Add Mac file chooser dialog.

Bug: 679313
Change-Id: Iae29d398c31e8791420ab27ce6cf08d46db79574
Reviewed-on: https://chromium-review.googlesource.com/c/1447311
Commit-Queue: Erik Jensen <rkjnsn@chromium.org>
Reviewed-by: Joe Downing <joedow@chromium.org>
Reviewed-by: Yuwei Huang <yuweih@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629819}
2 files changed