang-mac',
                       files) ]
   return []
 
 
 def CheckSingletonInHeaders(input_api, output_api, source_file_filter=None):
-  """Checks to make sure no header files have |Singleton<|."""
-  pattern = input_api.re.compile(r'(?<!class\s)Singleton\s*<')
-  files = []
-  for f in input_api.AffectedSourceFiles(source_file_filter):
-    if (f.LocalPath().endswith('.h') or f.LocalPath().endswith('.hxx') or
-        f.LocalPath().endswith('.hpp') or f.LocalPath().endswith('.inl')):
-      contents = input_api.ReadFile(f)
-      for line in contents.splitlines(False):
-        if (not input_api.re.match(r'//', line) and # Strip C++ comment.
-            pattern.search(line)):
-          files.append(f)
-          break
-
-  if files:
-    return [ output_api.PresubmitError(
-        'Found Singleton<T> in the following header files.\n' +
-        'Please move them to an appropriate source file so that the ' +
-        'template gets instantiated in a single compilation unit.',
-        files) ]
-  return []
+  """Deprecated, must be removed."""
+  return [
+    output_api.PresubmitNotifyResult(
+        'CheckSingletonInHeaders is deprecated, please remove it.')
+  ]
 
 
 def PanProjectChecks(input_api, output_api,
                      excluded_paths=None, text_files=None,
                      license_header=None, project_name=None,
                      owners_check=True, maxlen=80):
   """Checks that ALL chromium orbit projects should use.
 
   These are checks to be run on all Chromium orbit project, including:
     Chromium
@@ skipping 67 matching lines @@
       input_api, output_api, maxlen, source_file_filter=sources))
   snapshot( "checking tabs")
   results.extend(input_api.canned_checks.CheckChangeHasNoTabs(
       input_api, output_api, source_file_filter=sources))
   snapshot( "checking stray whitespace")
   results.extend(input_api.canned_checks.CheckChangeHasNoStrayWhitespace(
       input_api, output_api, source_file_filter=sources))
   snapshot("checking nsobjects")
   results.extend(_CheckConstNSObject(
       input_api, output_api, source_file_filter=sources))
-  snapshot("checking singletons")
-  results.extend(CheckSingletonInHeaders(
-      input_api, output_api, source_file_filter=sources))
 
   # The following checks are only done on commit, since the commit bot will
   # auto-fix most of these.
   if input_api.is_committing:
     snapshot("checking eol style")
     results.extend(input_api.canned_checks.CheckChangeSvnEolStyle(
         input_api, output_api, source_file_filter=text_files))
     snapshot("checking svn mime types")
     results.extend(input_api.canned_checks.CheckSvnForCommonMimeTypes(
         input_api, output_api))
@@ skipping 40 matching lines @@
   for f in affected_files:
     cmd = ['gn', 'format', '--dry-run', f.AbsoluteLocalPath()]
     rc = gn.main(cmd)
     if rc == 2:
       warnings.append(output_api.PresubmitPromptWarning(
           '%s requires formatting. Please run `gn format --in-place %s`.' % (
               f.AbsoluteLocalPath(), f.LocalPath())))
   # It's just a warning, so ignore other types of failures assuming they'll be
   # caught elsewhere.
   return warnings