add a presubmit check to avoid adding files with windows line endings

PRESUBMIT.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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
@@ skipping 1385 matching lines @@
           source_file_filter=lambda x: x.LocalPath().endswith('.grd')))
   results.extend(_CheckSpamLogging(input_api, output_api))
   results.extend(_CheckForAnonymousVariables(input_api, output_api))
   results.extend(_CheckCygwinShell(input_api, output_api))
   results.extend(_CheckUserActionUpdate(input_api, output_api))
   results.extend(_CheckNoDeprecatedCSS(input_api, output_api))
   results.extend(_CheckNoDeprecatedJS(input_api, output_api))
   results.extend(_CheckParseErrors(input_api, output_api))
   results.extend(_CheckForIPCRules(input_api, output_api))
   results.extend(_CheckForCopyrightedCode(input_api, output_api))
+  results.extend(_CheckForWindowsLineEndings(input_api, output_api))
 
   if any('PRESUBMIT.py' == f.LocalPath() for f in input_api.AffectedFiles()):
     results.extend(input_api.canned_checks.RunUnitTestsInDirectory(
         input_api, output_api,
         input_api.PresubmitLocalPath(),
         whitelist=[r'^PRESUBMIT_test\.py$']))
   return results
 
 
 def _CheckAuthorizedAuthor(input_api, output_api):
@@ skipping 165 matching lines @@
         problems.append(
           '%s:%d\n    %s' % (local_path, line_number, line.strip()))
 
   if problems:
     return [output_api.PresubmitPromptWarning(
         _IPC_ENUM_TRAITS_DEPRECATED, problems)]
   else:
     return []
 
 
+def _CheckForWindowsLineEndings(input_api, output_api):
+  """Check source code and known ascii text files for Windows style line
+  endings.
+  """
+  known_text_files = r'.*\.(txt|html|htm|mhtml|py)$'
+
+  file_inclusion_pattern = (
+    known_text_files,
+    r'.+%s' % _IMPLEMENTATION_EXTENSIONS
+  )
+
+  filter = lambda f: input_api.FilterSourceFile(
+    f, white_list=file_inclusion_pattern, black_list=None)
+  files = [f.LocalPath() for f in
+           input_api.AffectedSourceFiles(filter)]
+
+  problems = []
+
+  for file in files:
+    fp = open(file, 'r')
+    for line in fp:
+      if line.endswith('\r\n'):
+        problems.append(file)
+        break
+    fp.close()
+
+  if problems:
+    return [output_api.PresubmitPromptWarning('Are you sure that you want '
+        'these files to contain Windows style line endings?\n' +
+        '\n'.join(problems))]
+
+  return []
+
+
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(_CheckValidHostsInDEPS(input_api, output_api))
   results.extend(_CheckJavaStyle(input_api, output_api))
   results.extend(_CheckUmaHistogramChanges(input_api, output_api))
   results.extend(
       input_api.canned_checks.CheckGNFormatted(input_api, output_api))
   return results
 
@@ skipping 211 matching lines @@
   ]
 
   # Match things like path/aura/file.cc and path/file_aura.cc.
   # Same for chromeos.
   if any(re.search(r'[\\\/_](aura|chromeos)', f) for f in files):
     builders.extend([
         'linux_chromeos_asan',
     ])
 
   return GetDefaultTryConfigs(builders)