commit 03ce681fd67d297623ef2f2ceb3ed3fcf729c51a
author Min Qin <qinmin@chromium.org> Fri May 17 14:38:46 2019
committer Commit Bot <commit-bot@chromium.org> Fri May 17 14:38:46 2019
tree 3779c0ebd41738e6c5ea44aa6490288b9d774821
parent 3fb0bcf1cd3fcd40111c3db04cc01b78c49afbac

Add UMA to record the behavior of the first background download

When Comparing UMAs for download that are resumed without the browser
process, the reduced mode reports more downloads than the full
mode. And that makes it hard to compare the UMAs neck to neck.
If we only consider the first download that happens in the reduced
mode, than this is the only download that will report UMA in full
browser mode.
This CL will capture the UMA for the first download in reduced
mode. It allows us to compare the UMAs from full browser mode in
a fair condition.

BUG=963601

Change-Id: Ieb5c2dc06c985e5e2b545474a3f03a9dcbc3e165
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1615822
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Mohamed Heikal <mheikal@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660825}