[M149] [SPC] Guard SPC Controller destruction during dialog close.

Original change's description:
> [SPC] Guard SPC Controller destruction during dialog close.
>
> A `potential` UAF vulnerability exists in the browser process due to
> synchronous reentrancy inside SecurePaymentConfirmationController.
>
> This can happen if platform-specific synchronous activation dispatch
> from native_widget_->Close() that reaches
> ExtensionPopup::OnWidgetDestroying() inside the same call stack. Or
> CloseDialog() itself trigger a controller destruction.
>
> This change adds a guard to the `CloseDialog()` method that ensures the
> call inside SecurePaymentConfirmationController will not continue to
> prevent a memory crash.
>
> Fixed: 522568496
> Change-Id: Ifc0eaaebc42db33bb309e850881722df13cad35d
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7959279
> Reviewed-by: Slobodan Pejic <slobodan@chromium.org>
> Reviewed-by: Darwin Yang <darwinyang@chromium.org>
> Commit-Queue: Xuehui Chen <xuehuichen@google.com>
> Cr-Commit-Position: refs/heads/main@{#1649831}

(cherry picked from commit b87b4b251a81a1e17b4388046d56f93765b646b3)

Bug: 525968739,522568496
Change-Id: Ifc0eaaebc42db33bb309e850881722df13cad35d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8031405
Auto-Submit: chrome-cherry-picker@chops-service-accounts.iam.gserviceaccount.com <chrome-cherry-picker@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/7827@{#4132}
Cr-Branched-From: 9f3e9aaccba63bd2ec30334e45e0bfd07ebcc8f1-refs/heads/main@{#1625079}