Skip syncing if image_dir does not exist

Devserver should assume no image exists if image_dir is not found.

BUG=chromium:337533
TEST=None

Change-Id: I1fc03a53491711d5d3db6107a1aeaf5102b73b00
Reviewed-on: https://chromium-review.googlesource.com/183543
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Tested-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Yu-Ju Hong <yjhong@chromium.org>
1 file changed