The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/15240176470e8e27cbb130a064415fb5401a2cc2

commit 15240176470e8e27cbb130a064415fb5401a2cc2
Author: Ryan Sturm <ryansturm@chromium.org>
Date: Mon Jan 21 18:55:13 2019

Updating PreviewsState for IO thread redirects

This change does not currently affect any Previews (DRP and Offline do
not update state during a redirect); however, HTTPS server previews will
move from a UI thread triggering mechanism to a UI thread mechanism. To
support this behavior, the ResourceRequest is updated during a redirect.
This is still not enough to support DRP, but Offline and HTTPS server
lite pages (URLLoaderRequestInterceptors) will see the updated changes.
DRP may see the changes in the case that the network service URLLoader
is restarted, but that behavior is not consistent, and for that reason,
it is not supported. DRP uses a URLLoader request throttle, so it can
only update the request sufficiently at the start of the URLLoader.

I will add a browser test later for lite page previews around this
behavior once the URLLoader implementation is further along, currently
I have manually tested; it behaves as expected.

Bug:  921792 
Change-Id: I9fb2ad1efbc5af9555a640e9ce55844b799d39a5
Reviewed-on: https://chromium-review.googlesource.com/c/1413337
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Commit-Queue: Ryan Sturm <ryansturm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624639}
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/browser/frame_host/navigation_request.cc
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/browser/loader/navigation_url_loader.h
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/browser/loader/navigation_url_loader_impl.cc
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/browser/loader/navigation_url_loader_impl.h
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/browser/loader/navigation_url_loader_impl_unittest.cc
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/browser/loader/navigation_url_loader_unittest.cc
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/test/test_navigation_url_loader.cc
[modify] https://crrev.com/15240176470e8e27cbb130a064415fb5401a2cc2/content/test/test_navigation_url_loader.h