web_dev_style: add presubmit for superfluous </include> tags.

chrome/browser/web_dev_style/regex_check.py

+# Copyright 2014 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.
+
+
+def RegexCheck(re, line_number, line, regex, msg):
+  """Searches for |regex| in |line| to check for a particular style
+     violation, returning a message like the one below if the regex matches.
+     The |regex| must have exactly one capturing group so that the relevant
+     part of |line| can be highlighted. If more groups are needed, use
+     "(?:...)" to make a non-capturing group. Sample message:
+
+       line 6: Use var instead of const.
+           const foo = bar();
+           ^^^^^
+  """
+
+  def _highlight(match):
+    """Takes a start position and a length, and produces a row of '^'s to
+       highlight the corresponding part of a string.
+    """
+    return match.start(1) * ' ' + (match.end(1) - match.start(1)) * '^'
+
+  match = re.search(regex, line)
+  if match:
+    assert len(match.groups()) == 1
+    return '  line %d: %s\n%s\n%s' % (line_number, msg, line, _highlight(match))
+  return ''