This fixes the dangling ptr crash after the faster split view is
destroyed.

(cherry picked from commit a7331d628f3899102010b8958aca339d1efae5b4)

Test: added, verified it fails w/o fix in CL:5519580
Bug: b/336289329
Change-Id: I879d992802fbced5f26e99dbe2d10992814ad7c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5519302
Commit-Queue: Sophie Wen <sophiewen@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1297207}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5536217
Cr-Commit-Position: refs/branch-heads/6367@{#1167}
Cr-Branched-From: d158c6dc6e3604e6f899041972edf26087a49740-refs/heads/main@{#1274542}