Revert "Variations service now checks explicitely if previous attempt was HTTP."

This reverts commit 91d246885ead6155c131e027d99be1aa79b9ae3c.

Reason for revert: This CL made ChromeBrowserMainBrowserTest.VariationsServiceStartsRequestOnNetworkChange flaky (crbug.com/904108) reverting while investigating why.

Original change's description:
> Variations service now checks explicitely if previous attempt was HTTP.
> 
> Variations service now sets a flag if the last request was an HTTP
> retry, and uses it to decide whether to retry again, instead of
> relying on the scheme of the final URL. Also, retries are now disabled
> if the fallback url is HTTPS.
> 
> Bug: 902727
> Change-Id: Ibd6df4a22bc6302b231aff0ae32f8e1c8a1f277c
> Reviewed-on: https://chromium-review.googlesource.com/c/1325035
> Commit-Queue: Carlos IL <carlosil@chromium.org>
> Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#607022}

TBR=asvitkine@chromium.org,carlosil@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 902727
Change-Id: I67036ea20097f889e71de5179a2e4510a201388d
Reviewed-on: https://chromium-review.googlesource.com/c/1334421
Reviewed-by: Carlos IL <carlosil@chromium.org>
Commit-Queue: Carlos IL <carlosil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607882}
3 files changed