Add timeit.bat to tools\win

tools/win/subtract_time.py

Index: tools/win/subtract_time.py
diff --git a/tools/win/subtract_time.py b/tools/win/subtract_time.py
new file mode 100644
index 0000000000000000000000000000000000000000..4e1559b8d564c19d9542e15413d9fbde9abf93a0
--- /dev/null
+++ b/tools/win/subtract_time.py
@@ -0,0 +1,20 @@
+# Copyright (c) 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.
+
+"""
+This script converts to %time% compatible strings passed to it into seconds,
+subtracts them, and prints the difference. That's it. It's used by timeit.bat.
+"""
+
+import re
+import sys
+
+def ParseTime(time_string):
+  # Time looks like 15:19:30.32
+  match = re.match("(.*):(.*):(.*)\.(.*)", time_string)
+  hours, minutes, seconds, fraction = map(int, match.groups())
+  return hours * 3600 + minutes * 60 + seconds + fraction * .01
+
+print "%1.2f seconds elapsed time" % (ParseTime(sys.argv[1]) -
+                                      ParseTime(sys.argv[2]))