This includes an implementation of OSX timer and path_utils.

BUG=angleproject:891

Change-Id: Id5440a8321bcfd4a61f3fe35b4a3fc0c651f564f
Reviewed-on: https://chromium-review.googlesource.com/278211Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>