GitLab

- adds FILE_SYSTEM_LAST_PICKED_DIRECTORY website setting
- prerequisite to the implementation of suggested filenames and
  directories for the file chooser

Bug: 1139907
Change-Id: I886cc4c6552cefbf3780e20d5b216ad460646e22
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2478901Reviewed-by: Martin Šrámek <msramek@chromium.org>
Reviewed-by: Finnur Thorarinsson <finnur@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Austin Sullivan <asully@chromium.org>
Auto-Submit: Austin Sullivan <asully@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825357}