GitLab

In redirection error cases, we call DownloadResponsehandler::OnComplete().
And when connection is closed, OnComplete() could get called again, causing
an NPE exception.
This CL fixes the issue by early return on the 2nd OnComplete() call.

BUG=890525

Change-Id: I2222a7980d7f53ff885b66b96ab2bdd1d963db75
Reviewed-on: https://chromium-review.googlesource.com/1255882Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595667}