Don't use on-disk HSTS information for incognito requests.

This information can be used to fingerprint the browser in a way that
lets sites correlate non-incognito sessions with incognito sessions.

Bug: 104935, 774643
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I6d8dc9447458aa5d6d628f3f7f34283209eb1a3d
Reviewed-on: https://chromium-review.googlesource.com/757181
Reviewed-by: Mark Cogan <marq@chromium.org>
Reviewed-by: Chris Palmer <palmer@chromium.org>
Commit-Queue: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514798}
9 files changed