(reland) Optimize check_gn_headers.py for speed

build/check_gn_headers_unittest.py

 #!/usr/bin/env python
 # Copyright 2017 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.
 
 import logging
 import json
 import os
 import unittest
 import check_gn_headers
@@ skipping 40 matching lines @@
 a/b/c/white-end.c # comment
  dir/white-both.c  #more comment
 
 # empty line above
 a/b/c
 '''
 
 
 class CheckGnHeadersTest(unittest.TestCase):
   def testNinja(self):
-    headers = check_gn_headers.ParseNinjaDepsOutput(ninja_input)
+    headers = check_gn_headers.ParseNinjaDepsOutput(ninja_input.split('\n'))
     expected = set([
         'dir/path/b.h',
         'c.hh',
         'dir3/path/b.h',
         'c3.hh',
     ])
     self.assertEquals(headers, expected)
 
   def testNinjaWin(self):
     old_sep = os.sep
     os.sep = '\\'
 
-    headers = check_gn_headers.ParseNinjaDepsOutput(ninja_input_win)
+    headers = check_gn_headers.ParseNinjaDepsOutput(
+        ninja_input_win.split('\n'))
     expected = set([
         'dir\\path\\b.h',
         'c.hh',
         'dir3\\path\\b.h',
         'c3.hh',
     ])
     self.assertEquals(headers, expected)
 
     os.sep = old_sep
 
@@ skipping 12 matching lines @@
         'a/b/c/white-end.c',
         'dir/white-both.c',
         'a/b/c',
     ])
     self.assertEquals(output, expected)
 
 
 if __name__ == '__main__':
   logging.getLogger().setLevel(logging.DEBUG)
   unittest.main(verbosity=2)