This CL starts using a WeakPtr for `delegate_`. This is because
`ReportFeaturesToDelegate()` is posted and when it's executed,
`delegate_` might be destroyed.

(cherry picked from commit da7a6845e589dc71da9898f7e181a7c88a62e2e1)

Bug: 336012573
Change-Id: I9aa5ee7ae7d484d4208e6bdd8ea2853763d69a6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5493004
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Yuzu Saijo <yuzus@chromium.org>
Reviewed-by: Fergal Daly <fergal@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1297242}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5547038
Auto-Submit: Yuzu Saijo <yuzus@chromium.org>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/branch-heads/6367@{#1190}
Cr-Branched-From: d158c6dc6e3604e6f899041972edf26087a49740-refs/heads/main@{#1274542}