Use old download path for same-origin downloads

BUG=828963

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: I7d17bfdc8f4b312ff70bba4d700c528eaabd7948
Reviewed-on: https://chromium-review.googlesource.com/992322
Reviewed-by: Rick Byers <rbyers@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548465}
11 files changed