Revert "Do not expose DocumentLoader's request and original request"

This reverts commit 53a589aec52b701d134df33ae166d97f5084f49d.

Reason for revert: Believe this to be the cause of https://bugs.chromium.org/p/chromium/issues/detail?id=916829

Original change's description:
> Do not expose DocumentLoader's request and original request
> 
> Once we stop using WebURLLoader for navigations, there would be
> no Request in DocumentLoader. This patch removes some dependencies
> on it from outside of DocumentLoader.
> 
> There are still some dependencies through WebDocumentLoader - these
> will go later.
> 
> TBR=mmenke@chromium.org,rdevlin.cronin@chromium.org
> 
> Bug: 855189
> Change-Id: I0c44d7627804286ccce3a6eac14fb7cd92321411
> Reviewed-on: https://chromium-review.googlesource.com/c/1382506
> Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
> Reviewed-by: Nate Chapin <japhet@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#617992}

TBR=dgozman@chromium.org,japhet@chromium.org

Change-Id: Ifb00b5a6b706243a50d8ef03c5cf71fefaaeacb0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 855189
Reviewed-on: https://chromium-review.googlesource.com/c/1385479
Reviewed-by: CJ DiMeglio <lethalantidote@chromium.org>
Commit-Queue: CJ DiMeglio <lethalantidote@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618043}
18 files changed