To pass the offline page info to ResourceRequestInfo,
OfflinePageNavigationUIData will be added as part of NavigationUIData.
Setting OfflinePageNavigationUIData is done in
OfflinePageRequestJob::OnOfflineFilePathAvailable.

ChromeResourceDispatcherHostDelegate::ShouldForceDownloadResource will
check this bit in order to decide whether to treat it as download.

Most of changes to unittest files are just cosmetic changes due to
adding one parameter to ResourceRequestInfo::AllocateForTesting.
OfflinePageRquestJobTest is updated to cehck if
OfflinePageNavigationUIData is present or not.

TBR=jochen@chromium.org,benwells@chromium.org

Bug: 777019
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ib90388780f8d1b47226419bf514a30cd1eacbfae
Reviewed-on: https://chromium-review.googlesource.com/731251


Commit-Queue: Jian Li <jianli@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Dmitry Titov <dimich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514724}