Make the extension API docs point out the minimum version that supports an API call.

chrome/common/extensions/docs/build/build.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.
 
 """Docbuilder for extension docs."""
 
 import os
 import os.path
 import shutil
@@ skipping 42 matching lines @@
   if (os.path.isfile(input_file)):
     original = open(input_file, 'rb').read()
     os.remove(input_file)
 
   shutil.copy(_page_shell_html, input_file)
 
   # Run test_shell and capture result
   p = Popen([test_shell, "--layout-tests", generator_url],
       stdout=PIPE)
 
-  # the remaining output will be the content of the generated page.
+  # The remaining output will be the content of the generated page.
   result = p.stdout.read()
 
   content_start = result.find(_expected_output_preamble)
   content_end = result.find(_expected_output_postamble)
   if (content_start < 0):
     if (result.startswith("#TEST_TIMED_OUT")):
       raise Exception("test_shell returned TEST_TIMED_OUT.\n" +
                         "Their was probably a problem with generating the " +
                         "page\n" +
                         "Try copying template/page_shell.html to:\n" +
                         input_file +
                         "\nAnd open it in chrome using the file: scheme.\n" +
                         "Look from javascript errors via the inspector.")
     raise Exception("test_shell returned unexpected output: " + result)
-  result = result[content_start:content_end + len(_expected_output_postamble)] + "\n"
+  postamble_length = len(_expected_output_postamble)
+  result = result[content_start:content_end + postamble_length] + "\n"
 
-  # remove the trailing #EOF that test shell appends to the output.
+  # Remove the trailing #EOF that test shell appends to the output.
   result = result.replace('#EOF', '')
 
   # Remove page_shell
   os.remove(input_file)
 
   # Remove CRs that are appearing from captured test_shell output.
   result = result.replace('\r', '')
 
   # Write output
   open(input_file, 'wb').write(result)
@@ skipping 106 matching lines @@
   # and the os.remove will fail with a "Permission denied".
   time.sleep(1)
   debug_log = os.path.normpath(_build_dir + "/" + "debug.log")
   if (os.path.isfile(debug_log)):
     os.remove(debug_log)
 
   return os.EX_OK
 
 if __name__ == '__main__':
   sys.exit(main())