Don't store transient download into history DB

Since they are removed after completion, there is no need to store them
into history DB once in-progress DB is enabled.

BUG=942770

Change-Id: Ide628718d106d8632f709db32e39afb6d0b1d203
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1583078
Reviewed-by: Xing Liu <xingliu@chromium.org>
Commit-Queue: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654248}
1 file changed