Add end of file newline checks to PRESUBMIT.py.

PRESUBMIT.py

 #!/usr/bin/python
 # Copyright (c) 2009 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
 details on the presubmit API built into gcl.
 """
@@ skipping 42 matching lines @@
   return (LocalChecks(input_api, output_api, max_cols=0) +
           input_api.canned_checks.CheckDoNotSubmit(input_api, output_api))
 
 
 def LocalChecks(input_api, output_api, max_cols=80):
   """Reports an error if for any source file in SOURCE_FILE_EXTENSIONS:
      - uses CR (or CRLF)
      - contains a TAB
      - has a line that ends with whitespace
      - contains a line >|max_cols| cols unless |max_cols| is 0.
+     - File does not end in a newline, or ends in more than one.
 
   Note that the whole file is checked, not only the changes.
   """
   cr_files = []
+  eof_files = []
   results = []
   excluded_paths = [input_api.re.compile(x) for x in EXCLUDED_PATHS]
   files = input_api.AffectedFiles()
   for f in files:
     path = f.LocalPath()
     root, ext = input_api.os_path.splitext(path)
     # Look for unsupported extensions.
     if not ext in SOURCE_FILE_EXTENSIONS:
       continue
     # Look for excluded paths.
     found = False
     for item in excluded_paths:
       if item.match(path):
         found = True
         break
     if found:
       continue
 
     # Need to read the file ourselves since AffectedFile.NewContents()
     # will normalize line endings.
     contents = _ReadFile(path)
     if '\r' in contents:
       cr_files.append(path)
 
+    # Check that the file ends in one and only one newline character.
+    if len(contents) > 0 and (contents[-1:] != "\n" or contents[-2:-1] == "\n"):
+      eof_files.append(path)
+
     local_errors = []
     # Remove EOL character.
     lines = contents.splitlines()
     line_num = 1
     for line in lines:
       if line.endswith(' '):
         local_errors.append(output_api.PresubmitError(
             '%s, line %s ends with whitespaces.' %
             (path, line_num)))
       # Accept lines with http:// to exceed the max_cols rule.
@@ skipping 10 matching lines @@
       if len(local_errors) == 6:
         local_errors.pop()
         local_errors.append(output_api.PresubmitError("... and more."))
         break
     results.extend(local_errors)
 
   if cr_files:
     results.append(output_api.PresubmitError(
         'Found CR (or CRLF) line ending in these files, please use only LF:',
         items=cr_files))
+  if eof_files:
+    results.append(output_api.PresubmitError(
+        'These files should end one (and only one) newline character:',
+        items=eof_files))
   return results