Reland "Download Home V2 : Cleanup externally removed downloads"

This is a reland of 3bf50ad5026fa1237520a93d322598bd73a14ad9

Original change's description:
> Download Home V2 : Cleanup externally removed downloads
> 
> Bug: 976402
> Change-Id: Icef1bce64612e489c575d4ede2d892d76383b529
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1669990
> Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
> Reviewed-by: David Trainor <dtrainor@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#671875}

Bug: 976402
Change-Id: Ia860454ee99395e748dcad1011ee9fc218d6b6c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1676928
Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672289}
1 file changed