chore: cherry-pick 2941a90229 from chromium

[ppontes]

[Merge to M100] Don't use GetOriginalOpener to get opener's origin on FrameTree initialization

When setting the origin of the new main RFH on FrameTree initialization,
we base it on the opener's origin if it exists. GetOriginalOpener()
was used to get the opener, but that function will actually return the
main frame of the opener. This means when the FrameTree is opened by a
non-main frame, we might inherit the wrong origin.

This CL fixes the bug by getting the actual opener using GetOpener()
instead, and adds a regression test and warning note to
GetOriginalOpener().

(cherry picked from commit 4eb716ef5cdbca4db3a9377ee6390964d0d4025f)

Bug: 1311820, 1291764
Change-Id: I7e6f63a394ba4188eee3ce3043b174a2695508eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3564826
Reviewed-by: Charlie Reis <creis@chromium.org>
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#989165}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3600157
Auto-Submit: Rakina Zata Amni <rakina@chromium.org>
Reviewed-by: Nidhi Jaju <nidhijaju@chromium.org>
Commit-Queue: Nidhi Jaju <nidhijaju@chromium.org>
Owners-Override: Nidhi Jaju <nidhijaju@chromium.org>
Cr-Commit-Position: refs/branch-heads/4896@{#1179}
Cr-Branched-From: 1f63ff4bc27570761b35ffbc7f938f6586f7bee8-refs/heads/main@{#972766}

Notes: Backported fix for CVE-2022-1637.

[release-clerk]

Release Notes Persisted

Backported fix for CVE-2022-1637.