In a DCHECK inside SetPayload(), MSVC gives a C4806 warning. Use the
right types to avoid this.

Also add pointer-with-payload.h to BUILD.gn.

Change-Id: I10a415250e7d2f06dab7a10bff48eef5890bb723
Reviewed-on: https://chromium-review.googlesource.com/c/1297991
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57003}